Topic: Climate makes the man 1944

[Prometheus]

From https://archive.org/details/dli.ministry.01337/page/n9/mode/1up
1944
by

CLARENGE A. MILLS, M.D., Ph.D.

Why germany behaves as it does since 1900-climate and energy of nations 1942-page129 .
https://archive.org/details/in.ernet.dli.2015.48628/page/n129/mode/1up


  CONTENTS

Part I

1.   Sun Worshippers   7

2.   Helpers in the Laboratory   io

3.   Farm Animals in the Tropics   18

4.   Vitamins and Climate   24

5.   TheFallacyofEarlyTropicalMaturity   36

Part II

6.   The Price of Activity   44

7.   Drugs and Stimulants   54

8.   Stormy Weather and Respiratory Infections   65

9.   Tuberculosis, Leprosy, and Rheumatic Infections   72

10.   Cancer   80

11.   Shadows over Our Cities   85

12.   Rilling Heat   95

13.   Bad Moods and Falling Barometers   102

14.   Climate and Human Reproduction   107

15.   Made-to-Order Indoor Climates   115

Part III

16.   Life, Sunspots and the Atmosphere   126

17.   Ice Ages and Climates of the Future   134

18.   Climate, Weather, and World Dominance   141

19.   Thermometers and History   150

20.   Climate and World War   158

21.   Migration for Health   166

22.   From Flood Tide to Beginning Ebb   174

23.   Epilogue   185
 
  PART I

CHAPTER I

SUN WORSHIPPERS

To-day’s world turmoil and confusion have rudely awakened
man from his cherished dream that he alone is the master of his
own destiny. Even the most egotistic and confident person now
feels uncertain of his sacred powers as he surveys a universe in
which war and social revolution are striking at the very founda-
tions of the only civilization he has known. Altruism seems
suddenly to have given way to the rule of might, with humanity
slipping back toward another Dark Age.

People everywhere have begun to suspect that mighty external
forces are at work—forces against which their greatest efforts will
prove small and futile. This feeling of futility in the face of a
darkening future has awakened in the world’s thinkers a desire to
know more about these outside factors—what they are and how
they work. Fortunately Science has accumulatcd a considerable
mass of evidence regarding the surprising and powerful effects
exerted upon human beings by two of them: climate, the long-
term average of atmospheric conditions, and weather, the short-
cycle changes which make one day or hour different from the
next. These findings are helping to put man in his proper place
within the cosmic scheme of things, for the sun and planets
exert an indirect but well-proved effect on all life through their
control of earth temperatures and weather.

The awareness of a connection between the solar system and
human welfare is older by far than recorded history. When the
first human beings roamed a strange, hostile world some

500,000   years ago, they spent long nights huddled together in
caves to escape the unknown terrors of darkness. They looked
forward to the morning, for the first stages of man’s battle to
master his environment took place in broad daylight. It was only
natural for our primeval ancestors to regard the sun with awe
and gratitude, for it bropght them light and warmth. Ages and
civilizations passed, but this great feeling of dependence did not.

The Spaniards found this feeling in Peru during the sixteenth
century when they set out to conquer a territory rich in gold.
High in the lofty Andes little bands of Incas paused in reverence
  to face the rising sun and to receive its blessing before continuing
their journey to Cuzco. Everywhere throughout the far-flung Incan
empire other groups were bowing in similar adoration before the
Giver of Life, for sun worship was the state religion of those
people. They built massive and beautiful temples to provide the
sun with the dignity and place of first importance it held in their
lives. The moon and planets were also worshipped, but as deities
far inferior to the all-powerful sun.

Reverence for the sun and its satellites was carried to great
extremes in the eatliest civilizations. All phases of life were closely
regulated according to the positions of the planets and other
heavenly bodies. People believed that outside forces exerted
potent and direct influences over human afïairs, and the astrolo-
ger’s advice was always in demand. When men later discarded
such primitive beliefs, they ignored the intuitive rightness of the
feeling that humanity was not entirely its own lord and master.
Humility was replaced by a laboratory-gained egotism as sci-
entists obtained ever increasing control over their physical
environment.

This ovcr-confidence grew rapidly during the nineteenth
ccntury while researchers were piling discovery upon discovery.
New inventions enabled us to harness electricity and perfect the
telegraph, telephone, incandescent lamp, radio, ai}d power
transmission. Equally striking advances were made in the
knowledge of the human body, its inner workings, its diseases,
and the means of kceping it healthy. But the egotism which came
with these and other material accomplishments began slipping
in the last war; and to-day, when the notion that humanity
Controls its own fate has fallen into even greater disrepute, the
same science which produced over-confidence in man is be-
ginning to teach him a new humility.

Studies during the past few years have revealed that climatic
factors in life play a startling and dominating role in all we do.
Mtfn as an energy machine thinks and acts only because of the
burning of food in his tissues; but the speed of this burning—
and the intensity of his living—depends largely upon outside tem-
peratures and how easily he can get rid of his waste heat. Just
why this is so will be considered in detail on later pages;it need
only be said here that the climatic influences are real and clear-
cut. They affect man’s rate of growth, speed of developmerft,
resistance to infection, fertility of mind and body, and the amount
of energy available for thought or action. The heat of the tropics
lulls people into a passive complacency and saps their vitality;
residents of colder climates are driven onward into restless

8
  activity, since natural conditions pcrmit their tissue fires to burn
more brightly.

Climate affects man’s sicknesses as well as his health. In his
vegetative tropical existence he is much more susceptible to
infectious diseases, while in temperate coolness the stress of a more
energetic life causes frequent breakdown in his body machinery
and raises heart failure to a leading position among the causes of
death. People seldom wear out in warm climates; in cooler regions
breakdown diseases are now providing medical meiï with their
keenest worries. The matter is an exceedingly important onc for
individual and public health. It richly deserves the close attention
finally being accorded it.

People of the tropics can be raised out of their sluggish state
into a higher vitality and more active life only when faster food
burning can be maintained in their body tissues. In temperate
coolness, on the other hand, ways must be found for reducing the
stress of life and conserving the body machinery if we are to halt
the rising rate of breakdown which now threatens civilization’s
advance. Too many of society’s most progressive and valuable
individuals are now succumbing just as they reach their most
Creative period.

Weather changes affect man also, but somewhat differently
from climate. In many regions of the earth he has almost no
weather problem to face; sudden variations in temperature and
pressure seldom occur because cyclonic storms are lacking—only
the climatic and seasonai infiuences are left. Violent and fre-
quent storms bring to other regions major weather problems,
with sudden atmospheric changes which rack body and mind.
In the earth’s most active storm beits this turbulence becomes a
very important factor of existence, adding spice to life but at the
same time interfering with body functions and bringing on many
serious ailments. Such infiuences have been studied less than
those of climate and cannot be discussed in as much detail. It
should be kept in mind, however, that the two work together
upon man in many regions. In between weather and climate
come the seasons. They too are potent health factors—absent,
of course, in the tropics.

The picture of these forces acting upon man is a fascinating
one, still blurred in places, but with its main outlines clear-cut
and definite. The sun does far more than merely provide day-
light and the special forms of radiant energy needed by all grow-
ing things. Through its influence over world weather and
climatic characteristics it dominates many other phases of
human activity. Since the planets seem to be at the basis of
  changes in the sun’s influence, we now begin to see man in his
true relation to the solar system. He is not the independent
master of his own life as he so fondly believed a few decades ago,
but instead is pushed hither and yon by larger outside forces.
He could learn a great deal from primitive sun-worshippers, for
he is still a veritable pawn of the universe.

CHAPTER 2

HELPERS IN THE LABORATORY

"What real evidence have we that climate influences
mankind?” This will be the first question asked by many readers
as they begin perusal of these pages. People have always bristled
at the suggestion that they are not lords of creation. The idea that
weather and climate are to be credited with the ambitious
activity of temperate-zone citizens, or for the slower-paced life
of tropical dwellers, strikes at one of the firmest beliefs of human
beings: that their actions are independent of great and uncon-
trollable outside forces. It may not be flattering for the doubting
Thomas to learn that rats and other animals have helped furnish
much important evidence for humanity’s dependence upon the
elements; but such is the case, and these helpers in the
laboratory can never receive too much praise for their
contributions.

Few persons outside scientific circles appreciate how much
humanity owes to the laboratory animals. Rats, white mice,
rabbits, and the famed guinea-pigs are almost as fully domesti-
cated as horses, cattle, and hogs. Instead of doing our work or
supplying us with much-needed food, these docile creatures give
valuable information about how our bodies work and how to
keep them healthy. Only with their help could medical Science
make many of the wonderful discoveries that have brought the
great health improvements of the past half-century.

When you think of a rat, is it with almost the same aversion
you feel for snakes? Such dislike may be justified in the case of
wild rats, but I assure you it is not with the Wistar white rat. He
is an intelligent, gooa-natured fellow, scrupulously clean in
person and most reliable in his responses. His name was taken
from the Wistar Institute in Philadelphia, where careful breeding

IO
  through hundreds of generations weeded out abnormal and
unwanted traits. These animals are now highly standardized and
much favoured among scientists, responding to a given diet or
special vitamin with almost the regularity of pure Chemical
reactions in its test tubes. The results obtained in one laboratory
can be duplicated readily by far distant investigators under
similar conditions.

Two such rats, Ivan (not the terrible) and Hilda, his mate,
were adopted into the exclusive circles of our laboratory rat
colony early in childhood. They were likable and appealing,
with sparkling eyes and glossy fur, as they came to us just after
ha ving been weaned. New hands bothered them somewhat for
the first few days, but soon all strangeness disappeared. When
they became accustomed to the new surroundings a delightful
confidence and intimacy was established which has persisted to
adult life. Curious as it may appear from the human angle, Ivan
seems to enjoy handling and attention more than Hilda. He is
less wrapped up in himself, more easily influenced, worrying
little when his treacherous foster parents keep from him one
essential food element after another. Even if he does lose vigour
in the experimental “tropics” of a hot room, it is without ill-will
and with a most appealing trust in his keepers. Rcstoring him to
full health and vitality after a period of decline brings to us
almost as much pleasure as the recovery from serious illness of
our own human children.

Among our numerous white rats, Ivan and Hilda have been
willing co-workers for years as we have studied the various
phases of climatic influences. They have spent weeks shivering
in the cold without complaint and endured tropical heat with
calm complacency. When temperatures were too high and they
began to develop fever, they wet their fur on the nozzle of the
water bottle and lay relaxed to keep their own heat production
down to a minimum. They have been finicky about eating their
food in the heat and enjoyed gluttonous appetites in the cold.
They have provided much valuable information on climatic
dominance over basic body functions and vitality. Climatic
effects only suggested by human statistics have been made quite
clear and definite through their help. They well deserve a
Congressional Medal for services to the common good, but it
matters not to them that no politician has yet attempted to
Champion their cause.

We often become quite attached to these willing and friendly
helpers during months of close association. It is like watching an
adopted child grow from babyhood through the vicissitudes of

XI
  life, for we usually work with the rats from weaning time to adult
life. Some of them are like shy and retiring children, but the
majority are untroubled extroverts who love being handled. It
saddens us to watch these little friends lose their appetites and
fail in health as we omit from their diet some necessary element
or otherwise vary experimental conditions. But afterwards comes
miraculous recovery as the missing substance is restored. Over-
night the sick are made well again when we know just what to do
for them.

Rats are particularly valuable in studies of climate because
their basic life functions very much resemble those of human
beings. To grow, to reproduce, to digest food, to run and climb,
and to do the hundred and one other things which Ril the day
for the modern rat—all these require energy, whose sole source is
the burning of food in the body cells. But rats are no more
efficiënt than people in their ability to use combustion energy.
Like other warm-blooded animals, they must eliminate three or
four units of heat from their bodies for every single unit actually
used as energy to keep their life process going. In rats and human
beings elimination of this waste heat goes on best in cool, tem-
perate-zone climates. Tropical warmth slows the rate of heat
loss, while Arctic surroundings permit heat to escape too rapidly
for maximal efficiency. What these facts mean in the physiology
of daily living has been shown largely by studies on laboratory
animals.

In a fairly cool, natural environment, Ivan and Hilda
eliminated their waste heat at a normal and efficiënt pace. Ivan
ate greedily and grew at a rapid rate; always active and in-
quisitive, he reached maturity quickly. Hilda began her sexual
cycles early and reached a high level of reproductivity, giving
birth to large litters of lusty young. These offspring in turn went
through life with a zest and gusto which is possible only in cool
surroundings. Such active living requires much energy, however,
and necessitates the giving off of large amounts of waste heat.
When shifted to tropical heat, Ivan and Hilda were forced to
adapt their lives to a more leisurely pace. After about three
weeks of heat they ate less than half the food they had in the cool
surroundings and their rate of growth was correspondingly
reduced. Their cousins, who were kept permanendy in the heat,
matured late and were of low fertility. Although mating took
place just as freely as in the cold, it was difficult to achieve con-
ceptions or to produce healthy offspring. These animals of good
stock, kept in the heat but on entirely adequate diets and with
perfect sanitation, showed the same high stillbirth and infant-

12
  death rates found among human populations in tropical regions
where heat conditions are similar.

It is interesting that rats or mice subdued to a slow pace of
life by tropical heat live longer and come to old age later than do
their brothers or cousins kept in more invigorating coolness.
This is true, however, only if they are carefully shielded from all
infections and contagious diseases. In the heat their ability to
ward off or fight infection is sharply reduced. While living in the
cold, Ivan could survive an injection of pneumonia germs which
would be quickly fatal to him if he had been living for three
weeks or more in the heat. Vaccines also call forth a more active
defence response when he is living in energizing coolness.

White blood cells constitute the body’s first-line forces in the
fight against invading bacteria. At any point of attack they
quickly gather in large numbers, to ingest and destroy the in-
vading organisms. Theirs is often a suicidal defence, however,
for many of them are eventually killed by the toxins liberated
from the bacteria they ingest. These vital single-celled defenders
become sluggish in tropical heat, just as do all other body tissues,
and sit idly by while invading bacteria grow and multiply
unhindered.

Our animals from the hot and cold rooms show striking
differences in white blood cell activity when they are injected
with living bacteria. In those from the cold room, the white cells
spring into vigorous attack almost at once, gathering in and
digesting enormous numbers of the in vaders; but in the heat the
cells remain largely inactive, even though the living bacteria be
thick around them. Further chilling of the cold-room occupants,
sufficiënt really to lower the body temperature, renders even
those vigorous white cells less active. This effect probably ex-
plains why chilling is likely to bring on a respiratory infection,
for some of the disease germs are usually present in the nose and
throat awaiting an opportunity to attack when the white-cell
defenders are sluggish and off guard.

These observations on our thousands of laboratory animals
have helped greatly in explaining human behaviour under
different climatic conditions. People die early in the tropics from
infectious diseases, with few individuals reaching old age.
Malaria, tuberculosis, and many other diseases run a much more
rapid course in tropical countries than they do in temperate
lands.

Strange as it may seem, people in cool climates live longest,
but mainly because they are more resistant to infectious than
people of warmer regions. Those few tropical residents who do

13
  survive to advanced age show much less evidence of ageing in
their bodies than is seen in temperate-zone residents of similar
years. Their blood vessels show less hardening and are much
more elastic than those of people the same age in cool regions
where life has been full of stress. With Ivan and Hilda we can
quite thoroughly eliminate the infectious diseases and so study
the life processes from birth to a normal death. And when we slow
down their speed of life by making the loss of body heat difficult
in experimental hot rooms, we find that the changes of old age
are markedly delayed.

[Prometheus]

Scientists some time ago put forward the idea that each species
of animal, including man, has been allotted a given amount of
living—call it a credit balance in the Bank of Life. If this credit is
squandered by living at a rapid pace, then life comes to an early
end. A less active and more complacent existence, on the other
hand, means living to a riper age. We found evidence strongly
favouring such a theory when our animals were kept at almost
a vegetative level of inaction by a warm environment or driven
into a more energetic life by invigorating coolness. Professor
McCay, of Cornell University, has produced a similar delay of
the ageing process in his rats by underfèeding or limiting the
amount of food they have to burn. My rats in the warm chambers
eat and burn less food because of the difficulty they experience
in getting rid of the waste heat of such burning, while Professor
McCay’s rats burn less because they are held down to a smaller
daily ration. It seems likely, therefore, that Ivan and Hilda must
eventually pay the piper for their restless activity and tendency
to “burn the candle at both ends.” They are cutting many rat-
years off their lives by staying up so late for bridge or night-club
life, or whatever it is that constitutes exciting diversion for
sophisticated rats of this streamlined age. For real contentment
and a relaxed existence free from the stresses of effort and strife,
they should migrate to the calming warmth of the hot rooms.

With all our laboratory studies on rats and mice we still know
little of the diseases which normally cause their death. Usually we
lose interest in them when they have given us the answer we seek
for a particular problem. We did, however, watch one large
group of cancer mice from weaning time to death. Every mouse
was examined for the exact cause of death. Quite unexpectedly
we obtained very valuable data on pneumonia in relation to
temperature change. In the third of the group kept at 90-91° F.
there were no pneumonia deaths, and among those at 65° F.
there was only one. These artificial climates were steady and
unchanging, but the rest of the mice lived outside the controlled

14
  chambers in regular laboratory air at more variable tempera-
tures. Thirteen out of sixty-six in that group died of pneumonia!
This finding agrees well with observations on human respiratory
infections such as colds, sinus infections, and pneumonia, which—
as we shall see in later chapters—are linked to sudden storm
changes in the weather.

Rabbits have also played a useful part in our studies of climate.
They showed us that individuals adapted for weeks to tropical
heat stand chilling yery poorly. Their body temperature drops
rapidly; they are prostrated by the cold well before those accus-
tomed to cool surroundings show noticeable effects. They seem
unable to speed up the burning of food storcd in their tissues
quickly enough to prevent chilling. Among rabbits previously
adapted to colder, more stimulating environments, tissue fires
are at once fanned to a brighter flame by outside cold and
practically all stored food is used up before the bodv temperature
begins to fall.

Exposure to great heat, however, handicaps the vigorous cold-
room animal most severely. He cannot slow down his internal
heat production quickly enough to avoid fever and heatstroke,
and is overcome by heat which fails to bother his warm-room
cousins. Parallel conditions exist among men and women.
Human deaths from heat stroke occur not among tropical popula-
tions but rather among the more vigorous people of temperate
regions during the severe heat waves of summer.

Nature equips her children with ingenious heat-eliminating
mechanisms to reduce the chances of such serious upsets. Ivan,
for example, lacks sweat glands in his skin; but he possesses a
special heat-loss organ of great value to him in periods of stress.
That long tail of his is not as useless as it appears! It is warm with
a rich blood supply when he needs to lose more heat, becoming
cold and pulseless when he feels chilly and has to conserve
calories. The tail of a rat reared in the cold with small need for a
heat-loss organ is distinctly shorter than normal, while in a warm
environment it grows long and tapers to a fine point. Successive
generations raised in the cold have shorter and shorter tails, a
fact which perhaps offers a clue as to why man lost his tail.
Not long ago I read a news report about a native in the jungle
heat of Brazil who had grown a considerable length of tail at the
tip of his spine! The report failed to state, however, whether
this gave him any important advantage over his tailless
neighbours.

Rabbits also have a specialized part of the body for heat loss.
Those long ears are useful for other purposes than hearing—they

*5
  are really radiators. The ears of rabbits reared in a warm en-
vironment have 25 per cent. more surface than those of cold-
room animals, despite the fact that the total body size is much
smaller. As with the rat’s tail, a rabbit’s ears are gorged with
blood when the animal has difficulty keeping cool, and quickly
become pale and cold when he begins to chili. Perhaps it is the
mule’s long ears which enable him to keep on working in severe
summer heat better than the horse. And the way he flaps them
back and forth may be not just an expression of his droll humour,
but a means of losing more heat from their broad surfaces. If you
suspect your own infant of being chilly, what do you do? Put
your hand on his ear. If it is cold he needs more clothing or bed
covers, even though the rest of his head may be warm. His toes
get cold at about the same time as the ears, when he is with-
drawing blood from his most exposed parts to slow down heat
loss.

Although I mysclf have not delved into the privacy of Ivan’s
mental processes, a scientific friend in another university has
done so with astonishing results. He raised rats from birth at
three different temperature levels, 65° F., 76° F., and 90° F. As
young adults they were tested for their learning ability. Those
adapted to stimulating coolness required 12 trials, on the average,
to learn their way through a labyrinth to the spot where their
food had been placed. Those raised in moderate warmth learned
their way through in 28 trials; but the lazy ones reared in tropical
heat had grcat difficulty in solving the problem. Those which did
find their way through required an average of 48 trials, but many
of them simply gave up and quit trying.

His cold-room rats would dash through the mazes with never
a wrong move, once they had learned the proper turns to take.
Their memory signposts seemed to mark the way in clear fashion.
The intcrmediate group made more frequent errors even after
having found the proper path. But with those from tropical heat,
progress continued to be pretty much of a hit-and-miss affair
even after they had once got through. When retested after a
three-months rest interval, the cold-room rats remembered the
proper turns with almost no hesitation, the 76° F. ones had
forgotten somewhat, and those from the heat seemed to retain no
knowlcdge whatever of their former experience—they had to
start all over again.

Thinking is really work in energy terms, for the grey matter
of the brain uses oxygen and burns food far more rapidly than
any other tissue of the body. In my own case I find it difficult to
do mental work in tropical warmth, where such effort is almost

16
  as effective as physical exercise in bringing on profuse per-
spiration. The manual labourer, therefore, cannot claim that he
does all the world’s work.

Intelligence and aptitude tests show that college students, like
rats, think poorly in the heat, for scores are lower in summer than
in winter. This is particularly true in the South, where summer
heat is prolonged and depressive, but even as far north as
Indiana and Illinois, summer test ratings slump below those of
winter. In the northernmost tier of States, however, truly de-
pressive heat seldom occurs and test ratings are uniform through-
out the year. So, Hilda and Ivan, when you must face a difficult
problem or come to a decision of great importance to your
future, seek a cool and secluded corner for your thinking.

Our two laboratory helpers—and their near and distant
relatives—have helped us reach a clear understanding of how
climate dominates life. In cool surroundings, where body heat
can be lost with ease, health assumes an extremely positive and
buoyant character. The daily pace is swifter. More work is
accomplished. But the heightened tempo means a faster reduction
of the credit balance in the Bank of Life. Certain real dangers
accompany this more dynamic, cool-climate existence—dangers
of early exhaustion or breakdown of the body machinery. In
warm environments health assumes a negative, passive quality.
Most of life’s dangers arise from a lowered vitality and lessened
resistance to infection. Difficulty in losing body heat scems
inevitably to bring a slower burning of food in the cells and lcss
energy for living. Growth is retarded and in every way existence
drops closer to the vegetative level.

These conclusions are naturally based on more than animal
experiments. We have checked and cross-checked the findings
of such tests with actual observations among living things “in the
field.” It so happens that the rats, rabbits, mice, and other
animals have not informed us wrongly. Their reactions under
artificial conditions correspond to actual reactions as noted by
myself and other scientists during wide travels in different
locales and climates throughout the world. The following
chapters will teil the story of what we have found in the lands
outside the laboratory, but do not forget our debt to Hilda, Ivan,
and their fellows, who provided clues and confirmations in the
rigidly controlled climates of their hot and cold rooms.

17
  CHAPTER 3

FARM ANIMALS IN THE TROPICS

Oür helpers in the laboratory are not the only
animals to furnish vivid .evidence that life is under the in-
flucnce of climate. Temperature also plays a vital role in the
growth of the farm animals which help provide man with food.
Judging solely by what Hilda, Ivan, and their relatives have
shown us, we would suspect as much, but there is considerable
further proof to support such a conclusion. Several times I have
encountered hints that animal husbandry is severely handi-
capped in tropical surroundings, and last year I had an oppor-
tunity to make first-hand observations of this phenomenon when
I visited Panama and the Canal Zone at the invitation of the
Gorgas Memorial Laboratory in Panama City. My studies of
domesticated animals included investigations of conditions on
cattle ranches and hog, poultry, and dairy farms.

The effect of climate was vividly demonstrated at a large
hog farm a few miles outside Panama City, where I almost lost
my taste for pork—at least the local variety. As our car ap-
proached the feeding yards, a large flock of buzzards rosé from
the ground and flew off to perch in near-by trees. They had been
feeding on the decaying flesh of the pigs which had succumbed
to the heat. The sickly, puny little pigs wandered around every-
where, half of them to die before reaching adult size, while
meat-supplying porkers wallowed in the garbage tanks to keep
cool. Although I am accustomed to the hog as a dirty animal,
the buzzards and the garbage almost turned my stomach.

I learned with great interest that Panama places a five-dollar
penalty on the killing of its carrion birds. They were everywhere,
even in the city yards. I often watched them from my window as
they fought over the food of the laboratory dogs. They serve a
good purpose in the jungle country, for otherwise animal car-
casscs might quickly pollute wholc neighbourhoods in the
prevailing heat. Until I heard of the legal penalty, I wondered
why these birds should be so much more numerous in Panama
than in any other country I had visited. Never molested by men,
they show little fear, but a rather gruesome touch is added to
one’s impression of a country by seeing everywhere their death-

18
  watch circling and hearing their raucous cries as they tear apart
the rotting corpses.

Hogs, like chickens, are quite severely affected by hot weather.
They have no sweat glands and so wallow in the mud to keep
the cooling layer of moisture on their skin surface. Early in life
I learned by painful experience that hogs do not smear them-
selves with mud as an idle pastime during hot weather. One
summer when I was eight years old my father was fattening
about a hundred shoats for slaughter. In the wood lot back of the
barn on our Indiana farm there was an old gravel pit almost
filled at one end with muddy sediment. I learned to skate there
in winter, swim in summer, and fish in other odd moments.
There, too, the hogs loved to wade in hot summer weather. The
water was not entirely stagnant, for a small brook flowed through
the gravel pit. Early each morning we fed the hogs corn in a
separate feeding lot, with the gate to the water hole closed to
keep the cattle away. This gate was always opened as soon as the
hogs had eaten, so they could cool themselves in the water during
the heat of the day.

One August morning my father had to make a trip into town
and asked me to let the hogs out of the feeding lot as soon as they
h$d finished eating. The day was clear and the sun hot by ten
o’clock in the forenoon, but by that time I had forgotten all
about the hogs in the feeding lot with no water to wallow in.
Peaches and summer apples were just ripening. What fun it was
to piek out the good ones and munch on them in a cool spot of
orchard shade! But the shoats had no shade. I suddcnly remem-
bered the gate when I saw my father returning from town, but
by then eight of the hogs were already dead from the heat, and
many others were prostrated. Those still able to walk rushed for
the water when we at last opened the gate, and waded in up to
their snouts. We managed to rouse some of the others with sticks
and drive them down to the gravel pit. A few of the prostrated
ones were hauled to the water upon the little stone sled used for
clearing glacial boulders off the fields. In one frantic hour we
saved all the hogs not already dead on my father’s return. It
took another two hours of hard work to bury the unfortunate
eight that had died while I munched apples and peaches in the
orchard.

I recalled this sad experience vividly as I watched the Panama
hogs wander sluggishly in the midday heat. It was the dry
season, and they had no place to wallow except the concrete
garbage pits. Little pigs seemed to suffer most from the heat. I
suspect this was the main reason why so many died and the

19
  survivors lookcd stunted. The flock of carrion birds always
hovering over the farm only deepened my feeling that life for
these hogs was never far separated from death. How different
was this picture of sluggish stupor from that of the pushing,
squealing, fighting hogs on our northern farms! The enervating
effect of heat is one reason why it took 12 to 15 months to produce
a 200-pound porker on the Panama hog farms, while animals of
the same weight can be grown in 6 or 7 months in northern parts
of the United States. Although 200 pounds is about the largest
size reached by tropical hogs, in the North they grow to twice
that weight by the time they are two years old.

Even in our Southern States, where coolness prevails six months
a year, depressive summer heat provides a distinct handicap for
domestic animals. Early last October I visited the animal farms
of one of the leading agricultural colleges in the South. There I
found a caretaker turning the hose on a group of shoats being
fattened for the fall market. How they did like that cooling
spray after being out in the hot midday sun of the open fields!
With such de luxe service hogs do fairly well through the summer
heat, but the ordinary farmer cannot give them this luxury. His
hogs must seek their own wallowing facilities wherever they can
find available water.

The Hereford cattle on the experimental farms were also
panting in the hot sun, with fever-hot skin and listless attitude.
They stand the heat more poorly than do the Brahman cattle
of India origin. Ranchers of the Gulf coast have found these zebu
or Brahman cattle much more resistant to heat than the Hereford
or Angus breeds. While the latter two kinds develop several
degrees of fever as they pant in the hot summer sun, the Brah-
mans continue their grazing at a normal body temperature.
Adaptation to the heat of India through untold generations has
given them the same sluggish metabolism which hot-room
animals developed in the laboratory. Along with their resistance
to heat, however, goes the same slowing of growth I found in our
experimental rats and mice. While it takes only i£ to 2 years
to produce a iooo-pound steer in the northern United States,
Brahman steers along the Gulf coast are not ready for slaughter
until they are to 3 years old. The situation is even worse in
the tropics. One of Panama’s most progressive cattle ranchers
showed me his miles of range and thousands of cattle. He had
special pastures of Para grass for the final fattening of steers, but
even under these conditions he needed about four years to make
a iooo-pounder ready for slaughter. Canal Zone authorities
later told me that steers from Cuba, Colombia, or Panama—

20
  imported to the Zone for slaughter—did not reach the 900-tQ.
iooo-pound stage until they were 4J to 5J years old.

I also visited the large Mindi Dairy which supplies the major
part of the milk in the Canal Zone. About 1400 cows are kept on
concrete floors to prevent parasitic infections. They feed almost
exclusively on selected feeds imported from the United States
and mixed on the same scientific principles which are applied
to the nutrition of northern dairy herds. Most of the cows are
imported directly from the United States because experimental
breeding had shown that the Panama-born offspring of American
cows are inferior milk producers. Even so, these imported cows
yield only about three-quarters as much milk as similar stock in
the north. At that time milk from this Canal Zone herd retailed
at 18 cents a quart, so you can see that quality production is
costly in those sections.

[Prometheus]

Tropical heat not only directly slows the growth and pro-
ductivity of the farm animals which feed man, but also results in
inferior grasses and other plants which feed the farm animals.
The hogs so affected by hot weather on the farm near Panama
City received little fortification from their chief food, fermented
Canal Zone garbage. It contained plenty of vitamins A and C,
perhaps, but insufficiënt quantities of the vital B-complex
fractions. This deficiency is a particularly seiious one, because
the B vitamins speed up the burning of food and help counteract
the sluggish effect of climatic heat. I have a brother who raises
hogs in South Dakota where all animals eat and grow with real
zest; but even there it was found helpful to add to the wheat-
and-corn mixture a small portion of alfalfa leaf—an exceedingly
rich source of the B vitamins. My brother thus obtained much
faster growth and more pounds of pork per ton of feed. Neither
alfalfa nor the vitamin-rich cereals and grasses grow in tropical
heat. Native forage is coarse and full of fibre, and therefore
stock-raising is carried out under severe handicaps.

There is an interesting relationship between the rate of animal
growth and the quality of the grasses eaten. As was mentioned
earlier, it ususally takes less than two years to raise a iooo-pound
steer in the northern States, from 2$ to 3 years along the Gulf
coast, and up to 5^ years in the tropics. Correspondingly, Gulf
coast pasture grasses are not as coarse as those of Panama, but
neither do they have the fine texture of northern varieties.
Heavy rainfall throughout the spring and summer makes
Coastal grasses coarse and reedy, and during the wet haying
season farmers find it almost impossible to cure their erop without
having it spoiled by heavy dews or rains. Northern farmers often

21
  discard hay which is rained on between cutting and stacking
because so much of its vitamin and mineral content is lost in the
wetting; but in the South the farmers have no choice. The
animal husbandry professor at the Southern experimental farm
pointed in disgust to the poor quality hay he was feeding to his
pure blood Hereford buil—it was brown, coarse stuff which a
northerner would use only as winter bedding for his stock.

Since slow-growing tropical farm animals eat grasses low in
vitamin B content, we would expect their meats to show a similar
deficiency. Desiring more accurate information on the vitamin
content of meats from various climates, I arranged to have
animal products collected in Panama, along the Gulf coast, and
in the northern United States. The products from these three
sources are at present being analysed for their B vitamin content.
Although the study is still incomplete, it is already evident that
the tropically grown meats contain less of these vitamins than
do the meats grown in the North.

Eggs from Panamanian hens fed in the usual hit-or-miss
fashion are likewise low in vitamins. But if the hens are fed
importcd mash used by American poultry growers, the eggs are
almost as rich as those of the North. Other investigators had
previously found the vitamin content of eggs to be affected by
food intake. StucRes on the Gulf coast of Texas also have shown
considerably less vitamins in the meats of that region than of
Wisconsin. The evidence suggests that, hereafter, when you go
out to buy your eggs or meats, you will obtain a better bargain
if the products come from farms where animals are cool and well
fed.

' The dismal tale of tropical foods is not finished yet. I had often
wondered why meats served in the tropics required so much
chewing until I found that hot-climate steers are not ready to be
slaughtered for about five year^. That explained the mystery—
the steers were old and tough before they were large enough to
kill! Most tropical dwellers seem to like their meat tough, but I
prefer tender juicy steaks from fast-growing northern steers. I
actually timed myself on the mastication of a particuiarly tough
steak served one evening jn the hospital. Parking the bite of
steak in my cheek while I ate dessert, I finished the job during a
stroll along the nearby sea wall. It took eighteen minutes of
active chewing before that one bite was in fit shape to be swal-
lowed. Perhaps the loss of a few molar teeth has handicapped me
somewhat in eating tropical meats, but I find plenty of under-
standing listeners to my tale of woe.

True to the general tastes of tropical natives, Panamanians

22
  liked tough fried steaks, but most of the meats served were
actually tender because they had been cooked for a long while.
This practice provides the crowning point of a situation in which
everything seems wrong. It is not enough that tropical animals
grow slowly because of the heat and vitamin-poor foods, or that
their meat is consequently tough and stringy by the time they
are of slaughter size. But long cooking calculated to tenderize the
meat adds insult to injury by destroying a large part of the
meagre vitamin supply it naturally contains. In fact, sufficiënt
cooking to make the meat tender reduces its previously low
vitamin content almost to the vanishing point.

It is clearly evident that people of the tropics face a nutritional
problem of serious proportions in their vitamin-poor meats and
other animal products. They can ill afford to import the rich
stock foods used in temperate regions; indeed, it would be more
economical to let the crops be used where they are grown and
import the finished animal products for consumption in the
tropics. Such importation is much simpler to-day than it was a
few years ago, because refrigerated holds in ships and cold-
stbrage space in tropical cities are far more common.

Only a few years ago in Manila I was much amused at the
way hostesses competed for guests at dinner parties which they
wanted to hold the day after a fresh supply of choice American
beef had arrived in port. Even in many restaurants of our
Southern States recognition is given to the poor quality of native
beef. While driving from Cincinnati to New Orleans, my wife
and I once stopped in Southern Alabama to order dinner. The
menu listed western steaks at 75 cents and native steaks at 50
cents. Needless to say, we chose the western variety.

Although tropical countries should encourage importation of
meat from temperate regions, they have instead erected high
tariff barriers to protect the native stock-growers. Perhaps a
clearer insight into what good meats mean in terms of heaith
will eventually lead to a more intelligent handling of the matter.

Climatic dominance over domestic livestock seems to be just
as great as it is over our experimental animals in the laboratory
and over human beings in different regions of the earth. Proper
ease of body heat loss is everywhere the first requirement for
rapid growth and high vitality. All conditions seem to favour life
in middle temperate coolness—grain and forage crops growing in
abundance, good conditions for proper harvesting, and the
final meat products rich in much-needed vitamins. In these
climates, conditions are favourable for the best development of
all warm-blooded species. The more vigorous tissue lires seem

23
  less affected by occasional vitamin lacks which may be en-
countered by men and animals from time to time.

All persons considering entrance into the livestock business,
take notice. See that the location you choose has proper tem-
perature conditions. Avoid exposing your animals to the chilling
cold of winter or the devitalizing effects of severe summer heat.
Dairymen know that proper care of the milk-cow pays good
dividends; the same is true of poultry growing, and it also holds
for the raising of larger meat animals. Well-watered pastures
are a great boon in summer, but no more so than warm barns in
winter. Keep your laying hens at the right temperature and they
will produce well when those of your less careful neighbours are
on enforced vacations—and the price of eggs is high.

Animal husbandry experts of our Southern States, of South
Africa, and of other subtropical regions are now giving serious
thought to these phases of their problem. The matter has become
more urgent for them now that heat has been shown to make
their meats poor in much-needed vitamins. Their problems are
closely bpund up with those of human nutrition since tem-
peratures found best for animals are also good for man. In
addition, we shall see that tropical man stands in great need of
the vitamin-rich meats so difficult to produce in this climate.

CHAPTER 4

VITAMINS AND CLIMATE

As the spotlight of tropical studies sweeps past
animals and focuses on man himself, we find a wealth of new In-
formation and an urgent need to apply such facts to many practical
problems. The tropics, formerly suggestiveof exciting explorations
and big-game hunting, are now important as places of military
and strategie significance which have to be defended or won back
from Axis armies. Java, Bali, Ceylon, Madagascar, and other
once romantic places have had first-hand experience in the
business of waging a war or preparing for attacks. The working
efficiency of fighting men, natives, and non-combatants all
depends to a large degree on climate, for tropical temperatures
affect a thing very important to man—his diet.

Although it has long been known that people should cut down

*4
  on fats and large meals in general during hot weather, recent
studies show that climate also affects man’s B vitamin require-
ments. Of course, fruits and vegetables fresh from the garden
are desirable for supplies of vitamins A, C, E, K, and necessary
minerals, but in order to obtain the B fractions so important in
maintaining the tissue fires we need meat and more meat.
Beefsteak in hot weather! Not necessarily—cold cuts are just as
effective, especially liver sausage.

In the previous chapter we indicated the importance of the
B complex from a climatic and seasonal point of view. These
vitamins, like climate and weather, play a direct role in the
burning of food for human energy fuel. They act somewhat like
the tetraethyl lead added to automobile gasolines. The lead
compound serves as a catalyst which gives more even and com-
plete burning of gasoline in the cylinder chambers. The result is
greater power and elimination of the knock frequently heard
when raw gasolines are used. The B vitamins are the “tetraethyl
lead” in the burning of our foods. The combustion must go on by
slow stages so that too much heat is not produced at any time.
The blood and blood vessels act as our cooling system to carry
waste heat from cells to skin surface, and this system must not
be overloaded.

Slow burning of our food is made possible by the B vitamin
catalysts, each of which Controls one small stage of the oxidation
inside the cells. The energy liberated by this gradual burning of
food is thus available to run the body machine without the
dangers of overheating which would result if the fire burned
more vigorously. Inadequate supplies of the B vitamins mean
slower and more faulty burning in the cells and less energy on
which to live. Apparently, smaller amounts are needed in each
pound of food eaten by people of cool regions, where tissue fires
burn more brightly. With the more sluggish combustion of
tropical inhabitants, larger amounts of these vitamin catalysts
become especially important. Their life is already severely
handicapped by the body’s difficulty in getting rid of its waste
heat, so it is doubly essential that the greatest possible efficiency
be maintained.

This simple explanation of the function of B vitamins leads us
logically to expect that tropical dwellers would need a larger
daily amount of these food factors than people in cooler climates,
But logic alone is not enough, and, as has happened so often,
Hilda and Ivan and their relatives gave us the first concrete
evidence that such an extra need actually exists. Food mixtures
containing enough of the B vitamins to bring cold-room in-

25 ,
  habitants a long and healthy life left hot-room adults runty,
stunted, and prematurely wizened. In fact, our tests showed that
in order to grow normally rats living at the summer temperature
of go0 F. needed twice as much of the best-known of the B
vitamins, thiamin (also called vitamin Bx), in their food as did a
group of their fellow rodents placed in a room at 68° F. Moreover,
other tests showed how rats fed low thiamin diets differed in
personality depending upon the temperatures of their homes.

Our rats on special diets are given food in glass jars placed
inside the cages, so that they may eat as much as they wish.
When we are not especially interested in dietry studies, we give
them dog chow biscuits which contain an abundance of all food
elements. These are placed in a wire bin in one upper corner of
the cage, with an opening above for easy replenishment of the
supply. The rats gnaw on the biscuits through the wire mesh
whenever they like. The chow is excellent food and is eaten with
relish.

One of Ivan’s cousins on a low thiamin diet in the cold room
displayed most amusing cleverness in taking proper care of his
food requirements. After about two weeks of deficiënt meals our
canny friend decided to do something about the sad state of
affairs. One night he determinedly pushed open the door of his
cage, and we found him next morning with his house packed
full of chow biscuits stolen from rats some distance away. Show-
ing shrewd planning ability, he had pushed his own food jar out
to make more storage room. There he was contentedly sleeping
in one little corner, with the rest of the cage chock-full of chow.
No more starvation diet for that fellow! His body weight that
morning showed that he had not spent the whole night filling
his cage only, but had gorged himself as well. He was quite
good-natured about it as we emptied his cage and replaced the
jar containing the special deficiënt diet, although he probably
had his own opinion about our wisdom.

Before this episode he had begun to lose weight, but now he
gained rapidly for the next week and a half. He really must have
filled up that night! Two weeks later, when he had started losing
weight again on his deficiënt diet, he broke open the door of his
cage a second time and repeated the chow-stealing performance.
Later he did it a third time. That cold-room rat was displaying
the same aggressive ingenuity and industry which has prompted
people in cool climates to develop a high civilization and accom-
plish near miracles. Just as a check one night, we intentionally
left the cage door open for another rat on a deficiënt diet. He
duplicated the performance of our keen-witted friend. But when

26
  we left the door open for cold-room rats whose diet already
contained adequate supplies of vitamins, there was no apparent
interest in the chow biscuits.

Hot-room rats on diets deficiënt in thiamin take life much
more contentedly. Far be it from them to push open the cage
doors and seek a more adequate diet. Even when the door is left
open for them they are too lazy to seek the nearby supply of
better food. They demonstrate the tropical resignation and lack
of initiative which keeps large sections of the human race content
with a low level of existence.

Young chicks—little white Leghorn cockerels—kept in my
hot room also need extra supplies of the B vitamins. They develop
beriberi convulsions at dietary levels of thiamin upon which
chicks in the cold room grow and thrive. Another less well-known
B vitamin is even more important for existence in the heat.
This is choline—a distant relative of the bile acids—which we
obtain mainly from animal products. Rats need five times as
much of it at 90° F. as at 68° F. Placed on diets containing no
choline, they quickly develop a highly fatal haemorrhagic con-
dition of the kidneys in either hot or cold environments. Such
kidney trouble—acute haemorrhagic nephritis—is an important
and rather common cause of death among tropical residents and
may be found to be based upon the relative choline deficiency
existing in the heat. Brains, sweetbreads, and kidneys are our
richest food sources of this interesting substance. Others of the
B vitamin group show a higher requirement in tropical heat, but
none in such striking fashion as choline and thiamin. Most young
rats placed on choline-free diets die in about eight days; without
thiamin they live three or four weeks; but complete lack of any
single one of the other B fractions is less fatal, usually causing
only slower growth and stunted development.

Since our hot-room animals needed larger amounts of the B
vitamins, I decided to find out whether the same requirements
held for human beings in the tropics and planned my recent trip
to Panama and the Canal Zone for that purpose. The result
was a wealth of interesting information which showed the
existence of a widespread B vitamin deficiency. This situation,
plus the evidenee provided by Hilda, Ivan, et al., indicates that
such a lack is probably common to residents of all tropical
countries.

My trail, as in the animal husbandry studies, led to the Gorgas
Memorial Laboratory in Panama City, which was established
in memory of General Gorgas, the man responsible for cleaning
up the Canal Zone in its early days. It was he who showed that

27
  most tropical diseases could be banished by proper sanitation,
thus making it possible for the white race to live and work there
in good health. In recent years, however, the belief has been
growing that tropical climate itself has an enervating influence
on man, even after the infectious and parasitic diseases have been
largely eliminated. That this weakening effect is partly due to a
deficiency of B vitamins, which is aggravated by enervating heat,
soon became evident as a result of my studies.

One important clue was fumished in the case of a young
woman suffering severely from a lack of thiamin. A daily dose
as small as a tiny knife-point would have kept her in good health,
but when I saw the patiënt, she lay paralysed—a complete
invalid. Born and raised in Panama, she had been a talented
dancer until stricken. In September she had gone into the
hospital for an abdominal operation which was satisfactorily
performed. After leaving the hospital, however, she was bothered
by nausea and inability to eat or retain her food. In October she
suddenly developed beriberi, with swelling of her whole body.
In the hospital she was given thiamin and the swelling promptly
subsided. But a week or so later, she developed the paralysis
and loss of sensation in all her extremities which sometimes
occurs in this vitamin-deficiency disease. When I saw her four
months later, she was slowly regaining use of the muscles in her
arms and legs, although still unable to walk alone.

[Prometheus]

Only a few years ago, beriberi annually killed tens of thousands
among the rice-eaters of tropical and oriental lands. With a diet.
very largely made up of polished rice, these people unwittingly
discarded the parts of the kernei containing the B vitamins so
essential for health. Even after it was clearly shown that use of
unpolished rice would prevent or cure beriberi, many millions
still continued eating white rice. In temperate lands a similar
situation exists in the use of wheat. Most people prefer white
bread, even though they know that the greater part of the wheat
vitamin has been discarded in the flour-milling process. The bran
and middlings, so rich in these necessary substances, are largely
used as stock food while we keep for our own use the vitamin-
poor white flour. In many countries serious consideration
is now being * given to measures which will prevent this
vitamin loss in flour making, but beriberi is rare in temperate
climates.

It was not merely by accident that this disease struck down
the young woman in Panama. Such severe trouble from lack of
thiamin is common in tropical heat. She was advised to leave
the tropics for a more energetic life in the northern United States,

28
  where vitamin deficiencies are less prone to occur. At the last
report she was recovering rapidly in New Jersey.

To find whether Bi or thiamin deficiency occurred among
persons in a subclinical form—that is, without showing actual
symptoms—I prepared to make a series of special tests during
my first week in Panama. Man normally discards through his
kidneys part of the vitamins taken with his food. If his vitamin
supply is ample this excretion is high, while on deficiënt diets it
drops to progressively lower levels. With thiamin, the normal
day’s excretion is ioo to 500 micrograms (thousandths of a
milligram). A rate below 100 micrograms is taken to indicate
an inadequate supply in one’s food.

My first thiamin determinations were strictly a family affair.
My wife and our thirteen-year-old son accompanied me on the
trip, and while in Panama we were housed and fed in the
Panama Hospital just across the Street from the laboratory.
The food was almost entirely native in origin except for such
staples as sugar, flour, and salt. A plentiful supply of meat was
served, but it was locally produced, as were our daily breakfast
eggs. After three weeks of this hospital diet our thiamin excretion
rates had dropped from the 400- to 6oo-microgram Gincinnati
level to less than 100 micrograms a day.

Various other people living on native foods were found to have
similar low excretion rates. Native helpers in the laboratory,
hospital patients with inactive tuberculosis, and inmates of a
leper colony outside the city were all living at this deficiency
level. Meats from Argentina or the United States are extremely
expensive in Panama because of the high import duty, but
people with Canal Zone Commissary privileges avoid these
duties. Several of my human guinea-pigs used these imported
meats instead of the local products, and in every case the thiamin
excretion rate was considerably above the ioo-microgram level.
Some of us with low rates first tried a good helping of native pork
loin, and then, a few days later, a similar helping of loin imported
from the United States. Our thiamin elimination was almost
twice as much after eating the imported pork as after the native
product.

Meats are mentioned so frequently because they normally
provide us with the greater part of our B vitamin supply. Liver
is a particularly rich source, while lean pork, whether cured or
fresh, contains several times more thiamin per gram than does
lean beef, chicken, or fish. But it is not much richer in the other
B Vitamins than other meats. Additional important natural
sources for the B vitamins are unprocessed cereal grams—rice,

29
  wheat, oats, and rye. But Panamanians, like all persons who do
not eat many unprocessed cereals, must rely mainly on meats
and other animal products for their B vitamins.

It is particularly seripus that hot-climate livestock should
yield meats low in such essential elements. As we might expect
from the findings in the last chapter, meats grown in Texas and
Louisiana, as well as in Panama, are poorer in vitamins than
cuts from livestock in the northern United States. Panamanians
require an especially high vitamin B intake, but their meats are
deficiënt from this standpoint. The beneficial effect of cooler-
climate meat can be clearly detected. Time after time I observed
the thiamin elimination jump from a ioo-microgram levfel to
600 to 800 micrograms after a single helping of liver, ham, or
imported pork loin. One of my scientific friends in Panama had
been eliminating thiamin at the ioo-microgram level, but his
rate suddenly rosé and continued at about 250 micrograms.
Close inquiry revealed no change of any sort in his diet except a
shift from ordinary Panamanian eggs to those from a poultry
farm where all the hens had been imported as chicks from the
United States and fed only on a scientifically mixed imported
feed mash. Two of these eggs for breakfast had definitely im-
proved the man’s thiamin status. After this experience he decided
he would like to take the thiamin “straight” in tablet form.
Three milligrams a day—about the normal requirement in
northern climates—quickly raised his excretion to about 1500
micrograms.

Even while my son and I were losing less than 100 micro-
grams daily, the taking of 3 milligrams of thiamin by mouth
would raise our rate to about 1500 micrograms within a day’s
time. This indicated that our tissues were stül well saturated with
sufficiënt vitamin stores. The natives we studied, however, had
been on inadequate diets for years and needed 3 milligrams of
thiamin daily for 6 to 8 days before their tissues became saturated
and their excretion rate rosé to a 1500-microgram level.

Laboratory workers who volunteered as experimental subjects
unanimously reported that 3 milligrams worth of thiamin tablets
daily increased their energy and made them feel better generally.
The rat experiments indicate that the men would have benefited
even more if they had doubled this dose. But our work in Panama
also revealed the important and hitherto unsuspected fact that
overly large doses may actually poison the system. My wife was
case No. 1. She had become quite ill after taking only 10 milli-
grams daily for 2$ weeks, developing severe headache, restless-
ness, insomnia, rapid pulse, weakness, and prostration. Her

30
  symptoms cleared up within two days after she stopped taking
the tablets. A week later she began taking 5 milligrams a day,
and suffered a recurrence of the same complaints at the end of
4^ weeks. This experience put me on the alert to spot similar ill
effects during my stay in Panama, and in a lecture before a group
of physicians there I described these symptoms of apparent
'thiamin poisoning. The next few days brought numerous reports
<of just such reactions, which had not previously been attributed
to thiamin because specialists believed it to be entirely non-
toxic, even at daily dosages of 500 milligrams.

Since returning to Cincinnati, I have received many reports
of even more serious reactions to thaimin overdosage. Several
bad reactions have followed its injection in 10- to 50-milligram
dosages, and one death has been reported. But all patients who
suffered ill effects from overdosage could readily take 2 to 3
milligrams a day to cover their actual needs. The discovery that
too much thiamin may be harmful emphasizes one danger of the
current vitamin craze which grew up before all the research
results were in. Recent findings of new vitamins and their im-
portant functions in the body have been exploited rapidly in
both the lay and the medical Press. Even physicians have come
to regard vitamins as an almost universal panacea and have
sold this idea to the public at large. That they did an excellent
selling job is illustrated by the fact that Americans spent more
than $100,000,000 in 1940 for pills and other vitamin prepara-
tions.

But all-out enthusiasm is usually premature. Thiamin is
probably the most commonly used drug in America to-day. lts
popularity, and consequent large-scale production, has brought
enormous profits to the large Chemical concern holding the basic
manufacturing rights for its synthesis. Specialists studying
deficiency diseases in the United States had been resposible for
advocating large dosages; the only limiting factor seemed to be
the price of the vitamins. And as the cost of thiamin was reduced
from 5 cents a milligram to only one-fifth of a cent, the size of
prescriptions rosé accordingly. Daily doses of 30 to 50 milligrams
became common, even 500 milligrams being used in certain
instances.

Panama physicians only followed the lead of their American
colleagues in prescribing many times the amount of thiamin
needed by the healthy body. It was rather common practice to
give 20 to 50 milligrams a day in an effort to overcome the
physical let-down so often encountered by people migrating to
the tropics. The young woman patiënt mentioned earher in this

3i
  chapter was taking an average of 17 milligrams a day and had
previously received much higher doses. But our discovery shows
that such measures probably did more harm than good. As a
result of this work, physicians in the United States and Panama
have become more conservative in prescribing thiamin and are
keeping dosages down to nearer-normal levels.

Although extremely large daily doses of thiamin may be
poisonous, there is little danger from enriched white bread as
long as federal authorities strictly forbid addition of the vitamin
in excess of the whole-wheat flour content. Such rigid control is
also necessary over fortification of white sugar and other foods
which have lost their natural vitamins because of processing
methods. It should be remembered, however, that 2 to 3 milli-
grams of thiamin in northern climates and about doublé that
figure in the tropics are safe and necessary for health.

I’ve often wondered whether there might be good reason why
residents of tropical and subtropical lands like most of their
foods well seasoned with plenty of pungent spices and condiments.
Most spices are ground from small seeds rich in B vitamins, so
here may be an unwitting effort to remedy a dietary defect.
Spicy foods also stimulate freer flow of hydrochloric acid in the
stomach secretions, and here again is an effect particularly
needed in hot climates. Hot weather inhibits the normal pro-
duction of acid. The food in the stomach digests more slowly
and is more liable to bacterial spoilage. So don’t stint on the
spices for hot-weather use!

I have said little of any vitamins except those of the B group.
This has not been because others are not just as necessary for
our welfare but rather because we yet have no evidence linking
them so closely to climate. Lack of vitamin G caused thousands
of deaths from scurvy among seamen during the long sailing
voyages of two centuries ago. The discovery that lime juice
would protect them from this ailment, and its enforced use on
British ships, resulted in the nickname “limey” for British sailors.
Vitamin D, necessary for proper use of calcium and phosphorus
in the bones and teeth, has also never been shown to be affected
by climate. But there is much evidence of rickets among Pana-
manian children, even with all the bright sunshine. Close study
might reveal that people there require more of this vitamin,
just as they do of the B fractions.

But the need for further study must not hinder the applicadon
of knowledge already gained. Enough B vitamin facts have
accumulated to warrant specific steps in solving immediate
problems in the world outside the laboratory. In temperate-

3a
  zone climates, human needs are well known but not widely
applied. Two quarter-pound servings of northern lean meat
(one beef and one pork)and two eggs a day would give you
roughly 2 milligrams of thiamin, 1-5 riboflavin,, and adequate
amounts of pantothenic acid, nicotinic acid, biotin, pyridoxine
and the lesser-known B fractions. A quarter-pound serving of
liver contains more than the total daily need for all the fractions
except thiamin, and might well be eaten at least once or twice
a week to provide an added factor of safety. Fresh fruits, vegeta-
bles (especially the legumes), and cereal foods supply con-
siderable quantities of thiamin and riboflavin; but for most of
the other B fractions we rely chiefly on animal products.

Since prolonged cooking destroys much of the vitamin content
of food, eat raw fruits and vegetables as often as possible. Quick
cooking of meats gives least destruction and prolonged stewing
most. If vegetables are boiled, the water should be servcd with
them, for it has extracted much of the vitamin content. And do
not add baking soda to keep the vegetables green, for this
destroys the vitamins almost at once.

Yeast has been widely advocated as one of the richest B vitamin
sources, but for many of the fractions, liver and egg yolk are
about as rich and much more palatable. I must admit that so
far I have not been able to find an entirely satisfactory way of
taking yeast in the amounts needed. A great many people
build up an active dislike for its taste, and it often causes digestive
discomfort. In every way it seems wiser to obtain the B vitamin
supply from regular food.

Special suggestions are naturally pertinent for special con-
ditions. Wherever body heat loss is made difficult by high
temperatures, there extra supplies of the B vitamins are of
tremendous value in making the fires of life burn more brightly.
Industrial workers in boiler rooms and other hot environments
have found their duties less exhausting after taking 5 to 10
milligrams of thiamin daily. Men labouring in the holds of
naval and merchant ships would be similarly protected against
the debilitating effect of heat by such doses. The efficiency of
these workers in the vital war effort would probably be even
further increased by the consumption of more meats and other
animal products. The old ideas about avoiding proteins in hot
weather should be cast aside. Our rats need the same percentage
of protein in their diets at 90° F. as at 68° F., when their B
vitamins are supplied in pure form separately from the protein.
Unless you eat pork almost every day, or use whole meat or
enriched bread, it is probably wise to take a few milligrams of

Bcmm   33
  additional thiamin in pure form during the hot summer months.
But if the B vitamins are to be obtained from natural foods, there
is need for a larger proportion of the vitamin-rich proteins in
summer than in winter diets. Since less food is desired in hot
weather, the dietary items selected should be especially rich in
all these vitamins. Increased needs will be met by liberal
consumption of meat, eggs, cheese—and liver as often as
possible.

We people of the middle temperate regions are exceedingly
fortunate in many ways. Except for hot spells and pecufiar
occupational conditions, cool surroundings enable us to maintain
a high combustion rate in our tissues and thus to have an abund-
ance of vital energy. Although our tropical brethren are not so
fortunate, perhaps the day is near when they can enjoy the
riches of their homelands without their age-old sacrifice of
vitality. We now know that growth and vitality in animals can
be kept almost as high in hot as in cold climates, provided the
proper excess supply of B vitamins is maintained. The possibility
that similar benefits would apply to man was indicated among
our laboratory assistants in Panama, who reported that they
feit more vigorous and wide awake while taking thiamin. My
egg-eating friend decided to find out whether a few milligrams
of this B vitamin factor would give him more energy. It did. A
week later he was complaining that he had lost his relaxed
complacency and no longer feit like playing golf or dallying the
hours away as he previously had done.

If such results are any indication, it might be possible to
build new worlds in the tropics—worlds where the enervating
effects of climate would be overcome and where men would be
active and vigorously Creative in their own right. There are still
vast untapped natural resources of men and raw materials, and
such reserves are particularly important to-day. Vital supplies
of rubber and quinine for malaria from the Dutch East Indies
have been cut off by the Japanese invaders. There is quinine in
Peru. Rather considerable sources of raw rubber exist in the
steaming jungle of the upper Amazon basin. The natives
however, are too sluggish, too enslaved by tropical climates, to
care about collecting the raw materials, and fever-ridden
swamps have so far daunted efforts at exploitation by white
labour. We can only speculate as to whether a carefully organized
programme of B vitamin dosages would overcome this un-
fortunate situation. But it might help solve our problems of
shortages in rubber and other raw materials.

Furth^pnore, the task of winning a war demands a new output

34
  of energy which could conceivably bc produced by the wide-
spread application of new knowledge. Tropical fighting has
played an important role in the war to date and will play an
even more important part in the future. Soldiers defending
United Nations outposts in Africa, the Oriënt, or in our own
Caribbean bases will need special diets as well as proper sanita-
tion facilities. Our numerous experiments and observations show
that one item of particular dietary importance should be extra
supplies of the B vitamins. This step might well enable soldiers
to be as active in sizzling weather as they were in cooler surround-
ings back home. There can be no doubt that vitamins are as
important as bullets when it comes to beating a determined
foe.

As we have pointed out, the people of the United States who
remain behind to supply material for the war machine need
less of the B vitamins than do soldiers or natives in the tropics.
In our more energizing climate it is no wonder that our children
grow so rapidly and with an abundance of robust health, or that
adults feel equal to the great wartime task before them. The one
period of threat to our vitality comes with severe summer heat,
and the resulting slump which so many Americans encounter
in July and August can be largely prevented by taking extra
B vitamins.

You also need an ample supply of the B vitamins in winter
cold, of course, but a keener appetite usually sees that you get
them. It is quite possible that better resistance to colds and other
winter respiratory infections might be built up if there were more
of these combustion catalysts present to keep the vitality of the
white blood cells at a really top-notch level. For over twenty
years I have accomplished this in my own family by reinforcing
the dietary vitamin supply with the regular addition of a crude
extract of alfalfa leaves—alfalfa being one of the richest known
sources for most of the B vitamins. All thoso years I had been
advocating* use of the alfalfa extract only during the winter
season. Now perhaps I should urge it also for summer heat.

[Prometheus]

We of the cooler regions of the earth have little reason to be
proud or boastful of our more progressive spirit and record
of accomplishment Rather should we give humble thanks to a
kind Providence for having placed us under such favourable
climatic conditions and amid such an abundance of good food.
May we use these natural blessings wisely!

35
  CHARTER 5

THE FALLACY OF EARLY TROPICAL
MATURITY

One’s surroundings do considerably more than
simply affect his diet and vitamin requirements. As we have
already emphasized and shown in laboratory tests, environmental
temperatures regulate the very growth-rate and vitality of all
living things.

A good index to the devitalizing effect of hot climates is the
age at which tropical dwellers mature, and our tests and ob-
servations in connection with this interesting problem have led
us to contradict one of the most widely held misbeliefs in human-
ity’s long record of popular fallacies. Ninety-nine out of a
hundred persons are firmly convinced that maturity comes
earlier in the tropics than elsewhere.

No matter where one is—among the Chinese or the Japanese
or the people of Hawaii, in the jungles of Panama, or for that
matter in the temperate regions of the United States—one finds
it taken for granted that in hot countries the arrival of physical
maturity is speeded up. Time after time, mothers living in the
tropics have told me of sending their daughters out of the heat
to prevent too early a beginning of sexual functions. Physicians
in these areas are just as convinced as the laity. Yet my own
observations and researches over a long period of years lead me
to believe that the truth is quite otherwise. I realize that such
a statement will be regarded with scepticism if not with in-
credulity. Let me set forth the evidence on which I base it.

Hilda and Ivan have shown us that growth-rate‘and speed
of development are sharply retarded by continuous warmth.
Sexual cycles begin definitely later in the heat, and the onset of
fertility is still further delayed. In view of the common idea that
the tropics hasten human development, this evidence interested
me greatly, but nowhere could I find backing for the popular
conception. The beginning of sexual functions can be quite
sharply dated in girls and the event is usually remembered in a
woman’s life. Therefore it affords a basis for the collection of
fairly reliable statistical information on this phase of body
development. No such statistics, however, support the belief

36
  in early tropical maturity. All studies support the mute evidence
of Hilda and Ivan.

Childhood growth proceeds most rapidly and the sexual
functions develop earliest in people living in the coolness of
middle temperate latitudes. The average age for onset of puberty
in girls of the upper Mississippi basin is just slightly past the
thirteenth birthday, while in many tropical lands it comes after
the fourteenth birthday, and in regions of severe moist heat as
late as the fifteenth and sixteenth. So mothers who send their
daughters from tropical heat to temperate-zone coolness are
defeating their own purposes.

In Panama my wife and I spent a few months collecting
various kinds of statistics on the schoolchildren of the Ganal
Zone. I was particularly interested in Ganal Zone people be-
cause there we have Americans who migrated from invigorating
temperate climates to live in the tropics under conditions which
are otherwise just as favourable as in the American communities
from which they migrated. Proper sanitation has held tropical
diseases to a low level and Wholesale importation of food from
the United States has kept the American migrants free from the
undernutrition so commonly seen in natives living on tropically
produced foods. We found the Zone-born American children
smaller in stature and more retarded in development than those
newly arriving from the north. And the youngsters coming down
from the north, after living two years or more in the Zone,
showed definite retardation which in some ways made tlyem
inferior even to those of Zone birth. Here we obtained perhaps
the first definite evidence of the depressing effects of tropical
heat upon people kept free from the other undermining factors
usually encountered in such regions.

In Chapter II, the section devoted to Hilda and Ivan, we
presented reasons for the ad verse effect of the tropics. The human
body is a combustion machine, burning food in the cells and
aided by “no-knock tetra-ethyl lead” in the form of the B
vitamins. But you are not as efficiënt as you may have bclieved
yoursélf to be. Man himself has created a machine which can
convert a greater percentage of its fuel energy into work output
than can the human body. The Diesel engine is able to utilize
as high as 37 per cent. of its fuel energy, while your body rates
only 20 to 25 per cent. efficiency. That means you must eliminate
from your body three or four times as much heat as you use in
your living processes. And you must get rid of this waste heat
quickly, for if it piles up in your tissues you will develop fever
and die of heat stroke unless relief is obtained. You have an

37
  intricate and highly effective mechanism for getting rid of this
heat from your skin surfaces for brief periods. If faced with
difficulty in heat loss for two weeks or more, however, your body
automatically reduces its rate of food burning so that there will
be less heat produced. It is this lowering in combustion rate
within your tissues which makes you live less actively, and makes
your child grow more slowly, when faced with prolonged
external heat.

Practically every phase of your vitality is dependent upon
the energy you get from the burning of the food you eat, so any
reduction in the rate of burning compels you to live on a lower
level of vitality. That makes inevitably for retarded development
and a less vital existence in tropical heat. On a scientific basis,
therefore, there can be found no support for the belief in early
tropical maturity. Then how did it arise and become so widely
held in all countries of the earth?

I have approached the matter from the historical angle as well
as from studies on animals and the use of present-day human
statistics. Back through medical writings of recent centuries,
and on through the Latin and early Greek sources, the belief
in early tropical maturity found almost universal expression, but
was never supported by factual evidence. All statistics published
during recent centuries have shown earliest development taking
place in the temperate zones, with retardation in either tropical
heat or in polar cold. Even Hippocrates said that girls developed
earlier in the warmer countries, although he recorded an onset
of puberty at the average age of thirteen in girls of early Greece.

It would secm that this belief in early tropical maturity must
have originated several thousand years ago, nearer the last ice
age, when polar cold prevailed in present temperate regions and
optimal conditions for man were to be found only in what are
now tropical or subtropical lands. That the belief should have
been handed down through the past two thousand years without
factual basis makes it quite plausible that the origin of it goes
back much farther still. It has not been so very many thousand
years ago that the polar ice cap extended down to where I sit
writing in Cincinnati.

Body development seems retarded just as much by benumbing
cold as by tropical heat. Puberty comes on fully as late in Eskimo
girls of Labrador or Greenland as in girls living in the depressing
heat of tropical lowlands. Explorers and travellers have been
misled by the retarded growth of Eskimo children, just as they
were in thinking the stunted, child-like mothers in tropical
lands had matured early. Some writers even went so far as to

38
  call the indoor climate of an Eskimo igloo tropical. It is true the
igloo air temperatures are high, but they must be to overcome
the rapid loss of radiant heat to the icy walls on all sides. Even
what appears to be a heavy perspiration bathing the occupant’s
skin may well be largely moisture from the saturated air of the
room condensing on any surface available.

Only in middle temperate regions is the human optimum
reached and the earliest development attained. As earth tem-
peratures have risen through the past century to ameliorate
somewhat the polar cold, Eskimo puberty has tended to come
on at earlier ages. Even with our laboratory animals, too much
cooling retards growth and delays onset of the sex functions
just as effectively as does too much warmth. All warm-blooded
animals (including man) seem to do best when body heat is lost
with neither too great ease nor too great difficulty. At present,
the middle temperate regions seem to provide the happy mean
for greatest vitality.

Our children in Ohio and similar latitudes are the ones who
now grow most lustily and are fullest of bounding energy and
vitality. After twenty years spent in trying to direct intelligently
the energies of three growing youngsters in Cincinnati, I often
find myself envying tropical and Oriental parents their more
docile, better-behaved offspring. One must bear in mind, how-
ever, that positive lusty health is of necessity accompanied by an
abundance of energy and that this cxcess energy usually makes
the youngsters more asscrtive and parental discipline more
difficult.

Attached to the fallacious belief in early tropical onset of sex
functions is also a belief that motherhood is possible at earlier
ages and fertility is highest among tropical people. This also I
have found quite untrue. A few years ago, while collecting
statistics on climatic effects in a large naval port of a tropical
country, I was occupying a hotel room immediately overlooking
the harbour and motor-launch landing. Each afternoon between
four and six o’clock, scores of sailors in gleaming stiff white
uniforms were brought ashore from the warships in the launches
and hurried off the wharf toward the city. Between six and
seven o’clock each morning I was awakened by the same motor
launches taking back to the ships similar scores of white-clad
figures wilted by a night of city diversion.

Then during the day I collected statistics on illegitimate
first-births in the city’s largest hospital. Although there was an
almost unbelievable freedom of sex relations prevailing among
the oity’s lower economie groups, I found a late age for the first

39
  childbirth. One young unmarried mother had been consorting
for three years with a foreigner before giving birth to her first
child, another with two native men and one foreigner, andso
the stories went. The important point discovered, however, was
that the age of the mothers at the time of giving birth to the
first child was found to be the same whether they were married
or single. Evidently this age represented the average beginning
of real fertility in these women.

A similar late age at first childbirth was found among the
Chinese at Hong Kong, where illegitimacy is rare and every
effort is made to obtain children. Throughout regions of depress-
ing tropical heat, the average age for mothers at the time of
their first childbirth is about 19 years, regardless of whether
or not they are married. Even in India, which has been depicted
as the land of child-mothers, statistics record an average maternal
age, at first birth, of between 18 and 19 years. So there seems to
be little more than a very rare occurrence of motherhood among
tropical children. Retarded growth and stunted form may give
to many of the 17- and 18-year-old mothers a child-like figure
as viewed by people from more invigorating climates where
higher growth standards prevail. I experienced, for instance, a
tendency to underguess the ages of native tropical children by
about three years until I had grown accustomed to the general
undernutrition so prevalent there.

It is among girls of the earth’s more stimulating climates
that child-mothers could be found in abundance if the tropical
freedom of sex relations were not inhibited by a more rigid
moral code. Illegitimate first-births in Cincinnati come at an
average maternal age of 15 years instead of at 19, as found in the
tropics. The earliest recorded age for motherhood (with living
offspring) is that of a five-year-old girl in Lima. Although this
happened within tropical latitudes, it took place in a city where
temperatures are kept favourable throughout the year by the
cool Humboldt Current flowing northward from Antartic regions.

During a visit among the natives in the rice-terrace region of
northern Luzon (in the Philippines) I learned that relations
between the two sexes were entirely uncurbed through adoles-
cence and youth. A keen, American-trained native Bontoc
physician gave me a good description of such affairs among his
people. The parents keep their youngest child in the main hut
with them, but all older children sleep out in a so-called dor-
mitory, which looks like an overgrown doghouse. Here the
children and youths from different families may mix as freely
as they wish without any parental supervision whatever. When

40
  the form of a girl fills out, nearing the physical development
which indicates to her people the close approach of reproductive
capacity, she is properly married ofF. Illegitimacy is rare and is
much frowned upon, even though adolescent sex relations
receive no attention whatever.

One American schoolteacher with a high moral sense had
attempted to correct the dormitory situation just bcfore I
arrived, insisting that the sexes should be housed separately.
The result was a walk-out strike of ail her pupils which was
still in progress when I arrived. Neither side was yet rcady to
consider opening negotiations and the prospects were that the
American moral code would have to be abandoned before the
school could résumé its sessions. The natives thcre have tillcd
those magnificently terraced mountain-side rice fields for many
more centuries than American history covers, and thcir living
customs have become just as firmly planted as are the rice fields
themselves. Great engineering skill has been uscd in carrying
water for miles through bamboo troughs from one hillsidc paddy
to anothcr; and one may say that thcy developed the same
efficiënt realism in their social relations.

Proper use of the long period of adolescent sterility, as pracüscd
in many of the islands of the East Indies and South Seas, is
likely to lead to well-fitted matings for later life. Here again the
native customs seem appropriate.

Whenever I speak on the tropical depression of fertility, some
listener always bring up the point that tropical birth rates are
everywhere much higher than those of temperate regions. And
so they are—not because of a greater ability to reproduce, but
because lack of inhibitions allows every tracé of fertility to
yield results. Temperate-zone races could far out-breed those of
the tropics if they consorted with the same lack of restraint.
This can be clearly shown on laboratory animals kept under
conditions of tropical warmth and temperate coolness. They
mate with equal freedom and zest in both environments, but
conceptions are difficult to achieve in the heat, while in the cold
almost every mating results in a large litter of lusty young.

Climatic differences in human restraint often result in sur-
prising situations. High-pressure Northerners going from mid-
winter cold down into the relaxing warmth of Southern Florida
or the Caribbean region often find themselves face to face with
a sharp let-down in their moral code. Fuel is added to this fire
by the laxity of sex relations so common in the native people
about them. Many a person has behaved under such conditions
in a way which seems most surprising after a return to the North

41
  has stiffencd up the inhibitions. The “thou shalt nots” of Christ-
ianity are certainly appropriate for the energetic people of cool
climates where vitality runs high and submission to every
impulse would bring chaos.

The worst social evils of world migrations have often been
associated with those climatic differences in emotional restraint.
Large numbers of north-Europeans who migrated to the stimu-
lating climate of northern United States fitted in well with life
in the new land because its tempo was not so different from that
of their former home; but migrants from warmer regions found
themselves in great difficulty under the increased stimulation
of our invigorating climate. They suffered a marked increase
in bodily energy and desire for activity long before they had
developed the moral restraint necessary for harmonious existence
at high energy levels. Mexicans migrating northward, Negroes
coming up to work in our industrial cities, Europeans from the
warmer Mediterranean countries—those were the groups who
found themselves in greatest conflict with American moral codes
for a generation or two after migration.

Oh the other hand, I have seen many women who have
migrated to the tropics suffer a real breakdown because they
were unable to throw off their restrained code of northern life
and lead the more relaxed existence which seems necessary with
the lower energy level there prevailing. Women are more
affected than men in such migration.

The depressing effects of tropical heat on fertility appear in
still another way. Even in temperate regions there may be as
much as a 50 per cent. fall in conception rate during severe
summer warmth. Such was the case in Kansas City and in other
areas afflicted with the prolonged severe heat wave of the 1934
summer. Each year, Florida shows a 35 per cent. reduction
during her summer warmth. Accompanying this hot-weather
fall in fertility are frequent menstrual difficulties—cessation of
the monthly periods, painful cramps, or the secondary effects of
an upset endocrine system which make life miserable for the
person involved.

Our studies of man in hot weather and tropical climates show
that he is no lord of creation, but rather a pawn of his climatic
habitat. His activities and vitality shrivel in depressing warmth,
and the difficulty of body-heat loss shows most strikingly in his
ability to reproduce. Fertility declines sharply in the heat and
rises to a peak in optimal coolness. This is just as true with the
seasonal change from hot to cold as it is with climatic differences
between temperate and torrid regions; and it probably holds also

42
  for those slow changes in earth temperatures which cover many
centuries. For almost a hundred years now, earth temperatures
have been rising; is this to bring a reduction in racial repro-
ductivity and an easing of population pressure? Perhaps further
insight into the dynamics of life will one day answer that question,
but we cannot wait for the answer. The chapters to come will
take a closer view of ourselves, the people of cool climates, who
are always too busy to wait.