Meat per Day per
  Countries Capita in Grams

Australia                             306
U.S. of America                       149
Great Britain                         130
France                                 92
Belgium and Holland                    86
Austria-Hungary                        79
Russia                                 59
Spain                                  61
Italy                                  29
Japan                                  25

Sea-water contains iodine.  People living in contact with sea-water would be apt to get more iodine in their systems, and so a greater degree of thyroid activity.  On the other hand, certain bodies and sources of inland water hold something deleterious to the thyroid, so that whole populations in Europe, Asia and America drinking such water have become goitrous and cretinous, and a large percentage straight imbeciles.  Endemic cretinism is the name given to the condition.  In parts of Switzerland, Savoy, Tyrol and the Pyrenees, in America around some of the Great Lakes, there are still such foci.  Marco Polo described similar areas he encountered in his travels through Asia.

Certain foods with aphrodisiac qualities may act by stimulating the internal secretion of the sex glands.  A type of pituitocentric has an almost uncontrollable craving for sweets.  Alcohol and the endocrines remain to be studied.

Light, heat and humidity stand in some special relation to the adrenals.  Pigment deposit in the skin as protection against light is controlled by the adrenal cortex.  The reaction of the skin blood vessels to heat and humidity is regulated by the adrenal medulla.  A change in the adrenal as a response to changes of temperature and humidity in an environment would result in a number of concomitant transformations throughout the body.  So variation and adaptation are probably connected.  Most Europeans living for a sufficiently long time in the tropics suffer from a combination of symptoms spoken of as “Punjab head” or “Bengal head.”  The condition is probably the result of excessive adrenal stimulation by the excessive heat and light of the tropical sun, followed by a reaction of exhaustion and failure, with the consequent phenomena of a form of neurasthenia.  In the section on the pineal gland there was mentioned the relation between light and the pineal gland in growing animals, and how it serves to keep in check the sex-stimulating action of light.  The earlier puberty and menstruation of the warmer climates may be explained as due to an earlier regression of the pineal under the pressure of a great amount of light playing upon the skin.

All these, and many more could be cited, are instances of the direct influence of environmental factors upon one or more of the endocrines, and so upon the organism as a whole.  Indeed, stimuli may be considered to modify an organism only in so far as they modify the glands of internal secretion.  Consequently, climatic factors will tend to make a population possess certain points of resemblance in common.