212 



NATURE 



[November 6, 1919 



net in-goings and output of matter by the animal 

 body. Within the last' fifty years the applicability 

 of the principle of conservation of energy to 

 animals has been established by Rubner. The 

 energy-value of the important foodstuffs has been 

 ascertained, and the requirements of the human 

 body under various conditions of age, climate, and 

 occupation have been determined. 



This knowledge has been inadequately exploited 

 because everyone prefers to be a law unto himself 

 in the matter of food intake. It has served as a 

 basis for the rationing of armies and for the con- 

 struction of institutional dietaries. During recent 

 years, however, it has become increasingly ap- 

 parent that man cannot live on protein, fat, and 

 carbohydrate alone, but that a diet must contain 

 in addition small quantities of what, until they 

 can be isolated and identified, have been 

 designated "accessory food factors." The best 

 example of these is the for long recognised anti- 

 scorbutic substance in fresh vegetables and fruits. 

 The existence of at least three accessory food 

 substances has been since established. For all of 

 these the animal is dependent directly or indirectly 

 upon the vegetable kingdom. An insufficient 

 supply of any one of these leads to trouble. If 

 one of them is inadequate, scurvy results ; 

 deficiency of another leads to the disease beri- 

 beri ; and if deprived of the third an animal fails 

 to grow. There appears also to be no doubt that 

 rickets in children is due to a similar cause. 



This knowledge has for long been utilised tQ^ 

 prevent scurvy. Where it has been intelligently 

 applied it has eliminated beri-beri from coolie- 

 camps, the population of jails, and industrial com- 



munities of the Far East, and if it is utilised in 

 the efforts to feed the famished population of the 

 unfortunate countries of Eastern Europe it will 

 be the means of saving thousands of young lives 

 during the ensuing winter. 



Science has also been successfully applied in 

 recent years to the diminution of the dangers 

 incident upon certain industrial occupations, such 

 as mining, caisson working, and deep-sea diving. 

 During the last ten years, too, the influence of 

 industrial fatigue, alcohol, improper atmospheric 

 conditions in workshops, etc., upon the health and 

 efficiency of the worker has been seriously studied. 

 In these inquiries America has shown the 

 greatest energy, but in Britain the subject is 

 beginning to receive the attention its importance 

 demands. 



It is impossible to assess the effect of pre- 

 ventive medicine and improved hygienic surround- 

 ings upon the health and happiness of mankind ; 

 but the influence upon longevity can, in the case 

 of civilised communities, be determined. During 

 the last fifty years upwards of ten years have be<;n 

 added to the mean expectation of life of a child 

 born in Britain or in the United States of America. 

 An increase of 25 per cent, in so short a time is 

 cause for congratulation, but, on the other hand, 

 the fact that a million young men were found 

 unfit for active service indicates that all is not 

 well with Britain. 



We are still far from the possession of sufficient ' 

 knowledge to regulate satisfactorily our environ- 

 ment or to avoid all noxious influences, but owing 

 to lack of power, money, or sometimes sense, we 

 apply far less than we possess. 



THE ANTIQUITY OF MAN. 



Bv Dr. a. Smith Woodward, F.R.S. 



Jl 



AT the beginning of the Tertiary period, when 

 mammals began to spread widely over the 

 world, they were all very small and so uniform in 

 character that it is scarcely possible to classify 

 them into groups or orders. They all had a com- 

 paratively small brain of a simple kind, and as 

 in course of time they became gradually sub- 

 divided into the groups with which we are now 

 familiar, the brain increased both in size and 

 effectiveness, while many of the animals them- 

 selves grew larger. In the middle and towards the 

 end of the earUest Tertiary (Eocene) epoch some 

 of the low-brained hoofed mammals attained their 

 greatest size and then became extinct. Next in the 

 Oligocene another group with somewhat improved 

 brain grew even larger just before extermination. 

 In the following Miocene epoch several groups 

 that had by that time acquired a still more effi- 

 cient brain, such as rhinoceroses, horses, certain 

 carnivores, and primitive elephants, attained a 

 comparatively large size and soon reached their 

 maximum in the Pliocene. About ihe middle and 

 towards the end of the Miocene epoch true apes, 

 NO. 2610, VOL. 104] 



with a higher development of brain than any 

 mammal up to that time had acquired, also began 

 to grow to as large a size as most of the apes 

 of the present day. It may therefore be pre- 

 dicted that the earliest remains of the largest 

 members of the ape-series, with a truly overgrown 

 brain — the great ground-apes which were the im- 

 mediate forerunners of man — will not be found in 

 rocks of older date than the Pliocene, and prob- 

 ably not in any but the latest of this epoch. For 

 other reasons Sir William Boyd Dawkins came to 

 the same conclusion so long ago as 1880, and as 

 discoveries progress it becomes increasingly clear 

 that true man, of the family Hominidae, cannot 

 be earlier than late Pliocene or the dawn of the 

 Pleistocene. 



So few fragments of apes and man have 

 hitherto been met with that it is difficult to decide 

 upon the region of the world that may be most 

 hopefully searched. If, however, conclusions may 

 be drawn merely from teeth, the most promising- 

 field at present seems to be south-central Asia. 

 By the discovery of such teeth. Dr. Pilgrim has 



