CHAPTER XI 



BIOLOGY OF MAN 



PEDIGREE OF MAN. — Increased knowledge has confirmed 

 Darwin's carefully established conclusion that Man emerged from 

 a stock common to him and the divergent Anthropoid Apes. This 

 confirmation has included a number of discoveries of fossil remains 

 which have done something to lessen what Darwin called "the great 

 break in the organic chain between Man and his nearest allies". 

 This is the subject of the following paragraphs, essentially based 

 on such well-documented treatises as Sir Arthur Keith's Antiquity 

 of Man (2nd ed., 1925) and Prof. Marcellin Boule's Fossil Men 

 (trans., 1923). We would point out at the start that while the 

 opinions of experts differ as to the interpretation to be put on certain 

 fossils, this is not a case where the strength of a chain is that of its 

 weakest link. Even if a mistake in interpretation be made here and 

 there, the palaeontological evidence points clearly to a gradual 

 ascent of man from an ancestry common to the Hominoid and 

 Anthropoid stocks. 



In early Eocene ages the arboreal order of monkeys, technically 

 called Primates, was differentiated from the other mammalian 

 orders, such as Carnivora and Insectivora. From the generalised 

 monkey-like stock, of which few fossils are known, there diverged 

 first of all the broad-nosed (Platyrrhine) New World monkeys, and 

 later on the distinctly higher sharp-nosed (Catarrhine) Old World 

 monkeys, of which latter there are some interesting fossil repre- 

 sentatives in Egyptian deposits. In the Oligocene ages there 

 appeared the branch of small apes (Hylobatidae), the gibbon and the 

 allied siamang (Hylobates), with the simpler and fossil Propliopi- 

 thecus near the base of the branch. Hundreds of thousands of years 

 afterwards, in all probability, there occurred the great divergence 

 between the large Anthropoids and the Hominoids. Some refer this 

 dichotomy to the Oligocene, others to the beginning of the Miocene. 

 The large Anthropoids yielded (i) the Gorilla and Chimpanzee 

 lines, which are near one another; (2) the Orangs, somewhat by 

 themselves ; and (3) the extinct Dryopithecus line, which apparently 

 led to nothing. 



The important general fact is that we must not think of a linear 

 series, but of diverging collateral lineages, in fact as the branchings 

 of the genealogical tree, arising at different levels. Monkeys do not 

 lead on to apes; but there was an ancestral stem which yielded the 

 Platyrrhine and Catarrhine monkeys on the one hand, and the 



