306 GENERAL ZOOLOGY 



digit V on the forefeet, and three on the hindfeet; all the toes of 

 all feet touched the ground. Protohippus, about the size of a 

 donkey, lived in the Miocene epoch and had one large toe (III) 

 and two smaller ones (II and IV) on each foot; only the larger 

 one touched the ground. The earliest remains of the modern 

 horse Equus date from the Pleistocene epoch. It had a large, 

 well-developed, single digit and two very rudimentary splints 

 on each foot. This fossil series demonstrates the changes under- 

 gone in the morphology of the body of the horse, particularly 

 the steps by which the single-digited foot of the modern horse 

 has been arrived at. The teeth also show interesting transitions 

 (Fig. 177) . The evidence indicates that the horse was not created 

 as such in the beginning, but arrived at its present state after a 

 series of changes extending over millions of years from Hyraco- 

 therium, prior to which other forms, not completely known, push 

 the ancestry of the horse still farther into the past. As for the 

 horse, so for other forms of life. 



Evolution of Man. — The evidence for evolution in man is 

 similar to the evidence for the evolution of other animals. If 

 the principle of evolution is accepted for the animal kingdom 

 generally, it must also be accepted for man, since he is part of 

 the phyletic series of animals. The structure of the human body 

 is that of a mammal, without doubt the most intelligent mammal, 

 but neither more nor less than a mammal. Taxonomically, 

 man belongs to the Class Mammalia, Order Primates, Suborder 

 Anthropoidea, Family Hominidae, Genus Homo, and Species 

 sapiens. The oldest known member of the human race, the 

 Peking man or Sinanthropus pekinensis, lived in the early 

 Pleistocene epoch at the onset of the Great Ice Age in the northern 

 hemisphere, which occurred between 500,000 and 1,000,000 

 years ago. The site in which the remains were found was a 

 limestone cave, located 40 miles southwest of Peiping, China, 

 and filled with sand and debris, along with the remains of other 

 mammals, such as the rhinoceros, elephant, saber-toothed tiger, 

 horse, etc., all dating from early Pleistocene times. The first 

 complete cranium was found in 1929 and since then parts of 

 at least 11 individuals have come to fight. The skull is apelike 

 with heavy brow ridges and receding forehead (Fig. 178). The 

 lower jaw is heavy and without a chin. The Peking man could 

 build a fire and make tools. The Java man, Pithecanthropus 



