Man, Past and Present Part 64

4. Many of the differences that separate man from anthropoids of the _Sivapithecus_ type are retrogressive changes, following the profound change in food habits above noted. Here belong the retraction of the face and dental arch, the reduction in size of the canines, the reduction of the jaw muscles, the loss of the prehensile character of the hallux. Many other differences are secondary adjustments in relative proportions, connected with the change from semi-arboreal, semi-erect and semi-quadrupedal progression to fully terrestrial bipedal progression. The earliest anthropoids being of small size doubtless had slender limbs; later semi-terrestrial semi-erect forms were probably not unlike a very young gorilla, with fairly short legs and not excessively elongate arms. The long legs and short arms of man are due, I believe, to a secondary readjustment of proportions. The very short legs and very long arms of old male gorillas may well be a specialization.

5. At present I know no good evidence for believing that the separation of the Hominidae from the Simiidae took place any earlier than the Miocene, and probably the Upper Miocene. The change in structure during this vast interval (two or more million years) is much greater in the Hominidae than in the conservative anthropoids, but it is not unlikely that during a profound change of life habits evolution sometimes proceeds more rapidly than in the more familiar cases where uninterrupted adaptations proceed in a single direction.

6. _h.o.m.o heidelbergensis_ appears to be directly ancestral to all the later Hominidae.

_On the evolution of human food habits._

While all the great apes are prevailingly frugivorous, and even their forerunners in the Lower Oligocene have the teeth well adapted for piercing the tough rinds of fruits and for chewing vegetable food, yet they also appear to have at least a latent capacity for a mixed diet.

The digestive tract, especially of the chimpanzee and gorilla, is essentially similar to that of man and at least some captive chimpanzees thrive upon a mixed diet including large quant.i.ties of fruits, vegetables and bread and small quant.i.ties of meat[1352]. Mr R. L.

Garner, who has spent many years in studying the African anthropoids in their wild state, states[1353] that "their foods are mainly vegetable, but that flesh is an essential part of their diet." Other observers state[1354] that the gorilla and chimpanzee greedily devour young birds as well as eggs, vermin and small rodents.

Even the existing anthropoids, although highly conservative both in brain development and general habits, show the beginning of the use of the hands, and trained anthropoids can perform quite elaborate acts. At a time when tough-rined tubers and fruits were still the main element of the diet the nascent Hominidae may have sought out the lairs and nesting places of many animals for the purpose of stealing the young and thus they may have learned to fight with and kill the enraged parents. They had also learned to fight in protecting their own nesting places and young. And possibly they killed both by biting, as in carnivores, and by strangling, or, in the case of a small animal, by das.h.i.+ng it violently down.

We may conceive that the Upper Tertiary ape-men, in the course of their dispersal from a south central Asiatic centre[1355], entered regions where flint-bearing formations were abundant. In some way they learned perhaps that these "Eolith" flints could be used to smash open the head of a small strangled animal, to crack open tough vegetables, or to mash substances into an edible condition. Much later, after the mental a.s.sociation of hand and flint had been well established, they may have struck at intruders with the flints with which they were preparing their food and in this way they may have learned to use the heavier flints as hand axes and daggers. At a very early date they learned to throw down heavy stones upon an object to smash it, and this led finally to the hurling of flints at men and small game. Very early also they had learned to swing a heavy piece of wood or a heavy bone as a weapon. For all such purposes shorter and stockier arms are more advantageous than the long slender arms of a semi-quadrupedal ancestral stage and I have argued above (p. 333) that a secondary shortening and thickening of the arms ensued.

One of the first medium-sized animals that the nascent Hominidae would be successful in killing was the wild boar, which in the Pleistocene had a wide Palaearctic distribution.

From the very first the ape-men were more or less social in habits and learned to hunt in packs. Whether the art of hunting began in south central Asia or in Europe, perhaps one of the first large animals that men learned to kill after they had invaded the open country was the horse, because, when a pack of men had surrounded a horse, a single good stroke with a coup-de-poing upon the brain-case might be sufficient to kill it.

I have argued above (p. 321) that the retraction of the dental arch and the reduction of the canines is not consistent with the use of meat as food, because men learned to use rough flints, in place of their teeth, to tear the flesh and to puncture the bones, and because the erect incisors, short canines and bicuspids were highly effective in securing a powerful hold upon the tough hide and connective tissue. It must be remembered that with a given muscular power small teeth are more easily forced into meat than large teeth.

After every feast there would be a residuum of hide and bones which would gradually a.s.sume economic value. The hides of animals were at first rudely stripped off simply to get at the meat. Small sharp-edged natural flints could be used for this purpose as well as to cut the sinews and flesh. After a time it was found that the furry sides of these hides were useful to cover the body at night or during a storm.

Thus the initial stage in the making of clothes may have been a byproduct of the hunting habit.

Dr Matthew (_loc. cit._ pp. 211, 212) has well suggested that man may have learned to cover the body with the skins of animals in a cool temperate climate (such as that on the northern slopes of the Himalayas) and that afterward they were able to invade colder regions. The use of rough skins to cover the body must have caused exposure to new sources of annoyance and infection, but we cannot affirm that natural selection was the cause of the reduction of hair on the body and of the many correlated modifications of glandular activity. We can only affirm that a naked race of mammals must surely have had hairy ancestors and that the loss of hair on the body was probably subsequent to the adoption of predatory habits.

The food habits of the early Hominidae, and thus indirectly the jaws and teeth, were later modified through the use of fire for softening the food. Men had early learned to huddle round the dying embers of forest fires that had been started by lightning, to feed the fire-monster with branches, and to carry about firebrands. They learned eventually that frozen meat could be softened by exposing it to the fire. Thus the broiling and roasting of meat and vegetables might be learned even before the ways of kindling fire through percussion and friction had been discovered. But the full art of cooking and the subsequent stages in the reduction of the jaws and teeth in the higher races probably had to await the development of vessels for holding hot water, perhaps in neolithic times.

This account of the evolution of the food habits of the Hominidae will probably be condemned by experimentalists, who have adduced strong evidence for the doctrine that "acquired characters" cannot be inherited. But, whatever the explanation may be, it is a fact that progressive changes in food-habits and correlated changes in structure have occurred in thousands of phyla, the history of which is more or less fully known. n.o.body with a practical knowledge of the mechanical interactions of the upper and lower teeth of mammals, or of the progressive changes in the evolution of shearing and grinding teeth, can doubt that the dent.i.tion has evolved _pari pa.s.su_ with changes in food habits. Whether, as commonly supposed, the food habits changed before the dent.i.tion, or _vice versa_, the evidence appears to show that the Hominidae pa.s.sed through the following stages of evolution:

1. A chiefly frugivorous stage, with large canines and parallel rows of cheek teeth (cf. _Sivapithecus_).

2. A predatory, omnivorous stage, with reduced canines and convergent tooth rows (cf. _h.o.m.o heidelbergensis_).

3. A stage in which the food is softened by cooking and the dent.i.tion is more or less reduced in size and retrograde in character, as in modernized types of _H. sapiens_.

The following is an abbreviation of Gregory's arrangement of the Primates (pp. 266, 267).

Order Primates Suborder Lemuroidea Suborder Anthropoidea Series Platyrrhinae [New World monkeys]

Fam. Cebidae Fam. Hapalidae [Marmosets]

Series Catarrhinae [Old World monkeys]

Fam. Parapithecidae [extinct]

Fam. Cercopithecidae Fam. Simiidae Sub-fam. Hylobatinae [Gibbons]

Sub-fam. Simiinae [Simians or Anthropoid apes]

By the courtesy of the author we are permitted to reproduce his provisional diagram of the phylogeny of the Hominidae and Simiidae (p.

337).

[Ill.u.s.tration]

The following explanation is offered for the convenience of those who may not be familiar with the technical terms here employed.

_Simia_, the genus containing the orang-utan.

_Pan_, a name occasionally employed for the genus containing the chimpanzee. Most authorities place the chimpanzee and the gorilla in the genus Anthropopithecus.

_Hylobatinae_, the sub-family containing the gibbons.

_Palaeopithecus_, _Dryopithecus_, _Palaeosimia_, and _Sivapithecus_ are extinct simians.

_Pan vetus_ is the name suggested by Miller[1356] for the supposed chimpanzee whose jaw was found a.s.sociated with the Piltdown cranium.

He says "The Piltdown remains include parts of a brain-case showing fundamental characters not hitherto known except in members of the genus _h.o.m.o_, and a mandible, two molars, and an upper canine showing equally diagnostic features. .h.i.therto unknown, except in members of the genus _Pan_ [_Anthropopithecus_]. On the evidence furnished by these characters the fossils must be supposed to represent either a single individual belonging to an otherwise unknown extinct genus (_Eoanthropus_) or to two individuals belonging to two now-existing families (_Hominidae_ and _Pongidae_)."

He argues that the jaw was actually that of a chimpanzee and that the cranium was that of a true man, whom he terms _h.o.m.o Dawsoni_.

Gregory accepts this hypothesis. W. P. Pycraft[1357] has submitted Miller's data and conclusions to searching criticism and bases his deductions on far more ample material than that at the disposal of Miller. He says "That the Piltdown jaw does present many points of striking resemblance to that of the chimpanzee is beyond dispute. Dr Smith Woodward pointed out these resemblances long ago, in his original description of the jaw. But Mr Miller contends that because of these resemblances therefore it _is_ the jaw of a chimpanzee"

(_loc. cit._ p. 408). Pycraft points out that there is more variability in the jaws of chimpanzees than Miller was aware of, and that most of the features of the Piltdown jaw are well within the limits of human variation; in discussing the conformation of the inner surface of the body of the jaw he says "Between the two extremes seen in the jaws of chimpanzees every gradation will be found, but in no case would there be any possibility of confusing the Piltdown fragment, or any similar fragment of a modern human jaw, with similar fragments of chimpanzee jaws" (p. 407).

FOOTNOTES:

[1352] A. Keith, "On the Chimpanzees and their Relations.h.i.+p to the Gorilla," _Proc. Zool. Soc. London_, 1899, I. p. 296.

[1353] _Science_, Vol. XLII. Dec. 10, 1915, p. 843.

[1354] A. H. Keane, _Ethnology_, 1901, p. 111.

[1355] W. D. Matthew, "Climate and Evolution," _Ann. New York Acad.

Sci._ XXIV. 1915, pp. 210, 214.

[1356] Gerrit S. Miller, "The Jaw of Piltdown Man," _Smithsonian Misc.

Coll._ Vol. 65, No. 12, 1915.

[1357] "The Jaw of the Piltdown Man, a Reply to Mr Gerrit S. Miller,"

_Science Progress_, No. 43, 1917, p. 389.