SECTIONAL TRANSACTIONS.—C. , 371 
and rhenanus—may yet prove to be assignable to early forms of man. We are equally 
at a loss when we search for the ancestors of the gorilla, chimpanzee and orang amongst 
these fossil teeth and jaws. And yet it is probable that, in the assemblage, the 
ancestral patterns of teeth and jaws of modern anthropoids are represented. 
Evolutionary changes have converted teeth of the Dryopitheque pattern into those 
we find in man and gorilla, chimpanzee and orang. Not until we have discovered 
parts of the skulls and limb bones of these fossil anthropoids can we clear up the 
relationship which the great miocene anthropoids hold to their modern representatives 
and to man. 
When we go further back in the geological record in search of the ancestral forms 
of the great anthropoid stock of the upper miocene and lower pliocene, there is only 
one country at present which can help us. Thisis Egypt. In 1920 Dr. R. Fourtan 
made a discovery of the highest importance in deposits of the lower miocene at 
Moghara. He found teeth and jaws—representing two anthropoids—one a small 
form of Drypitheque—t he smallest so far discovered. The other there represented 
was a form of gibbon—Prohylobates. Dr. Pilgrim rightly claims that the Egyptian 
dryopitheque may be ancestral to some of his Siwalik anthropoids. Dr. Fourtan’s 
discovery is important in another respect ; it gives us definite information that the 
big-bodied higher primate was in course of evolution in early miocene times. 
Egypt also yields us the only evidence as to the point of evolution reached by the 
orthograde primates at a still earlier time—the beginning of the oligocene. In 1910 
Prof. Max Schlosser described teeth and jaws, which he assigned to a primitive and 
small form of gibbon—Propliopethecus; and to a Tarsioid—an early form of old- 
world monkey—Parapithecus. The teeth and lower jaw of Propliopithecus, the 
earliest gibbonish form known, serve so well as a prototype of the living gibbon that 
we feel justified in presuming that it too was orthograde in posture. We make the 
further presumption, namely, that this posture, peculiar to the higher primates, was 
evolved, or in course of evolution, at the beginning of the oligocene period. The small 
size of the jaw and teeth of Propliopithecus also supports the belief that at the 
beginning of the oligocene period the common ancestral stock of the orthograde 
primates was of small size. The discovery of Propliopithecus has this further 
importance—it serves as a fixed point from which students of human evolution may 
begin their speculations. Whether we suppose the human stock to have broken 
away in miocene times after the full evolution of the Dryopitheque type of anthropoid 
—as Dr. W. K. Gregory and Prof. Elliot Smith think most probable; or at a still 
earlier period—during the evolution of the big-bodied anthropoid type, as I believe ; 
or at still earlier phases—as Dr. H. Fairfield Osborn and Prof. Wood-Jones think, 
yet we are all agreed to accept Propliopithecus as a starting-point from which to 
derive the evolutionary history of man and ape. 
My instructions from the president of this section were to confine myself to the 
fossil evidence of man’s evolution. Manifestly this is impossible ; our search carries 
us very soon into a world of anthropoid apes ; we cannot discuss man’s origin apart 
from their origin. Now as the fossil evidence stands we could not from it alone 
construct man’s genealogical history. The geological evidence is as yet subsidiary ; 
it permits us to verify and amplify the theory of man’s evolution which has been 
constructed from the evidence of anatomy, physiology and embryology. The 
geological evidence justifies us in regarding the family of gibbons as retaining more 
of the early common orthograde ancestor than the great apes or man do. It also 
justifies us in regarding the anthropoid body as earlier and less changed than the 
human body. Indeed, man is by far the most specialised and changed member of 
the orthograde stock. Geological evidence also supports the belief that the orthograde 
posture and the massive body began to develop early in the oligocene. The larger- 
bodied Dryopitheque type of anthropoid was in course of evolution early in the 
miocene, and that by the end of the pliocene there were large-bodied, relatively 
big-brained primates in which the lower limbs had become modified for plantigrade 
progression, and that during the pleistocene period this peculiar group of primates 
underwent further changes—an enlargement and complication of the brain with a 
reduction of tooth and jaw. So far as it goes, the paleontological evidence now 
available favours the theory formulated by Darwin in 1870, namely, that man and 
anthropoid apes are the descendants of a common stock. If in the next fifty years 
geological records accumulate at the rate they have done in these past fifty years, 
our knowledge of man’s origin will be founded not as ours is on reasoned inferences, 
but on ascertained fact. 
BB 2 
