2d. During the Pliocene epoch, there lived in Java an anthropoid race possessing the "marche bipède," and intermediate, in cerebral development, between the highest forms of known monkeys and the human species.
We may fuse these two hypotheses into one, from the point of view of the theory of evolution, that is to say, we may consider with great probability the race in question not only as a race precursor for the human species, but also as a race ancestral, as the commencement of humanity.
That there is in all this much hypothesis, I do not deny. But the attributing of the pieces from Trinil to two or three unknown species closely resembling man, or to a single abnormal specimen of the human species, that is, also, merely hypothesis.
Then, since we are obliged to have recourse, in any case, to a hypothesis, we have to ask which one is the most suitable, not only to explain the facts directly on trial, but also to clear up this question henceforth thrust imperiously before us for examination, namely, what can have been the human species during the Pliocene and how can it have originated? In the presence of the discovery of Mr. Dubois, it is advisable to examine the question in its entirety.
The question does not admit of a mathematical demonstration, but there can be a degree of probability great enough to carry with it conviction. To admit as true, until there is proof to the contrary, a hypothesis which answers to a great number of facts without being contradicted by any, is to act in accordance with the scientific spirit. It has often been said that science does not consist in a heap, but in a chain, of facts. To discover this chain, hypothesis plays a necessary role. Certain zoologists suppose that the human species has had no ancestors. If this hypothesis, of which the probability is not of the first order, seems to them to be scientific and fruitful, the opposite hypothesis can boast of titles to belief at least equal, in our opinion. And if the human species did not appear by spontaneous generation,—if, on the other hand, the cranial characters of Quaternary man found in Europe represented a phase of evolution very little removed from the existing phase, there is cause for believing that there would be found in Pliocene deposits a race morphologically inferior to that of Neanderthal and of Spy. But this is precisely what has happened. The anthropomorphous human race, if you choose to call it so, found by Mr. Dubois, presents characters such that it may have resulted directly and progressively from the transformation of a race of anthropoid climbers. Under these conditions, if the doubt on the subject of the simian origin of Man is only proportionate to the reasons of a scientific order capable of giving rise to it, it seems to me it must be a very slender doubt.
