Whether the australopithecines were our ancestors or not, the proper ancestors of men must have been able to stand erect and to walk on their two feet. Three further important things probably were involved, next, before they could become men proper. These are:
1. The increasing size and development of the brain.
2. The increasing usefulness (specialization) of the thumb and hand.
3. The use of tools.
Nobody knows which of these three is most important, or which came first. Most probably the growth of all three things was very much blended together. If you think about each of the things, you will see what I mean. Unless your hand is more flexible than a paw, and your thumb will work against (or oppose) your fingers, you can’t hold a tool very well. But you wouldn’t get the idea of using a tool unless you had enough brain to help you see cause and effect. And it is rather hard to see how your hand and brain would develop unless they had something to practice on—like using tools. In Professor Krogman’s words, “the hand must become the obedient servant of the eye and the brain.” It is the co-ordination of these things that counts.
Many other things must have been happening to the bodies of the creatures who were the ancestors of men. Our ancestors had to develop organs of speech. More than that, they had to get the idea of letting certain sounds made with these speech organs have certain meanings.
All this must have gone very slowly. Probably everything was developing little by little, all together. Men became men very slowly.
WHEN SHALL WE CALL MEN MEN?
What do I mean when I say “men”? People who looked pretty much as we do, and who used different tools to do different things, are men to me. We’ll probably never know whether the earliest ones talked or not. They probably had vocal cords, so they could make sounds, but did they know how to make sounds work as symbols to carry meanings? But if the fossil bones look like our skeletons, and if we find tools which we’ll agree couldn’t have been made by nature or by animals, then I’d say we had traces of men.
The australopithecine finds of the Transvaal and Bechuanaland, in south Africa, are bound to come into the discussion here. I’ve already told you that the australopithecines could have stood upright and walked on their two hind legs. They come from the very base of the Pleistocene or Ice Age, and a few coarse stone tools have been found with the australopithecine fossils. But there are three varieties of the australopithecines and they last on until a time equal to that of the second alpine glaciation. They are the best suggestion we have yet as to what the ancestors of men may have looked like. They were certainly closer to men than to apes. Although their brain size was no larger than the brains of modern apes their body size and stature were quite small; hence, relative to their small size, their brains were large. We have not been able to prove without doubt that the australopithecines were tool-making creatures, even though the recent news has it that tools have been found with australopithecine bones. The doubt as to whether the australopithecines used the tools themselves goes like this—just suppose some man-like creature (whose bones we have not yet found) made the tools and used them to kill and butcher australopithecines. Hence a few experts tend to let australopithecines still hang in limbo as “man-apes.”