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Probaway - Eve

How we learned to walk on the ground among terrestrial carnivores.

© 2005 by Charles Scamahorn

The archeological record and the present morphologies of modern humans and modern pygmy chimpanzees show that our common ancestors lived in trees. What happened that permitted “our” ancestors to descend to the ground, become upright, develop larger brains and become humans? Why were we able to leave our cousins stuck in the trees with smaller brains and a more limited intelligence? It is mystery worth solving as that transition permitted us to come into existence and it underlies much of our uniqueness.

When animals live in trees, they fall out of them occasionally. If they happen to be small such as squirrels they are rarely injured by a fall but if they are large, more than about thirty pounds in weight, they do get injured and sometimes die of such falls. The brain in an arboreal animal is thus limited in size to one that will fit nicely into a body not exceeding thirty pounds. As a result, until an animal can descend permanently to the ground, it has a limited brain size and therefore a limited intelligence. Nevertheless, larger arboreal animals cannot descend to the ground for unlimited periods because their bodies, being adapted to moving about in the trees, are slow moving on the ground and they are easily caught by the predators who are much swifter in their own ideal environment.

For arboreal animals life in the trees is beneficent and in the tropical forests, where sufficient things to eat can be found, their life is safe and easy. However, occasionally a problem arises when they have to move from one tree to another, especially in those border areas near savannas. If the trees happen to be spaced too far apart for the chimp to make the trip arboreally, fully in the safety of the trees, it sometimes becomes necessary to descend to the ground and waddle over to the next tree. This experience can be life threatening if a surface-adapted predator is nearby. It is a difficult time even for unencumbered adults but for those who cannot move quickly, such as children or adults carrying infants, the trip, although short, may be nearly impossible.

Picture a moment, about six million years ago. A group of pygmy-chimps has eaten all the fruit from the tree in which they happened to be. They are ready to move on to the next tree, found some fifteen yards away, but as sometimes occurs a predator is lurking below, say a lion, “Leo.” Should they make a run for the next tree or wait until he departs? They break off some sticks and throw them at Leo but he does not go away, at least not very far. A couple of the bigger and faster males decide to run for it. They gesticulate wildly and throw a couple of rocks. As luck would have it, they do hit Leo. The stoning does not injure him but it does hurt. So he hunkers down and meditates on these painful experiences.

Next, a couple of the smaller adults try to cross over. They also gesticulate wildly, throw a few stones and get in a solid hit or two and make it across to the tree. Then comes poor little pregnant “Eve's” turn. She is smaller and slower than the males and she has the additional impediment of a child in tow. How can she possibly get across? She cannot! But she is hungry and thirsty. Her kid, “Cain,” is hungry too. He is screaming and there is nothing left in their tree to eat! What should she do? Eve descends and with Cain clutched in one hand, starts tentatively across. Leo, seeing a chance to catch the meal he has been waiting for, settles into his attack crouch.

Only one little rotten apple remains to be thrown. Eve picks it up, raises her arm and throws it. The apple bounces feebly off Leo’s nose. He blinks. Then in despair and defiance Eve raises her empty fist—and steps forward. She and everyone else who is watching expect him to charge and for her or Cain to be caught and eaten. Instead Leo hesitates! Why? Eve steps toward the new tree, he crouches warily forward and she raises her empty fist again and he hesitates yet again—how very strange! She walks the remaining few steps, waving her single upraised fist, to the safety of the new tree. The others of course marvel at this and imitate it with relish and glee. Every day after that, when they meet a predator, they throw rocks at it until they hit it and then do Eve’s special raised fist gesture. It works like magic! After the predators have been stoned, they always back off when they see the raised fist gesture—even though they haven’t been seriously injured by the previous pommeling.

Our first ancestors were now able to go from one tree to another in much greater safety and that enabled them to get more food, and more varied food too, as now they could move out on the open savanna where they had never dared travel before. Their cousins, in the deep forest did not learn the trick, due to their geographical isolation from the descendants of our ancestral group, and were thus limited to living close to trees as the pygmy chimps still do to this day.

At first this method was difficult and risky because it was necessary to train the predators with a few real hits but once they were trained they could be held at bay with a raised fist. Therefore, these first folks had to carry some rocks in their hands whenever they were on the ground. Carrying stones was not too difficult for knuckle walkers but it was also necessary to rear up on the hind legs much of the time and keep a fist raised whenever predators were nearby or else they would approach closer and closer and finally attack. Those who could stand on their hind legs and throw rocks lived on and reproduced but those who could not were soon picked off and eaten and left no progeny. At the first, walking even for short distances on two legs with one hand raised occasionally was difficult, but when predators were near, it was far safer than walking on three or four.

Once on the ground with the ability to fend off predators there was a tremendous selective pressure to build these qualities into the genes and morphology of the both group’s descendants. The predators descendants as well as the hominids. The predators at present seem to have learned to avoid people, especially those with uplifted arms even without being trained. Which suggests that that behavior has become imbued into their genes. But, it was much later and for other reasons that the hominids acquired their bigger brains. For a very long time these folks and their descendants got along just fine, spending a lot of time on the ground, with little to separate them from their arboreal cousins other than their special gesture, their increasing ease of upright posture and a little collection of throwable stones. Chimpanzees and baboons now have, or nearly have, these abilities and so, if we did not occupy our niche on the ground, in six million years or so, they might be gesturing with Apples and watching TV. Come to think of it—some already are.

Liability disclaimer statement: These Probaways contain new and unique information that has been created, tested and retested by me alone. You must approach these findings and materials very carefully as your results may differ greatly from my experience and I can offer no recompensation of any kind for any injuries.

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