We all "know" how apes became men, we just imagine that we are tossed out of the trees into the bare savanna. We then stood upright to overlook the grass to spot the hungry lions. Before the lions closed in on us, one bright member of our gang found a sharp stone to throw at them. Soon we ran out of sharp stones and we had to break some stones to make sharp weapons ourselves. Before tea-time we caught the last bus to "The Treetop Hotel", and that was our evolution in a nutshell.

This is the conventional wisdom version, and until lately science only offered variations on the above story as an explanation. The variations were about event what came first:

1. The shift from trees to the ground

2. The upright stance

3. Tool-use & society

4. The big brain

This 1-2-3-4 version was the original by Charles Darwin and later by Osborn.

Then came Keith with a 2-1-3-4 version with bipedalism developed in the trees. Imagine that!

Elliot Smith also carved a niche out by putting the big brain developed brain first: 4-2-1-3.

This left Smith Jones with a 2-4-1-3 version reversing Elliot Smith´s first factors.

So the gentlemen marked off their territories, the first scientists took the obvious version leaving the queerer ones to their successors. The public anyway felt that brain growth was terribly important and this could not happen soon enough. In the 1970´s a new theory by Owen C. Lovejoy blasted the old ones, claiming that too much brain development in the apes had driven their fertility rate down to a suicidal low level causing  the apes to be near extinction. The ape-experiment with bigger brains was clearly a failure compared to the plentyful small-brained monkeys that drove the apes into mountainous jungle (like the gorillas) or onto the ground like the chimps. The dramatic and fearful transition from trees to the ground is pure fantasy as the chimps master both levels without fanfare. Their problem is that they only have a child with 6 years intervals, a fatal risk for a species living one banana too far.

The small Bonobo-chimps even went matriarchal from patrical rule of the bigger chimpanzees. This fundamental change was not radical enough as the Bonobos also are threatened by extinction. Going bipedal was a radical solution to increase the fertility rate. With the erect posture the freed hands could carry food to the increasingly immobile bipedal mothers. The brain/bodysize rate development went up to a new plateau characteristic of the Australopedicines/prehumans. The brains now were bigger than the apes but it never reached human levels. The upright stance gave the prehumans a normal fertility-rate, and first then the prehumans could venture into the savanna. There was no place for  prehumans stumbling into the savannah as any sickly or undeveloped individuals are removed in nano-seconds by lions as the naturefilms so often tell us.

The Australopedicines was all about fertility with bipedalism restoring fertile normalcy so that  prehumans found a place on the savanna like all the other healthy animal species there. The inherent tedency of apes of having bigger brains was released in the Australopedicines but thier million years long reign in the savannah was marked by their brains only growing at the rate of their increasing body-size. Their succes was rather that they pushed by their own fertility could develop an increased utilisatization of their living space by altering their teeth and jaws. They lost their long apelike incisors to make a grinding motion of their jaws possible. Their "human-like"parabolic jaws were a result of their new small incisors and they developed millstonelike molars to utilize ever coarser plant food. The result was that the Australopedicines became ever more plentyful as they developed to ever more specialized plant eaters. It is almost a mystery that such succesful savanna-dvellers don´t live there today. What happened?

It would be tempting to say the usual bit about be too specialized. But it is quite possible that they were killed by the smarter humans that for million of years had co-existed with them? But what was the origin of humans? Countless explanations like change in climate, habitat, or whatever circumstances outside the prehumans themselves have been suggested. These are all less likely than an inherent trait in the near-apes themselves, namely the recurrent clash between brainsize and reproduction rate that can be traced back to Australopedicines, the apes back to the monkeys. The prehumans gained a higher proportional brain/bodysize ratio by becoming more fertile; when the fertility gain had had its run the other shoe dropped: a further gain in the brain/body rate was gained by reducing the fertility rate again, the pendulum between brain & fertility had swung with the humans as a result. The apemothers of these protohumans via a hormonal "warfare" again the fetus in the womb produced non-reproductive gays. The fertilityrate dropped, a "third sex" with valuable properties and bicameral brains were created so that the survivability of these flocks were increased. The braindevelopment inherent and recurrent in the ape-tribe had here found another escape hatch making the bicameral gay early humans the avenue for the increased brain/bodysize of humans.

The bipedalism of prehumans made a higher brain/body-ratio possible by increasing the fertilityrate. When this was completed it was a reduced fertilityrate that made even bigger human brains possible. This is at least a beautiful argument as it refers to itself as the circle is closed, but at a higher and higher level like a fugue. The fertile bipedals were made out of an inner necessity to develop an ever growing brain, and the fertilityrate were reduced to the same effect: the nature had again shifted gears using the fertilityrate. This explanation of brainsize linked to fertility rates is more parsimonious than the universal accepted link of brains to tools. Apes uses tools, the Australopedicines possibly also did so the link of tools to brainsize is not clear as it had been millions of years in the making. The unique experiment of the brainy apes has always been linked to fertility, the chimps, the bonobos, the Australopedicines and of course the humans. The increased number of gay apes had a more "cultural" brains as history tells us in modern times. The gay brain need not necessarily to have to have a higher IQ, the increased diversity  of 3 sexes inside the species was enough to be evolutionary significant. That and their different brain were the origin of homo.

    Origin of Homo