The Mammoth Encyclopedia of Unsolved Mysteries (63 page)

At some of the australopithecine sites, Dart found baboon skulls with a kind of double depression in the back. And the discovery of antelope front-leg bones (
humeri
) at these sites suggested to Dart that these early ape-men had used the bones as clubs. It led him to publish, in 1949, a highly controversial paper entitled. “The Predatory Transition from Ape to Man”, which argued that human intelligence had developed through the use of weapons. Wielding a club, Dart maintained, requires a certain degree of coordination between the hand and the eye. In short, Dart was suggesting that man evolved because he was the descendant of some primitive killer ape, while his more peaceful brothers stayed in the trees and developed into modern gorillas, orangutans, and so on. Dartian man went on to develop tools – stones with their edges chipped off to make primitive axes, which could be used to extract marrow from bones – about two million years ago.

Dart’s version of human evolution was popularized in 1961 by the playwright-turned-anthropologist Robert Ardrey, in a book entitled
African Genesis
. This, briefly, is how Ardrey sees human development: About fifteen million years ago, in the Miocene era, Africa was still covered with lush forests. Twelve million years ago the rains stopped, and the Miocene gave way to the long droughts of the Pliocene era. At some point in the Pliocene era, our human ancestors descended from the trees to take their chance on the savannahs. These became the two types of
Australopithecus
– the meat-eating “Dartians” and the vegetarian
robustus
. During this period, Ardrey believes, the “Dartians” learned to use weapons like bone clubs.

Then, about a million years ago, the rains came, and the Pleistocene era began. It was the bad weather, Ardrey thinks, that led man to develop his intelligence. Pebble tools made their appearance. So did hand axes. The gentle
robustus
vanished as rains gave way to periodic droughts, but “Dartian” man, the “bad-weather animal”, survived. And because his chief evolutionary advantage was his aggression, his killer instinct, he gradually became the most dominant species on earth.
This, Ardrey suggests, is why his greatest problem in our modern world is that he will exterminate his own species.

It is a gloomy picture, and it can hardly hold any comfort for antievolutionists who are pleased that we are
not
descended from the ape. But it is not necessarily the last word. Richard Leakey, son of the eminent anthropologist Louis Leakey (whom Ardrey quotes extensively), has argued that all the evidence shows that our primitive ancestors were peaceable creatures and that it was not until he began to create cities – with their overcrowding and other problems – that man became cruel and destructive. And the Finnish paleontologist Björn Kurtén developed his own views in a book entitled – significantly –
Not from the Apes
(1972). This, in summary, is his view:

Our tree-living Ramapithecine ancestors of about fifteen million years ago (in the Miocene era) were furry creatures about the size of a modern-day five-year-old child; but they had forward-looking eyes and human teeth. Kurtén suggests that these highly social creatures developed a “call system” – of warnings and so on – that developed into language. They became capable of “simple thought processes”.

With the coming of the droughts – and the savannahs – of the Pliocene era, these creatures came down from the trees – not because they were driven down but because the savannahs offered a richer way of life. The baboons descended from the trees at about the same time. But the baboons remained four-legged herbivores, while the manlike primates became two-legged carnivores. Their upright posture allowed them to see farther into the distance – an advantage for hunters. The need for periods of violent activity – chasing small animals for example – led to the gradual loss of fur.

Since the wandering life was hard on women and small children, the band was inclined to find itself a semipermanent home. The men went hunting while the women remained behind. Family life developed, and two-parent families became the nucleus of the population. Sex played an increasingly important part in their lives, instead of being a “sideshow” (Ardrey’s phrase), as it is for animals in the wild. Thinner fur made skin contact more sensuous. Because they walked upright, face-to-face mating gradually replaced sex from the rear. Lips became fuller and female breasts developed. (Kurtén acknowledges that he owes this idea to Desmond Morris’s
Naked Ape
.) And at this point, Kurtén agrees that the ability to manipulate weapons caused a development of intelligence. Something very like speech evolved from the “monkey chatter”.

Homo erectus
came into being about two or three million years ago and coexisted with Dartian man. But while Dartian man had a brain size of
about 500 cc, the brain of
Homo erectus
slowly developed until it reached 1,000 cc around 400,000 years ago. There it stopped, and
Homo erectus
gradually faded out.

But about half a million years ago a new species,
Homo sapiens
, came on the scene – no one quite knows how. (One scientist, Allan Wilson, has even suggested that
Homo sapiens
developed from
Homo erectus
in Australia.) What we do know is that his brain developed from
Homo erectus
’s 1,000 cc to modern man’s 1,800 cc in such a short period (in evolutionary terms) that scientists speak of “the brain explosion”.

What caused this brain explosion? We now know enough about evolution to know that things do not just “happen”. Evolution is not “natural”; the shark has remained unchanged for 150 million years. Kurtén has nothing much to suggest, except to point out the obvious – that our evolutionary capacities are drawn out of us by changes in the environment (like the bad weather of the Pleistocene). But as far as we know, there have been no such changes in the past half million years, except a succession of ice ages. It is possible, of course, that these “pressured” man into developing his brain; but it seems more likely that they would favour the development of fur or hair. Ardrey even suggests the possibility that the brain explosion may have been connected with a huge meteor that exploded over the Indian Ocean about seventy thousand years ago (its remains, called
tektites
, can still be found scattered over twenty million square miles) and caused a reversal in the earth’s magnetic field. He suggests that if the earth had no magnetic field for a brief intervening period, a rain of cosmic rays may have caused genetic changes in human beings.

Another anthropologist, Otto Kiss Maerth, devoted a book entitled
The Beginning Was the End
(1971) to the theory that human evolution was due to cannibalism – discoveries near Peking in 1929 seemed to show that the ape-men of six hundred thousand years ago ate the brains of their enemies. Maerth suggests that eating brains stimulates both the intelligence and the sexual instinct and that this explains the brain explosion. The objection to this theory is that there is not enough widespread evidence for cannibalism and the eating of brains to account for human evolution.

Ardrey has a more plausible basic hypothesis, which he calls “the hunting hypothesis” – the notion that men had to learn social cooperation because they had to learn to hunt together. But Ardrey had originally suggested that Dartian man became a carnivore during the Pleistocene era (in the past million years), when droughts made vegetation scarce. When Louis Leakey discovered evidence at Fort Ternan, in
Kenya, that
Ramapithecus
was a meat eater nearly fifteen million years ago, that view was undermined; yet it only increased Ardrey’s conviction that the “hunting hypothesis” explains human evolution. What he failed to explain was why wolves and other animals who hunt in packs have not evolved to the human level.

In fact, this problem has almost certainly been solved by an experimental psychologist named Nicholas Humphrey, who studied the brains of mountain gorillas in Rwanda, in central Africa, and wondered why they had such large brains when their lives are so crudely simple – eating, sleeping, and moving on to new feeding grounds. The answer came as he observed the gorillas closely and noticed their incredible sensitivity to one another’s feelings. The most important thing in a gorilla’s life is its relation to other gorillas. A gorilla’s family life is the equivalent of a university education; it learns to react delicately to the moods, feelings, and reactions of other gorillas. If Humphrey is correct, then the size of the brain has something to do with the complexity of social relations.

The “Humphrey theory” of evolution, then, would run like this: As man became increasingly successful because of his prowess as a hunter, his numbers increased, and social intercourse with other groups became increasingly important. As sensitivity and cooperation became survival factors, the brain flourished.

Yet the “hunting hypothesis” may pave the way to the next step in the argument. If Kurtén is correct in his belief that Dartian man ceased to be a wanderer in the Pliocene era and began to leave the women and children behind while he went hunting, then this would apply even more so to
Homo sapiens
during the great droughts and ice ages of the Pleistocene. Most anthropologists seem to recognize that sex played a basic part in human evolution – from Kurtén and Morris to Maerth, with his brain-eating theory. As Ardrey points out, sex is a sideshow in the world of nature. Wild animals only become interested in it when the female experiences her periodic cycle. But at some point in his evolution, human sexual desire became independent of that cycle, and man began to have sex at all times
except
when the female was menstruating. It seems logical to explain this in terms of the hunting hypothesis. If a hunter had been away from home for weeks, then he would expect to make love to his mate when he returned, whether she was “in heat” or not. Some females would naturally object to this; but they would have fewer offspring than the females who had no such objection – or swallowed their dislike – and eventually, the objectors would die out.

What no one seems to have recognized so far is the importance of sex
as an “internal” factor in evolution. When an animal has nothing else to do, it lies down and yawns. When a man has nothing else to do, his thoughts turn as often as not to sex. If there is a pretty girl in the vicinity, he may begin to brood on seduction – even if he happens to have a wife already. If he is too shy or otherwise inhibited, then he may simply daydream about sex. From being a “sideshow”, sex has become one of the central interests of human existence.

Now if we imagine Stone Age hunters in a period of scarcity, we can see that they may have had to have spent longer and longer periods away from the women and children of the tribe; a hunting expedition might have lasted a month or longer. Back at home, women were now permanently receptive and were consequently beginning to develop the sexual characteristics males found exciting – larger breasts, full lips, rounded buttocks. When the males came back from a long expedition, some skinny adolescent girls had suddenly begun to change into desirable women. The presence of these unattached females must have introduced an element of competition and excitement. Young men now had good reason for wanting to become successful hunters and fighters – it gave them the pick of the girls.

We note another interesting thing about human beings: that from babyhood onward they have a tendency to idealize possible mates. Little boys fall in love with the prettiest girl in the class and daydream of being cowboys who rescue her from a band of marauding Indians. We do not know, of course, whether dogs and cats experience these emotions, but it seems unlikely. As far as we can see, it seems to have been sex that taught human beings to use the imagination.

This means that, to a large extent, sex provides us with goals and objectives, even when there are no other stimuli. It is an “internal” factor in evolution, a psychological drive that operates most of the time. It could be the factor that explains why man became an “evolutionary animal”, an animal who went on striving even when he had a full belly.

Kurtén seems to skirt these ideas when he remarks: “Another semi-solution [to the problem of evolution] was the idea of an inner force of evolution, the
élan vital
, which would automatically carry us forward to new heights of nobility and spirituality. Unfortunately there is no evidence whatever for the existence of such a force”. But sex is precisely such a force, as Goethe recognized when he wrote: “The eternal feminine draws us upwards and on”.

In the previous paragraph Kurtén had dismissed another possibility: that by improving themselves, human beings produce better offspring. This is known as “the inheritance of acquired characteristics” and is a
theory of evolution that was suggested by Darwin’s predecessor, Lamarck. The simplest illustration of the difference between the two theories is the problem of how the giraffe came to have a long neck. According to Darwin, food shortages due to drought caused the original short-necked giraffes to become extinct. But the giraffes who,
by chance
, happened to have longer necks, were able to reach the leaves on higher branches and so survived. And eventually, all giraffes had long necks. Lamarck’s view was that when food became scarce, giraffes had to make strenuous efforts to reach higher branches, and these efforts gradually lengthened their necks.

The discovery of the genes (by Mendel) made it look as if Darwin was right and Lamarck wrong. For genetics seemed to prove that, even if a giraffe could stretch its neck by effort, it could not transmit this long neck to its children, whose genes would ensure that they had short necks.