Abstract

Contents Updated: Wednesday, December 15, 1999

"Darwinian Man, though well behaved, At best is only a monkey shaved!"

A Thinking Mammal

Lucy is the name Johanson gave to the fossil remains of an early hominid later shown to be some four million years old. The skeletal fragments were of a female and, when the prospectors returned to camp to tell of their discovery, a tape recorder was playing the Beatles’ recording of Lucy in the Sky with Diamonds. And so the remains were christened “Lucy”.

Johanson had woken that day feeling that “something terrific might happen” and, although pressed by organizational and bureaucratic work, he had agreed to go with a young graduate student, Tom Gray, to show him a site called Locality 162. After four hours on site they were beginning to get tired in the hot Ethiopian sun. Still feeling lucky, Johanson determined to take a quick look at a small gully that had already been expertly surveyed no less than twice by other members of the expedition. The pair were just about to leave when Johanson casually said to Gray, “look, that’s a bit of hominid arm”.

One of the most significant finds in human prehistory had been made and on a site that had already been thoroughly surveyed, just because a young and relatively inexperienced team leader had a hunch and felt lucky.

Lucy is the most complete ancient human skeleton yet discovered. She was 40 per cent complete, an hominid, that is an erect walking primate (her pelvis had fully adapted to the upright stance), only about four feet tall but full grown. In fact she must have been aged at least 20 because her wisdom teeth had erupted fully. Her head looked primitive and her brain was not much bigger than a chimpanzee’s with a volume of about 400 cm³. She was a four feet high ape with a human looking body but underdeveloped skull and brain. The human race obviously still had a long way to come in the four million years between then and now, but Lucy already showed clear distinctions from the other apes. The shape of her hip bones and her upright posture signal Lucy (or Australopithecus afarensis, to use the scientific name) as being closer to us than the chimpanzee, the closest living relative of man.

Though the difference between humans and chimpanzees is only about one per cent according to protein and DNA matching, the physiological and cultural differences are astonishing. Skeletal structure and posture, skin, muscles, brain, intelligence, speech, ability to make tools and social organization all differ remarkably for such close relatives, showing that humans have differentiated themselves very distinctly from other apes, including Lucy, in a puzzlingly short time. What difference of habitat or experience initiated these changes from the ancestral common stock, and what continued them after her? These are admittedly difficult questions to answer but perhaps an examination of the history of the primates, the mammalian order to which we belong, from the demise of the dinosaurs to the present time will yield some clues.

The very name “primates” betrays our self-centered view of the world. The order of primates is the first, the prime order, because we are in it. It comprises some 200 species whose characteristic features are binocular vision and grasping hands. Some of the diminutive mammals rather like shrews that inhabited the earth during the time of the dinosaurs took to the shrub and then, at about the time of the dinosaurs’ death, to the trees to become the forerunners of the primates.

These early arboreal mammals were insectivores needing to grasp and move quickly while not falling from the branches. By about 55 million years ago, they had developed the primate grasping hand with its nails instead of claws and a partly opposable thumb. Hands reduced the need for a snout with which to explore, and reduced the need for teeth—jaws became smaller. Their short snout and large, widely spaced eyes meant that vision was more important than smell. To catch insects efficiently and to leap accurately they had evolved binocular vision. The field of view from both eyes overlapped giving them a three dimensional view of the world so that they could accurately judge distance. The movement of the eyes to the front of the skull allowed the braincase and therefore the brain to enlarge.

The ancestor of the primates would have looked rather like the tarsier or, more so, the curious, primitive tupaia of South East Asia. The tarsier has immense eyes for its size (it is nocturnal) but its other features are plainly primate. The tupaia has long separable fingers but no opposable thumb and therefore has no grasp. It has claws instead of nails. It has large eyes but their fields of vision do not fully overlap. It has a snout and a keen sense of smell, and it lives mainly on the ground, though sometimes it runs up trees like a squirrel.

From such a creature evolved the prosimians, the pre-monkeys, of which the lemurs are one group. Through continental drift, Madagascar split from Africa about 55 million years ago and carried with it the primates then living there. Those left behind on the African mainland evolved into monkeys and the rest of the primate line but in Madagascar lesser changes took place. Pressure of competition was less keen and Madagascan lemurs remained essentially unchanged until today, although they did adapt to a variety of ecological niches.

The Madagascan ring tailed lemur has grasping hands with opposable thumbs and nails not claws. Their babies use their hands to cling tenaciously to their mothers. It has binocular vision, it is social and attentive to its offspring, but, on the ground, it walks on all fours. Another Madagascan lemur, the sifaka, can stand on two legs but cannot walk—it leaps along the ground as if it were leaping from branch to branch.

Meanwhile, on the mainland of Africa, about 40 million years ago monkeys evolved, derived it seems from ancestors that split from the lemurs much earlier. Their success drove the African lemurs into the night—they became nocturnal. All African monkeys are active during the day, and to take advantage of the daylight have evolved color vision, a boon for spotting ripe fruit. However they lost much of their sense of smell, unlike the lemurs. Color vision led to them using brightly colored features to signal their species, their sexual receptivity, and to distinguish friends and enemies. They also became raucous chatterboxes with a varied vocabulary of sounds, important for the emergence of speech.

Primates have tended to increase in size as they evolved. 30 million years ago some primates got too large to walk on all fours on the branches like monkeys and instead took to swinging beneath them—these became the apes. Today’s orangutans are the largest tree dwellers. At over 400 pounds they have reached their limit. Gorillas are bigger but they do not swing in trees as adults. A third of adult orangutans have broken bones. As they grow up they must often experience branches breaking under their weight. Adult orangs swing about in the branches of the tree they are already in, because they can feel the strength of the branches as they grip them. But, rather than making a bold swing to the next tree and risking a branch they have not tested, they descend to the ground and walk.

The step from monkey to ape required a change in mobility at the shoulder and adaptation of the muscles of the abdomen to the upright rather than horizontal posture. 20 million years ago apes were common—monkeys were rarer. Only from about ten million years ago has the situation reversed. In the intervening period significant changes occurred. The linking of land masses gives an opportunity for evolutionary divergence and it was about 18 million years ago that Africa collided with Eurasia causing a flurry of evolutionary activity. Antelopes, pigs, elephants and rodents have all evolved since then.

Part of the reason for this was the evolution of grass from about 24 million years ago, the potential of which was achieved only when the world became colder and more arid 15 million years ago, providing an environment to be exploited by the grazing animals.

David Pilbeam, an Englishman teaching anthropology at Yale, has shown that by ten million years ago there were two major groups of apes, the dryopithecines having apelike teeth, and the ramapithecines, having human-like teeth with reduced canines and a flatter face. If their teeth differentiated dryopithecines and ramapithecines, a significant change of eating habits must have led to their evolutionary separation. Ramapithecus proved a very successful ape, its remains having been found in Europe, Asia and Africa. But despite its teeth, a carefully reconstructed specimen looks too like an orangutan for it to be a sure ancestor of human beings. The teeth remain a puzzle. Why do they look so human?

The Taung baby mentioned above was a much later type of ape (later even than Lucy) called Australopithecus africanus or A africanus for short. Its teeth, says Don Johanson, a teeth and jaws specialist, are “very similar” to those of ramapithecus. Perhaps a link is still possible. In the four million years separating ramapithecus and Lucy, even the experts speculate unashamedly simply because there is no evidence.

Gribbon and Cherfas have suggested that the original brachiating apes, similar to orangutans or gibbons, emerged near the Indus which was then surrounded by dense forest. From there the apes spread out. Some moved Eastward through lush rainforests, ideally suited to them, to Indonesia where they still live relatively unchanged—the orangutan and the gibbon! Others migrated Westward via Arabia into Africa. They did not meet such familiar conditions. As they slowly migrated, the forests disappeared through increasing desiccation and the apes found themselves having to spend more time on the ground. By the time they reached Africa they had become knuckle walkers, and eventually chimpanzees and gorillas. Some chose to shelter in what woodland or forest the could find but others adapted to open grassland.

Orthodox savannah theorists believe that the apes were already in Africa but increasing desiccation forced some of the forest apes to adapt to woodland then to open country. A gradation of evolutionary niches were thus occupied by the apes; the apes which stayed behind in the deep forest became today’s gorillas, in woodlands were the chimpanzees and on the savannah, man’s family, the hominids.

The grassland’s new visitors lacked the obvious requirements of success on the plains, being slow, unarmored, relatively weak and without claws or powerful teeth, unlike their competitors already there, but they survived and had made the transition by the time of Lucy. They must have had some advantages. What were they? Are they factors in the growth of intelligence?

Desmond Clark has put forward one intriguing speculation based on tentative evidence. He found burnt tree stumps associated with remains of fossil hominids four million years old. Did Lucy’s contemporaries already use fire, keeping flame going by keeping tree stumps alight as farmers do today in India? If the answer is “yes”, fire could have been the vital factor that allowed hominids to move on to the savannah without having to fear predators. Domesticating fire might have been the essential step to humanity, and it might have happened very early on. A thought which must be regarded as not yet proven.

Other advantages were more evident: their binocular vision; their manipulative hands able to grasp a branch or a stone; their brachiating arms giving them the ability to brandish sticks and to throw stones; their well developed brains. Once on the savannah, lack of the usual specializations for grassland living forced them to compete by using these other advantages and by developing new ones, amongst which was the ability to stand erect. The apes had to be wary, and to use their keen vision to maximum advantage they had to stretch to their full height to look out for approaching cats or hyenas. They took to walking bipedally, a habit which then proved to have other advantages. Hands and arms were permanently freed to grasp and wield the natural weapons that lay about and to allow the apes to change and improve those weapons. Groups of the new savannah creatures could, with the aid of stones and sticks, keep off dangerous predators. They also found that, with stones they could stun and maim at a distance. A well thrown stone is a remarkably good weapon. As Richard Leakey puts it:

The extraordinary ability of modern humans to throw objects with force and with astonishing accuracy, even at moving targets is interesting… The brain mechanisms that underlie this unique accomplishment may have their evolutionary roots in the hunting activities of Homo erectus[†]Homo erectus. The variety of man that went before us..

The sort of skill Leakey means can be seen on the cricket field and the baseball diamond where outfielders can place the ball with amazing precision even from distances of 60 or 70 yards.

Having learned a variety of hunting skills, meat would have given the savannah apes an additional advantage because the energy and protein of meat is concentrated. But the gathering of fruit, roots, berries, grubs, insects and fungus would have continued to provide their basic needs.

In the gap in the fossil record between ramapithecus and Lucy when did the forest and savannah apes separate? Differences in DNA show that mankind is more closely related to the chimpanzees, the common chimp and the pygmy chimp, than the other great apes. Man is the third species of chimpanzee, or alternatively, chimpanzees are two other species of men. They differ less in DNA than do some populations of the same species. The three parted company with their next closest relative, the gorillas, about nine million years ago. Carl Linnaeus, the founder of modern taxonomy, classified mankind into a special category. Regretting his decision later, he said:

If I had called man an ape, or vice versa, I would have fallen under the ban of all the ecclesiastics. It may be that as a naturalist I should have done so.

Had Linnaeus had the courage to defy the churchmen, we might now be less anthropocentric, more humble and have more empathy with the other inhabitants of the planet.

I noted above that Sarich and Wilson found mankind and the chimpanzees to have separated as little as five million years ago. More unusual evidence of the date of our separation from the apes comes from DNA studies of the herpes virus. Herpes simplex causes cold sores and genital warts in primates. Though a single species, it exists in humans as two races each with its own preferred site for colonization. In the other apes, it exists as only one variety and does not mind whether it is introduced to the oral or the genital region. Why are there two herpes races for humans but only one for the other apes? Herpes is only transmitted by intimate contact—in the apes by sexual contact. Female apes are only in oestrus occasionally and male apes, like many other mammals, use their noses and tongues to determine when the female is becoming receptive. The virus has plenty of opportunity to get from one orifice to the other. Human females however are receptive all the time. The male has no need of a test for oestrus. Kissing became the main show of interest and affection. Human behavior cut down the opportunities for the virus to swap sites. Over several million years the virus has begun to evolve into separate species, one suited to genital transmission and one suited to oral transmission. Speciation is not yet complete possibly because oral sex, though serving no obvious purpose, is still indulged in by some humans for pleasure, an evolutionary anachronism. An American team of microbiologists have used the molecular clock to date the human herpes virus to somewhere between 7.5 and 10.7 million years ago. This is earlier than the more direct estimate of the antiquity of mankind but ties in well with the gap between ramapithecus and Lucy when the human line probably separated. Possibly, the apes’ behavior patterns were changing before the separation of the hominids occurred so that the emergence of the herpes races pre-dated it.

Interpolating as best we can, the hominids appeared perhaps seven million years ago, near the start of the gap in the fossil record which lasts until the time of Lucy (A afarensis).

Not all hominids were man’s ancestors. Some apes that made the transition from the woodlands (or evolved from the ones that did) failed to learn how to make stone tools and became extinct. Johanson and White regard A afarensis as ancestral to Homo, the species of men, and also to A africanus and A robustus, the extinct lines. The Homo branch split off about three million years ago and the result was ourselves. The Australopithecine line proved a dead end when africanus evolved into the more specialized robustus. This became extinct about a million years ago possibly because of the unwelcome attentions of hungry Homo, and competition in the same ecological niche from some monkeys, which, faced with the same problems as our ape ancestors about four million years ago, moved to open country, sleeping in trees and caves. They were baboons.

Walking upright preceded any other human traits—kissing would have accompanied this change. A afarensis stood fully upright but was not regarded by Johanson and White as Homo. If it were then all its descendants, the other upright Australopithecines, including robustus, would also have to be classified as being Homo. The key distinction between the Australopithecines and Homo is that only Homo seems to have made stone tools. Not that the Australopithecines did not use tools. Fairly surely they used what they found about them, perhaps even more so than chimpanzees which use objects found around them as tools and weapons, and can even fashion simple tools by stripping leaves from sticks. But only Homo has left evidence of manufacturing tools, by knapping stones, from about two million years ago onwards. Australopithecine hominids had been around for one or even two million years before tools are found, indicating that they did not invent them.

Not all anthropologists accept these ideas. Some believe that A africanus is indeed in the human line and did make a very simple stone tool by striking a stone to give it a sharp edge. They argue that this released the brake on the evolution of intelligence and progress speeded up leading to man. Only A robustus split off into an evolutionary dead end by sticking to a diet largely of fruit and leaves. With this diet they did not need to make tools and eventually, becoming easy meat for their brighter cousins, were hunted to extinction.

According to Johanson and White’s hypothesis, Homo and either one or the other of the Australopithecines lived in the same parts of Africa at the same time. Others believe that both A africanus and A robustus were contemporaries of early man. Obviously something must have occurred to distinguish such similar species all with the same ancestor and apparently inhabiting the same region at the same time. Had they been, at some stage, physically separated for long enough for speciation to occur? Or could speciation have occurred without such separation? According to some savannah theorists, natural barriers such as the rift valleys, rivers and mountains of East Africa could have isolated groups of apes for long enough for speciation into the Australopithecines and Homo to occur. The distinctions between them were then maintained through habitat and diet. For other savannah experts, these latter would have been sufficient for speciation without physical separation.

In Johanson’s view, A afarensis, an upright ape, differentiated by diet into two races that speciated ultimately into A robustus, an upright ape, and H habilis, the first man.

A robustus had a massive jaw. Its jaw muscles were so large they required a bony ridge along the top of the skull to anchor them. Their teeth were large and smooth. Microscopic examination shows marks similar to those on the teeth of a chimpanzee whose main food is fruit supplemented by a variety of other items such as eggs, ants, small mammals and lizards, but not roots, the grit of which causes deep scratches. The massive jaws, teeth and jaw muscles suggest a bulky diet of low grade food requiring a lot of chewing—probably fruit and leaves. H habilis was more omnivorous. Examination of their teeth shows them to be deeply scored like those of a rooting animal. A pig, for example, has scratched teeth from the grit it eats with its diet of roots. Early humans must therefore have taken a lot of grit with their food suggesting roots, meat—probably largely scavenged—and possibly dung. It is humbling to think that we might have set out as eaters of other creatures’ faeces!

H habilis used a fairly simple tool consisting of a rounded stone knapped on one side to give a sharp edge. The rounded side was held in the hand while the tool was used for scraping and cutting. Nigel Calder describes H habilis as “>mutant apemen with overgrown heads and an unprecedented ability to enlarge their brains after birth”. A modern human baby has a head only the size of an ape but it grows to three times its birth size during childhood, the greatest enlargements being in the region which has to do with solving problems and language. Nevertheless H habilis brains were only about half the volume of those of modern humans.

Their successors, H erectus, were hunters not scavengers. They were cleverer and used a hand axe, a stone chipped to a point and held, club-like in the palm. Cutting tools were important to herbivores turned meat eaters. Chimps and baboons, though they might have had the same intellectual potential, did not have the same incentive to make cutting tools as the weak toothed apes. They had no need to invent tools to help them eat meat because their teeth were strong enough. The simplest tools were stone flakes used to cut strips from carcasses.

A microscopic examination of stone chips can be used in the same way as a microscopic examination of teeth. It can reveal what materials they have been used on. An examination of stone chips from 1.5 million years ago shows that some were used for meat cutting, some for grass cutting, showing that gathering had become quite sophisticated, and some for wood whittling suggesting the use of wooden tools like wooden spears.

Between 1.5 and one million years ago, Homo erectus, the first true men, definitely used fire. From Homo habilis until the present day teeth have become smaller by 40 per cent mainly through the use of cooking to tenderize meat and vegetables. The increasing diet of meat might have served to distinguish one of the savannah hominids and provided a stimulus for the development of the tools to process it.

With all this manual activity, refinements of the hand and corresponding changes in the centers of the brain coordinating the hand led to Neanderthal man, who reached Europe 600,000 years ago, able to make sophisticated stone tools. Despite the brutal looking drawings of him in many books, Neanderthal man was probably of the same species as us although his bone structure was somewhat heavier. 200,000 years ago he painted the first pictures on the walls of caves. Arguably it is art that truly distinguishes mankind. Though several other animals can use tools of a sort, no other creature can make recognizable images. H sapiens neanderthalensis were also the first humans to bury their dead with tenderness and ritual. Bodies were laid carefully in their graves and decorated with freshly picked flowers.

But inexorably the human animal continued to evolve into new varieties and about 100,000 years ago Homo sapiens sapiens, anatomically modern man, arrived on the scene in Africa. It was to be another 60,000 years before he made a real impact. By 34,000 years ago Neanderthal man was extinct.

And so we come to civilization. Jericho was the first town with a population of 2000, some 11,000 years ago. Catal Huyuk, in present day Turkey, was the first city, 9000 years ago, with a population of 5000. Cities introduced the diseases of civilization, diseases of overcrowding and insanitation, of stress and pollution—venereal disease, plague, cancer, heart attacks, psychoses and warfare. The modern world had begun. Mankind, simple hunter gatherers, ate of the fruit of the tree of knowledge, noticed their nakedness and left the Garden of Eden. With their new found knowledge they invented agriculture and had to toil in the earth from dawn till dusk. But they had discovered an economic system that provided for the exponential growth of human population: 10,000 years ago there were less than ten million people in the world; today there are six billion.

This is a long story. It is a remarkable story—remarkably detailed. But is it true? No doubt we can have confidence in the narrative over the last few tens of thousands of years, but what of the previous ten million years? 40 per cent of the skeleton of Lucy was found, an astonishing proportion, for the truth is that everything we know about human evolution depends upon very few remains indeed. Lucy is the only skeleton of a species, likely to be in the line of man, living between 75,000 and 3.5 million years ago, that is anything like complete. The rest of the remains that this construction is based upon are merely fragments—mainly of skulls.

Don Johanson and Maitland Edey have noted: “postcranial remains were horribly scarce”. David Pilbeam and Stephen J Gould put it more scathingly:

Human paleontology shares a peculiar trait with such disparate subjects as theology and extraterrestrial biology: it contains more practitioners than objects for study.

Baron Cuvier could have felt quite happy about this situation, “We have half of a jawbone… There can be no doubt, the creature looked like this”. But maybe some experts today are learning how to be humble. Richard Leakey argued in the Scientific American in 1978 for the need for…

…caution in the making of taxonomic judgments… when the evidence at hand is a few isolated teeth.

Or in the blunt words of Clark Howell, Johanson’s teacher, and a most respected anthropologist, “you can’t tell a great deal from a single tooth”, a direct contradiction of Cuvier’s dictum.

Not only hominid remains are scarce, so are remains of our cousins the great apes—Johanson tells us that no fossil chimpanzee skull has ever been found. Over the 50 million years from our lemur like ancestors there are only six or seven distinct skulls which can be identified as stages in the evolution of man. Between Lucy of four million years ago and an ape found by David Pilbeam harking from about eight million years ago there is that vast gap in remains. We see the story of man told on television by polymath television personalities, but their reconstructions of human evolution are largely fantasy—simply because the supporting material has not been found.

As Lyall Watson so pictorially points out in Earthworks, his 1986 book:

All the physical evidence we have for human evolution can be put, with room to spare, into a single coffin.

What then of the story of man I have just related? Gribbon and Cherfas in The Monkey Puzzle, admit that though…

…many ordinary people believe that the riddle of human origins has been solved, in no case is this true, and all the ideas in print today—including our own—are more or less naked speculation.

From all this, students of human evolution have little reason to be dogmatic about their assertions. If their conjectures are accurate, it is not because they are based on unequivocal evidence. As Richard Leakey says with refreshing candor:

We [must] remain fully aware of the dangers of drawing conclusions from evidence that is so incomplete.

The paucity of hominid or prehominid remains contrasts with the richness of the dinosaur remains, perhaps surprisingly since mankind evolved sometime in the most recent ten million years whereas dinosaurs died off 65 million years ago. However our search for the intelligent dinosaur is not made easier for that simply because we are not comparing like with like.

• The period we are looking at for dinosaurs covered some 140 million years compared with about ten million for man’s development.
• The term dinosaur covers very many species whereas we are looking specifically for only a few in looking for man’s ancestors.
• The geographical distribution of the dinosaurs was virtually the whole world while man’s ancestors were localized.
• The population of the dinosaurs was huge while the first men by definition must have been small in numbers.
• Finally, the likelihood of any creature being fossilized depends upon the conditions where it died.

Mankind’s ancestors, it seems, were not easily fossilized. Despite an abundance of dinosaur remains compared with remains of human ancestors, there must have been many dinosaurs that lived and left no trace—or very little. At best there may be few fossils of the ones we would like, those ancestral to the intelligent dinosaurs, for the same reasons that there are so few fossils of pre-humans. But there are so few fossils of hominids that our speculations on the evolution of intelligence dinosaurs are scarcely less credible than the anthropologists’ on the evolution of mankind. Don Johanson tells us:

We do not have, even today, an agreed on definition of humankind, a clear set of specifications that will enable any anthropologist in the world to say quickly and with confidence, “This is human; that one isn’t”.

The experts cannot agree. What then does human evolution tell the layman about the features that are singularly human, or are the key to human success? In scrutinizing the evidence for the aquatic phase of human development later in this book, we shall identify a lot of peculiar characteristics humans have that other apes lack. Is just one of them the key to human intellectual development, or is it rather a complex of features?

Mankind’s legacy from the primate founder, the small nocturnal tree dweller which survived the disaster of 65 million—BC, comprised the grasping fingers and opposable thumb, with nails instead of claws. Later primates added first binocular vision then, when they became diurnal and fruit eaters, color vision. Subsequently they developed in size, intelligence and social behavior diverging to orangutans, gibbons, gorillas, chimpanzees and men (all apes), and baboons (a monkey). The last three are characteristically able to exploit all food available, a catholicity of diet based upon opportunism—the skill of taking whatever is going.

Related to this is another important characteristic, highly developed in the primates, curiosity. Curiosity prompts animals to explore new objects especially when young. Higher primates carry this into adulthood enabling them to discover new opportunities that they might learn how to exploit. These factors, the grasping hand, binocular color vision, an omnivorous diet, curiosity and opportunism might all be important but since our near relatives, the chimpanzees, and some rather more distant relatives, are endowed with them, they cannot be the factors peculiar to human evolution.

Humans also have: a constantly upright stance and striding gait uncommon in mammals, bipedalism; a large brain, intelligence; very short, fine hair giving a naked look and very sweaty skin with millions of sweat glands; highly manipulative forelimbs involving coordination of hands and brain; the ability to make sophisticated tools; parents who care for their offspring and attend to their needs for an unusually extended period; a complex social system based on sharing and cooperation; purposefulness, the ability to build in the brain, to scheme and plot with a vision of the outcome; communication by speech, art and writing.

Not all of these can be regarded as primary. The importance of walking bipedally is that the hands are freed to manipulate things, making the evolution of a large brain more likely and then toolmaking, art and written communication possible. Which, then, are the primary factors? Naturally different authorities have different emphases. We shall discuss them here to get some clues to indicate what characteristics an intelligent dinosaur might have.

Bipedalism

Don Johanson quotes Owen Lovejoy, an expert on locomotion, as stating, “from the standpoint of pure efficiency bipedalism is a preposterous way of running”. Preposterous? Inefficient? Besides humans, birds find bipedalism a perfectly efficient way of running as did many dinosaurs. Some say it was crucial to the development of mankind. Dr J Bronowski in The Ascent of Man writes:

When he put his foot on the ground and walked upright, man made a commitment to a new integration of life and therefore of his limbs.

“The origin of bipedalism must be seen as one of the major steps, if not the major step, in human evolution”, says Richard Leakey, a leading authority on the origins of mankind. He continues:

Habitually walking around on the hindlimbs, leaving the forelimbs free for other jobs, is an unusual (sic) mode of locomotion. Once our ancestors had adopted an upright stance many things associated with being human became possible, such as fine manipulation with the hands, and the carrying of food back to base camp.

Yet, if bipedalism is so vital to being human and is “a new integration of life”, and dinosaurs had made this commitment two hundred million years before man, why didn’t they develop human characteristics? Is it possible they did?

The change to bipedalism required major changes in our ancestors’ anatomy; bones, muscles, internal organs all had to alter. Dinosaurs did not need such drastic modification. They had evolved as bipedal animals. Why did our ancestors become upright? Not “so that man could make tools” as old fashioned schoolbooks told us. Evolution is not conscious—it cannot think ahead and make arrangements to meet its purposes. Furthermore, man was walking upright two million years before tools were made. The Laetoli footprints and Johanson’s discoveries show that primates were walking about fully erect almost four million years ago. The crude stone tools at found at Hadar were possibly 2.5 million years old, but some prefer an age of two million years. Watching for predators is a more likely answer.

Another is to do with feeding habits. Baboons partially sit upright while seeking scattered food items. Perhaps primitive prehominids did the same. Moving about upright would also have allowed food to be carried away to be eaten at leisure safe from predators. Gradually, because it conferred such advantages, they adopted the upright stance permanently. Such arguments emphasize the immense start the dinosaurs had in being upright from the beginning.

Brain size

Carl Sagan in Dragons of Eden gives four reasons, all to do with the brain, why intelligence in apes emerged only in the last few million years.

1. The brain had to grow bigger than a critical size
2. The ratio of brain to body mass had to exceed a certain value
3. The brain had to make more neural connections than before
4. The brain had to evolve particular functions (in the frontal and temporal lobes perhaps).

The first three imply only a quantitative change was needed but the fourth requires qualitative change instead (or as well).

It is plain from the fossil record that in the series of species that led up to man there has been a growth in brain capacity from about 350 cm³ in the apes to a maximum of about 2000 cm³ in recent and modern men. The human baby’s brain is now so large that mothers often experience difficult and painful childbirth. The English anatomists of Piltdown fame, Woodward and Keith, defined 750 cm³ as the critical size for intelligence. Later Le Gros Clark reduced it to 700 cm³. These definitions were purely arbitrary.

Brain size alone is not now regarded as sufficient to define a species—it is too variable. Cranial capacity in people today ranges from 1000 cm³ to 2000 cm³. Earlier hominids had brain capacities that overlapped considerably with preceding and succeeding ones. The H erectus range was 700 to 1250 cm³, overlapping with the H sapiens range. The H habilis range was 500 to 800 cm³, overlapping that of H erectus. And Hominid brains only started to get bigger than apes’ about two million years ago, apparently concurrently with the making of tools. The range is continuous and offers no basis in itself for deciding when intelligence occurred. What is more, brain size does not correlate with intelligence, though there is a correlation between brain size and body size. Men have larger brains than women because they have larger bodies—but they are no more intelligent than women. When fossil craniums are found that appear the same save for their size, they are likely to differ only in the sex of their owner.

Big brained people are not generally more intelligent than smaller brained people. Our brains seem to have overdeveloped for some reason—only a part is used. The bulk varies in size from person to person but, being unused, does not affect intelligence. A creature with a much smaller brain using it more efficiently might be capable of behavior just as sophisticated as our own.

According to David Attenborough, “the macaques are one of the most successful and versatile of all primates”. Although they have a small brain compared with ours, it is complex and large for their size and they are intelligent and adaptable. Some macaques have become media personalities in the last few decades. A group of Japanese macaques living in the cold mountains of northern Japan found some volcanic springs. Quickly the whole troop learnt how to shelter in the warmth of the hot spring water. In 1953 Japanese scientists were attempting to study a troop of macaques on the small island of Koshimu. To lure them into the open for ease of observation the scientist took to burying sweet potatoes in the sand. The monkeys were troubled by the dirt on the tubers until one female in a flash of gestalt took a tuber to a rock pool and rinsed away the particles of sand. Within a few months the whole troop had spotted and picked up the trick. The same monkey also discovered how to separate rice and sand by throwing the mixture into a pool and skimming off the rice. If the thinking animal’s niche were vacant, these monkeys could evolve into it over the next few million years—and they might still have the chance!

A bigger brained animal will be more intelligent than a smaller brained one, all else being equal. But since all else is not equal, we cannot be definite about a threshold brain size for intelligence.

Brain to body ratio

A better criterion of intelligence might be the ratio of the brain’s weight to that of the whole body. This allows for the tendency of larger creatures to have larger brains simply to regulate their larger bodies. Sagan gives the ratio of body to brain weights for the Hominids as: 90 for A robustus; 50 for A africanus; 60 for H habilis; 65 for H erectus; 45 for H sapiens. There seems to have been no significant decrease in this ratio since A africanus and indeed the early toolmaking hominids seem to have had smaller brains for their body size than the non-toolmaking A africanus. A robustus, if descended from A africanus, obviously regressed considerably—though there is some margin of error in these ratios. More importantly, the European pygmy shrew with a body weight of 4.7 grams and a brain weight of 0.1 grams has a body to brain weight ratio of 47, very similar to our own. On this criterion pygmy shrews should be as intelligent as us! Evidently it is no criterion.

Sagan’s two remaining criteria, the quantitative change in the number of neural connections leading on to the qualitative change needed for the development of different specialisms by the brain are probably more relevant. Regrettably, these are not easy to measure, though some clues can be had from casts of the interior of skulls. Bulges in certain parts of the brain can be related to the development of certain functions—like speech.

Speech

According to the biologist, George Gaylord Simpson, speech is “the single most diagnostic trait of mankind”. David Attenborough writes:

Man’s passion to communicate and to receive communications seems as central to his success as a species as the fin was to the fish or the feather to the birds.

Speech itself leaves no fossil records but we noted that the development of the lobes of the brain gives some clues. The part responsible for speech is Broca’s area. All the hominids have a swollen Broca’s area though it is most pronounced in man. Even in chimpanzees there is evidence of swelling here, suggesting a growth in conscious articulation.

The shape of upper and lower mandibles also can give clues because of their need to accommodate the speaking mammal’s unusual tongue.

Speech seems to be recent. Arguably it started as long as 100,000 years ago but did not become well developed until 45,000 years ago. “Rational thinking that is purely verbal is probably only tens or hundreds of thousands of years old”, Robert Bakker tells us. Were people before then not human? No one has any real idea how or why speech evolved. People have no need to speak to make tools, to hunt or to draw pictures. Our best guess is that it develops as a form of social cement for intelligent and social creatures that have largely lost their sense of smell and are close to developing the formalized social structures that become civilization. It is a derivative of and a symptom of intelligence rather than a factor in its birth.

Long childhood

Is extended parental care the essential ingredient? There are two extreme strategies for propagation of the species. One requires the laying and distribution of many small eggs which the parents leave to their own devices knowing that a few will survive. Let us call this the negligent strategy. In the other a lot of parental energy and attention is devoted to the few eggs and offspring they produce. Let us call the latter the indulgent strategy. Though the negligent approach is more common for less complicated life forms, the higher life forms are not the only caring parents. Even some fish build nests and protect their young, by hiding them in their mouths, for example.

Cold-blooded turtles adopt the negligent approach. They lay large numbers of eggs on a remote beach then swim off leaving the hatchlings to fend for themselves. But cold-blooded alligators build a nest mound for their eggs, guard it, help the hatchlings to free themselves then protect them in a nursery as they grow—an indulgent strategy. Dinosaurs did not produce many eggs indicating an indulgent strategy, and were at least as attentive parents as alligators. The higher primates have taken the indulgent strategy to its ultimate conclusion. They have only single young, very infrequently, and spend a lot of parental time and energy in raising them—chimpanzees have one child every five years only. Primate parents have a lot of responsibility and need to be resourceful—natural selection has therefore strongly favored intelligence. Perhaps this is the really crucial factor in human development?

Yet an extremely indulgent strategy is hazardous. Disease and misfortune to parents or young can be disastrous, despite any amount of parental care. When a child is dependent on its parents for a long time, the death of a parent can be the death of the child. If the child dies the parents have wasted a lot of their resources and energy and have to start the slow process again. The indulgent strategy has not been successful for the great apes. Today all apes except man have small populations in narrow geographical ranges on the verge of extinction.

Why should it have succeeded for humans? Anthropologist, Owen Lovejoy believes that bipedalism was the key to a successful modification of the indulgent strategy by mankind. By learning to walk bipedally the human female was no longer restricted to only one child at a time as were the other apes. She could gather food for herself and he older children while nurturing her baby. The change was drastic enough to trigger the evolution of a train of complementary features—continuous ovulation, pair bonding, sexual attraction between individuals, parental care, intelligence, need for larger brain at birth, need for learning, longer childhood, social grouping and toolmaking. The emergence of each trait stimulated the evolution of others in a complicated evolutionary pattern.

But in the sense that parental nurturing and care is longer and more intensive in humans than in any other primates, humans adopt the ultimately indulgent strategy. The other primates were not successful but mankind is. Lovejoy’s explanation is that the human strategy is less indulgent than the apes’. But, if being able to cope with more than one demanding child at a time makes the strategy less extreme than in other primates, it has surely only become true since human beings took to gardening 10,000 years ago. The hunter gatherers remaining today, like the T’Kung of South West Africa, have a reproductive strategy similar to that of the savannah apes. Hunter gatherer women do not ovulate while the previous child is still suckling and cannot become pregnant while suckling a child. But T’Kung women suckle their children until they are four years’ old by which time the child, though still dependent on parental support, is able to begin to help with the gathering. Thus the natural interval between successive children in human hunter gatherer females does not differ greatly from the chimpanzee’s. But the care invested in each offspring by humans is much higher because it takes much longer for a human baby to become independent. Human precursors had a more extremely indulgent strategy than the other great apes not a lesser one.

Furthermore some of the other characteristics of intelligence seem to depend heavily on a highly indulgent strategy. Purposefulness, creativity and imagination; thinking ahead, anticipating and predicting are all qualities which may be partly innate but need stimulation and teaching to develop. Attentive parents and a close social organization are necessary for this. For humans, if the degree of indulgence has fallen at all, it has only been since agriculture was invented. Having left the Garden of Eden human females stopped suckling earlier and lost the natural contraceptive protection that went with it. A natural restriction on the growth of population had been removed. “Civilized” women do not suckle their children at all. They feed their children on the milk of domestic animals. The result is that they begin to ovulate immediately and can be pregnant again within 12 months. After the loss of natural contraception and before artificial contraception was introduced, human females probably had three or four times as many children as they would have had naturally. So it is hardly surprising then that population should have exploded in the last 10,000 years.

Cooperation

Cooperation developed from the longer dependency of human young on their mother. A division of labor occurred. The females, responsible for bringing up the children, undertook the placid activity of gathering, providing a degree of security and the group’s reliable food supplies. The males, with less responsibility and able to risk their security, sought to get the richer animal protein, initially through scavenging for animal remains and later by actively hunting. But it was not how the food was obtained that triggered the emergence of mankind but the joint manner in which food was eaten and the cementing of social bonds that it entailed. While gathering, the females shared her food and her experience with her children, male and female. Males, used to sharing with their mothers, brothers and sisters, gradually adopted it as adults realizing that sharing provided more secure returns than individual prospecting. The sharing culture spread and eventually societies became more cooperative rather than purely competitive.

Baboons do not share although they do forage together. Chimps rarely share and when they do it is normally after prolonged scrounging. The habit acquired by human males from their mothers, of sharing food, distinguished humans from other primates where the dominant male was more likely to steal it, and led to cooperation and economic interdependence.

Hunting and tool making were luxuries that could be enjoyed because the females provided a secure base for the human group through food gathering. Even the first tools—sticks for reaching and digging, stones for cracking nuts, sharp stones for cutting roots, and bark for containers—might have been made by women to assist gathering. The technological invention that led to mankind might not have been the hand axe used by the hunters but rather the container which allowed a lot of food items to be collected by the gatherers, the women and children, and transported back to base for communal eating later.

Hunting

Several million years ago several environmental niches were filled by clever and adventurous primates. Chimpanzees, being woodland animals, mainly ate fruit. Baboons, like men, had moved on to the savannah and lived on roots, grass and seeds (both baboons and chimpanzees ate meat but it constituted only five per cent of their diet). The savannah apes had a similar territory and diet to the baboons but had discovered new strategies. The division of labor and sharing freed their males to spend more time getting meat. Gathering would continue to give the communes of apes reliable basic sustenance, but scavenging and then hunting provided concentrated protein. This was a vital step forward giving the apes time to think, and later time to philosophize.

Herbivorous elephants have to spend three quarters of their time eating their low quality food. The carnivorous lion on the other hand only spends about 15 per cent of its time seeking and eating its food rich in protein.

The step to scavenging was fairly easy. There was always some recently dead creature not far away on the savannah and the alert apes would have noticed circling vultures. At Sterkfontein in South Africa, Elisabeth Vrba and Philip Tobias found accumulations of savannah ape bones apparently collected by a predator (possibly a leopard) in its den. There were no stone tools in that layer but in a higher and more recent layer there were stone tools and a pattern of animal remains typical of a scavenger. It seems that the scavenger (Homo habilis) was a toolmaker while his predecessor who made no tools (A africanus) was prey. From scavenging it was not such a large step for the emergent men to appreciate that carcasses could be created.

Sherwood Washburn in 1956 argued that hunting was the key to human development. Washburn reasoned that, because the apes were slow they had to substitute cunning and cooperation for speed. The new art of hunting in groups required an effective means of communication at a distance: the development of language was the result. The hunting theory of Washburn became accentuated into the theory of “the killer ape” promoted by Robert Ardrey. Robert Ardrey says:

Man is man and not a chimpanzee, because for millions upon millions of years we killed for a living

But killing for a living cannot have led to speech. Shouting to companions is the last thing that a hunter would do if he did not want his prey to bolt, and speaking arose too late to have been triggered by hunting millions of years before.

The contentment of the hunter gatherers and their sensitivity to their environment belies the hunting hypothesis of human aggressiveness. The hunter gatherer way of life is not one of grinding insecurity, incessant toil and hardship. It offers as much, if not more, leisure than people have today. Hunter gatherer communities have total confidence in their ability to obtain sustenance from their environment and feel no need to store or save for the long term. Though it no longer appeals to us, pampered by our advanced technology, hunter gathering is comfortable and secure to those brought up to it. Moreover, many of today’s hunter gatherers like the San of South West Africa have been forced by gardeners and farmers into harsh environments on the margins of deserts. They comfortably survive, but, before they were thrust to the desert margins, the hunter gatherers would have had much lusher pickings. It is no exaggeration to call it the “Garden of Eden”—all was provided simply by reaching out or digging up a root.

Marshall Sahlins who has studied stone age economics in depth assures us “all people’s wants are easily satisfied”. Males of the T’Kung hunt for only 21 hours a week and the women (who provide two thirds of the food) gather for only 12 hours. In terrain which to us is inhospitable desert, they have sufficient.

Richard Leakey thinks our aggression may be a pathological response to the human condition that has emerged since the first urban communities of 10,000 years ago. He writes:

For perhaps two million years, human ancestors had practised nomadic hunting-and-gathering, in a way of life that was characterized by stability rather than change in terms of technology and culture. Then the ancient way of life was virtually abandoned over a period of a few thousand years.

We may be still suffering the trauma of that immense change. But mankind hunted animals to extinction long before we were shown the gate of the Garden of Eden. Of the savannah apes, the steps to scavenging and hunting were too great for A robustus. They did not realize the value of meat or, if they did, they found competition with Homo and the baboons too difficult. Homo forced them to eat less nutritious food needing a lot of processing. They evolved jaws suitable for low grade food but were marginalized by their proto-human rivals, became their prey and were pushed into extinction. Were our insensitivity to the other inhabitants of the Garden, our incompetence as custodians and our genocidal destructiveness the reasons for our expulsion? Have present day hunter gatherers been marginalized precisely because they are not aggressive enough?

A killer instinct is possibly a contributory factor to world domination, generating a particularly aggressive competitiveness that has been partly instrumental in mankind’s progress. Of course, many dinosaurs were savage killers too—our killer instinct might be part of our dinosaur heritage.

This survey suggests some factors that influenced the emergence of the intelligent mammal. They are: manipulative forelimbs with grasping fingers and opposable thumbs; binocular vision; color vision; omnivorous diet; curiosity and opportunism; upright posture; exceptionally lengthy childhood dependence on parental care enabling teaching to occur with development of higher skills and creativity; large brain; toolmaking; sharing, division of labor and cooperation; aggression and a callous indifference to other species, as well as other humans, fostered by hunting. Have the dinosaurs of 70 million years ago left any signs of their having any of these characteristics? I shall explore this in the next chapter.

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