Contents Updated: Tuesday, August 24, 1999
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, [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.
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.