A New Perspective On Human Evolution
The Living Primates -- Morphological, Molecular and Morphometric Agreement The Living Hominoids -- Molecular Disagreement Morphometrics and the Relationships of Apes and Humans The Relationships of the Fossils -- Current Consensus, Current Controversy A New View of the Relationships of the Fossils The Problem of Numbers -- The Problem of Sex The Impact of the New Studies of Teeth Homo -- Australopithecines -- Ramapithecines -- Gigantopithecus A Question of Pattern -- Lineage or Radiation? A Question of Time -- Five Million Years or Ten? A Question of Place -- Asia as well as Africa A Question of Sex -- Similarity and Difference Last Words -- New Thoughts
Thinking about a new perspective on human evolution requires that we first know the old. The old story can be told at a number of different levels. A first level is the entire Order Primates. There is remarkable unanimity among almost all investigators in the broad picture of primate relationships.
Since the time of Charles Darwin it has been well established that humans evolved from tree-living animal ancestors. We know this mainly from studies of classical morphology. Comparison of our anatomy with those of lower primates (creatures such as pottos, tarsiers and bushbabies), of monkeys (from both the New and Old Worlds) and, of course, of apes has resulted in a single broad view. It is one that sees all these animals belonging with us in the same zoological Order: the Primates.
A second level relates to us and our closest relatives. This is the idea that within the entire order, there is a natural alliance: humans and apes forming the superfamily Hominoidea.
These were the opinions of the older comparative anatomists such as the first Huxley ( 1895, see also Elliott, 1913). And they are also the consensus judgements of most of the primate biologists of the present century (e.g. Zuckerman, 1933; Le Gros Clark , 1959; Schultz, 1969).
In the last twenty years that broad picture has been confirmed by new studies of molecules. They corroborate the major groupings of the primates: prosimians, New World monkeys, Old World monkeys and hominoids. They especially confirm the link of humans with apes in the Hominoidea (Fig. 8:1).
Most recently of all, this broad picture has been further corroborated by morphometric studies of the type described in this book. They encompass multivariate statistical studies of measurements describing most regions of the anatomy of the body taken from more than fifty per cent of the genera of the Order ( Oxnard, 1981a, 1983a, b, 1984).
These agreements are most gratifying.
A third level of relationship is to do with associations among the various apes and humans. Thus most morphologists (e.g. Elliott, 1913; Simpson, 1945; Le Gros Clark, 1959 agreed that there was a major subdivision within the living Hominoidea. This was believed to be a subdivision between, on the one hand, all apes (gibbons, siamangs, orang-utans, chimpanzees and gorillas) and on the other, humans (including, of course, prehuman fossils).
This dichotomy is thought to be so strong that it remains, even today, formalized into classification through the taxonomic terms 'Pongidae' meaning the family of ape-like forms, and 'Hominidae' the family of human-like forms ( Hershkovitz, 1977). This view also implies that the phylogenetic division