Rethinking Primate Origins

The Linnean concept of the order Primates, which included the bats and colugos, was still current as late as 1870. In 1873, Charles Darwin's antagonist St. G. Mivart proposed ordinal boundaries which excluded these animals, but which included the prosimians as a suborder of Primates. If progressive adaptation to living in trees transformed a tree-shrew-like ancestor into a higher primate, then primate-like traits must be better adaptations to arboreal locomotion and foraging than are their antecedents. Wood-Jones proposed that the absence of primate-like traits in other arboreal lineages resulted from a period of adaptation in each lineage to terrestrial locomotion. F. W. Jones's version of the arboreal theory holds, not that the primate characteristics will be selected for in any arboreal mammal lineage, but that they all result from the primates' unique preservation of the grasping hands and mobile forelimbs supposedly found in the arboreal ancestors of the Mammalia.