Habitat Theory in Relation to the Evolution in African Neogene Biota and Hominids

Abstract

Abstract Hominids speciated repeatedly and also evolved markedly in morphology and behavior during the late Pliocene and earliest Pleistocene. Major novelties that first appeared then and thereafter evolved progressively include the “hypermasticatory” morphology of the “robust” australopithecines (Wood, 1995), advances toward obligatory bipedalism (Brown et al., 1985), and increased encephalization in at least one lineage. A momentous advance in behavioral evolution is reflected by the first appearance of stone tools. It is not yet clear how closely this event near 2.5 my. was linked to the commencement of encephalization (in the crude sense of relative brain enlargement), as there is a gap in the record of hominid crania betwee The elaboration of mental complexity that led to the beginnings of consciousness was a singularly dramatic change in the history of life. Consider the similarity between mental process and natural selection (see Lamarck, 1809, for an early discussion; Simon, 1962; Popper, 1978, for more recent ones). Natural selection is trial and error with eventual survival of combinations that are at least temporarily stable in the face of environmental challenges. The “trials” are variant bodies. The “errors” are those that die without reproducing. The mental processes of learning and hypothesis testing (such as implied by making and using tools) also involve trial and error until some ideas survive as internally consistent mental constructs-or as stable constructs, at least until additional tests force their disassembly and revision. Poincare (1913:387) expressed this in his analysis of mathematical invention: “Ideas rose in clouds. I felt them collide until pairs interlocked, so to speak, making a stable combination.” This is also selection, but this time conducted among hypotheses in the mind. Seen simply from a bi¬ological perspective, the evolution of human consciousness was a radical step because it replaced the energetically more wasteful, selective matching of bodies against the environment by selective matching of hypotheses within the mind-by purely mental trials and errors that pit past memories and new experiences against each other to arrive at a course of action in the mind. The fauna of the Burgess Shales represents the celebrated Cambrian evolutionary explosion of organic bauplans and shapes. The evolution of consciousness also led to an explosion of designs and shapes, but this time expressed in the cultural products of evolved minds rather than in bodies. This evolutionary step was no less radical than the one evidenced in Cambrian strata.