by Patrick H. Young 

Abstract

The australopithecines and Homo habilis have been publicized for years as examples of evolutionary transitional forms that launched our own human lineage. Dogmatic evolutionists have rationalized these claims on the basis of brain expansion, encephalization quotients, and bipedalism. However, any evolutionary justification for brain expansion in these extinct creatures must rest in a precise model for the determination of body mass. To insure an accurate body mass model, one must take into account whether the animal is quadruped, facultative biped, or obligatory biped. Past body mass estimates for the australopithecines and Homo habilis were based on assumptions about their bipedalism that have proven to be erroneous. When a body mass model is used accounting for the facultative bipedalism of the australopithecines and Homo habilis, the data shows that they are not highly encephalized, and hence nothing more than a microevolutionary adaptation of the pan-troglodytes.

 Introduction

One of the classic examples of alleged evidence for human origins that evolutionists have proposed to promulgate the evolutionary transitional status of the australopithecines and Homo habilis is a comparison of increasing cranial capacity versus their perceived evolutionary timescale (Falk, 1980; 1987; 1998; Kirkwood, 1997; Lee and Wolpoff, 2003; McHenry, 1994a). In this context, various fossilized crania are plotted against time as an attempt to demonstrate a gradual increase in brain volume from the time of our perceived most recent common ancestor to the large-brained humans we observe today (Figure 1). The goal of this type of demonstration is to provide visual evidence (however weak) that some evolutionary advancement in intelligence over time has occurred. 

Realistically, the scientific validity of using cranial capacity alone as a justification for brain expansion through any perceived evolutionary timescale is suspect at best, because there is no correction for body size (McHenry and Coffing, 2000; Kappelman, 1996; Holloway, 1988; Conroy et al., 1990). It is also in significant dispute as to whether the relative brain size of the australopithecines actually did increase over perceived evolutionary time (Falk, 1987; 1998; Martin, 1990). However, the majority view in evolutionary thinking appears to indicate that the australopithecines did possess a larger relative brain size than the apes (Pilbeam and Gould, 1974). Moreover, assuming it is a valid taxon (Brace, 1979; Wood and Collard, 1999), Homo habilis is believed to be the first creature to demonstrate a measurable increase in relative brain size (Falk, 1987; Lovejoy, 1981; Hawks et al., 2000; Pilbeam and Gould, 1974; Haeusler and McHenry, 2004; Ruff et al., 1997).

While a larger brain is not necessarily a predictor of higher intelligence (Beals et al., 1984; McLeod, 1983), brain size is known to have a strong positive correlation with body size (Jerison, 1970). In other words, a larger body size usually requires more neurons and thus a correspondingly larger brain to handle the increase in total structural mass. However, neither suggests any true evolutionary adaptation (Pilbeam and Gould, 1974; Jerison, 1976), nor evolution to a higher taxonomic group (Cheek, 1981; Custance, 1968; Hummer, 1977; 1978; Cuozzo, 1977). Also, Jerison (1976) noted: 

…large brains do not, in general, confer an evolutionary advantage over smaller brains. Instead large and small brains represent different but equally good evolutionary outcomes (p. 90)….

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