Re: "all hominins appear to be a single gradually evolving lineage"

From: James Michael Howard (jmhoward_at_anthropogeny.com)
Date: 11/26/04 

Date: Fri, 26 Nov 2004 17:09:26 GMT

On Fri, 26 Nov 2004 16:40:35 GMT, James Michael Howard
<jmhoward@anthropogeny.com> wrote:

>Homo. 2004;55(1-2):21-37. Related Articles, Links
>
>
>Hominins are a single lineage: brain and body size variability does
>not reflect postulated taxonomic diversity of hominins.
>
>Henneberg M, de Miguel C.
>
>Fossil hominin taxonomy is still debated, chiefly due to the
>fragmentary nature of fossils and the use of qualitative (subjective)
>morphological traits. A quantitative analysis of a complete database
>of hominin cranial capacities (CC, n = 207) and body weight estimates
>(Wt, n = 285), covering a period from 5.1 ma (millions of years) to 10
>ka (thousands of years) shows no discontinuities through time or
>geographic latitude. Distributions of residuals of CC and Wt around
>regressions on date and latitude are continuous and do not differ
>significantly from normal. Thus, with respect to these
>characteristics, all hominins appear to be a single gradually evolving
>lineage.
>
That sounds like it may support: "Human evolution consists of
chronological changes in gene regulation of a continuous and
relatively stable genome, activated by hormones, the production of
which are intermittently affected by endogenous and exogenous forces.
Periodic variations in the gonadal androgen, testosterone, and the
adrenal androgen, dehydroepiandrosterone (DHEA), significantly
participated in all hominid transformations. The hominid
characteristics of early Australopithecines are primarily a result of
increased testosterone. The first significant cold of the early
Pleistocene resulted in an increase in DHEA that simultaneously
produced Homo and the robust Australopithecines. Subsequent
Pleistocene climatic changes and differential reproduction produced
changes in DHEA and testosterone ratios that caused extinction of the
robust Australopithecines and further changes in "Homo." Changes in
testosterone and DHEA produce allometric and behavioral changes that
are identifiable and vigorous in modern populations."

"Androgens in Human Evolution," Rivista di Biologia / Biology Forum
2001; 94: 345-362

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