\doc\web\99\06\diffk.txt From: "J. P. Rushton" X-Mailer: Mozilla 4.04 [en] (Win95; I) MIME-Version: 1.0 To: Ian Pitchford CC: h-bd@egroups.com References: <29709846.243ba521@aol.com> <004401be805d$0f6bf600$02000003@oemcomputer> Subject: [h-bd] r-K and race Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Status: Ian Pitchford wrote: My main point was that I haven't been able to find any neurobiological evidence supportive of differential K theory. REPLY: What about the brain size-IQ relations? About a dozen studies using state-of-the-art Magnetic Resonance Imaging techniques find about a 0.40 correlation between brain size and IQ. Moreover the races clearly differ in average brain size, with Orientals averaging about 14 cc arger brain volumes than than Europeans and 100 cc more bran volume than Africans. Brain size differences are found using four converging techniques: MRI, autopsies, endocranial volume from skulls, and external head measures. Moreover, Asian women (and their descendants) double ovulate less frequently (producing fewer eggs per cycle and fewer dizygotic twins) than European women (and their descendants) who double ovulate less frequently than African women (and their descendants). The inverse relation between brain size and egg production is direct "neurobiological" evidence for r-K theory. There is no known sociological (or rival evolutionary) theory to explain this trade-off. Moreover, within race the relationship seems to hold for social class differences, at least among Whites.