Since size is one indicator of overall physical fitness, Genovese speculated that a fitness factor could be influencing the results. A fit person, for example, could be more likely to have both a larger head and smarter brain, with fitness (rather than head size) being the direct cause of intelligence.
It's hard to say for sure, said Genovese.
"It is quite possible that greater body size, head size and IQs are, in this sample, proxies for some other variables, such as nutrition or socio-economic status," he said.
Over the years, other researchers have looked at the possible link between head size and intelligence, and the results have been mixed. Michelle Luciano, a researcher in the Genetic Epidemiology Laboratory at the Queensland Institute of Medical Research, recently tested 4,395 teenagers for that link but could find no such correlation.
On the other hand, Laura Flashman of the Dartmouth Medical School did identify "a significant positive relationship" between IQ levels and measurements of the frontal and temporal regions of the brain.
Colin Groves, professor of biological anthropology at the Australian National University, contends that human brains have actually become smaller since the late Pleistocence, around 11,000 years ago. Groves agreed that head size may be linked to intelligence, but only between species and not within a certain species.
Since Neanderthals had big heads, it could then be that their smarts have been underestimated.
Genovese said, "I rather think that the Neanderthals get a bad rap."
Related Links:
IQtest.com
How to improve human intelligence
Neuroethics and Law Blog discussion on head size and intelligence
Neanderthals vs. Modern Humans
