Homo N. finger bones suggest heightened promiscuity

HughMcB · #1 by **HughMcB** » Nov 07, 2010 9:38 pm

Neanderthals Were More Promiscuous Than Modern Humans, Fossil Finger Bones Suggest

ScienceDaily (Nov. 5, 2010) — Fossil finger bones of early human ancestors suggest that Neanderthals were more promiscuous than human populations today, researchers at the universities of Liverpool and Oxford have found.

Scientists, in collaboration with researchers at the universities of Southampton and Calgary, used finger ratios from fossilised skeletal remains of early apes and extinct hominins, as indicators of the levels of exposure species had to prenatal androgens -- a group of hormones that is important in the development of masculine characteristics such as aggression and promiscuity.

It is thought that androgens, such as testosterone, affect finger length during development in the womb. High levels of the hormones increase the length of the fourth finger in comparison to the second finger, resulting in a low index to ring finger ratio. Researchers analysed the fossil finger bone ratios of Neanderthals and early apes, as well as hominins, Ardipithecus ramidus and Australopithecus afarensis, to further understanding of their social behaviour.

The team found that the fossil finger ratios of Neanderthals, and early members of the human species, were lower than most living humans, which suggests that they had been exposed to high levels of prenatal androgens. This indicates that early humans were likely to be more competitive and promiscuous than people today.

...continues...

Fossilised hands of an early modern human (left) and Neanderthal (right).
(Credit: Image courtesy of E. Trinkaus and the Israel Antiquities Authority)

Sityl · #2 by **Sityl** » Nov 07, 2010 9:40 pm

The bone they're supposed to be looking at doesn't actually have a bone. :coffee:

Darwinsbulldog · #3 by **Darwinsbulldog** » Nov 08, 2010 3:59 am

Hormone levels do not necessarily translate to change in morphology, biochemistry or behaviour in individual tissues, or individual bodies. The number of receptors and where they are also count. Development is in many ways modular, so certain Gene regualtory networks can have an effect on one segment of the body independently or semi-autonomously form another.

I find this paper highly speculative at best. The author's admit this, but I think their conclusions are worthless. Finger length could increase and behavior not be affected at all. Pleiotropy often occurs, but it does not invariably occur. To have greater confidence in their inferences, they would have to find evidence of other structures being differentially affected by the androgens. Something that would independently confirm the correlation, like testis size. [Unfortunately not well fossilized]. In extant primates, relative testis size is a reliable indicator of sperm competition. They are extrapolating this data too far.
:think:

Tyrannical · #4 by **Tyrannical** » Nov 13, 2010 8:51 pm

It is thought that androgens, such as testosterone, affect finger length during development in the womb. High levels of the hormones increase the length of the fourth finger in comparison to the second finger, resulting in a low index to ring finger ratio.

Even if that were true in modern Humans, is there evidence to suggest it is the same with Neanderthal? A better indicator of course is a certain fleshy male area that doesn't survive the ravages of time as well as bone. The size of the male testes as related to promiscuity seems to hold true for other surviving hominid species besides modern man.