WASHINGTON - Studying the ratio between the index and ring fingers of two Neanderthals and one Australopithecus afarensis skeleton, University of Liverpool researchers have shown that human ancestors conflicted on monogamy.

Lead researcher Emma Nelson says that the ratio between the index and ring fingers is thought to be a telltale marker for how much an individual was exposed to the androgen class of hormones-specifically testosterone-while in the womb.

She points out that, though highly contentious, studies indicate that individuals who receive high levels of androgen before birth are more likely to be stronger, faster, and more sexually competitive.

During her study, she observed that the Neanderthals had long ring fingers, suggesting they were a promiscuous bunch.

According to her, males might have likely either kept harems of female mates, or males and females each mated with multiple partners.

Emma further reveals that A. afarensis, which lives between 4 and 3 million years ago, long before modern humans, seemed to have short ring finger, which hints that they were faithful to single mates.

However, she says that that doesn’t sit well.

“These were small creatures that probably lived in groups and were being eaten by predators. How do you keep from mating with different members of the group?” Discovery News quoted her as saying.

She is presenting the findings of her study at the Society for Vertebrate Paleontology meeting in Bristol, UK.

Dean Snow of Pennsylvania State University in University Park said: “What they’re seeing is very interesting. The difference between being pair-bonded and non pair-bonded mating is a major watershed within primates. If a distinction is that Neanderthals weren’t pair-bonded and modern humans were, that would be a major consideration in trying to figure out why modern humans out-competed Neanderthals in Europe.”

The expert describes pair-bonded males as those who help feed and look after females while they are pregnant, adding that females and males both forage equally in non-pair bonded social structures.

However, given the tiny sample size involved in the study, Nelson says that it is highly speculative.

She believes that firm conclusions about the sex lives of our ancestors cannot be made until many more fossil hominids are examined, not least of which should be skeletons of H. sapiens that lived during the same period as Neanderthals.

However, her findings, if successful, may help explain why the modern human animal displays such an array of sexual behaviour. (ANI)