05/10/2012 12:31 BST | Updated 05/12/2012 05:12 GMT

The Latest Sexual Medicine Research: Does Size Matter?

The Daily Telegraph reported earlier this week an investigation by Richard Lynn from the University of Ulster, researching penis size measurements across the world, where significant racial differences emerged. What the press didn't relate was the true importance of the findings; they might reveal how our ancestors varied in the evolution of monogamy during sexual relationships.

The study has just been published in the academic journal 'Personality and Individual Differences' where Lynn reports a variety of different data, including a 113 nation study where penis length is found to be greatest in 'Negroids' (16.07cms), intermediate in 'Caucasoids' (13.89cms) and smallest in 'Mongoloids' (10.66cms).

Since male sexual organ size is linked to other body proportions such as height, feet and hand dimensions, it's no real surprise racial variations exist.

But Lynn's paper reports an evolutionary argument as to why penis size should consistently vary between races, based on the 'survival of the fittest' theory that our biology and psychology exists primarily to maximally disseminate our genes to future generations.

According to this argument, as reported by Lynn, longer penises evolved to displace semen left by other males in the female reproductive tract. There is, apparently, an evolutionary advantage in having a longer penis under ancient conditions of intense competition for women. In these 'cave man' circumstances, so the theory goes, males can't be sure that the females aren't mingling their genes with other men as well.

Lynn reports theories that races migrating thousands of years ago from equatorial Africa into colder, tougher environments of Europe and Northeast Asia, didn't face so much inter-male competition any more. Everyone became too busy trying to survive from freezing, rather than enjoying the luxury of sleeping around. 'Cave men' now merely had to reliably bring home the bacon, to secure women. Loyalty and therefore paternity became more assured and linked to 'provisioning'. This meant 'survival of the fittest' became who was most ingenious, and a better hunter, than who had the longest penis.

These theories remain controversial, but what is more established is that modern men's sexual organ size is disproportionately linked to how good they feel about their whole bodies, including how much they like their own face, and assess overall physical attractiveness. Researchers find almost 50% would prefer to have a bigger penis. Is this some kind of evolutionary competitive hangover?

But if size is about evolutionary advantage, Christian Grov, Jeffrey Parsons and David Bimbi based at City University of New York, surveyed 1,065 men who have sex with men, and found a significant association between those with an above average size penis and infection with Human Papilloma Virus (HPV) and Herpes Simplex Virus (HSV-2).

Entitled 'The Association Between Penis Size and Sexual Health Among Men Who Have Sex with Men', the study contends one possibility for this disproportionate number of viral skin-to-skin sexually transmitted diseases, is that size may play a role in condom slippage and/or breakage.

Despite their being some disadvantages to bigger size, the paper, published in the academic journal 'Archives of Sexual Behaviour', also explains that previous research reports 84% of women claim to be very satisfied with the size of their partner's penis.

However, the more the subject is researched, the more the findings don't appear quite so straight forward.

For example, Weijmar Schultz lead a team of researchers from the University of Groningen in the Netherlands, surveying sexually active women. The study entitled 'What Importance Do Women Attribute to the Size of the Penis?' found 20% declare length important and 1% very important; 55% and 22% of the women report length unimportant and totally unimportant, respectively, when it comes to sexual function.

Published in the academic journal 'European Urology', in fact the data suggests that for women, length was less important than girth: Roughly a third rated girth important while only one fifth assessed length similarly. The authors conclude that although a minority, nevertheless a considerable proportion of women attach substantial significance to size, in terms of sex.

Russell Eisenman from the University of Texas-Pan American, Texas, USA confirms this finding in his study entitled 'Penis size: Survey of female perceptions of sexual satisfaction' published in a journal called 'BMC Women's Health'. 50 sexually active female undergraduate students were asked which dimension was more important for their sexual satisfaction. None reported either they did not know, or that width and length were equally satisfying. A substantial majority, 45 of 50, verify width was more important.

Edwin Bowman, Retired Professor of Obstetrics and Gynecology, Louisiana State University, U.S.A, published an argument in the academic journal 'Archives of Sexual Behaviour' which seems to suggest this preoccupation with size is missing the point.

His more recent comment on Richard Lynn's study is that of course there are racial differences in penis size, these follow ethnic contrasts in vaginal depth.

Bowman's original paper is entitled 'An Explanation for the Shape of the Human Penis' and he contends that the foreskin is highly absorbent, as evidenced by the increased susceptibility of the uncircumcised male to HIV.

Most recently, over 40 studies have indeed established male circumcision significantly protects against HIV infection. Circumcised men are two to eight times less likely to become infected with HIV, yet we still don't know why.

It is possible, Bowman argues, that the primary function of the foreskin is to absorb 'behavior modifying chemical messengers' from the female. Bowman believes that future research on vaginal secretions, particularly of an ovulating female, is likely to show a surfeit of neuropeptides, which he contends enhance pair bonding and protective behavior in the male.

His conclusion is sexual intercourse became a medium of communication between men and women older than language itself.

It may be that this dimension, sex as a form of communication, has been somewhat overshadowed by how much sheer size has loomed over the subject, as evidenced by the way the press reported Richard Lynn's research this week.

So, then, it's not all about size, after all?