century females are far more similar to their cavewomen ancestors than originally thought, because the size of a man's penis still plays a key role in deciding how attractive a woman rates him.
The findings are based on 5,145 computer-generated images of men shown to over 100 adult women of all ages and backgrounds.
Each image showed a representation of the male form, with varying combinations of height, shoulder-to-body ratio and, of course, penis length. Flaccid penis sizes of between two and five inches (five to 13cm) were used because this is the typical size range found in Western men, according to the study carried out by researchers at the University of Ottawa, Canada. Women were then asked to rate the attractiveness of each man, according to the research published in the journal Proceedings of the National Academy of Sciences (PNAS).
The results showed that while women's opinions were influenced by a variety of physical features - tall and broad-shouldered men tended to be favoured over shorter men with bigger waistlines - the size of a man's penis reigned supreme in the attractiveness stakes. The findings contradict previous studies suggesting that the size of male genitalia was of no importance to women.
While researchers were unable to find the perfect penis size, proportion is crucial, they say. In what may come as a relief to many men, manhood must not be so large that it appears out of proportion to the rest of his body. The researchers also believe that the female preference for a larger penis may have influenced the evolution of its shape and size today.
They said: 'Our results directly contradict claims that penis size is unimportant to most females. They show that female mate choice could have played a role in the evolution of the relatively large human male penis.' 'Males with a larger penis were rated as being relatively more attractive, but, the proportional increase [in size] begins to decrease [in attractiveness] after a certain size,' said the report.
The Canadian study comes after another investigation carried out by the University of the West of Scotland found that a larger than average penis is more likely to bring women to orgasm. In the Scottish study, an average length penis was defined as being 5.8 inches (14.7 cm) long when erect - the same length as a ten pound note.
