Finally the debate is over: size matters, and women prefer men with larger packages because it predicts a man's sex appeal, according to a new study in the journal Proceedings of the National Academy of Sciences (PNAS).

The study, conducted by the Australian National University, revealed that the taller the man, the bigger the effect his penis size had on his sex appeal.

The group of researchers showed life-size, computer-generated figures of men that varied in body shape, height, and penis size to 105 women. The females then rated the figures' sexual attractiveness.

Professor Michael Jennions, from the ANU Research School of Biology, explained:

"This is a topic that has captured the imagination of people all over the world for a very long time. If you look at the magazine rack in your local newsagent, sooner or later you'll see an article entitled 'Does size matter?' We wanted to answer this age-old question with a valid scientific approach - " facts not opinions."

The findings showed that women preferred taller men with broader shoulders and narrow hips (V-shaped, instead of pear-shaped), which supports earlier research.

However, this study indicates that penis size is also relevant. Outcomes showed: the bigger, the better. Females documented the most appealing penis size was even bigger than the researchers tested, surpassing the penis size of 98% of Italian males.

Professor Jennions said, "We've found that penis size did influence a man's sex appeal, and it was just as important as height, which is a well-known factor in male attractiveness."

The study also noted that larger penises are ideal but were much more attractive on taller men than shorter men. "To put it bluntly, if you are short and pear-shaped, a large penis is not going to increase your attractiveness," Dr Mautz said.

Females Quick to Judge

The females were critical judges, making decisions on a figure's attractiveness in about three seconds, and even more quickly when seeing less attractive figures.

The quickness of the judgement implies that the women did not consciously go through the pros and cons of each figure - which means that rating is a total impression of attractiveness, not just an opinion on a certain body part.

Dr Mautz explained, "The only previous study of this topic in humans used five small drawings of male figures that differed only in penis length. It was very obvious to the female participants which character they were being asked to assess; in that situation, it's easy for people to self-deceive or lie and distort the results."

This judgement setting was also unique because several body parts were seen at once in 3D figures - a more realistic situation than looking at a figure drawn on paper.

The authors believe this topic is not just a comical topic to the general public, but also a serious scientific question.

Professor Jennions concluded:

"Humans have slightly longer, and notably thicker penises for their body size compared to other primates. It's been suggested that (before humans wore clothes) females used penis size as one of the deciding factors when choosing a mate, but until now there has been very little data to support that. Our results hint that humans might have larger penises because females in the past were more likely to mate with well-endowed males."

In 2011, a study found that the length of a man's penis can be predicted by his index and ring fingers on his right hand. The ratio between the second and forth fingers on the right hand correlate to the length of his flaccid and stretched penis.

Written by Kelly Fitzgerald