If she ever says that your package is King Kong-sized, try not to take it as an insult. After all, human men pack a great deal more between their legs than primates.

In fact, an adult male gorilla?s penis measures only around 1.5 inches?fully engorged. Chimpanzees, our closest ape relatives, are a little bit longer at around 3 inches, but that?s still dwarfed by our typical measurement of between 5 and 7 inches.

Sure, 7 million years of evolution separate us from monkeys . . . but how did we come so far?

One theory is that girls simply prefer a well-hung guy.

In a 2013 Australian study, researchers had women view life-sized, computer-generated images of men with various body types and flaccid penis length. As it turns out, the ladies generally rated the better-endowed guys as better-looking.

?Before we were wearing clothes, this is one way women could have judged a man?s attractiveness,? says study author Brian Mautz, Ph.D.

But why would our female ancestors who mated with increasingly larger schlongs over the course of human evolution want a bigger penis in the first place? Even modern woman?s preference for a big penis is uneven.

?Although women saw a larger penis as more attractive on average, there are women who have no preference at all,? says Mautz.

Mautz?s study even found that having broad shoulders was a better predictor of attractiveness than penis size, and taller men were universally found more handsome.

It?s possible women just prefer guys with athletic builds, and a proportionally sized penis is simply along for the ride.

At the same time, a larger penis may help women achieve vaginal orgasm, as opposed to orgasms from the clitoris.

Scottish researchers found that out of more than 300 women, about half experienced vaginal orgasms in a month, and one third of those ladies preferred guys who could reach deeper inside during intercourse.

The catch: The gals who favored longer shafts had experienced more orgasms in the previous month than all the other women studied.

The same may also be true for women who experience clitoral orgasms: In a study at the University of Texas, 90 percent of women said a thicker penis was more important than length when it came to their sexual satisfaction.

Or maybe the reason why we have bigger boners might be purely mechanical. Some scientists have suggested that the mushroom tip of the penis, which is unique among primates, may exist to remove the semen of a woman?s previous sexual partners during intercourse.

Researchers at the University of Albany even went so far as to verify this idea using artificial vaginas and penises?you know, ?masturbation aids.? The anatomically correct dildos managed to sweep out 91 percent of previous semen, compared to just 35 percent in the headless models.

?By filling the vagina, a longer penis would aid and abet the displacement of semen left by other males as a means of maximizing the likelihood of paternity,? says study author Gordon Gallup, Ph.D., an evolutionary psychologist at the University of Albany.

Of course, there?s not much research on how our penises have evolved over time to know for sure. ?Penises don?t fossilize,? says Gallup.

So as long as the woman in your life is happy?and 85 percent of women like their man?s package just fine, says a California State University study?take heart in knowing what really separates us from apes: Our massive genitals.