Men are from Mars and women are from Venus, right?

Wrong.

As it turns out, we come from the exact same place — and we are all left with a pair of chest decorations to prove it: nipples. That’s right, nipples. Men and women may have many differences, but any way you look at it, we do have two little things in common.

So, why do men have nipples?

The definition is this: “Nip-ple (n.) The small projection near the center of the mammary gland containing the outlets of the milk ducts through which young mammals obtain milk from the adult female; a teat. A corresponding projection of the male breast,” according to dictionary.com.

Since I can’t remember the last time I saw a man producing milk from his nipples, the question still remains.

“Although females have the mammary glands, we all start out in a similar way in the embryo. During development, the embryo follows a female template until about six weeks,” according to Why Do Men Have Nipples? by Mark Leyner and Billy Goldberg.

That’s right, guys: You essentially started out as female, too.

Testosterone — the hormone that makes all men so manly — doesn’t actually enter the field until nearly week six, and the male organs don’t begin to grow until about week 12.

“Prior to this point, males and females develop along the same path,” said Dr. John Amory, an associate professor of medicine specializing in reproduction. This process is called sex differentiation, he added.

The nipples are developed before the sex differentiation process takes place. Once the differentiation happens, men are left with little reminders of their beginnings: nipples.

Pamela Knowles, a consulting nurse at Hall Health, described nipples as more of a species trait as opposed to a specific sex trait. All mammal species have developed nipples; it’s a signature of mammals being able to feed their young.

“Nipples developed from sweat glands in the most ancient of animals, like duckbilled platypuses, and over a period of tens of millions of years, the females took advantage of the ducts, and now, in more developed animals, they became more specialized,” said Robert Steiner, a professor of obstetrics and gynecology.

Though male nipples don’t serve any real purpose, that’s not to say they can’t be enjoyed.

“A man’s nipples are loaded with just as many nerves as a woman’s,” according to the Feb. 2008 issue of Cosmopolitan. And in some cases, paying attention to a man’s nipples can spark and enhance arousal.

“Headlights” — causing the nipple to become hard — can be an important component to both male and female arousal.

“Small muscle cells arranged cylindrically within the nipple are responsible for the nipple becoming erect,” according to Leyner and Goldberg’s book. “This occurs when they are stimulated by cold temperature or sexual arousal.”

So, next time you see a guy without his shirt on, remember that we really are all created equal and we have two little nerve-packed areas to show it.

Hey, if ya got ‘em, flaunt ‘em.