Photo: ThinkstockBy Corrie Pikul
They Can Get It Up in the Womb
Fetuses as young as 16 weeks have been spotted with teensy protuberances that rise and fall throughout gestation, according to studies in the Journal of Ultrasound Medicine. Scientists aren't sure why this happens, but one theory, reported in the Los Angeles Times, is that these periodic movements help the penile tissue stay oxygenated and healthy.
RELATED: 5 Perfect Pairs of Boyfriend Jeans
Even the Most Masculine of Them Aren't Exactly Surging with Testosterone
Early in a life, males experience two bursts of testosterone: one tells their genitalia to develop male characteristics, and the other is believed to imprint a male pattern on their brains, writes urologist Abraham Morgentaler, MD, FACS, in his forthcoming book, Why Men Fake It: The Totally Unexpected Truth About Men and Sex. From shortly after birth and throughout childhood, though, little boys and girls have the same nearly undetectable levels of testosterone--it isn't until puberty that the hormone surges in guys. But even then, Morgentaler tells us, the average amount of testosterone in a healthy man under the age of 40 is 350 to 1,000 nanograms per deciliter of blood (a Men's Health writer puts this into perspective: "If you somehow managed to collect all the testosterone from your entire body, it would barely fog the bottom of a shot glass"). In fact, Morgantaler says that the concentration of testosterone (and many other hormones) is so low that it took about four decades after testosterone's discovery to develop a blood test capable of detecting such tiny amounts.
They Have a More Stable Base
Women tend to be smaller than men, in general. But even when a man and woman are the same height, his feet will be longer and wider, write Billy Goldberg, MD and Mark Leyner in Why Do Men Fall Asleep After Sex?: More Questions You'd Only Ask a Doctor After Your Third Whiskey Sour. They add that women also tend to have a higher arch, a shallower first toe, a shorter ankle length, a smaller instep--but a larger calf circumference. (In related news, the size of a man's foot has no correlation to the size of his you-know-what. The most commonly cited study on this issue, in which two urologists measured the stretched penile length of 104 men and related this to their shoe size, found no scientific basis for this persistent myth.)
The Have the Ability to Slow the Aging Process-if They're Careful
From the neck up, men tend to age better than women: They lose collagen density more slowly than women, which means their skin resists wrinkles and sagging as they get older. Dermatologists claim that both men and women lose about 1 percent of collagen per year after age 20, but the loss accelerates significantly in women when they hit menopause. But because men are often more lax about taking care of their skin than women are, they're more susceptible to sun damage and shaving-related surface trauma, and this can negate their natural advantage. Daily use of broad-spectrum sunscreen goes a long way toward helping men retain their skin's suppleness and vitality.
They're Designed to Keep Other Men from Coming Between Them and Their Beloved
Talk about competitive! A 2004 study in the journal Evolutionary Psychology suggests that the unique shape of the human penis evolved not only as a way deposit sperm into a vagina but also to displace the semen of a recent rival. Researchers from SUNY Albany tested an array of artificial phallus shapes and found that the penile head, with its pronounced ridge, does a fine job of ousting sperm that had been left behind and replacing it with new contenders.
They Can Actually Make Milk
Men have mammary glands, and they can produce milk--but not enough to feed a baby. In fact, male lactation is usually caused by an interference with prolactin, the hormone necessary to produce milk. The most common trigger is a tumor in the pituitary gland, but it can also be spurred by heart medication (digoxin), opiods or hormone treatments for prostate cancer, write Goldberg and Leyner in Why Do Men Have Nipples?. In rare cases, extreme starvation can throw off hormone levels and also cause male breasts to produce a small amount of milk.
They, Too, Can Get Yeast Infections
Those itchy, embarrassing and annoying infections hit men in the same ballpark area as they do women: between the legs. They're relatively common in men who are uncircumcised, heavyset or prone to excessive sweating, says Morgentaler, who is also an associate clinical professor of urology at Harvard Medical School. The symptoms he cites include a red rash, and, occasionally, the same type of discharge that afflicts women (for the approximately 25 percent of women who make it through life without ever having a yeast infection: It resembles cottage cheese). Fortunately, Monistat and other OTC anti-fungals don't discriminate, and work just as well on men.
KEEP READING: 6 Things Women With Gorgeous Skin Do Every Day
More from Oprah.com: