Finding Explanations For Our Differences

Why doesn’t Eve have an Adam’s apple? Why do women crave chocolate and men a hamburger? Why do women wrinkle before men?

We all know men and women have their differences, but why? These excerpts from Carol Ann Rinzler’s book, “Why Eve Doesn’t Have an Adam’s Apple” (1996, Facts On File, Inc.) provide scientific explanations for some of our perplexing distinctions.

Why do women crave chocolate?

In the five years between 1989 and 1994, more than 50 scientific papers were published on the subject of food cravings. The studies confirm what most people knew by instinct: On average, women crave sweets, and men crave meat.

In a 1991 survey of food cravings among 1,000 undergraduates at McMaster University in Hamilton, Ontario, 97 percent of the women and 67 percent of the men admitted experiencing specific food cravings. While both craved fat, women seemed to prefer to get their fat from sweets such as chocolate; the men, from protein foods such as steaks, hamburger and seafood.

The female craving for carbohydrates, which activate brain chemicals that increase a feeling of well-being, appears to rise and fall along with levels of female hormones during the phases of the menstrual cycle.

Do women have a higher pain threshold than men?

Women are commonly thought to feel pain less acutely than men, but much of the lore relating to women’s greater tolerance for pain is based on their ability to survive childbirth.

Modern research shows nature does appear to arm an expectant mother for delivery. During pregnancy, cravings for salty, fat or sweet foods may be linked to the ability of these foods to facilitate the production of the neurotransmitter serotonin, a chemical that stimulates smooth muscles, such as the muscle of the uterus, and promotes a feeling of well-being.

Why doesn’t Eve have an Adam’s apple?

The quintessential gender difference between a male and a female neck is the bump in the front - a V-shaped cartilaginous structure at about the level of the fifth cervical vertebra with an angle that points forward further in men than in women.

This protuberance is the thyroid eminence, also known as the promenentia larynges, the protuberentia laryngea, or, more familiarly, the Adam’s apple.

The Adam’s apple is a secondary male sex characteristic that appears at puberty when the male larynx enlarges and the voice cracks.

And that is why Eve doesn’t have an Adam’s apple.

Which sex is more likely to have Alzheimer’s disease?

A 1987 survey of Alzheimer’s patients conducted at six diagnostic and treatment centers by University of Southern California scientists suggests that more than two-thirds of all Alzheimer’s victims are women.

There is evidence that female sex hormones may have a role to play in facilitating the production of critical enzymes in brain cells and maintaining the network of fibers that transmit neurological impulses from one nerve cell to the next.

If this is true, then the decline in estrogen secretion at menopause might logically be thought to accelerate the kind of neuron and brain-cell loss that characterizes Alzheimer’s disease, eventually affecting cognition and memory.

Is a bigger brain better?

The average adult human brain weighs about 3 pounds. And, as a rule, a male brain is about 10 percent heavier than a female brain, reflecting a general difference in body size.

But with age, the male brain seems to deteriorate faster. In April 1991, a team of researchers at the University of Pennsylvania used magnetic resonance imaging (MRI) to measure the relative atrophy of brain fluid and tissue in 34 men and 35 women, ages 18 to 80. They found brain tissue in the male brains deteriorating two to three times faster than in female brains.

In addition, the male brains showed more changes on the left side, the side that governs language and speech. Changes in the women’s brains were symmetric.

Should you ask a man or woman for directions?

Ask a woman how to get to Bloomingdale’s, and she’s likely to tell you to walk two blocks past that big building on the corner, while a man will tell you to head north four blocks.

In other words, when it comes to finding their way, on foot or in a car, by ship and plane, women remember landmarks, while men appear to operate on an innate sense of compass readings and an estimate of how far they have come. (They’re also better at reading maps.)

Should women get more physically active?

The American Heart Association and the National Center for Health Statistics (NCHS) agree that in the United States men are more likely than women to exercise on a regular basis.

Heart Association research shows that 44 percent of American men exercise on a regular basis. NCHS numbers for men are slightly lower: 40 percent claim to engage in sports or vigorous exercise for 15 minutes three or more times a week.

Women are less active.

American Heart Association statistics show that 38 percent of American women engage in regular exercise. This number is roughly confirmed by a 1995 report from the Centers for Disease Control in Atlanta showing that nearly three-quarters of American women do not get enough exercise.

Statistically, the least active are black women.

Are women getting enough sleep?

Women complain of insomnia twice as frequently as men, and most sleep studies show more women reporting trouble getting to sleep.

In a 1994 analysis of 43 previous surveys comparing sleep behavior in men and women, 16 of 21 studies reported women having more trouble falling asleep and staying asleep through the night; 14 of 17 studies showed that women are more likely to use drugs to get to sleep.

Who would most likely smell a crisis in the middle of the night?

Like the sense of hearing, the sense of smell waxes and wanes in a circadian rhythm controlled by the secretion of adrenal hormones. On a normal sleep/wake cycle, both senses peak at around 2 a.m. to 3 a.m., but at every point in the cycle, a woman’s sense of smell will be sharper than a man’s, says Robert Henkin, director of the Taste and Smell Clinic at the Center for Molecular Nutrition and Sensory Disorders in Washington, D.C.

Young or old, women tend to do better on tests measuring sensitivity to odors.

Who is more likely to wake up with a stomach ache?

A gnawing pain in the middle of the body in the middle of the night is a common symptom of an ulcer - either a duodenal ulcer (in the upper part of the intestinal tract) or a gastric ulcer (in the stomach).

A man’s risk of a duodenal ulcer is twice as high as a woman’s, but his risk of a gastric ulcer is only slightly higher than hers.

Female hormones appear to offer some protection. Women with ulcers often find that their symptoms recede while they are pregnant.

Why do women wrinkle before men?

There are two reasons why this should be so.

First, a woman’s skin is thinner than a man’s. Second, her sebaceous glands are not as efficient later in life.

Skin is composed of several layers of cells. The top layer, the epidermis, is equal in depth in men and women, but the dermis, the second layer of skin cells, is microscopically thicker in male skin.

With age, everybody’s dermis thins and sags, but because the male dermis starts out thicker, a man’s skin stays thicker and firmer longer.

In addition, an older man’s sebaceous glands continue to secrete normal amounts of sebum to lubricate the skin longer than an older woman’s. Therefore a woman’s skin generally wrinkles earlier than a man’s.

MEMO: Carol Ann Rinzler is a medical writer and a frequent contributor to such magazines as American Health, Redbook, Woman’s Day and Family Life.