A Book Review by Louis A. Berman
Professor of Psychology (retired),
University of Illinois at Chicago
March 31, 2006 - My eyes popped when I saw the title of the New Yorker writer Mark Leyner and Dr.
Billy Goldberg's little book, Why Do Men Have Nipples? I felt, I confess, more
than a touch of envy when their book hit The New York Times Bestseller list, and
came out in a paperback edition. My book, The Puzzle (Godot Press, 2003), covers
the topic more thoroughly, and discusses the role of nipples in the sex life of
both straight and gay males.
The Puzzle argues that male homosexuality results from an interaction between inborn and social factors, and that an important inborn factor is low brain masculinization. Why do male brains have to become masculinized at a given stage of embryonic development? Because for the first six weeks of life, all embryos are proto-female. Afterwards, some male brains become more thoroughly masculinized than others. Males whose brains are masculinized to a lesser or minimal extent, are more likely to display gender-discordance, or to drift toward homosexuality as a way of correcting or accommodating to their felt deficit.
A well-trained embryologist cannot tell the difference between a male and a female embryo if the embryo is less than seven weeks old. At that early stage of prenatal life, there is a fork in the road of development. If there are no hormonal changes in the prenatal environment, the embryo developes into a female. If, however, the embryo is destined to become a male, its Y-chromosomes trigger the production of testosterone (the male hormone), which masculinizes the brain and genitalia (internal as well as external) of the embryo. But it takes no female hormone to produce a female infant. (Only at age ten or later does the female body begin to produce the hormones that transform the girl into a woman.)
Every person begins life with a proto-female brain. Testosterone masculinizes the brain (and genitals) of those embryos that are genetically marked to develop as males. Almost all male genitals are thoroughly masculinized. (There are, unhappily, rare exceptions.) But, there is some direct evidence, and lots of indirect evidence, that there is a wide range of variation in the degree to which the male brain is masculinized. The Puzzle argues that the low-masculinized brain shades the inner life of the individual with female thoughts, feelings, and wishes. This tendency, it is hypothesized, underlies gender-discordant behavior, fear of homosexuality, and homosexual behavior. As one unhappy homosexual man lamented, "I am a male with a female brain."
So the problem (for those for whom it is felt as a problem) or the fact of their homosexual situation begins with the fact that we all begin life as a proto-female, and that a few males end up with a low-masculinized brain. What is the evidence that life begins for all of us as proto-females? We all have nipples, that's the evidence. As Leyner and Goldberg put it, "During development, the embryo follows a female template until about six weeks, when the male sex chromosome kicks in for a male embryo." But before the end of the sixth week, a pair of sweat glands on the chest has already begun to differentiate as nipples. All infants are therefore born with nipples and some breast tissue. As they approach puberty, the female hormones that course through the bloodstream of girls reshape their body in womanly ways, including the development of their breasts. Males are left with vestigial nipples, a reminder that life begins for all of us as proto-females, and some of us are fated to become more masculinized than others.