Women After All: Sex, Evolution, and the End of Male Supremacy by Melvin Konner

the sperm of the snail that shot it and, at the same time, ups the number of eggs in the mate that takes the hit.
    Each snail tries to launch these missiles during sex, having stored one or more darts near the penis, which is attached to each owner’s female organs. Snail biologist Ronald Chase has said, “Love is coming down to war in a way. Sexual conflict plays out,” even between hermaphrodites. Apparently all’s fair in the snails’ love-war, and it does seem a pretty macho way to have sex. Yet I would argue that we can fairly call both snails female, because each goes on to create new life, laying around eighty eggs in the soil that, with luck, will grow up in a year or two. Also, although it’s not ideal, each as a last resort can reproduce alone.
    Chase thinks that the myth of Cupid and his love darts came from the ancient Greeks’ knowledge of snails. The Greeks were good naturalists and would have noticed this display. Cupid’s darts, according to the story, make you fall in love—you are smitten, we often say—and while this can happen to both partners, it is not always equal, and sometimes the one more deeply smitten gets put at a serious disadvantage. This is an asymmetry we have in common with garden snails.
    One further case of two-sexes-in-one: the red-tipped flatworm, named for its gorgeous coloring, which includes a red-tipped white stripe down the back of an almost iridescent blue body. It is about two inches long and speeds around coastal bays, reefs, and lagoons in the oceans from Myanmar to Australia. In addition to female reproductive organs, each worm has two penises, which it uses tofence—again, the scientists’ word—in the ritual leading up to mating. The two would-be lovers rear up with their back ends on the ocean floor and fence it out in a way that looks hypermasculine, each striking and parrying as best he—she?—can.
    The contest—romance?—takes up to an hour; it is described in detail in a paper called “Sex and Violence in Hermaphrodites.” The worms are not using weapons that some might claim symbolize penises. They are using their actual penises, two each, slapping them against their partner’s—opponent’s?—penises and trying to jab at least one of their own into the other’s flesh, to stick without getting stuck. They don’t have to aim for any special spot or cavity, just pierce the skin. They can inject anywhere, and the stream of sperm will find its way to the other’s ovaries, making pale streaks that look like lightning, visible through the worms’ translucent bodies.
    Thus the war between the sexes—without sexes. Each is at once aggressive and coy, intrusive and choosy. But as Leslie Newman, who coauthored the paper with her colleague Nicolaas Michiels, said, “It is better to stab than to be stabbed.” Each dueler is trying to choose by resisting fertilization. This limits mating to only the most skillful rivals and ensures that the victor’s offspring will have the same skills. Naturalist William Eberhard called it “selective surrender.” If you are pricked, so to speak, you make offspring. On the other hand, if you stab but escape stabbing, you have no flesh wounds to heal and no burden of eggs, yet you pass on your genes.
    It is not difficult to see how males might evolve in such a system, and there are other species of flatworms that are conventionally male and female. Those females avoid some males and welcome others, and it’s not the most aggressive males who get the prize. Perhaps sex originally evolved from hermaphrodites, though it could also have happened the other way around. The possibility of evolving back and forth seems clear.
    Either way, these instances of intense competition during sex itself highlight a key fact: all organisms are to some extent in conflictwith all others, no matter how intimate the relationship. Yes, many species have cooperation and even altruism, but those nice behaviors always involve limits. The