Read Online The Darwin Awards Countdown to Extinction by Wendy Northcutt - Free Book Online Page A
Authors: Wendy Northcutt
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Why Do Without? The Cost of Sex
Sex always costs—not necessarily in money, but in the more primal currencies of energy, time, and exposure to danger. Exhausting fights over mates raise the cost of business in the sexual world—ask any stag during rutting season. And consider over-the-top mating displays like the nine-foot blossom of the carrion flower, the peacock’s tail feathers, or the human’s silly, showy “peacock” brain. (See “Sex on the Brain,” p. 109 for a treatise on human brains and runaway sexual selection.)
Elaborate mating structures take time and energy to make and increase exposure to predatorsas well as potential mates.A peacock’s huge tail feathers slow him down; the leopard who pounces on a poky peacock is reaping a cheap lunch subsidized by the cost of sex—fancy plumage—to her prey. Time spent attracting a mate could be spent feeding, gathering energy, and growing clones. Nonsexual creatures avoid all that mating hassle by just doing it solo.
Lesbian Lizards
The most fascinating sex-free creatures are the ones who have given up sex after enjoying it for millions of years. There are all-female species of whiptail lizard, blue-spotted salamander, and topminnow. Tellingly, all of these species have mating behaviors that show their recent evolution from sexual ancestors. All-female blue-spotted salamanders mate with males of related species; the sperm triggers development of their eggs, but contributes no genes. The live-bearing desert topminnow, Poeciliopsis lucidus, does the same.
Whiptail lizards of the desert Southwest go one step further: Members of the all-female species Cnemidophorus uniparens take on male-like behavior and mate with other females in a process called pseudocopulation. Their female-on-female behavior stimulates egg production and the birth of clones.
If so many organisms get along fine without sex, why are the rest of us still doing it? Especially, note evolutionists dryly, when mathematical models show that asexual females should take over any population within fifty generations, due to the time and energy they save.
But—that’s fifty generations without natural selection— with no new trends in weather, no new diseases, no new tricks by your predators. Do you see the problem?
Nature is never free of natural selection. Even when the physical environment is stable, the ecosystem of predators and pathogens is not. You are food for them, and if there is one thing stronger than the sex drive, it is the need to feed. Even Darwin would agree: You must survive until you can pass on your genes. Food comes before sex, and organisms will do anything to get it—or avoid becoming it—even swap genes. If everyone else is swapping genes in an arms race to eat you, and you’re standing there having sex with yourself, you’re falling behind.
In a nutshell, sex is an engine of diversity: More varieties of organisms are birthed when they are conceived with a partner. A family of clones is obviously less diverse than a family with mixed genes. And when your genotype is the delicious flavor of the day, you’ll want to make sure your offspring are something your predators have never tasted before. Whether you need faster legs, a longer tongue, or slimier skin—sex is the way to go.
Now that the case has been made in favor of sex, how do creatures get by without it? If a hungry world is chasing them, why do lesbian lizards have any place in nature?
Studies show that asexual plants and animals thrive in marginal environments with little competition, but cannot compete with sexual relatives in mainstream habitats. Asexual butterflies flutter on alpine mountaintops, asexual plants pop up in plowed fields and after volcanic eruptions, and asexual vertebrates make their homes where it’s hot, icy, or dry. Note that the all-female species mentioned above are the desert topminnow and lizards of the desert Southwest. These asexual desert creatures have
Why Do Without? The Cost of Sex
Sex always costs—not necessarily in money, but in the more primal currencies of energy, time, and exposure to danger. Exhausting fights over mates raise the cost of business in the sexual world—ask any stag during rutting season. And consider over-the-top mating displays like the nine-foot blossom of the carrion flower, the peacock’s tail feathers, or the human’s silly, showy “peacock” brain. (See “Sex on the Brain,” p. 109 for a treatise on human brains and runaway sexual selection.)
Elaborate mating structures take time and energy to make and increase exposure to predatorsas well as potential mates.A peacock’s huge tail feathers slow him down; the leopard who pounces on a poky peacock is reaping a cheap lunch subsidized by the cost of sex—fancy plumage—to her prey. Time spent attracting a mate could be spent feeding, gathering energy, and growing clones. Nonsexual creatures avoid all that mating hassle by just doing it solo.
Lesbian Lizards
The most fascinating sex-free creatures are the ones who have given up sex after enjoying it for millions of years. There are all-female species of whiptail lizard, blue-spotted salamander, and topminnow. Tellingly, all of these species have mating behaviors that show their recent evolution from sexual ancestors. All-female blue-spotted salamanders mate with males of related species; the sperm triggers development of their eggs, but contributes no genes. The live-bearing desert topminnow, Poeciliopsis lucidus, does the same.
Whiptail lizards of the desert Southwest go one step further: Members of the all-female species Cnemidophorus uniparens take on male-like behavior and mate with other females in a process called pseudocopulation. Their female-on-female behavior stimulates egg production and the birth of clones.
If so many organisms get along fine without sex, why are the rest of us still doing it? Especially, note evolutionists dryly, when mathematical models show that asexual females should take over any population within fifty generations, due to the time and energy they save.
But—that’s fifty generations without natural selection— with no new trends in weather, no new diseases, no new tricks by your predators. Do you see the problem?
Nature is never free of natural selection. Even when the physical environment is stable, the ecosystem of predators and pathogens is not. You are food for them, and if there is one thing stronger than the sex drive, it is the need to feed. Even Darwin would agree: You must survive until you can pass on your genes. Food comes before sex, and organisms will do anything to get it—or avoid becoming it—even swap genes. If everyone else is swapping genes in an arms race to eat you, and you’re standing there having sex with yourself, you’re falling behind.
In a nutshell, sex is an engine of diversity: More varieties of organisms are birthed when they are conceived with a partner. A family of clones is obviously less diverse than a family with mixed genes. And when your genotype is the delicious flavor of the day, you’ll want to make sure your offspring are something your predators have never tasted before. Whether you need faster legs, a longer tongue, or slimier skin—sex is the way to go.
Now that the case has been made in favor of sex, how do creatures get by without it? If a hungry world is chasing them, why do lesbian lizards have any place in nature?
Studies show that asexual plants and animals thrive in marginal environments with little competition, but cannot compete with sexual relatives in mainstream habitats. Asexual butterflies flutter on alpine mountaintops, asexual plants pop up in plowed fields and after volcanic eruptions, and asexual vertebrates make their homes where it’s hot, icy, or dry. Note that the all-female species mentioned above are the desert topminnow and lizards of the desert Southwest. These asexual desert creatures have
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