[National Review Online; September 4, 2009]
“In the Womb: Animals” by Michael Sims (Washington, DC: National Geographic, 2009)
What is life like “In the Womb”? Thanks to National Geographic, we can refresh our memories with a beautiful book by that title, as well as a TV miniseries that makes use of the most advanced video technology. A new book and series now examines the prenatal life of our fellow mammals—and it’s weirder than you’d think.
Of course, you might be a professional zoologist, and nothing here would surprise you. But I was amazed to learn that an elephant’s trunk is a hundred times more sensitive than our fingertips. It contains 40,000 individual muscles, while the entire human body requires only 639. And did you ever think about an elephant’s feet? Don’t those enormous, calloused feet look like they would ache, from stomping around under the weight of maybe 11,000 pounds of elephant all day? But the feet are so sensitive that they can receive sound waves through the ground; elephants can “hear” through their feet. And though those massive feet look flat as pancakes, the sole is actually spongy and convex (a design that Nike might want to study).
“In the Womb: Animals” is indeed mesmerizing, and can turn you or anyone you know into a veritable fountain of Wow Facts. Since the book is about gestation, it is also about sex, and there is a lot more variation in how animals mate than I’d ever suspected. The male elephant’s “curvy three-foot-long penis” never actually enters the female; the male lemon shark doesn’t even have a penis. Perhaps irritated about being teased for this, he and some buddies grip the female in their jaws while assaulting her, a process that will leave her with scars, “and some females don’t survive mating at all.”
Slipped off into handy-fact land again; sorry. An aspect of this book that I particularly appreciated is the deftness of author Sims’ prose. It doesn’t read like one amazing info-bit after another, though to a large extent that’s the material he has to deal with. The tone is conversational and lightly amusing. Discussing the prenatal development of a dog’s mouth, he writes that it is also the equipment he will use to bark, “that impressive tool dogs use to greet, notify, and threaten, as well as to torment writers who are trying to concentrate.” In mating, dogs “lock together in the ‘tie’ stage that provokes so much embarrassment when dogs mate in front of the children and neighbors.” Though the actual mating takes place immediately, dogs are initially unable to separate, and can struggle into a tail-to-tail position where they remain for up to an hour, “failing to look nonchalant.”
But why in the world is dogs’ equipment designed for this to happen? “Scientists theorize that this posture evolved to allow the participants to better defend themselves if a predator catches them in flagrante.”
On virtually every page a theory is proposed to explain why this or that odd feature evolved. “All female dogs go through a pseudo or phantom pregnancy.” (All? I didn’t know that.) This feature evolved so that unmated females can nurse the puppies of a momma dog needed elsewhere (e.g., to hunt). Puppy eyelids appear a month after conception, in order to seal the eyes shut against waste in the amniotic fluid. Dewclaws on a dog’s leg indicate a five-toed ancestor; over time, dogs’ feet evolved so they could run faster, on tiptoe.
Some theories sound more theoretical than others; the tendency to wonder and guess is one of the human creature’s most endearing characteristics. So sometimes we seem to be in the land of Rudyard Kipling’s “Just So” stories: this is how the leopard got his spots, this is how the rhinoceros got his skin, and this is how the dog got his dewclaw.
But at times these suggestions raise more questions than they answer. If evolution is the result of random mutation offering superior benefit for survival, what survival advantage did the “tie” condition offer to dogs? Surely the standard mammalian practice allowed dogs to defend themselves better.
Any mutation may, of course, occur; the question is how disadvantageous mutations could have become the prevailing mode. How did baby kangaroos evolve to be born in a nearly fetal state and then struggle up to their mom’s pouch, when the usual pattern of remaining longer in the womb is so much safer? It’s great that a shark’s yolk sac, its prenatal food source, is able to turn into a placenta after it depletes—but why did it evolve to deplete prematurely, before the shark was finished developing?
Why did the sand shark evolve so that the strongest fetus devours all his brothers and sisters in utero? Wouldn’t that quite literally inhibit rather than advance reproduction?
Scientists don’t claim to have all the answers; as Sims says, “All over the planet, human beings are amassing such facts and doing the best they can to interpret them. When nature reminds us that our explanations are approximate, we tweak them again.” This work of observing and theorizing is thrilling, somehow; it is always exciting to learn something new about our very complex world. “How exciting,” Sims writes, “to decipher old mysteries and discover new ones in previously uncharted territory—inside molecules, at the bottom of the sea, beyond our galaxy, and in the womb.”
And how awesome it is to recognize that only human beings have evolved to find this knowledge exciting. Whether you search beyond the galaxy or in the bottom of the sea, you won’t find another animal this fascinated and thrilled to study other creatures. As G. K. Chesterton said, the simplest lesson of the ancient cave drawings is that an observer has now “dug very deep and found the place where a man had drawn the picture of a reindeer. But he would dig a good deal deeper before he found a place where a reindeer had drawn a picture of a man.” This beautiful record of animal life “In the Womb” is not produced by cats or crocodiles but by members of our own human race, the most curious (in all senses of the word) creature of them all.