A Field Guide to Humans

Rebecca Skloot reviews Hannah Holmes new book, The Well-Dressed Ape. This seems like an interesting book.

A Field Guide to Humans

The foraging style of Homo sapiens now verges on suicidal.

Reviewed by Rebecca Skloot

Sunday, January 18, 2009

THE WELL-DRESSED APE

A Natural History of Myself

By Hannah Holmes

Random House. 351 pp. $25

Humans are strange creatures, biologically speaking. We're fixated on the topic of mating, though we're the only species that often makes the evolutionarily illogical choice to mate without reproducing. We're also the only creatures on Earth obsessed with analyzing themselves -- which is precisely the drive behind Hannah Holmes's new book, The Well-Dressed Ape, in which she explores herself (and her human mate) as if discovering a new species.

Biologists have long created fact sheets on other animals, organizing their traits into categories including physical appearance, habitat, behavior and reproduction. While researching her previous book, Suburban Safari, in which she explored the wildlife of her backyard, Holmes realized that no field description existed for Homo sapiens. She set out to create one, and the result is sometimes illuminating and often funny.

While examining herself for the Physical Description chapter, Holmes explains how extra food that isn't burned off as energy gets converted to oil stored in fat tissue. "Evidently I've done this a few times," she writes, "because cookies are too damned easy to capture." Her mate's nonfunctional male nipples are "useless as an eye on the bottom of a foot." And in the chapter on Reproduction, while discussing the length of time it takes to raise human offspring, she writes, "I've encountered legitimate and degree-holding theorists who argue that offspring need parental guidance and assistance for only their first ten years of life. Having been eleven years old myself, I respectfully disagree."

The Well-Dressed Ape is full of interesting facts, such as: "A male boxer in top condition can punch with a force of a thirteen-pound mallet swung at twenty miles an hour." Holmes covers hormones and brains, our use of tools, how we see, smell and hear, our tendency toward territoriality and our complicated relationship to food.

"Of all the human young that perish each year (twelve million)," she writes, "the failure to find food is the underlying cause for about half the deaths." At the same time, she points out, humans in developed countries often eat with a "foraging style" that "borders on suicidal." This is "an anomaly in the natural world," she notes, as is the preference for an impossibly thin female body. Cultures that "passionately prefer fat females to the hourglass ones" make more biological sense, she writes, since "reproducing is a primal drive, and it's fueled by fat."

Holmes touches briefly on such complicated and socially loaded topics as race, homosexuality and gender differences. At points, she does this with refreshing frankness. About race, she writes: "While one scientist has characterized racial variation in the genome as being 'scientifically and mathematically trivial,' these differences are certainly not ecologically trivial." Humans evolved different skin colors based on their proximity to the equator; regions with more sun produced darker people. Scientists have long thought this was to protect against skin cancer, Holmes writes, but some now believe it's for maintaining vitamin balance instead: Ultraviolet rays penetrating the skin break down folate, an essential vitamin, but also provide vitamin D. People with darker skin fared better in sunny climates because extra melanin in their skin prevented too much folate breakdown. Lighter skinned humans fared better in darker climates because their skin let in the right amount of vitamin D.

Holmes generally does a good job of conveying scientific ideas. But she dips into some large topics so briefly that the result is vague at best, scientifically skewed at worst. An example: After mentioning that men with ring fingers longer than their index finger may have high testosterone levels, Holmes provides "a list of traits you may be able to predict from a male's high-testosterone ring finger." These include being more likely "to be aggressive," "to mate with many females" and "to be gay." Then, in a move that may rile left-handed people, she lists traits correlated with being a leftie: autism, dyslexia, stuttering, deafness and homosexuality.

But research on finger length and such traits as sexuality and aggression has been dubbed pseudoscience by some experts. Studies linking similar traits with left-handedness also have been questioned because of small sample sizes. The connections Holmes lists aren't proven fact, and there is no agreement on what they might mean if they were. But the average reader wouldn't know that, because Holmes doesn't mention any criticisms of the studies. She sometimes goes for the laugh rather than the science, as in describing her ring finger as "a dipstick displaying the strength of the hormonal marinade that gave my brain its sexual slant."

Nevertheless, The Well-Dressed Ape is aimed at educating a general audience about human biology, and for the most part it succeeds. One essential point Holmes returns to several times is this: Many traits often touted as being uniquely human -- such as self-recognition, intelligence and complex communication skills -- actually exist in other animals. Biologically speaking, humans aren't as unusual as they might like to think. ·

Rebecca Skloot teaches nonfiction writing at the University of Memphis.