Mutants: On Genetic Variety and the Human Body

by Armand Marie Leroi

ISBN: 0670031100

Leroi is fascinated with the development of bodies. The sort of body-sculpting that happens in the gym or with the plastic surgeon’s knife isn’t his thing, the growing of five fingers or six on a hand still in the womb is.

His fascination is rendered in clinical terms. He doesn’t talk about collectors of human oddities like Peter the Great, instead he talks about gene sequences and includes MIM numbers in footnotes. (MIM stand for Mendelian Inheritance in Man, an online database of genetic disorders.)

The book’s chapters are organized by type of mutation: conjoined twins, things that go wrong with the head, with the limbs, with skeletons, with growth rates, with genitals, with skin, and with age. It is quite remarkable, given the plethora of things that can go wrong in the growing of a human body, how often those things don’t happen. Well, it might seem so, until Leroi points out that mutations which are lethal or which seriously impair an organism’s reproductive chances generally don’t do well in the gene pool, and so are rare.

One of the odd things about this book is its lack of passion. I mean this in a good way: before I read it, I would have been hard pressed to imagine a book that spends so much time discussing fetal development without defending a woman’s right to choose, condemning the availability of choice, or trying to define the moment when a growing embryo should be considered a human being. In other words, Leroi sticks to the science of mutant or non-mutant development, and leaves everything else alone. He takes the same tack with animal experimentation — much of what we have learned about mutant genes has been learned from experimenting on animals — yet Leroi doesn’t talk about the ethics of experimentation. The only time Leroi talks about right and wrong is when he talks about the Ovitz family. Many of the Ovitz family members had pseudoachondroplasia (a type of dwarfism) and that is what allowed them to survive: Mengele took enough interest in them to conduct pointless, cruel experiments on them. The section about them in the book ends with the line: “Josef Mengele was never tried for his crimes, but died on a Brazilian beach in 1979.” From Leroi, this is a damning indictment, one that it would have been monstrous not to make.

A sense of humor does creep into the book at various points, mostly when discussing the names scientists have given different tiny parts of the developmental stew. These include sonic hedgehog (a signalling protein, one mutant variation of the gene encoding it causes cyclopia); noggin (a protein that helps the brain and spinal cord develop); and “multi-tasking proteins” called moonlighters.

There are numerous illustrations in the book, most taken from sources hundreds of years old. There are reproductions of engravings and painted portraits, and relatively few photographs. The photographs that do appear are generally from the early 1900s. Using older sources perhaps reinforces the idea that these disorders are as old as humanity itself and it is only now that we are beginning to discover how they happen; or perhaps modern-day parents are more reluctant to allow scientific use of of the deformed and stillborn. The most disturbing photographs date from the late 1800s and show the skeleton of twins so severely conjoined as to appear two-headed, and another of a stillborn infant revealing autopsy stitching and a second mouth where a pair of eyes should have been. A portrait from 1700s taken to illustrate piebalding is nearly mirrored in a photograph from 1912. The amazing variations of the human condition, and not the horror of the extremes of development, is what Leroi is most concerned with.

He does a good job of explaining what we now know of how and why those variations and mutations develop. In not quite layman’s terms (if you aren’t handy with medical terminology, be prepared to look up different -plasia to get the hang of things) Leroi manages to tell an accessible and interesting story about how our parts come to be (or fail to be) what they are expected to be. Recommended for for folks with an interest in genetics and/or the odd.

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