Mutants: On Genetic Variety and the Human Body [Paperback]

We are all mutants. But some of us are more mutant than others.

I especially enjoyed the fact that I was finally able to understand the genetics of my aunt's 6th toe and the fact that Leroi uses redheads to explore the boundary between mutation and polymorphism [I'm okay with the fact that being a redhead makes me a mutant].

Despite the way Leroi handles the material, this is not a book for the squeamish. The black and white illustrations may be disturbing to some readers. I think the perfect reader for this book would be a person with the background from a 9th grade biology class and an interest in learning more about human genetics. People with an interest in history and the process of doing science should also find much of interest in Mutants.

For example, Carl Herman Unthan was a violin virtuoso by age twenty, although he had no arms. Of course, not all such mutants are so successful. Harry Eastlack had a defect that told his body to make bone whenever it made any repair, so that bruises and tears would turn into bone, not healed flesh. The stillborn babies here are strange indeed. One has a second developed mouth in its forehead. Another child was born with over twenty half-developed fetuses in his brain. The book, however, is far from a chamber of horrors. Even the most bizarre of the mutants do show us things about the process of becoming and being a human creature. Conjoined twins, for instance, are closely examined here in many ways for many lessons, like how our developing bodies can know left from right. The deformities in limbs show the importance of embryonic limb-buds, a signaling protein called "sonic hedgehog," and "hox" genes that are the same ones that help keep our vertebral segments orderly. The same hox genes work to make the segments in worms. Leroi writes of the "breathtaking similarity" living creatures have in such arrangements, as evolution has built variations on the same basic plan. "We are, in many ways, merely worms writ large."

There are pygmies and dwarfs here, and giants, and men / women of intermediate sex, albinos, piebalds, cyclopes, and families covered all over in hair. There is natural curiosity about such "monsters," but Leroi shows there needs to be more. They are all products of molecules gone wrong, molecules we can now detect and understand, to better appreciate how molecules go right in the unimaginably complicated dance that creates organisms. There is a fascinating chapter near the end to show that perhaps ageing and death are caused by specific mutations (we are mutants all, remember). The final chapter is about the importance of human diversity, and the importance of beauty as a general evolutionary force (as Darwin knew it to be). A beautiful face has appeal at least in part because imperfections, the myriad types of imperfections as illustrated here, are not apparent, indicating health and fitness. With a declaration for biological beauty, this is a well-informed, life-affirming book by a scientist who has used molecular errors to ponder deeply the human condition.

However, it's a very good book, humanely and thoroughly written, which doesn't treat its subject matter salaciously. I'll look forward to future works by the author.