Book 20: Mutants

Mutants: On Genetic Variety and the Human Body
Armand Marie Leroi
2003
448 pp.
Rating: 4 of 5

I'm not quite sure how I got sidetracked onto these science-related books, but I'm really enjoying it. They actually interact with the religion books in an interesting way, but more on that later....

Anyway, Mutants is not a sensationalist/sideshow sort of book at all. It's really about genetics. I can sense your eyes glazing over already, but wait --  Mutants is a great read. Leroi does a great job of explaining a lot of interesting information about genetics by using it to explain a lot of common human mutations. Why do conjoined twins occur? Why is our skin the color it is (or isn't, if you're albino)? Why are some people incredibly tall and others short? There are a lot of very interesting biological processes behind these variations in human anatomy, and they all get explained here. For example. while we're fetuses, apparently there is some group of cells that have the job of starting as a bump on our torsos, then they build an appropriate appendage from wherever they are. If they are in the wrong starting place, voila, you've got an arm growing out of your back!  If they give out before they get the fingers done, you might be electrodactyl. Or if they keep working too long, you end up with 6 fingers (a pretty common human mutation, you don't see it much because doctors tend to cut off extra digits).

There's a great section on intersex/hermaphrodite genetic mutations as well. Some estimates put hermaphroditism at occurring somewhere (to some degree) in one in every 2000 people. That would put the intersex population of the US at somewhere around 150,000.  Our normal "XY or XX" understanding of male or femaleness is woefully inadequate, there are several variations on those two combinations available. I haven't seen much if anything written about how this might relate (or might not) to homosexuality or transgender issues - but that would be interesting to know.

It's also worth noting that we share much genetic information with other animals on the planet. 98% of our genes are the same as a chimps. 90% of our genetic material is identical to any other mammal's - from a whale to a mouse. 60% of our genes are identical to those of insects, for gods' sake.  This is where things start to get interesting to me. One experiment showed that if you snipped the genetic codes out of a fruit fly that make a fruit fly eye, and you put them in a mouse (in place of the mouse codes for mouse eyes), what happens is not a mouse with fly eyes, but a mouse with regular old mouse eyes. That is to say, most of our genetic material is actually - literally even! - interchangeable with other animals.  This really puts humanity in it's place, I'd say. Or at least I'd hope so.

Finally, understanding how these genetic and biological processes work is always astounding. It's pretty incredible that such complex (and simultaneously fragile and robust) evolved to make you or I. I'm not doubting that evolution is what created it, it's just interesting that it's one of those things that's bigger than the human mind can really consider well - I think both because it happens on  a scale so much larger than us (in terms of time) and simultaneously so much smaller than us (the physically microscopic). In a certain way, you do have to take it on faith that the systems exist and occur as we are told they do.