Human Fragility and Evolutionary Advantage: A Possible Answer

Last week I wondered why humans are so uniquely fragile. Since then I've read Elizabeth Kolbert's book The Sixth Extinction: An Unnatural History, and she has something to say that might be related. With regard to humans causing the extinction of prehistoric megafauna, she notes that species gain from gigantism by being too large to have a predator. Such animals have longer gestation periods, which makes them more susceptible to extinction. (I'd reference page numbers but I already returned it to the library, so you'll just have to trust me: it was in the last couple chapters.) So humans are threatened by childbirth because we have giant babies so our adults are too big for most predators to eat.

Meh, maybe. But why does every wound get infected and kill us? It's not just childbirth fragility that seems odd. Another explanation from Kolbert's book might be that these viruses and bacteria have emerged too recently for our immune systems to have learned how to fight them, but wouldn't that be true for all animals' immune systems? Why are we alone in dying from wounds at so high a rate?

Thomas Jefferson, Murderous Psychopath

I started reading The Sixth Extinction: An Unnatural History by Elizabeth Kolbert. In the second chapter, she writes of mastodon bones discovered in Kentucky in 1739. No one knew what they were for a while, and one European doctor called the animal the incognitum. And this is where psycho Thomas Jefferson comes in.

Writes Kolbert:

Jefferson concocted his own version of the incognitum. The animal was...the largest of all beasts--"five or six times the cubic volume of the elephant."...The creature...was probably carnivorous. But it was still out there somewhere. If it could not be found in Virginia, it was roaming those parts of the continent that "remain in their aboriginal state, unexplored and undisturbed." When, as president, he dispatched Meriwether Lewis and William Clark to the Northwest, Jefferson hoped that they would come upon live incognita roaming its forests. [p. 27]

Say what? Jefferson thought there was a carnivorous animal six times the size of an elephant and he sent Lewis and Clark to GO BE EATEN BY IT. That is some straight-up psychopathic scientific discovery. Imagine his disappointment when they returned.

Human Fragility

How did evolution leave our species so fragile? A lion can grab onto a wildebeest and give it a few bites before losing it, and the wildebeest will be fine. Calvin Coolidge's son stubbed his toe and died.

Seriously, what is the maternal mortality rate in the animal kingdom? A gazelle drops a kid and is, like, "Whoa, I feel a lot better now," and walks away. No one is worried about whether the mother gazelle is going to survive. In fact, I can't get any relevant results when I Google "maternal mortality in the animal kingdom." It's all about human maternal mortality. Are we the only species that is SO threatened by childbirth? What's the evolutionary explanation for that? Thrill-seeking women (you get more babies out of a lady who's more likely to die from childbirth because YOLO)? Motherless children grow up to be sexier?

This isn't a "so evolution isn't true!" post; I just don't understand why something as fundamental as reproduction is so dangerous uniquely for humans.

PS: Remember, "math" is the science label.