Another common misconception of evolution is the idea of design optimality. It’s as if all creatures are perfectly honed to take advantage of their environment, and every species is getting better over time. Utter rubbish of course but it’s wrong for two main reasons. Reason the first: when evolution tries to optimise, it often fails. Miserably. Reason the second: nature never optimises for the sake of an organism. It’s just too stingy.
On reason one here’s a great video of Neil deGrasse Tyson (what moron would put an entertainment system in the middle of a sewage canal?). I’d like to talk about the reason two. Evolution’s all about making as many copies of a species as possible. Everything else is not just secondary, it’s non-existent; and invisible to evolution. 2 examples:
Why Do We Sleep?
Dennett has a great point in Darwin’s Dangerous Idea. You often hear in the media about “mysteries of sleep”; how we still don’t know why we sleep. Perhaps true, but why should we think sleep requires any explanation at all? Why do we think organisms should be awake as the default? That’s chauvinism: being awake is actually a very wasteful state. The question should not be why do we sleep? but why do we wake?. After all, most branches in the tree of life (fungi, slime moulds, plants) aren’t ever awake. And doing just fine.
The point isn’t about the biology of sleep per se. Just that it’s an interesting question. Carlin has a great piece on the irony that only living people say life is sacred (clearly vested interest!) [EDIT: old link doesn't work, here's another one -- hat tip Robin]. Here, only beings that wake ask “why do we sleep?”. Evolution is stingy. Minimalist states like sleep are the default — not extravagances like the four Fs of biology (fight/feed/flee/fuck).
Why Do Elephants Starve?
You’re an elephant. You’ve reached your 5th decade happily munching on plants, all the time oblivious to the terrible suffering evolution is about to impose on you. You have but 5 sets of teeth that get rapidly worn out. Once the last set falls out you can’t chew. You’ll die a slow agonising death by starvation, just like all elephants reaching the same age as you (HT Eliezer). One consolation: as an elephant you’ll spend your life blissfully ignorant of this.
At that age elephants no longer reproduce and are hence invisible to natural selection. Suppose some elephants have genetic variations that make them suffer less in old age (eg. they stampede off a cliff once they have no teeth — to at least avoid a slow death). These elephants will NOT have more grandchildren than the regular elephants: the suicide trick doesn’t affect reproduction. There are about 550,000 elephants in the world, so I’d estimate about 50,000 are starving to death right now. All because nature is too stingy to take any care of any organism.
Interesting thing is humans are no different to elephants in this respect. Of course our organism deteriorates with age. But we probably also have get-cancer-genes, which is why we get cancer in old age. These kick in after people stop having kids and so aren’t selected out by evolution. Nature is too stingy to give us more life, or better quality of life in old age. But we’ll show it!