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!
12 comments ↓
So what are we waiting for to send them dentists? A new, booming sector of economy
Haha, elephant dentures will cost a pretty penny.
Then again a painting by an elephant was sold for $30K so they can probably pay for it!
So… I’m a molecular biologist… a few thoughts:
nature never optimises for the sake of an organism. It’s just too stingy.
Lazy’s more like it. As long as it works, there’s no need to optimize. Whatever works. Whatever survives.
we still don’t know why we sleep.
Really? Haven’t read up on sleep much. I think it’s obviously a device to slow down the body on a regular basis to heal and grow.
At that age elephants no longer reproduce and are hence invisible to natural selection.
Did not know about the elephants. Interesting.
There’s an old mystery, why do we age? Many people believe that aging is not determined by specific genes. Since aging is a phenomenon that occurs primarily after the age of reproduction, there does not appear to be any driving evolutionary selective force for genes that actively promote aging.
However, it remains possible that aging is a byproduct of genes that are necessary before reproduction.
Hi Shul, thanks for commenting. We might know of some reasons why we sleep but the popular media tends to paint it as a big mystery. We do have sleep patterns quite different to similar animals so I reckon there are still unanswered questions.
As for aging do you think at least SOME of the effects could be due to genes that weren’t selected for but have still snuck in to our genome? (It seems there’s a lot of useless code floating around the human genome, even amongst the DNA sequences that code for proteins)
Why do we (animals) sleep? Sleep is an anti- photosynthetic period. Green plants respire all the time, but photosynthesize only in sunlight, animals respire all the time, but sleep only (largely) in anti-sunlight (darkness).
NS theoretically can operate on some gene/traits that manifest themselves long after the reproductive years, and so it is not necessarily correct to say that traits in such individuals are invisible to NS.
For example, it probably would be beneficial to the survival of an elephant’s grandchildren (who share some genes) that they stop consuming precious local resourses. So it’s not inconceivable that there might be selection pressure *against* the development of a 6th set of teeth, and *for* the development of late-onset fatal diseases.
Divalent — you might be right on the elephants, however it would also depend on a few other factors. For instance, if 100 grandchildren were alive there might only be 4 or 5 grandparents alive by then (the others dying previously for various reasons) — combined with the fact that older organisms consume less and are slower to find food etc, the math might work out to say that there isn’t sufficient advantage to the grandchildren to provide selection pressure for stopping at 6 sets of teeth. But yes, they could have been selected for.
DDeden — not sure what you mean — isn’t the fact that sleep can be conceptualised as anti-photosynthesis just a coincidence? (Since photosynthesis evolved independantly of animals and sleep)
“But we probably also have get-cancer-genes, which is why we get cancer in old age.”
They are called oncogenes.
[...] Perhaps a certain biologist going all silly billies should brush on his basic evolutions. [...]
[...] All a sexual reproducing species has to do is be suave enough to get someone up the duff**. After that you can run away and die. Everything after the “act” is generally no consequence. Incidentally, that’s why elephants starve to death in old age (which we’ve already covered). [...]
Thanks for the post – I was looking for a reference on the elephant thing, and I came upon it.
(P.S. the Carlin sketch link is down – here’s another copy.)
Thanks Robin, will edit the link