> So if it's that easy, why did natural selection not find this solution?
Evolution is still working; who's to say it wouldn't have? Your question should be, "why did not natural selection not find this solution YET?" at which point the answer is obvious.
We're not "evolved", we're just the most recent step in evolution. As long as we (or anything) lives, there's more to go.
I hope I'm not feeding a troll; your question smacks of a thinly veiled "Ha! See?!" type creationist rebuttal.
Now, with a little googling, I learn the following things:
"Most viruses encode proteins that can inhibit apoptosis"
There is actually already cellular machinery for triggering apoptosis when a cell is infected with a virus
Some viruses induce apoptosis themselves, to their own benefit. When the cell falls apart during apoptosis, the virus ends up packaged with bits of the host cell, which stops the immune system from responding to it!
Please assume good faith. My question is, "Is it more likely that natural selection didn't find the apoptotic strategy, or that the apoptotic strategy wasn't a net win, in the environment in which the natural selection happened?"
So let's try to get a handle on which it is likely to be.
The Time article says:
> To fight infection, human cells have proteins that attach to dsRNA and trigger a cascade of reactions that stop viruses from copying themselves.
So, what we observe is:
- Human cells have a mechanism to detect dsRNA; - Human cells have a set of countermeasures that they can produce to block viral replication;
- Human cells have a mechanism to produce those countermeasures when dsRNA is detected (and I'll give you good odds that they have other ways of detecting viral infections that also activate the countermeasures);
- Human cells also have an apoptosis pathway (which, as it turns out, the cell is not shy about activating in other circumstances, like if too much DNA damage is detected)
One of the following must be true
(1) All of the existing machinery (dsRNA detection, existing countermeasures, and the linkage between the detector and the countermeasures), taken together, must be much simpler than this little transducer they engineered that connects the existing dsRNA detection signal to the existing apoptosis pathway, so that X years of natural selection was likely to find the existing machinery but unlikely to come up with this new solution
(2) Blindly triggering apoptosis when you detect dsRNA is not the way to maximize the amount of sex your children have
(3) The only reason viruses exist, and plague mankind, is that we got incredibly unlucky
My money's on (2). (1) seems unlikely because it seems like you have to search a much larger space of DNA base pairs to find this whole complex of dsRNA detectors and virus replication inhibitors, than to find this transducer. (3) is unlikely a priori.
So, what would explain (2)? Like I said, several options:
(A) The drug isn't valuable in practice (the cure ends up being worse than the disease)
(B) The drug is valuable but has a lot of side effects, so taking it all the time is bad. You only want to take it when you have a really nasty viral infections. The machinery to detect the correct case in a cell is too hard, but now that we have brains, doctors, and the internet, we can make a better decision than a cell could about when dsRNA should be connected to apoptosis than a cell could.
(C) Having the linkage was a bad idea for most of the history of mammals, but is a good idea for humans today. Maybe we used to have a lot of immune resistance that we no longer have because of our super clean environment. Maybe we have better nutrition and that somehow makes speculative apoptosis hurt less. Maybe viruses are more dangerous in the dense urban environments where we now live. Maybe it's a bad idea for young people, but a good idea for old people.
Sure, it's all possible, but evolution isn't an optimum-finding strategy; it's just a "good enough to be better than the last one". And, it's random, so even if a "6" on a dice roll is better than a "5", it's still possible to roll 1 through 5 ten-billion times in a row. And even if I do roll a 6, it's possible no one would see it, or I die immediately afterwords and can't take whatever advantage such a roll would invoke.
So the question of "Why didn't evolution come up with this?" is, to me, somewhat nonsensical.
But reasonable people disagree, and I'm no expert.
Evolution is still working; who's to say it wouldn't have? Your question should be, "why did not natural selection not find this solution YET?" at which point the answer is obvious.
We're not "evolved", we're just the most recent step in evolution. As long as we (or anything) lives, there's more to go.
I hope I'm not feeding a troll; your question smacks of a thinly veiled "Ha! See?!" type creationist rebuttal.