[AndrewC]

I've no doubt that mortality rates creep up faster in carriers than in non-carriers later on in life, but the goal is to pass on your genes, which you can't do if you die at the age of 14 months

Yes, but that chart shows a big deficit for the HbSS. It does appear that the benefit for the HbAS goes on beyond 16 months, but it is unclear when that benefit would be lost. In any case reproductive capability should be around 120 months. Fourteen months of benefit compared to possibly 100 months of detriment does not sound like a profitable transaction.

[general_re]

"Detriment" is being defined in terms of something other than basic survival, though. As far as evolutionary pressures are concerned, surviving your childhood uncomfortably anemic is better than being comfortably dead.

It's a total kludge - this is not what we might call an "elegant" solution to the problem of malaria. But it's the sort of solution that evolutionary processes produce - designers, we would hope, might set their sights just a bit higher than settling for such a tradeoff.