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from the On-a-Pale-Horse-vs-Being-a-Green-Mother dept.
The world population is growing because the birth rate exceeds the death rate, so to stabilize the world population either the birth rate needs to drop, or the death rate needs to increase. The most cited reference for population studies is the projections of future population (PDF) made by the Population Division of the United Nations. The UN report projects the world population to eventually stabilize as a result of countries settling in to a birth rate that falls around the replacement level.
A commentary by Stephen Warren in the open access journal Earth's Future takes the UN report to task for focusing on birth rate. He notes that all species generate offspring in numbers well above the replacement level of two, but you don't see historically the kind of population growth like you do with humans. He argues that despite all the negative feedback mechanisms on population (such as war and pestilence), it seems that Malthus (PDF) was correct that food supply is the driving factor, and wonders whether it is even possible to stabilize the world population until food production levels off.
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(Score: 2) by FatPhil on Thursday May 28 2015, @04:19PM
The fitness function can select for fewer kids if the people expressing that meme are not competing with those who are not expressing it. Which is how things are at the moment. You seem to assume that eventually they will be in competition, but all the evidence of the last 50 years points to that not being the case. Sure, those who adopt the meme earlier will end up as a smaller proportion of the total population when steady state is achieved, but that doesn't mean they're dying out, or even being resource-starved. Of course, there's no proof that the trends of the last 50-100 years will continue, and no proof that we will S rather than J (which has several wildly different possible outcomes) - we're all just passengers on this ride.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 1) by albert on Friday May 29 2015, @05:25AM
Something did select for traits which now, in a different environment, lead to fewer children. Nothing is currently selecting for fewer children, at least not in the parts of the world where large families don't actually lead to death by starvation.
We had a different environment just a century or two ago. There was no welfare state, child support, birth control, or secure food supply. A bit of resistance to having kids was beneficial. That bit of resistance was balanced off by sexual desire, leading to people producing roughly the number of kids that would maximize the ultimate (accounting for death) number of offspring.
Our environment has changed, but our population still largely contains traits more suited to the prior environment. Those traits don't go away instantly, though they are very strongly being selected against.
A few generations from now, we'll be back to double-digit families as the norm. The traits which lead to this are uncommon in our population today, but this is rapidly changing.