but by ucblockhead (4.00 / 1) #9 Thu Apr 24, 2008 at 03:59:15 PM EST
The one does not preclude the other. The effect off famine on fertility is very well known.
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Yes it does by TheophileEscargot (2.00 / 0) #10 Thu Apr 24, 2008 at 04:04:55 PM EST
A famine doesn't starve everyone to exactly the same extent. Some people have enough to eat. Some are a little short of food. Some are literally starving.

In a famine, at whatever level of starvation this effects shows up at, there would be some people at this level, which means the effect would show up demographically.
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"Everything is vague to a degree you do not realize till you have tried to make it precise." -- Bertrand Russell
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Starving to the same extent by ucblockhead (4.00 / 1) #11 Thu Apr 24, 2008 at 04:18:34 PM EST
If people aren't starving to the same extent, then the effect wouldn't be 59%...
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No by TheophileEscargot (2.00 / 0) #12 Thu Apr 24, 2008 at 04:31:23 PM EST
But if you're narrowing the calorie range at which this effect shows, it's even more puzzling that it happened showed up so strongly in the small sample of the study.

Remember this effect allegedly exists to help women produce smaller girl offspring when short of calories. Yet somehow in a situation when people are genuinely short of calories, it's so small as to be statistically indetectable with a sample size in the hundreds of thousands. Yet it shows up in a sample of hundreds when considering prosperous, well-fed mothers in the developed world. And it doesn't affect the sex ratios born to the overweight and obese: that would surely have shown up by now too.

It doesn't make sense: an economy measure that only shows up when there's a miniscule deviation from a healthy food intake, disappearing completely whenever there's a significant calorie surplus or deficit.
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"Everything is vague to a degree you do not realize till you have tried to make it precise." -- Bertrand Russell
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Maybe by ucblockhead (4.00 / 1) #14 Thu Apr 24, 2008 at 05:59:13 PM EST
I still think you are far too quick to call this "bad science" based on historical data. It seems to me like calling the life-extension effect of calorie restriction a crock because people don't live longer after famines.
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Well, that's probably wrong for similar reasons by TheophileEscargot (2.00 / 0) #15 Fri Apr 25, 2008 at 03:19:47 AM EST
A single famine might not make a difference, but if there was a significant life-extension effect it would show up in the demographics. You could look at the developing world, Marx-Leninist economies (there's some interesting data from Cuba), isolated and religious communities and so on.

If there is any effect in humans, it must be pretty tiny to have not shown up by now.

It works in rodents of course. Rodents are highly optimized to grow fast, pump out a load of babies and expire, so there's plenty of room for life-extension trade-offs. But humans take about 13 years to get to reproductive age, and 25 before the brain fully matures. Having invested all that time maturing, evolution needs us to take advantage of it. It's a pretty fair bet that we're already got all the easy life-extension genetic switches and mechanisms turned all already.
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"Everything is vague to a degree you do not realize till you have tried to make it precise." -- Bertrand Russell
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Not just rodents by ucblockhead (4.00 / 1) #17 Fri Apr 25, 2008 at 11:51:32 AM EST
The effect has shown up in every animal from tapeworms to rhesus monkeys that have been studied and is pretty much accepted by the biological community as most likely existing in humans.

See here.
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I think that article by R Mutt (2.00 / 0) #18 Fri Apr 25, 2008 at 12:34:25 PM EST
Illustrates Wikipedia's tendency to be provide evenly balanced arguments when the actual evidence is heavily weighted one way.

The "Effects on humans" section basically just talks about the normal ill-effects of being overweight. When it does cite actual scientific papers about calorie-reduced life-extension in humans it's papers like this: "Why dietary restriction substantially increases longevity in animal models but won't in humans."

That paper bears out the earlier point: there's a trade-off between fast reproduction and longevity. Humans have already traded off for that: we reproduce very slowly and live very long lives. Any life-extension effects of this in humans are likely to be noexistent or very small.

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When I'll have time by ucblockhead (4.00 / 1) #19 Fri Apr 25, 2008 at 12:55:09 PM EST
I'll dig up more concrete stuff. It really is pretty well accepted these days.
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The mechanism I'd heard was different. by ambrosen (4.00 / 1) #20 Sun Apr 27, 2008 at 06:34:17 PM EST
The mechanism that I'd heard, and strikes me as plausible, is that the male offspring have a much greater variance in the number of children that they have, so if your situation is good relative to the social background, then male children are the best, cause they'll all go round getting lots random women pregnant, but if you're at a low social point, far better to have daughters, and they'll all have one or two children with the cads from the posh family, and all will be well.

But this story seems a bit different. I'd like to see a reconciliation of the one I'd heard (a relative wealth situation) and the one presented in those articles.

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I have the same objection by TheophileEscargot (2.00 / 0) #21 Mon Apr 28, 2008 at 03:25:21 AM EST
If there's one thing that historians have an Imperial Fornication-Ton of data on, it's aristocratic genealogy. If this effect is real and significant, it's the easiest thing in the world to prove. Look at the records of posh familes (Kings of England is a good place to start) and just see how many male and female children there are.

If you look up what they call Pathological Science or Voodoo Science, not all of the features but a disturbing number of them seem to apply to sociobiology.

1. Discoverers make their claims directly to the popular media, rather than to fellow scientists.

2. Discoverers claim that a conspiracy has tried to suppress the discovery.

3. The claimed effect appears so weak that observers can hardly distinguish it from noise. No amount of further work increases the signal.

4. Anecdotal evidence is used to back up the claim.

3 is the critical one. For 2, it's "political correctness" rather than a conspiracy which is assumed to be covering things up.

Anthropologists, historians and social scientist have spent an awful lot of time and effort painstakingly eating grubs with remote tribes, spending lifetimes analysing gravestones and parish records and so on; and applying the incredibly sensitive pattern-recognition system of the human brain to the resulting data.

I wish biologists who venture into their realm would start looking at their data, instead of just assuming that as mere social scientists they're just too thick to have done anything worthwhile.
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"Everything is vague to a degree you do not realize till you have tried to make it precise." -- Bertrand Russell
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All good points. by ambrosen (4.00 / 1) #22 Mon Apr 28, 2008 at 07:50:25 AM EST
I concede all of them.

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