Adaptive Evolution of the FADS Gene Cluster within Africa
Rasika A Mathias cs 2012 PLoS ONE 7(9):e44926
doi 10.1371/journal.pone.0044926
Long-chain poly-unsaturated fatty acids (LC-PUFAs) are essential for brain structure, development & function: adequate dietary quantities of LC-PUFAs are thought to have been necessary for brain expansion & the increase in brain complexity observed during modern human evolution.
Previous studies (in largely European populations) suggest:
Hs have limited capacity to synthesize brain LC-PUFAs (e.g. DHA) from plant-based medium-chain-PUFAs, due to limited desaturase activity.
Population-based differences in LC-PUFA levels & their product-to-substrate ratios can (in part) be explained by polymorphisms in the FA-desaturase (FADS) gene-cluster, ass.x increased conversion of MC- to LC-PUFAs.
Here we show:
these high efficiency converter alleles in the FADS gene cluster were likely driven to near-fixation in African populations by positive selection ∼85 ka:
did selection at FADS variants, which increase LC-PUFA synthesis from plant-based MC-PUFAs, allow African populations, obligatorily tethered to marine sources for LC-PUFAs in isolated geographic regions, to rapidly expand throughout Africa 60-80 ka?

sorry for the title: should be:
Only after c 80 ka, aquatic foods were no longer strictly necessary for H.sapiens.

> Adaptive Evolution of the FADS Gene Cluster within Africa
> Rasika A Mathias cs 2012 PLoS ONE 7(9):e44926 doi 10.1371/journal.pone.0044926

> Long-chain poly-unsaturated fatty acids (LC-PUFAs) are essential for brain structure, development & function:
> adequate dietary quantities of LC-PUFAs are thought to have been necessary for brain expansion & the increase in brain complexity observed during modern human evolution.
> Previous studies (in largely European populations) suggest:
> Hs have limited capacity to synthesize brain LC-PUFAs (e.g. DHA) from plant-based medium-chain-PUFAs, due to limited desaturase activity.
> Population-based differences in LC-PUFA levels & their product-to-substrate ratios can (in part) be explained by polymorphisms in the FA-desaturase (FADS) gene-cluster, ass.x increased conversion of MC- to LC-PUFAs.
> Here we show:
> these high efficiency converter alleles in the FADS gene cluster were likely driven to near-fixation in African populations by positive selection ∼85 ka:
> did selection at FADS variants, which increase LC-PUFA synthesis from plant-based MC-PUFAs, allow African populations, obligatorily tethered to marine sources for LC-PUFAs in isolated geographic regions, to rapidly expand throughout Africa 60-80 ka?

littor...@gmail.com wrote:

> sorry for the title: should be:
> Only after c 80 ka, aquatic foods were no longer strictly necessary for H.sapiens.

As has been pointed out though, humans brains have SHRUNK since the dawning
of history -- the written word. This very likely has to do with agriculture, farming,
animal husbandry. With the invention of "Civilization," you not only had agriculture
but all the systems in place for the control and trade of agricultural products.

Agriculture produced a surplus of food, but you needed law & order to keep it from
being stolen. You needed communications and transportation (roads?) to move
it. You needed markets. You needed scribes, priests and artisans, soldiers and
bureaucrats to consume it though not producing it...

Before all that happened, you could over produce grain but you couldn't ship it to
a far away city. For one thing, who was going to buy it (trade for it?). Why not just
kill you? Why wouldn't someone else just kill you?

So 3 to 5 thousand years ago all the pieces fell into place... and brains started to
shrink.

It's a good model. Well, I mean it appears to fit. And there is science that says
brains did shrink. So even if we can "Make do" without the seafood, we were
better off with it.

And are.

-- --

https://jtem.tumblr.com/post/705327690238017536

Op dinsdag 3 januari 2023 om 08:50:08 UTC+1 schreef JTEM is so reasonable:
> littor...@gmail.com wrote:

> > sorry for the title: should be:
> > Only after c 80 ka, aquatic foods were no longer strictly necessary for H.sapiens.

> As has been pointed out though, humans brains have SHRUNK since the dawning
> of history -- the written word. This very likely has to do with agriculture, farming,
> animal husbandry. With the invention of "Civilization," you not only had agriculture
> but all the systems in place for the control and trade of agricultural products.
> Agriculture produced a surplus of food, but you needed law & order to keep it from
> being stolen. You needed communications and transportation (roads?) to move
> it. You needed markets. You needed scribes, priests and artisans, soldiers and
> bureaucrats to consume it though not producing it...
> Before all that happened, you could over produce grain but you couldn't ship it to
> a far away city. For one thing, who was going to buy it (trade for it?). Why not just
> kill you? Why wouldn't someone else just kill you?
> So 3 to 5 thousand years ago all the pieces fell into place... and brains started to
> shrink.
> It's a good model. Well, I mean it appears to fit. And there is science that says
> brains did shrink. So even if we can "Make do" without the seafood, we were
> better off with it.
> And are.

Yes, arguably the enzymes MC-PUFAs->LC-PUFAs "allowed" Hs to leave the waterside more permanently, and to become dependent on agriculture.