Francisco Ayala & autogenocide

Interesting profile of Roman Catholic evolutionary biologist Francisco Ayala. As an aside they note:

In conducting the studies he had suggested, Ayala also made the unexpected discovery that the parasite P. falciparum can reproduce not just sexually, but clonally as well: it can fuse male and female gametes - sexual reproduction - or transmit all of its genes as a single unit, the cloning that was an unexpected phenomenon.

Ayala's discovery has helped reveal that malaria, which now kills up to 2.7 million people per year - mostly African children - became common only within the last 5,000 years; while it once existed only in a small region of Africa, the adoption of slash-and-burn agricultural practices enabled the disease, which is transmitted by a certain type of mosquitoes, to flourish.

I suspect that the rise of agriculture and resultant population densities were one of the greatest selective forces to reshape the the genetic structure of the human species. The book 1491 chronicles the collapse of Amerindian societies in the face of Eurasian super-bugs. In North America the less numerous natives were overwhelmed by European settler colonies, while in South America a rising mestizo tide has inundated indigenous islands. Today on the Great Andaman Islands only a few dozen descents of the thousands of ancient hunter-gatherers have survived on the pathogenic onslaught unleashed by settlers from the Indian mainland. No doubt the cries of hundreds of thousands of hunters and gathers on the edge of the expanding front of cereal cultivation and the swarming folk over the past 10,000 did not merit attention because their fate was the nature of things, their gods had abandoned them.

The Neolithic Revolution is often characterized as dualing paradigms of "demic diffusion" and "cultural diffusion," whole populations radiating outward on a Fisherian wave of advance, or the transmission of agricultural techniques along trade routes. But in the wake of grain and its regular bounties the horsemen of the apocalypse arrived in the train, shadows of pestilience in the wake of civilization's victory.

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I suspect that the rise of agriculture and resultant population densities were one of the greatest selective forces to reshape the the genetic structure of the human species

The Moyzis & Pritchard papers both found strong selection for alleles of genes implicated in smell. I speculated (here) that this was due to what you mention -- more bugs to be on the look-out for (that's how we detect them). Once you have human settlements, lots of nasty shit (literally & figuratively) can pile up, and you'd better be good at sniffing out the foul from the fatal.

Steve then posted a comment mentioning Jerry Pournelle's speculation that domestication of dogs led to strong negative selection on sites related to smell, since they can do our prey-tracking job for us. We don't really know which of these is the case, or both... it also brings up a nice broader point: the more civilized we become, the more distributed & web-like our sensory & motor responses become. I smell with my dog's nose, and I plow land with my ox's feet. Even among hunter-gatherers, it's not like every man is an island, but it's still less distributed.

This frees up vacant lots for greater use by higher reasoning etc. Just like when primates switched to being highly visual, the space taken up by smell shrunk and that taken up by visual exploded. And now that we have new fangled electronic gadgets doing even a lot of that, plus social services obviating much of the need for "social intelligence" to get what you want, the highest-breeding people will now have even more brain space open to be filled by -- what?

Ah, and back to smell -- that might be another reason why those in pathogen-wracked environments aren't as bright as elsewhere. Aside from here-and-now infections that could disrupt development, the evolutionary freeing up of brain space for higher reasoning etc. is under tighter functional constraint if they've got to devote more of their space to smell for detecting pathogens. That can't matter too much, since Greeks aren't stupider than Finns, but then again, Greece isn't s-S Africa bug-wise.

...and of course NE Asians have the least need for detecting bugs

native americans the least of all, the new world is relatively benign (was) for hominids (they also had dogs).

Had we remained Hunter-gatherers, we'd be dying young from internecine feuding, disease.

Now that we're *civilized* & domesticated, we live much longer, but we all get *owned* by our SES superiors, & have to work 'til we're almost elderly, then die penniless on medicaid after the we've exausted the life's savings :(.

Is there anyway we can make this thing called life tolerable?

But Native Americans didn't have extensive civilizations like China, India, Middle & Near East, etc. So compare them w/ other such pops -- s-S Africans -- and they're smarter. Among pops w/ equal pathogen load, level of civilization increases smarts. Lots involved, but lower pathogen load probably helps by relaxing functional constraint on amount of cortex dedicated to smell.

Native Americans were nomadic for the most part. Even established villages got moved periodically.

By matoko_part_cherokee (not verified) on 18 Apr 2006 #permalink

But Native Americans didn't have extensive civilizations like China, India, Middle & Near East, etc

this isn't an either|or situation. the pop densities in mesoamerica and peru were probably always relatively high.

Its not clear to me how "slash and burn" agriculture could cause malaria to flourish. More likely to be irrigation agriculture and other water control efforts used to create and control high-density populations of workers.

More likely to be irrigation agriculture and other water control efforts used to create and control high-density populations of workers.

not in coastal west africa. irrigation not needed.