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Nono · Aug 12, 2005, 10:48 am

Writing in the Toronto Star, Jay Ingram remarks on evidence of how breathtakingly small in number the Out of Africa trekkers were who eventually colonized the rest of the planet.

What I can't deduce from this article is whether he's saying that absolutely all non-Africans are descended from this tiny group, or whether probably most are (or something similarly vague). Anybody know?

dejadee · Aug 12, 2005, 04:22 pm

It says the evidence comes from genetic testing, which is testing different people in a population to see what genetic mutations they share (meaning did they have a common ancestor about how many generations back was this ancestor alive). By testing genes of a ton of different people, scientists can see what gene sequences they share and group people into difference gene sequences. The idea is that there was one dude in the past with that sequence who passed it down to his/her kids. The article is very misleading since it implies that a group 70 - ~100 people wandered out of Africa tens of thousands of years ago and populated the entire planet. In fact, genetic evidence is nowhere near that specific.

Its true that people are (in evolutionary terms) closely related. Given two random caucasian people, they probably have a common ancestor who lived about 200 generations ago, or sooner. So maybe all Native Americans are descended from 40 people who left African in 80,000 B.C. but genetic evidence CANNOT tell you:
- how many people actually left (Maybe millions of people left Africa but not all their kids or grandkids or great great etc. grand kids survived. So we can't see their genes today because their line died out.)
- did they leave all at once (There could have been multiple migrations. I mean, a bunch of people could have taken a vacation in Europe every summer and we wouldn't be able to tell.)
- when they all left (It's 80,000, give or take a couple thousand years so it's very imprecise anyways.)

The article just exaggerates the findings by involving some colonization story. What's really amazing is how closely we're all related.

(edit: If you want to read more, there's "Adam's Curse" and "The Seven Daughters of Eve" by Brian Sykes.)

Nono · Aug 12, 2005, 06:01 pm

Thanks, d. I too was disturbed by, as you say, the extent to which the conclusion was implicit rather than explicit.

On reflection, the geographical exit from Africa being as tiny as it is and the total human population being, until recently, very small, it stands to recent that the trekkers were few in number.

Milton Bradley · Aug 13, 2005, 02:45 am

Which places even more credibility on the genetic bottleneck theory, and evolution in general.

gallo · Aug 13, 2005, 11:51 am

Here is a site with some discussion of the various theories and the evidence on which they are based.

The Recent African Genesis of Humans

Multiregional Evolution

Population Bottlenecks and Volcanic Winter

The debates have been going on for quite some time. African Exodus by Christopher Stringer and Robin McKie (Henry Holt and Company, 1996) discusses the theories.

Also, the already mentioned The Seven Daughters of Eve by Bryan Sykes is informative.

Aug 12, 2005, 10:48 am	#1 (permalink) (top)
Nono Throbbing Member Location: Old Europe Posts: 6,774	Small world, ain't it? Writing in the Toronto Star, Jay Ingram remarks on evidence of how breathtakingly small in number the Out of Africa trekkers were who eventually colonized the rest of the planet. What I can't deduce from this article is whether he's saying that absolutely all non-Africans are descended from this tiny group, or whether probably most are (or something similarly vague). Anybody know? "I wish I was as cocksure of anything as Tom Macaulay is of everything." -- Viscount Melbourne

Aug 12, 2005, 06:01 pm	#3 (permalink) (top)
Nono Throbbing Member Location: Old Europe Posts: 6,774	Thanks, d. I too was disturbed by, as you say, the extent to which the conclusion was implicit rather than explicit. On reflection, the geographical exit from Africa being as tiny as it is and the total human population being, until recently, very small, it stands to recent that the trekkers were few in number. "I wish I was as cocksure of anything as Tom Macaulay is of everything." -- Viscount Melbourne

Aug 12, 2005, 04:22 pm	#2 (permalink) (top)
dejadee Sedimentary Rock Posts: 6	It says the evidence comes from genetic testing, which is testing different people in a population to see what genetic mutations they share (meaning did they have a common ancestor about how many generations back was this ancestor alive). By testing genes of a ton of different people, scientists can see what gene sequences they share and group people into difference gene sequences. The idea is that there was one dude in the past with that sequence who passed it down to his/her kids. The article is very misleading since it implies that a group 70 - ~100 people wandered out of Africa tens of thousands of years ago and populated the entire planet. In fact, genetic evidence is nowhere near that specific. Its true that people are (in evolutionary terms) closely related. Given two random caucasian people, they probably have a common ancestor who lived about 200 generations ago, or sooner. So maybe all Native Americans are descended from 40 people who left African in 80,000 B.C. but genetic evidence CANNOT tell you: - how many people actually left (Maybe millions of people left Africa but not all their kids or grandkids or great great etc. grand kids survived. So we can't see their genes today because their line died out.) - did they leave all at once (There could have been multiple migrations. I mean, a bunch of people could have taken a vacation in Europe every summer and we wouldn't be able to tell.) - when they all left (It's 80,000, give or take a couple thousand years so it's very imprecise anyways.) The article just exaggerates the findings by involving some colonization story. What's really amazing is how closely we're all related. (edit: If you want to read more, there's "Adam's Curse" and "The Seven Daughters of Eve" by Brian Sykes.)

Aug 13, 2005, 02:45 am	#4 (permalink) (top)
Milton Bradley BANNED Location: Ohio Province, Rep. of Comerica Posts: 7,320	Which places even more credibility on the genetic bottleneck theory, and evolution in general.

Aug 13, 2005, 11:51 am	#5 (permalink) (top)
gallo Homo sapiens Posts: 1,980	Here is a site with some discussion of the various theories and the evidence on which they are based. The Recent African Genesis of Humans Multiregional Evolution Population Bottlenecks and Volcanic Winter The debates have been going on for quite some time. African Exodus by Christopher Stringer and Robin McKie (Henry Holt and Company, 1996) discusses the theories. Also, the already mentioned The Seven Daughters of Eve by Bryan Sykes is informative.