Archaic Genes in Modern People?

Science Magazine | 2005-04-22 | Elizabeth Culotta

[blam]

"one rare variant, appropriately named haplotype X, appeared in nine individuals from Europe to Oceania but was entirely absent in Africa."

Prefessor Stephen Oppenheimer has documented the 'X' gene in American Indians and some Europeans and no-one in between. His explanation is that the Toba eruption 74,000 years ago killed everyone in between and broke the link. Oppenheimer opines that humans were probably in Australia prior to the Toba eruption.

[ken21]

why not?

the ancient greeks thought we were descended from the blood of snakes dropped on the ground.

[Junior]

Ping.

[PatrickHenry]

EvolutionPing

A pro-evolution science list with over 260 names. See the list's description at my freeper homepage. Then FReepmail to be added or dropped.

[blam]

"All the research into the past is fascinating but I'd really like to see where scientists think that human evolution is occuring most today. Is it in areas with large numbers of births and deaths? It seems like advanced countries have lower birth rates, which goes counter to evolution."

I have an idea that I've been working on for a while, here it is:

Evolution is occuring every minute, every hour and every day of every year all over the world. Let's take humans.
Women have something called 'spontaneaous abortion' where the union of an egg and sperm is made and immediately aborted, many times even without the knowledge of the woman because of an anamoly.

Now, let's say that anamoly is drugs or pollution. Any pregnacy that makes it to term has made it through the 'spontaneous abortion' barrier because it was a union strong enough to withstand the drug or pollution (or a hundred other factors) present at the time of conception.
I believe this is a continuous 'weeding' process and only the 'strongest' unions survive. I also believe that some retardation at birth is due to causes similar to the one mentioned and the retatded person born was at the bottom limit of the survivability level.
I expect that many of us are 'immune' to many things we would be suprised to learn.

This is a continuous process and if environmental conditions change dramatically , only a small handful of us would survive to pass on those genes.

[mikegi]

Women have something called 'spontaneaous abortion' where the union of an egg and sperm is made and immediately aborted, many times even without the knowledge of the woman because of an anamoly.

The total miscarriage risk, starting from fertilization, is extremely high at around 60-80%. By the time you see a heartbeat on an ultrasound at 6 weeks LMP, the risk drops to 5-10%. I think this can be considered "maintenance" more than evolution as it involves the filtering of gross genetic errors.

I guess I go back to the line in "Jurassic Park" where the mathematician says "life finds a way". For example, in advanced countries with declining birth rates, it turns out that the very technology that allows for declining birth rates also allows for directed evolution. Science is unravelling/understanding the genetic code while simultaneously providing a way to control reproduction (eg. IVF with PGD). It's only a matter of time before the two are combined. This was explored in the movie Gattaca and other sci-fi works. In another 50 years, this technology will be available to millions of people and many will find it irresistable when starting a family (imagine almost guaranteeing that your child won't have a chronic disease).

I guess it comes down to a battle between natural evolution and human-directed evolution. Which will win?

[lizma]

Oxford has a program.

They will trace back your X or Y chromosomes to their original "clan", but charges about $300 a chromosome and you have to be of European origin.

[SunkenCiv]

Huh?

[VadeRetro]

I like this for some reason. It means that, yes, most of our heritage came out of Africa recently but there probably was some interbreeding with the hominids who had fanned out earlier, including the neanderthals.

I thought all would depend upon isolating neanderthal nuclear DNA, a thing which may never happen. However, I wasn't reckoning with the ingenuity of the scientists in the field. There's another way. They have found some few genes which a lot of non-Africans have and which Africans don't. These genes may be the heritage of our interbreeding with not-so-related hominids after the last radiation from the breeding ground.

I'm pinging blam because I know he also likes the idea that the neanderthals are still around -- in us.

[SunkenCiv]

It would seem to me that the region with the most genetic variations is the go to region not the migrated out of region.

All else being equal, I'd agree with you. Just in the past 3000 years Africa has been changed a great deal by immigration and invasion. But, the longterm way of life has the most to do with the supposed greater variability. Settled agriculture (which is at least 14,000 years old, based on RC date for a multirow barley sample recovered in a dig in the Near East somewhere; the plant is a breed, not a wild variety, also it requires irrigation) leads to larger family sizes, and in just a few generations that skews the data as to what population is "older". Hunter-gatherer cultures have different lifestyles and more isolated populations.

[VadeRetro]

Pinged you just now but of course you're already here.

[wardaddy]

the ancient greeks thought we were descended from the blood of snakes dropped on the ground.

We are you heretic.

[exDemMom]

It would seem to me that the region with the most genetic variations is the go to region not the migrated out of region.

No. If the original population has genes A, B, C, D, E, F, and G, and one family decides to leave, and they all have gene D, then wherever they settle, their descendants--the new population--will have gene D, but not the other genes. While the original population still has all the genes represented (unless that family that left represented the only gene D carriers in the population).

[PatrickHenry]

It means that, yes, most of our heritage came out of Africa recently but there probably was some interbreeding with the hominids who had fanned out earlier, including the neanderthals.

Not necessarily. This old "non-African" gene could have originated in Africa, but it might have been a local thing, and was mostly concentrated in the tribes that migrated out. The migrants took it with them before it had a chance to spread throughout Africa.

[blam]

"I think this can be considered "maintenance" more than evolution as it involves the filtering of gross genetic errors."

That's exactly what I'm talking about. Genetic errors caused by (?) something...anything...it shifts the genes. (Ever so slowly)

If mosquitos had gone extinct thousands of years ago, could you today explain the cause/source of Cycle Cell Anemia?

[ken21]

just read euripidies or aeschyulus and you'll find their origin beliefs.

[VadeRetro]

Spoilsport!

If enough of these "ancient" genes turn up, your explanation is the first to fall.

[Ditter]

Thanks for the link. I have always wanted to do that.

[blam]

The Peopling Of The World

[Thumper1960]

Bump!