Just how useful is the Y chromosome as a population tracking gene?

Question

It's generally assumed that Y chromosome Adam existed prior to the human expansion out of Africa. But if this quote from an article I read is true, are we only tracking the expansion of a superior mutation, not a population movement?

"The Y chromosome was once thought to be devoid of genetic information. However, recent work shows that it contains numerous genes related to sperm production and dimorphic traits (such as body size and tooth development). Among mammals, these traits influence a male's competitive ability in male–male contests and in sperm competition. Therefore, sexual selection could have favoured genes on the Y chromosome that enhance male fertilization success because they spread unaltered through the male line. "

Answer 1

It's useful for tracking populations because different populations will have different mutations marking them.  It's not about the genes themselves, just the markers they contain.

Answer 2

Actually what's great about both mitochondrial DNA and Y-chromosomes is that there is not sexual recombination, so it's easy to track its lineage based on an average mutation rate. Since the Y-chromosome has less information than mitDNA it was less used initially, but now it has gained much popularity in evaluating trends of early human populations.

As for sexual selection, it is obvious that the Y-chromosome is responsible for most male secondary (and primary) sexual characteristics, but actually only a few genes control these processes.

Great article find.

Answer 3

sorry i can't comment on your question

Answer 4

It is the scientific methodologies that are leading to error, primarily the highly over-rated process of "computer modeling".  The results are only as good as the data that is inputted into the programs.  And the data that is inputted into the programs is only as thorough as the individual who is doing the inputting.

Six months ago at the Pasadena Jet Propulsion Laboratory (JPL) "climatologically computer models" where launched to produce a forecasting template of this season's climatic conditions for the west coast of the United States.  The conclusions predicted in June of 2007 for our current winter season claimed this would be the driest winter on record EVER in recorded climatology history.

NOPE… the rain and snow just keeps on coming, and we've had 4 deadly avalanches in the mountains above Los Angeles.  I've lived in LA for 36 years, and in those 36 years we had zero avalanches.  

The "experts" and the "scientists" were completely and totally wrong.

If science cannot accurately predict with computer modeling a mere and infinitesimal 6 months in advance, then how on earth can anyone in their right mind take seriously these computer model calculations and conclusions with utterly gargantuan million year time spans?

Frankly, it’s rather idealistic and even hopelessly Pollyannaish.

Answer 5

Jim Z. How could a superior mutation move ahead of the actual tribal movements? Fly? You talk about the ideology of the Out of Africa theory and then turn around and posit coitus between people that may, or may not have happened and you have not one scintilla of evidence to support that claim.

So, Mathilda, willing thinker has the most cogent answer here. Flee from the " dark side " ( anthropological incoherence ) and go to the light of science.

How useful is the Y as a tracking gene? Very!!!

The lactose gene?!?! No you could not tell anything from that gene except who were herders!!! I suggest you review your data on Monod's work with the lac operon.

That is why s*x chromosomes are used. Did you think that was an arbitrary choice? And who cares that it spread with the possibility of more motile sperm? That is part of the sexually selective game plan.

Answer 6

Quote: "It's generally assumed that Y chromosome Adam existed prior to the human expansion out of Africa."

Sorry, the way I interpret that sentence is that it's assumed that Adam and Eve existed and the Y chromosome in Man comes from Adam. While Intelligent Design theorist will assume this to be correct the majoriy of the scientific community will not assume this as Evolutionary speaking it's simply not true.

That aside, the Y chromosome can be very useful for population tracking since individual mutations can be traced and so the movement of a populace. The artical you quote is badly worded and quite frankly out of date. Genetic research has come a very long way since 1999 and quoting a single 9 year old paper is not good scientific method.

Given recent advances it is now possible to trace individual point mutations within the genetic code and it is these point mutations that you look at to track population expansion, not the symptoms they generate as the paper you quote seems to suggest.

Answer 7

The truth is human populations migrate.  It is impossible to tell (unless you have actual fossils with DNA I suppose) where the traits came from.  You could map the genes on a map and still the degree of uncertainty would still be high.  A superior mutation could move independent of actual tribal movements also.  It might spread like a wild fire accross a population over thousands of years.  I am skeptical of those that claim to be able to track it.  It seems more likely they are simply paying homage to the Out of Africa Theory that seems to be a requirement in some circles of anthropology.

Answer 8

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Oh, and some of those scams I mean 'tests' tests are a rip-off. Hope I'm not too late.

Here are some links to help ya out:

http://www.dna-bioscience.co.uk/service_...

http://www.discern-genetics.org/genetic_...

Ooops! I almost forgot, you asked about the fact that all lineages are branched from African. It's true. If you're wondering how this is done, it's simple. We track the random genetic mutations that happen over time. So, when we test someone we see which one they have.

We can also assign these, with certainty in most cases, to an area of the "birth" or mutation.

Different genes don't mean different species, sub-species, 'races', or species origins.

Mutations branch of.

E underived splits into E1, E3,

E3 splits into E3b, E3a,

E3b splits into E3b1, E3b2, and E3b3.

And so on.

I'm glad you've taken up an interest in evolution, as you need to understand that pretty well to understand most things biology. Most have a mis-understanding about evolution, which is the reason, for comments like Jim Z's.

Too many people's decisions are myred in the confusion of politics, be it 'racial' politics, or even religious politics.

In sciene we don't "accept you into the community" simply because you accept the rule of our "circle", LOL. The reason the Out of Africa theory is the prevalent one, is rooted in it's simplicity; they have not found a single human who is not descended from a small population of Africans.

Don't worry about the dude above me, I caught that you were using "Adam" figuratively. Why Eve comes up, I don't know, when the genetica "Adam" and "Eve" (male, and female, respectively, who are responsible for all of their s*x's s*x chromosome today). Around the time of the Adam, infact, there were many females responsible for continuing the populating ;).

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"I get how it works Willing Thinker, it's the neutrality of the chromosome I'm disputing. If you decided to study the European gene for lactose distribtion, you could come to the conclusion that our population all originated from some point near the Black Sea, 8k years ago."

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^Actually, the "mutation" or the lactose trait (that mutated) lies in an allele on an automal gene.

Look up autosomal gene. ;) lol

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"Since the bulk of our specie's mutations are African"

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Correction. Our species is African.

The mutations in the mtDNA, and Y- chromosome that we use as markers, are not. Atleast, for European populations.

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", we can't really dispute that they contributed most of our ancestry,"

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Arbitrarily, we're all African.

However, as far as recent ancestry goes, you are European, for the most part, though Europeans, especially Southern Europeans have significant amounts of recent African ancestry.

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" it's just using one or two bit's of non neutral DNA as irrefutable proof that there were no minority contributors from outside Africa that grates."

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Oh, so you're a non-subscriber to the OOA theory. Ok.

A.) The theory hasn't been disproved.

B.) Because, there have been found NO genes found that are not derivatives of the African one.

What's rediculous is a mathmatical (abstract) analysis that says there's a chance that some primitive sapian that died off is responsable for Asia's non-male ancestry.

Here are some pages that may interest you, if you want to look into the possibility, or look at more thourough methods:

http://www.egyptsearch.com/forums/ultima...

...There was a link to a *purely mathmatical* study that asserted that Europeans/Asians may have been derived from another sapien.

If I come across it again, I'll be sure to give it to you, especially if you vote my answer right.

http://www.crystalinks.com/africacreatio...