Human Evolution and one race

[jmanscience]

Does anyone know what consequences there would be if there was only one "race" of humans? Wouldn't the lack of diversity be bad for our evolution, or would it be better? I read once that somewhere, I believe in Sardinia, people lived to be very old because there seemed to be no immigration to the Island. This caused the genes to continually be passed on without mixing. Thoughts?

[mith]

have you heard of inbreeding?

[mcar]

In the case of inbreeding, the chances of homozygosity increases. Most of our deleterious genes are usually expressed when they pair in such a way. Variation is said to be so important in developing many strategic and evolutionary traits advantageous for survival. Variation is possible if the genes of a population spread too.

[jmanscience]

Mith: thanks for the scientific explanation on "inbreeding"

mcar: It makes sense that homozygosity increases due to inbreeding, but with the "one race" theory, would it really be inbreeding? Take for example china. It's population is growing drastically, and there isn't any inbreeding occurring there. I do understand that each race is more predisposed to certain diseases because of their DNA, but if there were "one race" wouldn't we still evolve again like we did when we left africa?

[biohazard]

If the population is large enough, one race only should be plenty. However, in the case of man the term "race" is pretty dodgy anyway, since you really cannot draw a line anywhere.

[mith]

Put it this way, if you're diverse enough, you could hardly be considered a race, and if you're not diverse enough, one potato blight would kill off all your kind. Given that greater diversity is almost always beneficial, why would you limit yourself to one race?

The only way I could think of this as being viable is if you had one strain that is clearly superior to the other types. For example, wheat that is planted is pretty much all identical due to selection for big grains, fast growth etc. You would not plant any other types of grain. You can offset the risks of a decimating disease by having a seed bank in Antarctica that you can use to hybridize the crops in the event that it happens. Of course, this method if applied to humans is hardly ethical.

[biohazard]

Ok, let me rephrase: one race, if big enough (e.g. the Chinese / Asian / somesuch) should be well enough, whereas some Micronesian race that has 12 members probably isn't. And if there is more than one race, then it's usually better - but this doesn't necessarily mean one race wouldn't be "enough".

Of course, there are possibly several races among the Chinese people and even more so among the Asian folk, it all depends on what definition you use - after all there are many anthropologists and scientis who would ditch the whole term "race" when it comes to humans...

Anyway, to the original question: diversity is usually a good evolutionary tool, so I don't think one distinct human race would be better than the diversity of "races" we have now. Only in some special cases (like in mith's wheat field), one distinct race/strain with desirable abilities may be a better option - at least until you get that blight or something!

[JorgeLobo]

You may be thinking of the concept of "hydrid vigor".

biohazard makes an excellent point - race is more a sociologic than biologic concept. Identifying one is typically based on obvious external characters of skin color and indeed one can find genetic differences based on that character. There are also differences between not so obviously different groups.

[Darwin420]

Mcar - great text book definition .

[mcar]

I will not deny that I have read the information from a book and I am happy that I was able to generate useful informations that I could possibly share. Since I have read the question, information popped in my mind. I just need to think of some other words maybe; just to make it not book-like definition. Thank you for letting me know that Darwin. I still have some things that I have to make an effort to develop definitely. Well some parts of growing up.

In the case when same relatives of the close degree marry each other, the chances of developing some abnormalities in their child is also increased.

[JorgeLobo]

Your high school texts are silly - as you are mcar - just shut up.

[mcar]

Is that so?