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Human Gamete Compatibility Going Backwards

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Human Gamete Compatibility Going Backwards

Postby BiologicalRush » Thu Jan 02, 2014 7:08 pm

If one could take a human gamete from today and 'test' it for compatibility against every birth of every creature starting at the most recent birth and going backward in time, would one reach a first-to-produce a compatible gamete individual? By 'compatible' I mean able to form a zygote that results in a fertile, viable offspring.
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Postby Cat » Sun Jan 05, 2014 5:40 pm

Depends how you want to go about doing it. From in vitro stand point the main requirement is same number of chromosomes - therefore, Reeves's Muntjac and Sable Antelope could be fully "compatible" with humans. I don't think anyone tested this in vivo...
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Postby JackBean » Mon Jan 06, 2014 10:10 am

@Cat
it's not that simple. Przewalski and domestic horse differ in chromosome number, yet they are able to produce viable offspring
http://en.wikipedia.org/wiki/Przewalski ... e#Taxonomy
http://www.biolib.cz/en/main/

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Postby JackBean » Mon Jan 06, 2014 10:11 am

on the other hand, although we may have the same number of chromosomes as antelopes, they will be hardly homologous so there will be no cell division
http://www.biolib.cz/en/main/

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Postby Cat » Sat Jan 11, 2014 7:56 pm

Nice examples JackBean. Another one would be normal human + human with extra Y chromosome... Anyway, all I was trying to say is that because of the ethical considerations compatibility of humans with other species was not and probably will never be tested.

Your point on homology, however, may or may not be relevant. Theoretically, haploid genome should be sufficient to produce an organism as it contains full complement of genes. However, because some critical genes can be recessive, two copies are required. This leads to the requirement for the homologous gene from the second parent. In theory, if neither parent organism has any such genes, the organisms are "compatible". Once embryo is formed, the new genome will dictate appearance of a new organism (whether it's going to be a hoof or a hand). Unless there is a serious clash between the two organisms that cannot be reconciled, a hybrid will be born. This hybrid will not breed true and can only be considered a first step toward the creation on new species...
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Re: Human Gamete Compatibility Going Backwards

Postby JackBean » Fri Jan 17, 2014 10:07 am

BiologicalRush wrote:By 'compatible' I mean able to form a zygote that results in a fertile, viable offspring.

my emphasis
http://www.biolib.cz/en/main/

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Postby BiologicalRush » Tue Jun 24, 2014 9:01 pm

I'm not sure my question was worded very well. . .

I'll provide more detail and less generic. If you could take human sperm back, say, 500 years and "test" it for compatibility with every female ovum you would find general compatibility. In other words, if a modern male and a female from the 1,500's had sex, a normal offspring would be likely. So, continue back in time with the modern sperm. Maybe back 10,000 or 100K years and try again (the actual time is arbitrary for the question). It seems that at some point, reproductive compatibility would begin a decline. At X years back, you see only 99% compatibility. At X+100K years back, maybe you see 50% compatibility. The question is, does it follow that at some point in the past was born the first female to be reproductively compatible with modern male?
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Postby JackBean » Wed Jun 25, 2014 12:17 pm

I'm not sure it would be some slow decline. Because that would mean that some are compatible and some are not, while they all must be compatible to each other (more less)
http://www.biolib.cz/en/main/

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Re:

Postby BiologicalRush » Wed Jun 25, 2014 8:10 pm

JackBean wrote:I'm not sure it would be some slow decline. Because that would mean that some are compatible and some are not, while they all must be compatible to each other (more less)

Thank you for your comment - Like the timescale, the rate of decline seems arbitrary. It could be rapid or not. I'm wondering if there was a first 'ancient' female that could successfully reproduce with a modern male?
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Postby JackBean » Sat Jun 28, 2014 12:52 pm

I didn't speculate as much about the speed of the decline as that it would be rather stepwise. At least locally, for some homogenous group.
http://www.biolib.cz/en/main/

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