Human, Orangutans and Chimps

[kjkent1]

Relevance to the fact that chimps and humans have free cycle esterus?

Evidence is logically relevant if it tends to prove or disprove a matter of consequence in the dispute.

Here, proof of many horizontal gene transfers between Old World Monkeys tends to show how different traits may have been inherited by humans, because similar genetic patterns found in Old World Monkeys are also found in the human genome.

This, the appearance of one trait, such as free cycle estrus does not conclusively prove that chimpanzees are our closest relation in the primate world, because it may be just one trait of many, picked up "along the way."

 

[Dancing David]

Evidence is logically relevant if it tends to prove or disprove a matter of consequence in the dispute.

Here, proof of many horizontal gene transfers between Old World Monkeys tends to show how different traits may have been inherited by humans, because similar genetic patterns found in Old World Monkeys are also found in the human genome.

This, the appearance of one trait, such as free cycle estrus does not conclusively prove that chimpanzees are our closest relation in the primate world, because it may be just one trait of many, picked up "along the way."

Okay, but given the overwhelming nature of chimps and humans sharing more of their genetics than orangs and humans, the divergence of orangs and humans is farther back than the divergence of chimps and humans.

 

[articulett]

The split between simian species was messy, but the chromosome banding patterns are clear--

Behold humans, chimps, gorillas, and orangutans side by side:

http://www.indiana.edu/~ensiweb/lessons/chro.all.html

Also the similarity of the pseudogenes for vitamin C (fossil gene that stopped working) shows the same mutation with additional junk mutations that that are closest between humans and chimps. The pseudogenes are great for showing common descent...and also great for illustrating the branching since the event since mutations build up quicker in pseudogenes (they are neutral) than in functional genes.

 

[kjkent1]

The split between simian species was messy, but the chromosome banding patterns are clear--

Behold humans, chimps, gorillas, and orangutans side by side:

http://www.indiana.edu/~ensiweb/lessons/chro.all.html

Also the similarity of the pseudogenes for vitamin C (fossil gene that stopped working) shows the same mutation with additional junk mutations that that are closest between humans and chimps. The pseudogenes are great for showing common descent...and also great for illustrating the branching since the event since mutations build up quicker in pseudogenes (they are neutral) than in functional genes.

That's a great example. It's interesting to me that some of the chromosomes appear more similar between humans and chimpanzees, while others seem mor similar between humans and orangutans. Not that this sort of "eyeball" pattern matching is particularly scientific or conclusive.

Anyway, how do you think the first recipient of the gene fusion was able to successfully pass the mutation to subsequent generations (feel free to speculate)?

 

[articulett]

Well, this is from the article:

Our data support a model where ancestral chimpanzee and gorilla species were infected independently and contemporaneously by an exogenous source of gammaretrovirus 3–4 million years ago. While similar infections with a related retrovirus appear commonplace among the Old World monkeys, contemporary human and orangutan populations show no molecular vestiges of this infection (see Figure 2). The molecular basis for this historical difference is unclear.

...

Several speculative scenarios may be envisioned to explain the absence of retrovirus in both the orangutan and human lineages. It is possible that the African apes evolved a susceptibility, or humans and Asian apes developed resistance to infection, although in either scenario convergent evolution would have had to have occurred with respect to the viral infections. Studies of the retroviral infection of the Lake Casitas mouse population reveal that such susceptibility/resistance genes may emerge very quickly among closely related strains of mice [34]. Another scenario may be that the lineage that ultimately gave rise to humans did not occupy the same habitat as the ancestral chimpanzee and gorilla lineages. An excursion by early hominids to Eurasia during the time that PTERV1 infected African great apes and then a return to Africa would explain this phylogenetic inconsistency. It is also possible that this effect may have been created by dramatic differences in ancestral population structure. If, for example, the ancestral populations of humans and orangutans were substantially larger than those of the African great apes, the fixation of new insertions (1/2N) would occur much more rapidly within small inbred populations even if similar infection rates existed. A similar model has recently been proposed, albeit in the opposite direction, to explain an increase of “apparent” Alu Ya5 and Yb8 retroposition activity in the human lineage but not in chimpanzees and gorillas

And I suspect this is probably on the right path. Chimps and Gorillas and Old World monkeys seem to have separate infections, right... The study is over 2 years old, so I'm sure we must have more information by now--the more we find out...the more we find out just how much there is to still find out.

 

[kjkent1]

Well, this is from the article:...

You misunderstood my question...or I miscommunicated. I simply mean, given a human ancestor with 23 chromosomes, due to a mutant gene fusion, among a tribe of human ancestors with 24 chromosomes, how do you think that this positive mutation was able to propagate?

My view is that chromosomal non-disjunction occurs with some frequency in biological organisms (albeit, mostly harmful, but not always: XYY human males), so it must have been the case that our original ancestor was inter-fertile with his/her contemporaries, despite the gene fusion.