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Author Topic:   Human Evolution
caffeine
Member (Idle past 1025 days)
Posts: 1800
From: Prague, Czech Republic
Joined: 10-22-2008


Message 7 of 102 (556366)
04-19-2010 11:45 AM
Reply to: Message 4 by DrJones*
04-18-2010 3:34 PM


It might have already happened. Can we be sure that the average H. sapiens of 2010 is interfertile with the average H. sapiens of 1510?
Yes. As evidenced by the last 500 years of mass migration around the globe, human populations that had been separated for thousands of years are still quite interfertile with one another.

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caffeine
Member (Idle past 1025 days)
Posts: 1800
From: Prague, Czech Republic
Joined: 10-22-2008


(1)
Message 23 of 102 (586613)
10-14-2010 9:17 AM
Reply to: Message 19 by matt101
10-14-2010 8:44 AM


Monkeys, humans and HIV
My word. That's a lot of nonsense to cram into one paragraph. I'll just pick out one argument from the melange, or this post could take three years to write.
If we came from a monkey, we would be "IMMUNE" to "HIV"
Your argument seems to be that, because a monkey possesses x (in this case immunity to HIV), humans must all possess x if they descended from them. In order to make this argument, it wasn't necessary to go for something as obscure as a protein that blocks HIV from working. You could have pointed to tails, for example.
It's important to note that not all monkeys are the same - New World monkeys tend to have prehensile tails while Old World monkeys don't, for example. Proboscis monkeys have huge noses, snub-nosed monkeys have almost no nose. Since their common ancestor, these monkeys have diversified - some traits were lost in some populations, others were gained in some populations. Humans, also, have changed from our common ancestor with monkeys. We don't have tails, we stand upright, we've got massive brains and we have a different form of the TRIM5-alpha protein (the protein which seems to block the spread of HIV in some monkeys).
Basically, what your arguing here is 'evolution can't have happened, because humans are different to their ancestors'. If you think about that sentence, I think you'll see that you've drastically missed the point.
Edited by caffeine, : for clarity
Edited by caffeine, : To remove an errant letter 'p'

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 Message 28 by matt101, posted 10-14-2010 9:58 AM caffeine has replied

  
caffeine
Member (Idle past 1025 days)
Posts: 1800
From: Prague, Czech Republic
Joined: 10-22-2008


Message 31 of 102 (586631)
10-14-2010 10:15 AM
Reply to: Message 28 by matt101
10-14-2010 9:58 AM


Re: Monkeys, humans and HIV
Why should people be immune?
HIV isn't traced back to an origin in one species of monkey. The direct ancestor of HIV is believed to be the SIV (simian immunodeficiency virus) in chimpanzees, which itself is believed to have arisen from a hybridisation event between two different viruses found in monkeys - the red-capped mangabey and greater spot-nosed monkey.
Many different African monkey species have their own type of SIV, all of them having evolved from a common ancestor to become adapted to different hosts, and one of which eventually became adapted to humans.
Now, as it happens, the human form of the virus doesn't work in at least some types of African monkey, and one explanation put forward is that the old-world monkey form of the protein TRIM5-alpha, which works as part of the immune system in primates, seems to prevent the virus from shedding its protective protein coat and reproducing.
Because, however, humans and old world monkeys have different forms of this protein, on account of them evolving seperately for millions of years, the human form doesn't work against HIV in the same way (if it did, the virus would never have become HIV, as it couldn't have infected humans). Note that this protein doesn't protect the monkeys against various forms of SIV - those versions of the virus adapted to infect old world monkeys.
So I don't understand your point. Why should humans be expected to possess the same form of a protein as cousins that our ancestors split from some thirty million years ago (give or take 5 million)?

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