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| Before Lucy, there was Ardi | |
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| Tweet Topic Started: Oct 2 2009, 05:58 AM (1,821 Views) | |
| ngc1514 | Oct 2 2009, 05:58 AM Post #1 |
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http://news.yahoo.com/s/ap/20091001/ap_on_sc/us_sci_before_lucy_6 |
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| Brewster | Oct 2 2009, 09:29 PM Post #2 |
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I think there are still many twists and turns to learn about Human evolution. |
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| ngc1514 | Oct 2 2009, 10:33 PM Post #3 |
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No doubt, Brew. The biggest is separating out all the various hominid species. Rather than a single path from precursor to man, there were many branchings in the tree with most of the branches dying out. Young Earth Creationism offers no explanation why ANY of these fossils should exist. But there they are. |
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| Brewster | Oct 2 2009, 11:39 PM Post #4 |
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To me, the most interesting period was, as I recall, about 200,000 years ago, where according to my rather faulty memory, the entire Human population was narrowed down to less than 20,000 people. We nearly went extinct, but it probably eliminated a huge number of non-survival traits in one go. Last time I looked into it, it seemed to have a giant impact on our intelligence as well, as it was about then that our technology really took off... Now I've got myself interested again - time to do some reading... |
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| ngc1514 | Oct 3 2009, 01:03 AM Post #5 |
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If you find a really good and fairly current book, please let me know! There is so much going on in the field of human evolution, it's hard to keep up. |
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| Brewster | Oct 3 2009, 04:44 AM Post #6 |
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Still looking for a book, Eric, but I did find some interesting dates online: 200,000 years - mitochondrial Eve - all women have descended from her, or at most a very small number of related women - It is estimated that there were 4-5000 women of breeding age at that time. This is also the time of the earliest traces of modern Homo Sapiens - I suspect these two facts are closely related. 71,000 years ago - the Toba catastrophe - A mega volcano, the largest in the last 25 million years, blew up on Sumatra, intensifying the ongoing ice age at the time. It wiped out many species of mammals, including, it is suspected, most of the hominid lineages. Homo Sapiens was also hit severely, and populations declined severely for the next 10,000 years. 60,000 years - Y-Chromosomal Adam - As with Eve, all men have descended from him. It is estimated that there were as few as 1000 breeding pairs of humans at that time. (Creationists take note - this does NOT verify the Biblical account of Adam and Eve - these two individuals lived about 140,000 years apart - I doubt that they ever met.) Shortly thereafter, the weather started to improve, and a small number of humans moved out of Africa - some estimates put it as low as 150 individuals. These people are responsible for a HUGE percentage of all lineages now alive around the world. |
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| Brewster | Oct 3 2009, 04:44 AM Post #7 |
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Amazon has a book that looks very interesting: "The Journey of Man - A Genetic Odyssey" bySpencer Wells It's supposed to be quite thorough, but written for the educated public, not specialists... I just may pick it up... Edited by Brewster, Oct 3 2009, 05:50 AM.
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| ngc1514 | Oct 3 2009, 06:34 AM Post #8 |
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Thanks for the suggestion. The library system has it and I just requested it. Should be here in a couple days. The odds of man becoming man are incredibly slim. This is why I suspect life is ubiquitous in the universe, but intelligent life very rare. Assuming no helping hand of one intelligent being in guiding the evolution of other beings. I wouldn't be surprised if all our searching for intelligence is in vain and we are the only intelligent specie in our Milky Way Galaxy. Disappointed, yes, but not surprised. |
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| Brewster | Oct 3 2009, 07:27 AM Post #9 |
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I agree about the rarity of intelligence. I strongly suspect that we'll find primitive life just about everywhere, including a few planets and moons in our own solar system, but intelligence is quite a different matter. Just today I read a short piece (Forgot just where I read it. If I remember, I'll let you know.) which said it has just been discovered that when the human brain engages in intense abstract thought, a specialized protein is produced. It turns out that that protien is unique to us - it has to be a mutation that occurred after the split of humans from apes. It seems to be very closely linked to all functions that we consider advanced intelligence. It is just possible that it is the mutation that started modern humans down our present road 200,000 years ago. It was probably a subtle, mild effect initially, unlikely to be enough of an intelligence enhancer in a relatively benign climate to ensure our survival, and not all humans would have it. Now think of the scenario on Post #6. Just try to calculate the odds that this mutation happened just in time for our ancestors to carry it as they survived as the only Hominid after the Toba catastrophe, and that it would be such a near run thing that we were down to only 1000 breeding pairs, and that gene was probably inbred to become central to all survivors. Almost enough to make you believe in ..... Nahhh... Edited by Brewster, Oct 3 2009, 07:28 AM.
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| ngc1514 | Oct 3 2009, 09:31 AM Post #10 |
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Nahhh is right. That's just a restatement of the idea that evolution is directed towards some goal. It's not. If that is the protein and it didn't develop, we'd not be here wondering about it. Just a restatement of the Anthropic Principle. |
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