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Topic: Likely that early man did not have sex with his cousin (Read 1297 times) |
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Hermit
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Likely that early man did not have sex with his cousin
« on: 2006-11-15 21:19:11 » |
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DNA from Neanderthal leg shows distant split
Source: Reuters
Authors: Maggie Fox (Reuters Health and Science Editor)
Dated: 2006-11-15
Researchers have sequenced DNA from the leg bone of a Neanderthal man who died 38,000 years ago and said on Wednesday it shows the Neanderthals are truly distant relatives of modern humans who interbred rarely, if at all, with our own immediate ancestors.
They estimate that modern humans and Neanderthals split from a common ancestor at least 370,000 years ago, and possibly 500,000 years ago, although we share 99.95 percent of our DNA.
"We see no evidence of mixing 40,000, 30,000 years ago in Europe. We don't exclude it, but see no evidence," Edward Rubin of the U.S. Department of Energy Joint Genome Institute in Walnut Creek, California, who led one study, told reporters.
This conflicts with some evidence from other researchers, including a team who said earlier this month that humans may have inherited a brain gene from Neanderthals.
The researchers reported their findings jointly in the journals Nature and Science.
Rubin's team used one method to isolate and sequence part of the Neanderthal's DNA, while another team, led by Svante Paabo of the Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany, used a separate method to sequence a much larger amount.
Paabo was the first scientist to find and sequence Neanderthal DNA, in 1997, and first suggested that Neanderthals did not mix with modern humans.
"I think the sequence data will serve as a DNA time machine that will tell us about biology and aspects that we will never be able to get from their bones and a limited number of associated artifacts," Rubin said.
Neanderthals and modern humans are both descended from Homo erectus, which left Africa and spread around the world about 1.5 million years ago.
LIVING SIDE BY SIDE
Neanderthals lived in Europe and the Middle East until about 30,000 years ago. Cro-Magnon people, the ancestors of modern humans, started a second wave of migration out of Africa about 10,000 years earlier.
One huge question is how closely they interacted. Paabo's and Rubin's genetic analysis both suggest there was little sexual contact, at least according to the genes from this one male found at the back of a cave in Croatia.
Paabo's team sorted through 70 Neanderthal specimens before they found a bone well-preserved enough to provide DNA. They took the tiniest samples they could to preserve the valuable bones.
They know it was a male because the DNA has a Y chromosome. Females have two X chromosomes.
Paabo's team used a gene sequencer made by 454 Life Sciences Corporation, a majority-owned subsidiary of CuraGen Corporation. He said they have refined their methods and hope to have a complete genetic sequence within two years.
They said the Neanderthal sequences are 99.95 percent identical to human DNA sequences. This compares to about a 98 percent similarity between humans and chimpanzees, who split from a common ancestor 6 million to 7 million years ago.
Three-way comparisons among the human, chimpanzee and Neanderthal genomes should shed light on what makes modern humans unique, experts agreed.
Rubin and other experts stressed that while full sequences of the human genome are available, very little is understood about what the code actually means.
"We have the book but we haven't yet read it," Rubin said.
They found, for instance, sequences linked with eye color but cannot read the code to tell what color Neanderthal eyes were.
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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Bass
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Re:Likely that early man did not have sex with his cousin
« Reply #1 on: 2006-11-22 09:03:03 » |
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Interesting. But in order to class this a "fact", so to speak wouldn't evolution need to be proven, I mean the Darwinian type.
I mean I know that evolution is the only rational explanation we have which can tell us why we are here and how far we have come, but it's still not proven to be true or a fact as far as I am aware.
Whilst I am not saying evolution is a lie, those exact kind of statements (people who say it is a fact when more evidence is needed) are what annoy me a lot about this kind of stuff. "This is an actual fact" is not factually true.
Before I begin let me make sure that this is an example of what I mean by we are told told it is fact rather than actual statements, for my example I will use the out of Africa theory, (yes, still a theory):
1) A Giants Bone if found, Scientist examines it.
2) To determine the year they look at the soil around it, the layers in the bone and realize the bone is 40k years old.
3) They do some DNA tests, this reveals there is a connection between this Giants bone and the bones of Humans.
4) Whilst it is a theory this is labeled as to many people as a fact this Giant is connected to humans and is roughly 40k years old.
Ok, now here are the problems I can see.
1) Giant's bone, now if they find this a large amount that reveals this is a human then ok, but you can't find the rest then to connect to humans is flawed.
2) For the most part this is a flawed way of working out time, to work out how old each layer is you would have to be not only able to compare it to something else at that period of time but you would have to examine the landscape and pin point some source which is part of that time which is on the same level as it. This would be impossible because you can not go back in time and see that thing to be there at that point in time (Which if you could would make this part redundant), and the would bring you back to the first position effectively running around in circles.
3) Unverified/rubbish really, a mouse has something like 97% of our DNA, does that mean we are descendants from mice? No, that just shows the DNA had molded the same way as did ours, through evolution yes, but that doesn't mean they came from the same place. Take this example:
There are two men in ancient times, one from Sweden and one from Japan. The Swede builds a hut in his own design, at the same time halfway across the world the Japanese man builds a house of his design, the houses have the same structure and everything, these two men have never ever met. Both built them on the same day, and to spice it up lets just say the Japanese man was an experiment from the planet Asia, and evolved completely from there... and the Swede is an experiment from the planet Scandinavia... these two planets had no contact with each other, does this mean that houses are produced from men with only Swedish or only Japanese blood and they are connected? Not one single bit.
4) Just because something is repeated over and over doesn't make it true (otherwise I'd have many things I have ordered by now). You can find one method of doing something, and if that works for you then good on you, but that don't ever say your way is the "absolute truth", because there are many paths that people have not yet gone down, I do believe you can manipulate something into being considered truth whether it is or not.
Everything is flawed, nothing is absolute and saying something is, is a good example of the Christian mindset. I love the way some people are determined to disprove Christianity, yet some push their ideas down peoples throats as absolute truth just like Christians do (I've seen much of this where I study). By no means am I supporting Xtians, I just find the irony quite amusing between the religious and the scientific in some cases.
Anyway, the process of Evolution is nothing new even in Darwins time. Popular in Pagan belief is a concept called Wyrd, this was that life was a journey and throughout that journey you are setting out "to become", aka evolving into something, I believe that because Western Europeans hang onto this belief and even spread it far off to places such as India it has succeeded in the advancement's seen in society today. It is pretty much the same thing as Evolution except with more of a Spiritual side to it, and unlike today people really striven to become what they set out to become. Simply put, Evolution is a kind of European Pagan tradition labeled with Science; that kind of proves my thoughts to be fairly accurate, at least in this aspect to me.
I just don't see how one could say that evolution is a fact; althought the article doesn't exactly say that. I think, and my take, is that Darwinian evolution has yet to "evolve" into an actual science.
But the article was a very interesting read.
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Hermit
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Re:Likely that early man did not have sex with his cousin
« Reply #2 on: 2006-11-22 11:49:10 » |
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I think you have some misunderstandings to clear up. Let me try to help.
Evolution is a lot of things.
One thing it is not, despite how it may have been presented to you, is a continuous process of improvement. It is not even a discontinuous or punctuated process of improvement. Technically speaking, evolution is nothing more (or less) than a change in allele frequencies over time. An allele is how a chromosome or plurality of chromosomes express themselves. So evolution says that we see changes in chromosomes over time. not improvements.
This happens. We have observed it over and over. In situations as diverse as virus (like the flu virus which comes back each year sufficiently changed to get past our immune systems), speciation in fish populations left in isolated ponds as rivers change course or dry up, changes in birds and insects songs as populations become diversified and so on. So in this sense, evolution is a fact. It is as solid a fact as science gets to. Not a theory. Note that this does not mean that evolution is "proved" to be true. Science doesn't work that way. If we find some creature that does not experience a change in allele distribution over time, science would be completely happy to extend its observations about evolution and possibly its understanding of evolution to deal with that too. So far it hasn't happened. My bet is that it won't.
Then there is the theory of evolution. This explains why there are changes in allele frequencies over time. Currently the best theory we have is Darwin's theory of evolution, that organisms adapt to to changes in the environment through a process of natural selection. We call Darwinian Evolution a 'strong theory' because it has been tested for over 100 years and there is no instance where it has been shown to be insufficiently general or to have inadequate explicatory power to explain any instance of a change in allele frequencies over time. Notice that Darwin's theory is a theory because it is a well supported scientific hypothesis. It remains a theory because all well supported scientific hypothesis are theories, even the ones which earlier were tagged as "laws". Scientific hypothesis and theories are in principle falsifiable by finding sufficient instances of significant weaknesses in the theory. In the case of Darwinian evolution, like the case of actual evolution, my bet is that this is not going to happen.
The reason I bet this way is because I and every other modern scientist have a massive advantage over Darwin. We understand the building blocks of evolution, DNA, RNA and the mechanisms of reproduction including selection. This understanding, and the tools we have developed to evaluate them, has provided us with the ability to view selection on the fly so to speak. Everything we have observed confirms the Darwinian explanation. Very significantly, there is no ghost lurking in the machinery to introduce other effects. In other-words, we now know that there are not other mechanisms, and the mechanisms we know about are only expressed through Darwinian processes.
As a second level of confirmation, strengthening my bet, improvements in modelling and artificial intelligence have allowed us to build systems which exhibit complex behaviours from simple components, including behaviours that are not susceptible to our current levels of analysis, proving that arguments to complexity are as ridiculous as biologists have always said that they were.
Evolution is not something where there is wriggle room. Our ability to work from DNA - even tiny fragments of DNA - allows us to unravel the tapestry and see where we came from and even to an increasingly large extent, how we have adapted, in other words, what pressures were applied to us to make us what we are.
Finally, please realize that dating is a complex field, and it is seldom the case that a single dating method is used. For example, when an ancient bone is found with some viable DNA it can be analysed by:
Stratigraphic analysis (which you mentioned)
Radiographic analysis (Carbon and other radionuclide dating)
Morphological analysis (What other well dated bones does it resemble)
Chromosome analysis (DNA testing. This last is extremely reliable, as we are able to determine maternal relations and also calculate the number of observed mutations from other dated finds, both of which provide dating mechanisms)
When these methods are combined, using double-blind methods (as is almost always the case these days) and provide mutually supporting results, the likelihood of significant error is almost non-existent because the methods rely on largely independent or completely independent factors.
I don't know where the "giant" came from, so I won't address that.
We do know from mitochondrial DNA (which is passed on, largely unchanged from mother to child) where mankind has split and who their mothers were. We can determine from evidence in the DNA more or less how many generations passed between splits.
From the above, we can determine when the last common mother occurred after a speciation event.
Based on the degree of diversity found in the DNA from single individuals as well as across groups, we can make very good estimates of the size of the population and the pressure upon the population.
From this you might conclude that there is a lot more solid evidence for Darwinian evolution than you were previously aware of. Once again, books are your friend. Books by Richard Dawkins are especially useful. These include:The Selfish Gene
The Extended Phenotype
The Blind Watchmaker
River Out of Eden
Climbing Mount Improbable
Unweaving the Rainbow
Have fun
Hermit
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With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg, 1999
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Bass
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Re:Likely that early man did not have sex with his cousin
« Reply #3 on: 2006-11-24 18:22:37 » |
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I must say there are some things said there that I didn't know before Hermit. Thanks for clearing that up.
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Bass
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Re:Likely that early man did not have sex with his cousin
« Reply #4 on: 2006-12-23 18:15:41 » |
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With evolution as such a strong theory (and fact) would it automatically disprove all other theories such as ID? Is there any other explanation other then Evolution for us having progressed and come this far in the universe?
I'm not sure that evolution follows any set rules or laws and it seems like abit of a free for all.
Regards
Bass
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Blunderov
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Re:Likely that early man did not have sex with his cousin
« Reply #5 on: 2006-12-23 23:40:38 » |
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Quote from: Bass on 2006-12-23 18:15:41
With evolution as such a strong theory (and fact) would it automatically disprove all other theories such as ID? |
[Blunderov] I don't think so - it could still be claimed, however speciously, that some sort of devine agency itself set evolution in motion. (The FSM springs to mind.)
The very first time that some evidence for this point of view is produced it will have my undivided attention. Until then we "have no need of this hypothesis". Such speculation clarifies nothing and raises more questions than answers.
Best regards.
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