| Topic: |
Religions > Atheism |
| User: |
"johac" |
| Date: |
07 Jun 2006 02:05:31 AM |
| Object: |
Tooth gives up oldest human DNA |
Creationist: "But the world is only 6000 years old!"
Neanderthal: "Guess again."
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Tooth gives up oldest human DNA
By Helen Briggs
BBC News science reporter
Scientists have recovered DNA from a Neanderthal that lived 100,000
years ago - the oldest human-type DNA so far.
It was extracted from the tooth of a Neanderthal child found in the
Scladina cave in the Meuse Basin, Belgium.
The study, reported in Current Biology, suggests our distant cousins
were more genetically diverse than once thought.
Their diversity had declined, perhaps because of climate change or
disease, by the time early humans arrived in Europe about 35,000 years
ago.
Past diversity
French and Belgian researchers isolated the genetic material from
mitochondria. These are "power pack" structures in cells which contain
their own DNA.
Diversity tells us about how old a population is and its demographic
history
Dr Robert Foley
The scientists decoded the sequence of 123 DNA "letters" (base-pairs, or
bp) and compared it with other known Neanderthal DNA sequences from
specimens dated between 29,000 and 42,000 years old.
"The Scladina sequence has revealed that the genetic diversity of
Neanderthals has been underestimated," a team led by Dr Catherine Hanni
of Ecole Normale Superieur in Lyon, France, wrote in the journal Current
Biology.
"Thus, more Neanderthal sequences than the six presently available and
longer than 100 bp are needed to fully understand the extent of the past
diversity of Neanderthals."
Disease threat
The findings suggest that genetic diversity was greater in earlier
Neanderthal history than in later times, when humans started to arrive
in Europe.
Such changes are thought to reflect fluctuations in the population,
caused by disease or environmental change, as well as random genetic
mutations over time.
"Diversity tells us about how old a population is and its demographic
history," said Dr Robert Foley, an expert in human evolution at the
University of Cambridge, UK.
Neanderthals lived between 230,000 and 28,000 years ago in Europe,
Central Asia and the Middle East.
They were skilled hunters and well adapted to living during the ice
ages; but they started to die out after modern humans (Cro-Magnons)
appeared on the scene in Europe.
The reason for their sudden demise is unknown, but various theories have
been proposed, including biological, environmental and cultural factors.
The DNA studies conducted so far suggest little, if any, interbreeding
between Neanderthals and modern humans took place.
---
http://news.bbc.co.uk/1/hi/sci/tech/5052414.stm
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
.
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| User: "" |
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| Title: Re: Tooth gives up oldest human DNA |
07 Jun 2006 03:09:22 AM |
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johac wrote:
The DNA studies conducted so far suggest little, if any,
interbreeding between Neanderthals and modern
humans took place.
This is one of those "Red Flags" that appear in our
media, making me quite nervous.
First off, I'm not aware of any studies on which any
claim could be based.
You're certainly never going to get any useful data
just from comparing Y-chromosomes & MTDNA from
Neanderthals with that of modern human populations.
Secondly, assuming the single most conservative, the
safest & most logical guess is correct -- and there
was interbreeding -- of course the genetic contribution
is going to be small! But is the assumption that,
when it comes to genes, significance can only be
determined by number?
To a lesser extent, though still annoying, the use of
"little" in the above is undefined & meaningless.
"Little" in terms of.... what?
Raw numbers? Period of time it took place?
Percentage of population? Which population?
What, if anything, are the above estimates based
on?
And what if I could prove to you in no uncertain
terms that the only genetic contribution from
Neanderthals was white skin in Europeans?
Genetically you could argue that it's quite small,
while in terms of social development, identity
and impact of global history we'd all have to admit
it was quite big... huge.
It's all so frigging annoying.
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| User: "johac" |
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| Title: Re: Tooth gives up oldest human DNA |
07 Jun 2006 11:50:26 PM |
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In article <1149667762.718458.79560@y43g2000cwc.googlegroups.com>,
wrote:
johac wrote:
The DNA studies conducted so far suggest little, if any,
interbreeding between Neanderthals and modern
humans took place.
This is one of those "Red Flags" that appear in our
media, making me quite nervous.
First off, I'm not aware of any studies on which any
claim could be based.
That's the problem with science press releases. You only get part of the
story and no data. The science editors at the BBC are usually good, but
even they get it wrong sometimes.
You're certainly never going to get any useful data
just from comparing Y-chromosomes & MTDNA from
Neanderthals with that of modern human populations.
Secondly, assuming the single most conservative, the
safest & most logical guess is correct -- and there
was interbreeding -- of course the genetic contribution
is going to be small! But is the assumption that,
when it comes to genes, significance can only be
determined by number?
Not at all.
To a lesser extent, though still annoying, the use of
"little" in the above is undefined & meaningless.
"Little" in terms of.... what?
Raw numbers? Period of time it took place?
Percentage of population? Which population?
What, if anything, are the above estimates based
on?
Again you would need to see the original article and the citations
quoted. I believe it was to be published in Current Biology.
And what if I could prove to you in no uncertain
terms that the only genetic contribution from
Neanderthals was white skin in Europeans?
Is there evidence for this? Anthropology really isn't my field so I was
just wondering.
Genetically you could argue that it's quite small,
while in terms of social development, identity
and impact of global history we'd all have to admit
it was quite big... huge.
It certainly would.
It's all so frigging annoying.
What caught my eye was that they could recover DNA from that far back
and sequence it. Since it was only a fragment, I don't think that we
could learn that much anyway. Hopefully, more specimens will be found.
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
.
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| User: "" |
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| Title: Re: Tooth gives up oldest human DNA |
08 Jun 2006 02:31:53 AM |
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johac wrote:
What caught my eye was that they could recover DNA from
that far back and sequence it. Since it was only a fragment,
I don't think that we could learn that much anyway. Hopefully,
more specimens will be found.
I don't believe Neanderthal specimens alone could do it.
To do it absolutely right we'd also need DNA from modern
humans BEFORE they left Africa. That way we could not
only establish what genes the Neanderthals carried, but
what genes the moderns did not.
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| User: "johac" |
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| Title: Re: Tooth gives up oldest human DNA |
08 Jun 2006 11:33:41 PM |
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In article <1149751913.699569.55690@f6g2000cwb.googlegroups.com>,
wrote:
johac wrote:
What caught my eye was that they could recover DNA from
that far back and sequence it. Since it was only a fragment,
I don't think that we could learn that much anyway. Hopefully,
more specimens will be found.
I don't believe Neanderthal specimens alone could do it.
To do it absolutely right we'd also need DNA from modern
humans BEFORE they left Africa. That way we could not
only establish what genes the Neanderthals carried, but
what genes the moderns did not.
Or we might look at contemporaneous DNA from sapiens sapiens in areas
which Neanderthals did not inhabit, if we can extract it.
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
.
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| User: "" |
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| Title: Re: Tooth gives up oldest human DNA |
08 Jun 2006 02:52:34 AM |
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johac wrote:
And what if I could prove to you in no uncertain
terms that the only genetic contribution from
Neanderthals was white skin in Europeans?
Is there evidence for this? Anthropology really isn't
my field so I was just wondering.
Evidence? Sure. But nothing you would ever want to
bet the farm on.
White skin certainly dates to the right time... or within
the right window of time ( 20 to 50 thousand years ago).
Disclaimer: A genetic contribution from Neanderthals
wouldn't necessarily be limited to the modern European
population.
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| User: "johac" |
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| Title: Re: Tooth gives up oldest human DNA |
08 Jun 2006 11:24:35 PM |
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In article <1149753154.754574.316400@c74g2000cwc.googlegroups.com>,
wrote:
johac wrote:
And what if I could prove to you in no uncertain
terms that the only genetic contribution from
Neanderthals was white skin in Europeans?
Is there evidence for this? Anthropology really isn't
my field so I was just wondering.
Evidence? Sure. But nothing you would ever want to
bet the farm on.
White skin certainly dates to the right time... or within
the right window of time ( 20 to 50 thousand years ago).
Since the Neanderthals settled in Northern climates first, it's likely
that they got the mutation first which they could have passed on to the
later migrants.
Disclaimer: A genetic contribution from Neanderthals
wouldn't necessarily be limited to the modern European
population.
True. Neanderthal remains have been found in the Middle East.
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
.
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