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400,000 year old human DNA found. Evolution questions follow.

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A

alr1ght

bish gets all the credit :)
http://www.nytimes.com/2013/12/05/s...human-dna-yet-found-raises-new-mysteries.html

Scientists have found the oldest DNA evidence yet of humans’ biological history. But instead of neatly clarifying human evolution, the finding is adding new mysteries.

In a paper in the journal Nature, scientists reported Wednesday that they had retrieved ancient human DNA from a fossil dating back about 400,000 years, shattering the previous record of 100,000 years.

The fossil, a thigh bone found in Spain, had previously seemed to many experts to belong to a forerunner of Neanderthals. But its DNA tells a very different story. It most closely resembles DNA from an enigmatic lineage of humans known as Denisovans. Until now, Denisovans were known only from DNA retrieved from 80,000-year-old remains in Siberia, 4,000 miles east of where the new DNA was found.

The mismatch between the anatomical and genetic evidence surprised the scientists, who are now rethinking human evolution over the past few hundred thousand years. It is possible, for example, that there are many extinct human populations that scientists have yet to discover. They might have interbred, swapping DNA. Scientists hope that further studies of extremely ancient human DNA will clarify the mystery.

“Right now, we’ve basically generated a big question mark,” said Matthias Meyer, a geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a co-author of the new study.

Hints at new hidden complexities in the human story came from a 400,000-year-old femur found in a cave in Spain called Sima de los Huesos (“the pit of bones” in Spanish). The scientific team used new methods to extract the ancient DNA from the fossil.
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But the DNA did not match that of Neanderthals. Dr. Meyer then compared it to the DNA of the Denisovans, the ancient human lineage that he and his colleagues had discovered in Siberia in 2010. He was shocked to find that it was similar.

“Everybody had a hard time believing it at first,” Dr. Meyer said. “So we generated more and more data to nail it down.”

The extra research confirmed that the DNA belonged on the Denisovan branch of the human family tree.

The new finding is hard to reconcile with the picture of human evolution that has been emerging in recent years based on fossils and ancient DNA. Denisovans were believed to be limited to East Asia, and they were not thought to look so Neanderthal-like.

Based on previously discovered ancient DNA and fossil evidence, scientists generally agreed that humans’ direct ancestors shared a common ancestor with Neanderthals and Denisovans that lived about half a million years ago in Africa.

Their shared ancestors split off from humans’ lineage and left Africa, then split further into the Denisovans and Neanderthals about 300,000 years ago. The evidence suggested that Neanderthals headed west, toward Europe, and that the Denisovans moved east.

Humans’ ancestors, meanwhile, stayed in Africa, giving rise to Homo sapiens about 200,000 years ago. Humans then expanded from Africa into Asia and Europe about 60,000 years ago. They then interbred not only with Neanderthals, but with Denisovans, too. Later, both the Denisovans and Neanderthals became extinct.
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S

Skellig Gra

Member
Pretty cool. I'm not sure why the scientists were shocked though. It was 400,000 years ago, how could we ever know what really was going on back then with any accuracy.
 
O

Opiate

Member
New evidence arrives, scientists adjust their understanding of history. Even in pretty significant ways, as in this case.

It would be so much cheaper if scientific textbooks required no revision and no editing. If only they could avoid costly revision and editing like many religious texts do, I'm sure my Biochem textbook from Sophomore year would have been noticeably cheaper.
 
D

~Devil Trigger~

In favor of setting Muslim women on fire
giorgio-tsoukalos.jpeg
 
D

Damaniel

Banned
gumby_trucker said:
I thought DNA deteriorated much sooner than 400,000 years.
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As time goes on, we get much better at reconstructing sequences from more and more deteriorated samples. You probably don't need very many intact markers to make the link to any particular genetic tree.
 
M

Mariolee

Member
CorvoSol said:
Cool new scientific discovery?

Must be a good reason to take a dump on religion!
Click to expand...

.

It really is uncalled for when the article itself makes no mention of religion at all. It's like if I brought up how much Sony sucks in a Mario thread or something.
 
S

Septimius

Junior Member
Khalifa Jayy said:
My question is: How do we know that our fossil record and DNA dating methods are precise and accurate?
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There are many great sources for this out on the internet. I'd try to form a reply, but I'm not knowledgeable enough on the field to make a concise answer, and the question is a bit off of a tangent for the topic at hand. To me, it's a bit like asking how we know we revolve around the sun in a discussion of solar winds.
 
K

Kenka

Member
No Metroidians ?

They could have given our grandfathers a cool name, at least. Awesome find nonetheless !
 
Jackben

Jackben

bitch I'm taking calls.
I was shocked to learn the one on the far right with all the hair was actually a female.
CorvoSol said:
Cool new scientific discovery?

Must be a good reason to take a dump on religion on the internet!

Yeah!
Click to expand...
There is no need to be upset.
 
I

i-Lo

Member
Wow, we've made a mind numbing tech leap in the last 50 years when put in context of our species' existence.
 
M

Mgoblue201

Won't stop picking the right nation
gumby_trucker said:
I thought DNA deteriorated much sooner than 400,000 years.
Click to expand...
From Nature:

"By comparing the specimens' ages and degrees of DNA degradation, the researchers calculated that DNA has a half-life of 521 years. That means that after 521 years, half of the bonds between nucleotides in the backbone of a sample would have broken; after another 521 years half of the remaining bonds would have gone; and so on.

The team predicts that even in a bone at an ideal preservation temperature of −5 ºC, effectively every bond would be destroyed after a maximum of 6.8 million years. The DNA would cease to be readable much earlier — perhaps after roughly 1.5 million years, when the remaining strands would be too short to give meaningful information."
 
-COOLIO-

-COOLIO-

The Everyman
Opiate said:
New evidence arrives, scientists adjust their understanding of history. Even in pretty significant ways, as in this case.

It would be so much cheaper if scientific textbooks required no revision and no editing. If only they could avoid costly revision and editing like many religious texts do, I'm sure my Biochem textbook from Sophomore year would have been noticeably cheaper.
Click to expand...
do ebooks get patched?
 
E

efyu_lemonardo

May I have a cookie?
Damaniel said:
As time goes on, we get much better at reconstructing sequences from more and more deteriorated samples. You probably don't need very many intact markers to make the link to any particular genetic tree.
Click to expand...

Mgoblue201 said:
From Nature:

"By comparing the specimens' ages and degrees of DNA degradation, the researchers calculated that DNA has a half-life of 521 years. That means that after 521 years, half of the bonds between nucleotides in the backbone of a sample would have broken; after another 521 years half of the remaining bonds would have gone; and so on.

The team predicts that even in a bone at an ideal preservation temperature of −5 ºC, effectively every bond would be destroyed after a maximum of 6.8 million years. The DNA would cease to be readable much earlier — perhaps after roughly 1.5 million years, when the remaining strands would be too short to give meaningful information."
Click to expand...

I read that too, and I must be misunderstanding something about how this works, because 400,000 years is roughly 800 half-lives. And 1/2^800 is such a small number, I don't see how there would be anything meaningful left even the initial sample was all the DNA in all the cells in a million people.

According to the internet there are roughly 6 billion base pairs per human diploid cell, and roughly 100 trillion cells in the human body. So one human (or denisovan in this case) would contribute about 6*10^23 base pairs.

edit: That means a million people would contribute roughly 10^30 base pairs, but 1/2^800 is about 10^-240..

edit 2: In other words, conditions in this cave in Spain had to be such that the DNA's half life was closer to 5000 years than 500 years, in order to be able to retrieve a sample of length in tens or hundreds of bases long, assuming there were initially about 100-1000 individuals in the cave.
 
O

Opiate

Member
CorvoSol said:
Cool new scientific discovery?

Must be a good reason to take a dump on religion on the internet!

Yeah!
Click to expand...

I'm sympathetic to this view generally, but this happens to highlight the primary contrast between science and religion.

Science adjusts its conclusions and understandings as new evidence is introduced; by definition, religion does not do this, as it is based on faith and not evidence-based conclusions. Most primary religious texts (e.g. The Bible, The Bhagvad-Gita, the Quran, etc.) are viewed as the inerrant word of God or of the Prophet.

This distinction is, again, the most significant difference between the two philosophies, which are otherwise not necessarily at odds. They agree on lots of things; most religions, for example, believe that helping people is a good thing, and most science operates on that pretext as well (e.g. medical science). Both science and religion view the universe as an awesome, beautiful place.

So science and religion aren't necessarily or always at odds. But in this particular way, they are; science corrects itself when new evidence is presented that contradicts previously held belief. Religion does not. Again, I completely agree that people often take gratuitous potshots at religion, and frequently view science and religion as absolutely antithetical, which they are not.
 
DanteFox

DanteFox

Member
Interesting how some people treat science itself almost like a kind of faith. They take time to praise science and denigrate religion preemptively almost as if to make themselves feel better about their beliefs instead of commenting on how interesting the discovery itself is like a normal human being.
 
F

Funky Papa

FUNK-Y-PPA-4
CorvoSol said:
Cool new scientific discovery?

Must be a good reason to take a dump on religion on the internet!

Yeah!
Click to expand...

Not religion, but a very particular, very nasty, highly malodorous branch of religious people whom have turned their very existence into a joke.

I'm sorry if I can't empathise with them like you do.

And BTW, this discovery is some radical shit.
 
A

Anura

Member
DanteFox said:
Interesting how some people treat science itself almost like a kind of faith. They take time to praise science and denigrate religion preemptively almost as if to make themselves feel better about their beliefs instead of commenting on how interesting the discovery itself is like a normal human being.
Click to expand...

To be fair when it comes topics with religious/scientific implications being a jerk is almost par for the course for either side. And for whatever reason evolution is a controversy in some religious folks...
 
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