Posted on 07/26/2007 12:12:38 PM PDT by blam
Elephants, Human Ancestors Evolved in Synch, DNA Reveals
Hope Hamashige for National Geographic News
July 23, 2007
The tooth of a mastodon buried beneath Alaska's permafrost for many thousands of years is yielding surprising clues about the history of elephants—and humans.
A team of researchers recently extracted DNA from the tooth to put together the first complete mastodon mitochondrial genome.
The study, published in the journal PLoS Biology, significantly alters the evolutionary timeline for elephants and their relatives.
The research may put to rest a contentious debate by showing that woolly mammoths are more closely related to Asian elephants than African elephants.
Comparing the new genome with that of other animals in the elephant family also provides evidence that the elephant family diverged on roughly the same timeline that primates separated, suggesting there may have been a common cause for the splits.
"I think the divergence is the most interesting thing from this study," said lead author Michael Hofreiter, an evolutionary biologist at the Max Plank Institute for Evolutionary Anthropology in Leipzig, Germany.
Reason to Evolve
According to Hofreiter's research, African elephants diverged from mastodons about 7.6 million years ago, about the same time gorillas split from the line that gave rise to humans and chimpanzees.
Mammoths and Asian elephants speciated around 6.7 million years ago, roughly the same time humans and chimps split.
Alfred Roca is a geneticist at the Laboratory of Genomic Diversity in Frederick, Maryland, part of the U.S. National Cancer Institute. He was not involved in the new research.
He called Hofreiter's work "outstanding," noting that the research pushes the previously believed dates for the divergence of elephants by several million years.
He added that several groups of modern animals—not just elephants and humans—went through significant change during that time, the late Miocene period. (Related: "Mastodons Driven to Extinction by Tuberculosis, Fossils Suggest" [October 3, 2006].) The most widely held theory about what happened then is that climate change led to the expansion of grasslands in Africa, which fragmented habitats and spurred many species to evolve.
The new study lends further credibility to the notion that climate change can lead to evolutionary change.
"Ours is one more piece of evidence that definitely supports the idea that climate change is a key event in speciation," lead study author Hofreiter said.
Pieced Together
The new research marks a significant departure from previous studies.
Until now, scientists had reconstructed the history of the elephant family primarily using fossil evidence.
Mitochondrial DNA, which is passed on only from mother to child, provides an easy way to trace lineages and is a more accurate source of information. But its use has always been limited, because DNA in ancient fossils begins to breaks down.
Hofreiter and his colleagues, however, developed a way to piece together the genome from small samples of fragmented DNA.
They applied the technique to a mastodon tooth collected in 1999 from Alaska's Ikpikpuk River.
Radiocarbon dating of the collagen in the tooth places its age at at least 50,000 years. But researchers have concluded, based on the dating of other material from the area, that the fossil may be as old as 130,000 years old.
Never before have researchers successfully sequenced a genome from such an ancient piece of bone. Previously, Hofreiter said, the oldest fossil from which scientists were able to extract a complete genome was about 30,000 years old.
In this case, the team cut about 7 ounces (200 grams) from the root of the molar of a mastodon and extracted small fragments of the DNA from bone. By piecing together the overlapping fragments, the team was able to sequence the entire genome.
"It is amazing they were able to extract a complete genome from a bone that old," noted Anna-Sapfo Malaspinas, a researcher at the University of California, Berkeley and one of the authors who helped to analyze the sequencing after the genome was extracted.
Because the animal was encased in permafrost before being exposed to river erosion, the DNA in the mastodon was fairly well preserved, researchers say.
"It is hard, using fossils to come up with accurate dates," Roca, the geneticist, said. "But using DNA makes it easier."
Elephant in the Room
This new research may also put to rest a heated debate about the history of elephants.
"There has been controversy over whether woolly mammoths are more closely related to Asian or African elephants," said Stephen O'Brien, lab chief at the Laboratory of Genomic Diversity.
Both fossil evidence and incomplete mitochondrial genomes had previously indicated that woolly mammoths' closest relatives were African elephants.
Two years ago, however, Hofreiter was also the first to sequence a complete mitochondrial genome from a woolly mammoth. His research contradicted earlier studies because it indicated a tighter kinship to the Asian elephant.
The information extracted from the mastodon, a close relative to both mammoths and elephants, supports Hofreiter's earlier work.
According to O'Brien, studies using incomplete genome sequences from woolly mammoths are likely not as reliable.
"This is the most robust data we have seen to date."
You're kidding? The guys will begin fussing over the girls the first night there, lol.
I'm thinking of a seed population of between 500-5,000 humans to begin the re-population efforts. We need real humans, not frozen 'seeds', etc.
Sperm and egg 'donations' may be a good idea for the re-population of 'food' animals.
Enough 'candidates' will be pre-selected that enough will survive to populate this effort. 'The facility' will have the means to locate and transport the 'qualified' to 'the facility.'
Well, I'm the supreme leader and you just blew your chance to be 'selected.' (ahem)
Now you can go to 'your facility' and spend the rest of your life with a security guard and a janitor-centifruge operator.
If I were a billionaire I'd do something similar with the human population...always have a list of humans who fulfilled a list of qualifications such as:
1. High IQ
2. Free of genetic defects.
3. Pass a DNA test that would detect recessive disease problems
4. etc.
5. (female applicants only) Has the hots for and desires to copulate with the 'supreme leader.'
(There, fixed that)
Oh Yeah - if the Yellowstone caldera blows - I can see that working.
LOL!
If you are joking - you’re funny;O If series- you’re nuts.
I’m going with #2!!!!!!!!!!
Do you know how to operate a centrifuge?
I’ll work on the janitor!
LOL.
Click on the Dark Ages link on this post, that was a catastrophic time too.
“””that was a catastrophic time too”””
Interesting that ‘societies’ without cell-phones, radios etc., managed their daily lives based on what they had been taught and what they were eager to learn. Also interesting that ‘religion’ was far more practical - I’m not convinced it was propaganda as much as learned hygiene (eating pork was probably a health hazard until the 20th century)
Not sure that we are as curious and capable of such resourcefulness. Witness Katrina.
AP
Posted: 2007-07-27 11:01:07
Filed Under: Science, World
ATHENS, Greece (July 26) - Researchers in northern Greece have uncovered two massive tusks of a prehistoric mastodon that roamed Europe more than 2 million years ago - tusks that could be the largest of their kind ever found
Saw that yesterday, thanks.
Casualties.
(eating pork was probably a health hazard until the 20th century)Human flesh and pork are practically indistinguishable; I've come around to the view that is what led to the prohibition on eating pork among the Jews, and later among the Muzzies.
D@mn. I guess you get to be supreme leader because you called it. I was too slow. ;’)
I think it relates to the fact that pigs and humans have to eat the same thing. Cows, horses and etc can digest cellouse and humans and pigs can't. During a famine people would be pretty upset if you were the owner of pigs...whether you were the king or not, hungry people will kill you because they know you're feeding the pig something you could be eating.
Religious leaders probably recognized the potential for conflict and worked this prohibition into the religious texts.
Also, cattle are 75% more efficent at digesting cellouse than horses and archaeologists use the ratio of horse/cow bones to detect drought/famine conditions, especially out on the steppes.
I think the food laws begin with Leviticus 11 — animals which go on the cloven hoof and chew their cud, and not animals which lack one or the other, are permissible; more detail is in Deuteronomy 14:3-6.
I was about to posit that the most likely common reason for the simultaneous split of elephant and primate lines (obviously a few orders of magnitude older than the event you mention) would be some catastrophic event that isolated groups. Weather-induced seems more likely than geographic, but who knows.
The problem with this theory would seem to be that normal climate change happens so frequently, but the important evolutionary branches less so.
They were killed by polar bears who used them as flotation devices.
algore told me so. ;)
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