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."
:’)
I just wish some of you brainiacs would apply what you know about past evolutionary changes in the size & structure of animals to a discussion on the future physique of humans, in say (?) 200K years.
If we stop smoking, eating meat, have no means of transportation, cannot walk outside because of global air pollution, have sexual confusion and use only Government pre-selected ova and sperm to procreate in labs, continue to sit at computers to communicate, what form will homo sapiens take?
My guess is we will look very much like Roswell aliens.
I’m going to sleep now;)
This one’s for you - but I forgot to ping you;)
I just wish some of you brainiacs would apply what you know about past evolutionary changes in the size & structure of animals to a discussion on the future physique of humans, in say (?) 200K years.
If we stop smoking, eating meat, have no means of transportation, cannot walk outside because of global air pollution, have sexual confusion and use only Government pre-selected ova and sperm to procreate in labs, continue to sit at computers to communicate, what form will homo sapiens take?
My guess is we will look very much like Roswell aliens.
I’m going to sleep now;)
We're not likely to be here. Some natural disaster, super-volcano, asteroid-comet impact, super-pandemic and etc will probably wipe us out. Only the humans who have made it to other celestial bodies will survive to repopulate the earth.
“”””Only the humans who have made it to other celestial bodies will survive to repopulate the earth...””””
Details details........when (?) and what will they look like??? Will they be selected on size, shape and brain volume? Ability to procreate? Or will they comprise all males and take frozen eggs with them? Or all females and take frozen sperm with them?
See (?) You have to imagine!
In 200,000 years, almost everyone will look quite a bit like the modern population of India, with a some eastern Asian eyefold and European freckles and recessive hair colors thrown in — unless, as Blam noted, there is some kind of worldwide catastrophe extinctifying large areas of the planet in some unpredictable fashion.
You don’t contemplate a more dramatic change in our functional appendages, other than skin features & color?
It is remarkable (in just a few decades) how much our diet and lack of manual labor has caused a discernable increase in the number of grossly obese people. Not just layers of fat skin, but huge, huge buttocks and breasts in women and large, large abdomen in men.
Focus on this - bring some catastrophe to the template - use your anthropology expertise - like tail bones - create some prototypes - you can do it;)
Go on!
May you find your way as pleasant.
Sure. Humans rode elephants into the New World to escape the dinosaurs.
It is a good beginning but where’s your research?
Then where are the domesticated new world elephants?
apropos of nothing...
http://www.freerepublic.com/focus/news/1872486/posts?page=9#9
Perhaps Humans will be extinct — but certain life forms will persist:
http://www.freerepublic.com/focus/f-chat/1647010/posts
http://www.freerepublic.com/focus/f-chat/1646657/posts
http://www.freerepublic.com/focus/f-chat/1654389/posts
http://www.freerepublic.com/focus/f-chat/1692612/posts?page=49#49
http://www.freerepublic.com/focus/f-chat/1692612/posts?page=53#53
http://news.bbc.co.uk/1/hi/world/americas/5067912.stm
If there’s some kind of show-stopper, such as a series of impacts (it’s pretty likely that impacts arrive in groups of at least two; the SL-9 impacts 13 years ago about now numbered more than 20), civilization will cease, and surviving human populations (y’know, after internal struggle and atrocities against one another) will be isolated from one another. Due to isolation, genes would get concentrated on a random basis and lead to pronounced ethnicities which don’t exist per se today — the same process by which we all got to where we are today.
Provided such survivors aren’t hunted out by a top predator, IOW, assuming the survivors preserve tools, or re-learn toolmaking skills, islands of genetically compatible groups will diverge from one another, but still be genetically compatible. There’s no way to predict what they’d look like, or whether they’d lose their wee-wee toes and earlobes.
“”””civilization will cease, and surviving human populations (y’know, after internal struggle and atrocities against one another) will be isolated from one another.””
There are so many possible scenarios - we should consider them all individually and in combination. TWC “It Could Happen Tomorrow” are interesting vignettes, but they are only regional, climate/weather related events, based on our current circumstances. They are relatively insignificant and make no mention of long-term effects, recovery or adaptation.
More remarkable is that our ancestors envisioned how life would ebb and flow - they must have reached the end of their imagination with the Apocalypse - total end - total destruction. Have we not projected anything more scientific? 6 billion people later and 6 billion people right now...with more on the way.
Bing - there’s another one - it’s a boy;)
Ahem, I beg to differ.
Late Pleostocene Human Population Bottlenecks. . . (Toba)
"The last glacial period was preceded by 1000 years of the coldest temperatures of the Late Pleistocene, apparently caused by the eruption of the Mount Toba volcano. The six year long volcanic winter and 1000-year-long instant Ice Age that followed Mount Toba's eruption may have decimated Modern Man's entire population. Genetic evidence suggests that Human population size fell to about 10,000 adults between 50 and 100 thousand years ago. The survivors from this global catastrophy would have found refuge in isolated tropical pockets, mainly in Equatorial Africa. Populations living in Europe and northern China would have been completely eliminated by the reduction of the summer temperatures by as much as 12 degrees centigrade. "
Now you’re talking - and I shall be reading.
I know what you’re thinking - and it isn’t nice;)
sod
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.
After a world affecting catastrophic event and before everyone on the list died of starvation, etc. Collect these people and sprint them to a pre-preparded facility (probably underground) that contained food stocks, equipment, books, mfg equipment, raw materials of all sorts to re-start civilization. The energy for the facility could by supplied by small nuclear reactors (and some in waiting) that could be 'fired up' over the decades that may be necessary to produce a 'critical mass' of humans.
The list of humans 'qualified' to enter the facility would be heavy on those in their child-bearing years.
Everyone would be required to contribute.
“”””The list of humans ‘qualified’ to enter the facility would be heavy on those in their child-bearing years””””
NO NO NO NO NO!
And I don’t say that because of my age - I say that because we should start NOW - asking for egg & sperm donations (although I am adamantly opposed) from people who have already proved their bone fides.
In such a catastrophe we could not possibly locate all of the best candidates and shuttle them into the bank. Plus they would be too traumatized to copulate. We just need a janitor and a security guard with centrifuge experience.
You better get a better plan. The first one ain’t gonna work.
All interesting, but where does the Morroccan Elephant fit into this break? Was it an offshoot of the asian that didn’t leave Africa, or an offshoot of the African Elephant?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.