The Internet has been burning up with an ice age storyline over the past few days: Researchers in Japan led by Akira Iritani announced their plan to clone a woolly mammoth within four to six years, recreating a colossal beast not seen on Earth in thousands of years. But as enthusiastic as DISCOVER is for cloned mammoths (and believe us, we’re psyched), the project is still a long way from success.
First, the backstory.
Researchers from Kinki University’s Graduate School of Biology-Oriented Science and Technology began the study in 1997. On three occasions, the team obtained mammoth skin and muscle tissue excavated in good condition from the permafrost in Siberia. However, most nuclei in the cells were damaged by ice crystals and were unusable. The plan to clone a mammoth was abandoned. [Daily Yamiuri]
That initial effort was a DISCOVER cover story back in 1999. Now, though, the dream is back, thanks to newly developed methods to get around that icy problem.
The team, which has invited a Russian mammoth researcher and two US elephant experts to join the project, has established a technique to extract DNA from frozen cells, previously an obstacle to cloning attempts because of the damage cells sustained in the freezing process. Another Japanese researcher, Teruhiko Wakayama of the Riken Centre for Developmental Biology, succeeded in 2008 in cloning a mouse from the cells of another that had been kept in temperatures similar to frozen ground for 16 years. [AFP]
When it comes to explaining why the woolly mammoths died out, “death from above” could be down for the count.
Nearly 13,000 years ago, North American megafauna like the mammoths and giant sloths—and even human groups like the people of the Clovis culture—disappeared as the climate entered a cold snap. As DISCOVER has noted before, there’s been a controversial hypothesis bubbling up saying that a comet impact caused it all, but other scientists have been shooting holes in that idea of the last couple years. In a study in this week’s Proceedings of the National Academy of Sciences, a team led by Tyrone Daulton pooh-poohs what may be the last major evidence that supports the impact idea.
That evidence takes the shape of nano-diamonds in ancient sediment layers, a material said to form during impacts only.
It took more than being woolly for woolly mammoths to survive the wintry climates in which they lived. A new study in Nature Genetics suggests that the weighty mammals had hemoglobin in their blood that could keep oxygen moving even at low temperatures, giving them a kind of “antifreeze” blood:
For the mammoth, this meant that they could keep extremities cool and concentrate heat internally, minimizing heat loss. In addition, it meant that when food was scarce they could live on less of it since they didn’t need as much heat (or calories) to move the oxygen to the tissues [The Guardian].
Researchers figured this out through a lengthy process of analyzing 43,000-year-old mammoth remains unearthed in Siberia. But to understand the secrets of this huge creature, they had to enlist the help of a microorganism.
The mammoth DNA sequences were converted into RNA (a molecule similar to DNA which is central to the production of proteins) and inserted into E. coli bacteria. The bacteria faithfully manufactured the mammoth protein. “The resulting haemoglobin molecules are no different than ‘going back in time’ and taking a blood sample from a real mammoth,” said co-author Kevin Campbell, from the University of Manitoba in Canada [BBC News].
A fungus found within ancient mammoth dung is providing scientists with clues about how the large ancient mammals collectively known as megafauna went extinct. The fungus, Sporormiella, produces spores in the dung of large herbivores. These are then preserved in the layers of mud and can provide an index of the number of these animals, or megafauna, that roamed the environment at a particular time [BBC News]. For a new study, researcher Jacquelyn Gill collected and analyzed spores in sediment samples from an Indiana lake and several sites in New York.
From Gill’s analysis, published in the journal Science, she concluded that North American megafauna began a slow decline around 15,000 years ago and vanished about 1,000 years later. The data suggests megafauna started going extinct much earlier than previously though, which basically wipes out two theories of their extinction.
Minuscule diamond fragments found in a sediment layer dating from thousands of years ago are bolstering the theory that a catastrophic comet impact wiped out many forms of life in North America, including what are thought to have been the first human settlers of the continent, the so-called Clovis people. The nano-diamonds are buried at a level that corresponds to the beginning 12,900 years ago of the Younger Dryas, a 1,300-year-long cold spell during which North American mammoths, saber-toothed cats, camels and giant sloths became extinct. The Clovis culture of American Indians also appears to have fallen apart during this time [Reuters].
The new study adds evidence to the controversial theory, but some skeptics are not convinced. “The whole thing still does not make sense, and there are lots of contradictions,” said Christian Koeberl, a professor of geological sciences…. His chief reservation is that there is no crater. “A body of this size does not just blow up without a trace in the atmosphere,” Dr. Koeberl said. “Physics won’t have it” [The New York Times]. In reply, supporters of the theory say that some of the comet fragments may have exploded in midair, while others may have hit an ice sheet that was several miles thick, lessening the possibility of a crater forming.
The last woolly mammoths, who tromped around the Siberian tundra before going extinct about 10,000 years ago, had North American roots, according to a new genetic analysis. Scientists studied DNA from the remains of 160 mammoths from across North America and Eurasia, and determined that the last remaining mammoths were migrants who had come to Siberia via the Bering land bridge, and somehow replaced the endemic population.
Researchers believe that mammoths originally spread from Asia to North America via the land bridge, creating two genetically distinct populations. Now, they’re hypothesizing that some members of the North American group eventually made a return trip and proved hardier survivors than the Siberian group. “For some reason the North American guys went back over and became kings,” says [lead researcher] Hendrik Poinar [New Scientist].
Neanderthals don’t have the best reputation. In the public mind, the heavy-browed hominids are thought of as a stupid species that couldn’t compete with brighter Homo sapiens, as the also-rans that therefore went extinct. But a newly discovered trove of Neanderthal tools in Sussex, England may help rehabilitate their image. The tools, which date from the end of the Neanderthal era at around 30,000 B.C., show surprising sophistication, archaeologists say.
“The tools we’ve found at the site are technologically advanced and potentially older than tools in Britain belonging to our own species,” said [University College London]’s Matthew Pope. “It’s exciting to think that there’s a real possibility these were left by some of the last Neanderthal hunting groups to occupy northern Europe,” he added. “The impression they give is of a population in complete command of both landscape and natural raw materials with a flourishing technology — not a people on the edge of extinction” [Discovery News].
Woolly mammoths may all look the same in your average natural history museum display — the extinct animals are always depicted with the same curly tusks, shaggy hair, and lumbering feet. But researchers have just discovered that they were not all the same, that two genetically distinct groups of mammoths roamed the Siberian plains many millennia ago, and that one group avoided extinction for an extra 30,000 years.
Researchers first went in search of tufts of mammoth hair that had been frozen in the permafrost. They then used a new technique that allowed them to read the complete DNA sequence of an animal’s mitochondria (an energy-producing organelle within a cell) from a single hair. The DNA in mitochondria is passed only through the mother’s line, and doesn’t give information about changes in gene function, as nuclear DNA can. But it is useful because it doesn’t change from parent to offspring, making it easy to show when different animal groups are present [Nature News].