Posts Tagged ‘pleistocene’

Neanderthal life spans similar to modern humans

January 12, 2011
By Charles Q. Choi, msnbc.com 1/11/2011
Original article here

Those who investigate Neanderthal remains have long known of a puzzling gap — elderly individuals are rare. Scientists have thus suggested that these prehistoric humans might have had an inherently shorter life expectancy than us modern humans, with our lineage ultimately outnumbering theirs, and so contributing to their demise.

Not so, according to a new study. Our once closest living relatives likely had similar life spans as us.

Our species, Homo sapiens , is the only surviving lineage of the genus Homo. Still, there once were many others, all of whom could also be called human.

Anthropologist Erik Trinkaus at Washington University in St. Louis analyzed fossil records to gauge the adult life spans of Neanderthals and early modern humans, which coexisted in different regions for about 150,000 years. He found roughly the same number of 20- to 40-year-old adults and adults older than 40 in both Neanderthal and early modern human populations, suggesting life expectancy was probably the same for both.

“Arguments for longer survival among early modern humans causing the demise of the Neandertals have no basis in fact,” Trinkaus told LiveScience. (Neanderthals are also called Neandertals due to changes in the German spelling over the years.)

Trinkaus did caution that a number of factors might skew his life-expectancy calculations. For instance, all these archaic and modern humans apparently had very mobile lifestyles during the Pleistocene to search for their next meals. That likely means any older members who could not keep up were left behind to die, and their remains would have been scattered by scavengers and lost from the fossil record.

Still, “new fossil discoveries could change the pattern some, but it is unlikely to alter it very much,” Trinkaus said. Overall, he contends that longevity did not factor into the extinction of Neanderthals. If early modern humans did have a population advantage, he argued, it was probably more due to high fertility rates and lower infant mortality.

Trinkaus detailed his findings online Jan. 10 in the Proceedings of the National Academy of Sciences.

One scientist’s hobby: recreating the Ice Age

December 19, 2010

Russian claims his theory to introduce herds of animals to Siberia can slow global warming.

By ARTHUR MAX The Associated Press 11/27/2010
Original article here


Semi-wild Yakutian horses are seen at the Pleistocene Park, a 40,000 acre wilderness in northern Siberia, Russia. Russian scientist Sergey Zimov is trying to recreate conditions from the end of the Ice Age when this area was rich in wildlife and summer meadows.

CHERSKY, Russia — Wild horses have returned to northern Siberia. So have musk oxen, hairy beasts that once shared this icy land with woolly mammoths and saber-toothed cats. Moose and reindeer are here, and may one day be joined by Canadian bison and deer.

Later, the predators will come — Siberian tigers, wolves and maybe leopards.

Russian scientist Sergey Zimov is reintroducing these animals to the land where they once roamed in millions to demonstrate his theory that filling the vast emptiness of Siberia with grass-eating animals can slow global warming.

“Some people have a small garden. I have an ice age park. It’s my hobby,” says Zimov, smiling through his graying beard. His true profession is quantum physics.

Climate change is felt most sharply in the Arctic, where temperatures are warming faster than anywhere else on the planet. Most climate scientists say human activity, especially industrial pollution and the byproducts of everyday living like home heating and driving cars, is triggering an unnatural warming of the Earth. On Monday, negotiators representing 194 countries open a two-week conference in Cancun, Mexico, on reducing greenhouse gases to slow the pace of climate change.

‘Interesting experiment’
Zimov is trying to recreate an ecosystem that disappeared 10,000 years ago with the end of the ice age, which closed the 1.8 million-year Pleistocene era and ushered in the global climate roughly as we know it.

He believes herds of grazers will turn the tundra, which today supports only spindly larch trees and shrubs, into luxurious grasslands. Tall grasses with complex root systems will stabilize the frozen soil, which is now thawing at an ever-increasing rate, he says.

Herbivores keep wild grass short and healthy, sending up fresh shoots through the summer and autumn. Their manure gives crucial nourishment. In winter, the animals trample and flatten the snow that otherwise would insulate the ground from the cold air. That helps prevent the frozen ground, or permafrost, from thawing and releasing powerful greenhouse gases. Grass also reflects more sunlight than forests, a further damper to global warming.

It would take millions of animals to change the landscape of Siberia and effectively seal the permafrost. But left alone, Zimov argues, the likes of caribou, buffalo and musk oxen multiply quickly. Wherever they graze “new pastures will appear … beautiful grassland.”

The project is being watched not only by climate scientists but by paleontologists and environmentalists who have an interest in “rewilding.”

“This is a very interesting experiment,” said Adrian Lister, of the Natural History Museum in London. “I think it’s valid from an ecological point of view to put back animals that did formerly live there,” he told AP Television News. He disapproved of suggestions to rewild nonnative species — for example, relocating elephants and rhinos to the American plains.

Zimov began the project in 1989, fencing off 160 square kilometers (40,000 acres) of forest, meadows, shrub land and lakes. It is surrounded by another 600 square kilometers (150,000 acres) of wilderness.

It is an offshoot of the Northeast Science Station, which he founded and where he has lived for 30 years. Already icebound by October, the park is 40 kilometers (25 miles) inland from the station, accessible only by boat in summer and by snow vehicles after the rivers freeze.

A 32-meter (105-foot) tower inside the park gives constant readings of methane, carbon dioxide and water vapor. The data feeds into a global monitoring system overseen by the U.S. National Oceanic and Atmospheric Administration.

Zimov’s research on permafrost, greenhouse gas emissions and mammoth archaeology has attracted world scientists to his laboratories, a small cluster of cabins and a tiny chapel on a rocky bluff above a channel of the Kolyma River. A 20-bed barge is used for field trips in summer, and a $100,000 hovercraft is on order. Zimov sometimes uses an old Russian tank to bring supplies from the Chinese border, 2,000 kilometers (1,200 miles) away.

Part of the station’s attraction — and deterrence — is its remoteness. It is 6,600 kilometers (4,000 miles) and eight time zones east of Moscow. The nearby town of Chersky, with some 5,000 people, has few amenities, and the nearest city, Yakutsk, is a 4-1/2 flight. Many researchers, particularly Americans, prefer to work in Alaska or northern Canada, which are more accessible.

“Most of the Arctic is in Russia, and yet most of the Arctic research isn’t,” said Max Holmes, of Woods Hole Research Center in Massachusetts, director of the Polaris Project, which has sent undergraduates to the station for the last three summers.

‘What’s $1 million?’
Zimov started the park with a herd of 40 Yakutian horses, a semi-wild breed with a handsomely long mane that is raised by Yakuts and other native people for their meat. Short, sturdy and broad-backed, they survive harsh Siberian winters with the help of a furry hide, thick layers of fat and the ability to paw through a meter (3 feet) of snow to forage.

Of his first herd, Zimov said 15 were killed by wolves and bears, 12 died from eating wild hemlock that grows in the park, and two slipped through the perimeter and made their way back some 1,000 kilometers (600 miles) to their

But he bought more. Now the horses have learned to avoid poisonous plants and to resist predators. Over the last three years, more colts were born and survived than horses lost.

The challenge is to find the right balance between grazers and predators, and how to help his animals get through their first winters.

His workers still give occasional buckets of grain to the horses to supplement their diet with salt. About half the horses come regularly to the cabin where a caretaker stays year-round. The other half are rarely seen except for their tracks.

Zimov also has had problems with the moose that he brought inside his enclosure. Moose still live in small numbers in surrounding forests, and the males jump back and forth over the 6-foot-high fence.

In September he traveled to a nature reserve on Wrangel Island, about five hours by boat across the East Siberia Sea, and brought back six 4-month-old musk oxen. One died a few weeks later. The others are kept in a small enclosure and fed hay until they can fend for themselves.

His objective is to see whether a thriving population of grazing animals will regenerate grasslands that disappeared long ago, which would slow and even halt the accelerating pace of permafrost thaw. So far, he says, the results are encouraging.

Today he has 70 animals in the park. He wants thousands to restock Siberia. To bring 1,000 bison from North America would cost $1 million, Zimov says, a small price to pay.

“If permafrost melts, 100 gigatons of carbon will be released this century,” he said. “What’s $1 million? One regular grant.”

___

AP Television News producer Siobhan Starrs and APTN cameraman Dmitry Kozlov contributed to this story.

Neanderthal bedroom

August 11, 2010
  • An apparent Neanderthal sleeping chamber has just been unearthed within Esquilleu Cave in Cantabria, Spain.
  • The room likely contained grass beds, which served double duty as seats, near a hearth.
  • Other research supports that Neanderthals constructed such functional living spaces within caves and rock shelters.

Anthropologists have unearthed the remains of an apparent Neanderthal cave sleeping chamber, complete with a hearth and nearby grass beds that might have once been covered with animal fur.

Neanderthals inhabited the cozy Late Pleistocene room, located within Esquilleu Cave in Cantabria, Spain, anywhere between 53,000 to 39,000 years ago, according to a Journal of Archaeological Science paper concerning the discovery.

Living the ultimate clean and literally green lifestyle, the Neanderthals appear to have constructed new beds out of grass every so often, using the old bedding material to help fuel the hearth.

“It is possible that the Neanderthals renewed the bedding each time they visited the cave,” lead author Dan Cabanes told Discovery News.

Cabanes, a researcher at the Weizmann Institute of Science’s Kimmel Center for Archaeological Research, added that these hearth-side beds also likely served as sitting areas during waking hours for the Neanderthals.

“In some way, they were used to make the area near the hearths more comfortable,” he said, mentioning that artifacts collected from various other Neanderthal sites suggest the inhabitants prepared stone tools, cooked, ate and snoozed near warming fires.

For this study, Cabanes and his team collected sediment samples from the Spanish cave. Detailed analysis of the samples allowed the scientists to reconstruct what materials were once present in certain parts of the cave at particular times.

The bedding material was identified based on the presence and arrangement of multiple phytoliths from grasses near the hearth area. Phytoliths are tiny fossilized particles formed of mineral matter by a once-living plant.

There was no evidence of plants growing, soil developing or animal transport of phytoliths via dung, so the scientists believe the only plausible explanation is that Neanderthals gathered the grass and placed it in this room of the cave.

While the hearth contained some grass phytoliths, most belonged to wood and bark, “indicating that this material was the main type of fuel used,” according to the researchers. Some animal bones were also tossed into the hearth, perhaps to dispose of them after dinner and/or for use as extra fire fuel.

Evidence is building that Neanderthals in other locations constructed such functional living spaces within caves and rock shelters.

Earlier this year, Josep Vallverdu of the Catalan Institute of Human Paleoecology and Social Evolution and his team identified a “sleeping activity area” at Spain’s Abric Romani rock shelter.

Similar to the Esquilleu Cave finds, Vallverdu and his colleagues discovered the remains of hearths spaced enough for seating and sleeping areas.

“This set of combustion activity areas suggests analogy with sleeping and resting activity areas of modern foragers,” Vallverdu and his team wrote. They added that such information can allow anthropologists to estimate the size of Neanderthal populations, in addition to learning more about how they lived.

The big question, according to Cabanes, is how such a resourceful species went extinct.

“In my opinion, Neanderthal extinction may have been caused by several factors working at the same time,” he said. “Environmental changes, a slightly different social organization, a different rate of reproduction, spread of diseases, direct competition for resources and many other factors may have played an important role in the fate of Neanderthals.”

He and other researchers have also not ruled out that Neanderthals were simply absorbed into the modern human population.

Cabanes is hopeful that future analysis of phytoliths, as well as other less obvious clues that have often been overlooked by scientists in the past, may shed additional light on the still-mysterious Neanderthals.

Original article here