Wednesday, July 14, 2010

MORE ON EARLY BRITS -- DATING DATA

The earliest humans moved to Europe from Africa around 1.8 million years ago. But because they were adapted to a warmer climate, archaeologists have so far believed that they didn't get as far north as Happisburgh - a comparatively cold, Inhospitable place.

Other studies at archaeological sites in Germany and France have shown signs of Human activity in the north around the same time, but the dating of these sites is perhaps not as well established as that at Happisburgh.

The dating of the Happisburgh site is based on a combination of methods. The artifacts were entombed in sediment that records a reverse in the polarity of the Earth's magnetic field - the north and south poles switching places -at the time that they were laid down. The last polarity reversal is known to have been 780,000 years ago, making it probable that the Happisburgh artifacts are at least that old.

But smaller, fleeting polarity reversals also happen, which can complicate such palaeomagnetic dating. So the team backed up these results by looking at plant and animal fossils found in the sediment, such as the 'southern mammoth' (Mammuthus meridionalis).

The known overlap time between the disappearance of some species and the appearance of others narrows down the date bracket. The researchers' analysis, which also includes geological evidence from the ancient River Thames, indicates that the early humans occupied Happisburgh during the later part of a warm interglacial period, around 840,000 or 950,000 years ago.

The team used beetle and plant fossils from the site - which, unsurprisingly for a former floodplain, is extraordinarily rich in fossil species - to estimate the climate in Happisburgh at the time. The climate is thought to have been similar to that of southern Scandinavia today.

"The case is not absolutely watertight, but it is pretty good - the collective evidence strongly suggests that this is the oldest northern European site occupied by humans," says Andrew P. Roberts, a palaeomagnetist at the Australian National University in Canberra.

"We had accepted that there were people in the area 700,000 years ago, and we could explain it by the fact that it was really warm at that time," says Chris Stringer, a palaeoanthropologist from the Natural History Museum in London and a co-author of the study.

"The plants and animals in Britain at this point were the same as the ones in Spain - so they could have come up briefly under warm, peak temperatures, but were thought to have died out very quickly when it got cold," he says.

It is not known exactly how the early humans adapted to the cold climate - whether they made fires, built shelters or used clothing, says Stringer. And because there are no human remains at the site - they probably just visited it to hunt or scavenge - it is hard to make any predictions about the population size or organization of these people. "... but we speculate that it could be the extinct species Homo antecessor - the 'Pioneer Man' - as it is the only species known in Europe at that time."

0 Comments:

Post a Comment

Links to this post:

Create a Link

<< Home