Their investigations have revealed that, 300,000 years before the emergence of anatomically modern humans, prehistoric Britons were selecting their domestic real estate with tremendous care.
Nutritional and security considerations appear to have been the main criteria, according to the new research carried out by scholars at the University of Southampton and Queens University, Belfast.
A survey of 25 major British and north-west French sites dating from 500,000 to 200,000 years ago has revealed that early humans – members of the now long-extinct species Homo heidelbergensis – predominantly chose to live on islands in the flood plains of major rivers. They avoided forests and hills – and the upper and middle reaches of river systems, and their estuaries.
It is the first ever detailed interdisciplinary investigation into early humanity’s home location preferences. The degree to which they preferred to choose just one specific type of location has surprised the archaeologists.
“What has amazed us is the degree to which they appear to have deliberately and consistently sought out the same type of ideal location for establishing their major camps.”, said the research project’s co-director, archaeologist and geographer Professor Tony Brown of the University of Southampton.
The reasons for choosing flood plain areas and avoiding other locations were complex – but help to explain why Homo heidelbergensis was so successful for so long.
The flood plain allowed them to develop a virtually perfect ‘Palaeolithic diet’ in which protein consumption was balanced by carbohydrate and fat intake. This was because, more than any other ecological zone, river flood plains produced unusually rich grass which attracted larger numbers of big herbivores (especially wild horses). It also attracted substantial numbers of other animals – including deer, rhino and beavers, as well as large flocks of water birds. What’s more, the flood plain generated vast numbers of water plants with nutritional edible roots.
Horse and other animals yielded fat and protein. Bone marrow in particular was rich in fat, while water bird eggs were high in protein. Reed and bull rush roots were rich in carbohydrates – and leafy vegetables and water cress, particularly common on flood plains, would have helped provide folic acid, crucial for healthy child-bearing.
Flood plains also provided raw material for making tools and lighting fires. River gravels were rich in flint nodules which could be transformed into axes, cutting tools and scrapers. Reeds themselves may have been useful for making things, although no evidence of their use at this period has yet been found. Beaver dams, extremely common on flood plains, were almost certainly a key source of wood – from trees already conveniently cut down by the animals themselves. What’s more, the use of beaver pelts (warmer than most other animal skins) as garments would have certainly enabled the human population to survive low winter night-time temperatures.
Flood plains, with their shallow running water and plentiful game, were also the ideal places to catch eels (particularly rich in protein and fat), potentially by using horses’ heads as bait - the subject of ongoing archaeological research by Professor Brown. Hungry eels like burrowing into the brains of large dead herbivores – and by depositing a horse’s head in a shallow channel and then retrieving it a few days later, these prehistoric Brits would have been able to easily catch up to a half dozen eels, said Professor Brown. Horse, beaver, rhinoceros, deer and eel bones as well as beaver-felled timber and evidence of fire-use have been found on Homo heidelbergensis occupation sites.
Although flood plains were economically attractive to early humans, they were also very dangerous because, just as the zone’s rich fat and protein resources attracted humans, they also attracted big cats like lion and hyaena.
To avoid these predators, Homo heidelbergensis only favoured particular parts of flood plains – namely the islands formed by a river’s intersecting channels. Big cats do not like water, let alone swimming, so flood plain islands became the ‘des res’ homes of choice for these early Brits.
The nutritional resources around their tiny island refuges would have allowed them to achieve very well balanced diets – and extremely good levels of health, say medical researchers.
“Looking at the nutritional resources available to these populations, we think that they would not have suffered from much heart disease, cancer or most viral diseases”, said Professor Brown.
“We think that most of them would probably have ultimately died as a result of hunting accidents, extreme weather conditions and consequent food shortages, and as a result of predation by big cats or by other humans,” said the project’s lead archaeologist Dr. Laura Basell of Queen’s University, Belfast.
During the 300,000 year period of Homo heidelbergensis’ dominance in Europe, they had to retreat south on many occasions when glacial or other particularly cold periods set in. In total, they therefore probably lived in Britain and north-west France for only 10-15% of that period, at maximum. In aggregate, in that area over those millennia, there were probably only a few hundred or at most a few thousand individuals at any one time – and skeletal scraps of less than ten of them have ever been found there. Only 25 major occupation sites are known in the area. Yet, despite their tiny numbers they succeeded in surviving for at least 3000 centuries and probably contributed, via Neanderthal Man to our modern human gene pool.
We got a dusting of snow again yesterday, so we're over our share for the winter. But those of us shivering in the cold front across the U.S. should note that things could be a lot worse. Or at least a lot colder.
Ted Scambos, lead scientist at the National Snow and Ice Data Center (NSIDC), and his team found temperatures from −92 to −94 degrees Celsius (−134 to −137 degrees Fahrenheit) in a 1,000-kilometer long swath on the highest section of the East Antarctic ice divide.
The measurements were made between 2003 and 2013 by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on board NASA's Aqua satellite and during the 2013 Southern Hemisphere winter by Landsat 8, a new satellite launched early this year by NASA and the U.S. Geological Survey.
"I've never been in conditions that cold and I hope I never am," Scambos said. "I am told that every breath is painful and you have to be extremely careful not to freeze part of your throat or lungs when inhaling."
The record temperatures are several degrees colder than the previous record of −89.2 degrees Celsius (−128.6 degrees Fahrenheit) measured on July 21, 1983 at the Vostok Research Station in East Antarctica. They are far colder than the lowest recorded temperature in the United States, measured at −62 degrees Celsius (−79.6 degrees Fahrenheit) in Alaska, in northern Asia at -68 degrees Celsius (−90.4 degrees Fahrenheit), or even at the summit of the Greenland Ice Sheet at -75 degrees Celsius (−103 degrees Fahrenheit).
Scambos said the record temperatures were found in several 5 by 10 kilometer (3 by 6 mile) pockets where the topography forms small hollows of a few meters deep (2 to 4 meters, or 6 to 13 feet). These hollows are present just off the ice ridge that runs between Dome Argus and Dome Fuji -- the ice dome summits of the East Antarctic Ice Sheet. Antarctic bases sit on each of the sites and are generally not occupied during Antarctic winters.
Under clear winter skies in these areas, cold air forms near the snow surface. Because the cold air is denser than the air above it, it begins to move downhill. The air collects in the nearby hollows and chills still further, if conditions are favorable.
"The record-breaking conditions seem to happen when a wind pattern or an atmospheric pressure gradient tries to move the air back uphill, pushing against the air that was sliding down," Scambos said. "This allows the air in the low hollows to remain there longer and cool even further under the clear, extremely dry sky conditions," Scambos said. "When the cold air lingers in these pockets it reaches ultra-low temperatures."
"Any gardener knows that clear skies and dry air in spring or winter lead to the coldest temperatures at night," Scambos said. "The thing is, here in the United States and most of Canada, we don't get a night that lasts three or four or six months long for things to really chill down under extended clear sky conditions."
Scambos and his team spotted the record low temperatures while working on a related study on unusual cracks on East Antarctica's ice surface that he suspects are several hundred years old.
"The cracks are probably thermal cracks -- the temperature gets so low in winter that the upper layer of the snow actually shrinks to the point that the surface cracks in order to accommodate the cold and the reduction in volume," Scambos said. "That led us to wonder what the temperature range was. So, we started hunting for the coldest places using data from three satellite sensors."
More than 30 years of data from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA Polar Orbiting Environmental Satellite (POES) series gave Scambos a good perspective on what the pattern of low temperatures looked like across Antarctica.
"Landsat 8 is still a new sensor, but preliminary work shows its ability to map the cold pockets in detail," Scambos said. "It's showing how even small hummocks stick up through the cold air."
Scambos suspected they would find one area that got extremely cold. Instead they found a large strip at high altitude where several spots regularly reach record low temperatures. Furthermore, dozens of these extremely cold areas reached about the same minimum temperatures of −92 to −94 degrees Celsius (−134 to −137 degrees Fahrenheit) on most years.
"This is like saying that on the coldest day of the year a whole strip of land from International Falls, Minnesota to Duluth, Minnesota to Great Falls, Montana reached the exact same temperature, and more than once," Scambos said. "And that's a little odd."
The scientists suspect that a layer in the atmosphere above the ice plateau reaches a certain minimum temperature and is preventing the ice plateau's surface from getting any colder.
"There seems to be a physical limit to how cold it can get in this high plateau area and how much heat can escape," Scambos said. Although an extremely cold place, Antarctica's surface radiates heat or energy out into space, especially when the atmosphere is dry and free of clouds.
"The levels of carbon dioxide, nitrogen oxide, traces of water vapor and other gases in the air may impose a more or less uniform limit on how much heat can radiate from the surface," Scambos said.
Scambos and his team will continue to refine their map of Earth's coldest places using Landsat 8 data. "It's a remarkable satellite and we've repeatedly been impressed with how well it works, not just for mapping temperature but for mapping crops and forests and glaciers all over the world," Scambos said.
"The uses for Landsat 8 data are broad and diverse," said James Irons, Landsat 8 project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "And Scambos' work is an example of some of the intriguing science that can be done using Landsat 8."
In the longer term, Scambos and his team will try to design weather stations and set them up in the area where the record temperatures occur to confirm the data from Landsat 8 and MODIS. Currently, most of the automated weather stations in the vicinity do not work properly in the dead of winter.
"The research bases there don't have people that stay through the winter to make temperature measurements," Scambos said. "We will need to investigate electronics that can survive those temperatures."