800,000-year-old footprints found in Norfolk, Britain; oldest ancient human footprints found outside Africa

Footprints left by ancient humans 800,000 years ago have been found in Britain, the earliest evidence of such markings outside Africa.

Researchers discovered the footprints, which were left by both adults and children, in ancient estuary mud at Happisburgh in Norfolk in eastern England.

The only older footprints found so far are at Laetoli in Tanzania, at about 3.5 million years old, and at Ileret and Koobi Fora in Kenya at about 1.5 million years, researchers said.

"This is an extraordinarily rare discovery," Nick Ashton of the British Museum, who led the research team, said.

The find came at an archaeological site that has yielded several previous discoveries of stone tools and fossil bones, including mammoth remains.

The researchers found the prints at low tide when waves washed away much of the beach sand to expose the silt below.

"At first we weren't sure what we were seeing but as we removed any remaining beach sand and sponged off the seawater, it was clear that the hollows resembled prints, perhaps human footprints, and that we needed to record the surface as quickly as possible before the sea eroded it away," Dr Ashton said.

The group of early humans that left the footprints appeared to have consisted of at least one male and several smaller people believed to be females and youngsters, the researchers said.

"They are clearly a family group rather than a hunting party," Dr Ashton said.

Footprint owners estimated to be about as tall as modern humans

Analysis of the prints found that they were from a "range of adult and juvenile foot sizes" equating to modern shoe sizes of up to British 7 or 8.

The researchers estimated that the height of the ancient humans who left the prints varied from about 0.9 metres to over 1.7 metres, not far off the height of modern humans.

They were dated at 800,000 years old partly on the basis of the site's geological position beneath glacial deposits, but also because the fossils there come from now-extinct types of mammoth and horse and early forms of vole that were alive at that time.

But the question of exactly what type of ancient humans left their footprints in the sands of time remains a mystery.

They may have been related to people of a similar period in history found in Atapuerca in Spain, assigned to the species Homo antecessor, or Pioneer Man, said Chris Stringer of the Natural History Museum.

"These people were of a similar height to ourselves and were fully bipedal," he said.
Homo antecessor apparently became extinct in Europe 600,000 years ago and was perhaps replaced by the species Homo heidelbergensis, followed by the Neanderthals from about 400,000 years ago, and eventually modern humans some 40,000 years ago.

AFP

Fossil fish re-defines origins of walking

Color illustration of Tiktaalik swimming and walking in water. (Source: Kalliopi Monoyios/University of Chicago)

Jennifer Viegas
Discovery News

Fossils of a creature that looked part-fish and part-limbed animal, the precursor to walking land animals, were recently found in northern Canada, according to a new study.

The beastie, Tiktaalik roseae, represents the best-known transitional species between fish and land-dwelling animals, according to researchers.

The fossil, described in this week's edition of Proceedings of the National Academy of Sciences, lived 375 million years ago.

"Tiktaalik was a combination of primitive and advanced features," says co-author Edward Daeschler, Associate Curator of Vertebrate Zoology at the Academy of Natural Sciences of Drexel University.

While classified as a fish, Tiktaalik looked like a cross between a fish and a crocodile. It could grow to nearly 3 metres in length, and likely spent its days hunting in shallow freshwater environments. It had gills, scales and fins, but also had features associated with terrestrial animals. These included a mobile neck, a robust ribcage and primitive lungs.

Of most interest to the researchers, its large forefins had shoulders, elbows and partial wrists, which allowed it to support itself on ground.

The presence of these limb-like features challenges the theory that such mobile hind appendages developed only after species transitioned to life on land.

"Previous theories, based on the best available data, propose that a shift occurred from 'front-wheel drive' locomotion in fish to more of a 'four-wheel drive' in tetrapods (four-footed animals)," says co-author Neil Shubin, who is a professor of Anatomy at the University of Chicago. "But it looks like this shift actually began to happen in fish, not in limbed animals."

Some modern fish can walk, such as the African lungfish. Lungfish often look like they are slithering, more than walking, but if you see them in an aquarium, their little limbs are evident, and they do walk around.

It's likely that Tiktaalik did the same, with its later relatives walking completely out of water and onto land, where they eventually evolved into land animals.

"Regardless of the gait Tiktaalik used, it's clear that the emphasis on hind appendages and pelvic-propelled locomotion is a trend that began in fish, and was later exaggerated during the origin of tetrapods," Shubin says.

Old trees 'star players' in carbon uptake

The researchers found that old-growth forests shouldn't be left out of the carbon trading equation (Source: Markku Saarinen)

Anna Salleh
ABC

The largest trees in the world grow more quickly, and thus take up more carbon dioxide, than younger, smaller trees, say researchers.

The findings, published today in the journal Nature add to our understanding of how tree growth rates change over time.

"We found that tree growth rates increased continuously with tree size so, on average, the biggest trees in the forest are the fastest growing trees in the forest in terms of mass", says lead author, Dr Nate Stephenson, a research ecologist with the US Geological Survey.

Stephenson says the majority view to date has been that trees have a similar growth pattern to humans - starting off slowly, getting a growth spurt in adolescence, and then slowing down again as they get older.

But, he says, a number of scientists have argued trees continue to grow faster and faster the larger they get.

"It turns out that that's the case for the large majority of tree species."

Stephenson says the latest evidence comes from the largest study to date on the growth rate of trees across the globe.

He and colleagues measured the change in diameter of 650,000 individual trees from 403 species in both temperate and tropical areas.

"On average, every year trees put on more mass than they put on the year before," says Stephenson.
"Old trees are the ones putting on the most bulk in old forests. They are the star players."

"We think it strongly supports the minority view about tree growth rate."

Paradox

Stephenson says the majority view has been supported by previous research that, among other things, has shown as a tree gets older its growth rate per leaf decreases.

"A given leaf on a big tall eucalyptus tree photosynthesises less than one on a smaller tree," says Stephenson.

Studies have also found that, overall, older forest stands grow at a slower rate compared to younger stands.

But, says Stephenson, such measurements have been made at the scale of individual leaves and at the scale of forest stands.

"Most people have just inferred that the same has to be happening at the scale of the individual tree but it's not," he says, adding the latest findings are not incompatible with earlier observations at the leaf and forest stand scales.

"Our observation is compatible with those other observations but it just may not be intuitive," says Stephenson.

He says even though productivity per leaf in older trees decreases, this is counteracted by the fact that these trees have a lot more leaves that collectively result in the tree's faster growth rate.

"A tree that is a metre in diameter has, on average, 100 times as much leave mass as one that is only 10 centimetres in diameter."

At the other end of the scale, more young trees than old trees are packed into the same area of forest, and so this explains why collectively forest stands consisting of young trees put on more mass than those consisting of fewer old trees.

Implications

Stephenson says the findings will have implications for our understanding the role of trees in the carbon cycle and greenhouse gas concentrations in the atmosphere.

"We already know that the biggest trees are the most important ones to preserve for carbon sequestration because they already hold so much carbon in them. It think the finding adds a little more support to the idea we need to protect these big trees," he says.

"Not only do they hold the most carbon but they are putting on a huge amount every single year."

Mars once had fresh water on surface

Data from the Opportunity rover on the rim of Endeavour crater indicates an asteroid impact changed Martian water forever (Source: NASA)

Stuart Gary
ABC

The surface of Mars once flowed with water fresh enough to sustain life, according to data collected by two of NASA's Martian rovers.

The findings, published in the journal Science, suggest freshwater rivers and streams once existed in the Meridiani Plains region near the Martian equator, 3.8 billion years ago.

But all that changed when a huge asteroid impact turned the fresh water into a highly acidic soup.
"All the evidence we have indicates the local Martian water was like spring water that you could drink," according CSIRO's Dr Paulo de Souza, a scientist with NASA's Mars exploration rover program.

"It would have been hospitable to any microbial life that may have existed at the time."

But, according to de Souza, the asteroid impact exposed volcanic rocks that were then subjected to chemical weathering, resulting in salts dissolving into the water.

"As time passed with this and other impacts in the region, a more acidic environment developed, with the water becoming as strong as vinegar," he says.

De Souza and colleagues can determine the chemistry of the water based on the different types of minerals formed in the sediments left behind.

"We not only know that there was water on Mars, but we can see how that water changed over time forming different minerals," says de Souza.

"Looking at those minerals is just like looking at a book of history, with the story of the planet recorded in those minerals."

Eyes in the sky

The researchers sent Opportunity to investigate part of the Endeavour Crater rim where NASA's Mars Reconnaissance Orbitor spacecraft detected iron- and aluminium-rich clay minerals.

The rover sampled a geological feature called the Matijevic formation, a grouping of fine-grained, layered rocks enriched with clay minerals.

Analysis of the spherules, veins and fractures in these mineral rich rocks indicates the Matijevic formation predates the impact event that formed Endeavour crater.

They represent the oldest Martian rocks, as well as the earliest evidence of water activity, so far encountered by Opportunity.

The authors found these older rocks were formed in conditions that would have been favourable to life or prebiotic chemistry.

"The formation on the rim of this crater had evidence of a more suitable environment for life to form and evolve in fresh water," says de Souza.

"We haven't actually found the fresh water, that would have been there four billion years ago, but what we saw were the minerals that could only be formed if we have fresh water present."

Meanwhile, the younger rocks sitting on top of the formation, which are believed to date from after the impact event, contain signatures for super-salty, highly-acidic water, which would have made life tough for even the hardiest extremophile microorganisms.

Ongoing mission

NASA's twin six-wheeled Mars exploration rovers, Spirit and Opportunity, landed on opposite sides of the red planet in January 2004, on what was expected to be a 90-day mission to search for geological evidence of past water.

Spirit's mission ended in March 2010, however its twin Opportunity is still exploring the red planet, ten years after landing.

"We've travelled over 38 kilometres across the surface of Mars ... Opportunity has just come out of another Martian winter," says de Souza.

"And a wind storm the other day has cleared the dust off the rover's solar panels."

According to de Souza, that means despite a decade of service, there's lots more science that can still be done.

'Dark Matter Disc' Discovered Over The Equator?

A disc of dark matter might have just been found hanging over the Equator of the Earth. But don't panic.

The startling claim has been made by a scientist examining why the Earth appears to be slightly heavier than previously thought.

Dark matter is the almost-theoretical substance which helps explain why there is nowhere near enough visible matter in the universe to account for the way it's developed since the Big Bang.

But while most models of the universe suggest dark matter is abundant, experiments have tried (and so far mostly failed) to find direct evidence of it.

Now one scientist says it might have been hanging above our heads the entire time.

Ben Harris, from the University of Texas, said at the American Geophysical Union that GPS data implies the Earth is heavier than it 'should' be.

The difference between the number he's calculated, and that taken as read by the International Astronomical Union, could be caused by the presence of nearby Dark Matter, he thinks.

In his study, Harris used data from the European Galileo, U.S., GPS, GLONASS and Russian satellite groups, and measured the weight of the Earth. His result is 0.005-0.008 percent bigger than current estimates. A disc of dark matter over the equator could account for the difference, he said - being picked up by satellites overhead while being missed by regular methods used to weigh our planet.
This disc would be 191 kilometres thick and 70,000 km wide, he suggests.

However, we have to add a hefty load of caveats here. First, there are potential flaws with the methodology. New Scientist points out that the study doesn't account for subtle changes in the orbit of satellites caused by relativity and the gravity of the sun and moon. It's also pretty much conjecture, even if the data is accurate - there is no direct evidence of dark matter above our Earth, and much more study would be needed to get it.

On the other hand, if 80% of our universe really is dark matter, it wouldn't be crazy to think there would be some nearby. If only it wasn't so - well - dark, we might just be able to see it in plain sight very close to home indeed.

Weather at Tolkien's Middle Earth mapped

Alyssa Danigelis
Discovery News

 J.R.R. Tolkien created a masterfully detailed world in his classic Lord of the Rings trilogy, right down to the topography and languages.

Now a British climate researcher has plugged Tolkien's maps into a supercomputer and predicted weather patterns for Middle Earth.

Dan Lunt, a scientist at the University of Bristol who specialises in climate modelling research, decided to put the Advanced Computing Research Center's supercomputer to a dorktastic test.
Lunt took Tolkien's detailed maps of Middle Earth showing continents and mountains, and essentially "scanned" them into the supercomputer, the Guardian reported. Then he ran the numbers to get a 70-year model.

In a mock research paper published under the name Radagast the Brown, Lunt details climate details and weather predictions for Tolkien's fictional world. He compared the climate surrounding Mount Doom in the heart of Mordor to that of Los Angeles and western Texas. He argues that those areas have dry, hot climates with little vegetation and therefore match the conditions in fictional Mordor.

Lunt also concludes that the Shire's climate would have been close to that of real UK "shires" Lincolnshire or Leicestershire. Other insights include: "The climate of Middle Earth has a similar distribution to that of Western Europe and North Africa" and "Ships sailing for the Undying Lands in the West set off from the Grey Havens due to the prevailing winds in that region."

Dwarfs and elves can read the mock paper, too.

Lunt told the Guardian that the exercise does have a serious side. Our climate models have become incredibly powerful, bringing together our understanding of science, fluid mechanics, cloud convection, sun radiation, biology and other factors.

"And because of that, they're not just tuned for the modern Earth, they can simulate any climate," Lunt said. Including ones that only exist in the future.

Climate change

The climate of England has been characterized as generally damp and relatively sunless but, as every native knows, the weather is as various as the land. In the south-east the summers are warm and the winters are cold, while in the north-west the winters are mild and the summers are cool. In the north-west four and a half hours of sunshine light up an average July day, while on the south coast six and a half hours can be anticipated; the western seaboard attracts 40 per cent more rainfall than the eastern. The predominant wind of autumn and of winter is from the south-west; in the spring it is the east. This was the weather that created a land of damp forests of oak and ash, of marshes and heath wrapped in mist. In the north and the west lay the moors and the mountains, where the soil was thin. This was the land of pasture rather than of crops, and the local farmers grew only as much corn as they needed for themselves. The south and east were the lowlands, with gradual undulations in the rich earth; this was ground as fit for corn as for cattle. It was the territory of ‘mixed farming’.

In the history of England these patterns of climate are of the utmost importance; if there is a drop in temperature of two degrees, as in the period from 500 to 300 BC, the prospect of adequate harvests in the north is noticeably curtailed. A difference of one degree made a failure of the harvest seven times more likely. In this period, then, we see the abandonment of upland farms and settlements. The southern land was warmer, and more stable; it was the home of the plentiful harvest, and the general dampness meant that crops could even be grown on lighter soils where sand and chalk prevailed. It is a general truth, therefore, that in the south-east the land was devoted to wheat whereas in the north it was given over to oats. But important regional variations were still found. Oxfordshire and north-east Suffolk grew wheat, whereas Norfolk grew more rye. Oats were the main crop in Lancashire, while rye was dominant in Yorkshire. Wheat and barley shared the ascendancy in Wiltshire whereas, in the rainier country west of that shire, barley predominated.

The people of the south were wealthier if not healthier than their counterparts in the north. So the climate is active in human history. It may also be that the drier east creates human communities different from those of the rainier west; marked contrasts of social systems in the first millennium BC are in fact evident, with small centres of lordly power in the west and more scattered settlements in the east. The isolated farmhouse and the small hamlet were characteristic of the north and west; the village and the manorial system of common cultivation were more usual in the south and east.

At the time of the Roman occupation the weather was warmer than at any period in subsequent history, but this was succeeded by colder and wetter conditions by the end of the fourth century. For ten years, beginning in AD 536, there was a very low level of sunlight; this would have been a time of dearth and famine, hitherto unrecorded. It might also be noted that Alfred was credited with the invention of a clock that allowed him to tell the time when the prevailing fogs obscured the sun.

The climate of 1009 and 1010 was recorded by a Benedictine monk, Byrhtferth, who dwelled in East Anglia; the winter lasted from 7 November to 6 February, being cold and moist; the spring from 7 February to 8 May was moist and hot; summer from 9 May to 6 August was hot and dry; autumn from 7 August to 6 November was dry and cold. He was only one of the clerics who kept a detailed record of the conditions of the weather.

The eleventh and twelve centuries were in fact warmer than those immediately preceding them, but a deterioration of climate took place in the thirteenth and fourteenth centuries; the annals of these later centuries also mention the increasing incidence of floods and droughts, suggesting greater instability. Hard frosts lasted into spring, and violent gales brought down the trees of the forests. The Thames froze in the winter of 1309–10, and the years 1315 and 1316 were marked by endless rain. The harvests failed, and the dead were buried in common graves. It was a time of epidemic disease. Crime rates rose proportionately.

The increase of rainfall, in the fourteenth century, is marked by the construction of drainage ditches and house platforms; church floors were raised, and the lower halves of some villages were deserted. The carpenter in Chaucer’s ‘The Miller’s Tale’ reveals an obsessive fear of another Great Flood covering the earth. The extraordinary wind of 14 January 1362 was widely believed to be a harbinger of the Day of Judgment. In the medieval period the weather is the lord of all. Outer weather creates inner weather. It would be possible to write the history of England as the history of the English climate.