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Neanderthal Sex

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Ancient human bone helps date our first sex with Neanderthals

Oldest genome sequence of a modern human suggests Homo sapiens first bred with Neanderthals 50,000-60,000 years ago

Neanderthal DNA specialist Svante Pääbo examines the anatomically modern human femur, found near Ust’-Ishim in western Siberia. Photograph: Bence Viola/MPI EVA

An ancient leg bone found by chance on the bank of a Siberian river has helped scientists work out when early humans interbred with our extinct cousins, the Neanderthals.

A local ivory carver spotted the bone sticking out of sediments while fossil hunting in 2008 along the Irtysh river near the settlement of Ust’-Ishim in western Siberia. The bone was later identified as a human femur, but researchers have learned little else about the remains until now.

The importance of the find became clear when a team led by Svante Pääbo and Janet Kelso at the Max Planck Institute for Evolutionary Anthropology in Leipzig ran a series of tests on the fragile material.

Radiocarbon dating of pieces of the leg bone put the remains at around 45,000 years old. The team went on to extract DNA from the bone, which allowed them to reconstruct the oldest modern human genome ever.

The genetic material showed that the thigh bone belonged to a man who carried about 2% Neanderthal DNA, a similar amount to people from Europe and Asia today. The presence of Neanderthal DNA meant that interbreeding between them and modern humans must have taken place at least 45,000 years ago.

But amid the DNA were more clues to when humans and Neanderthals reproduced. Strands of Neanderthal DNA found in modern humans can act like a biological clock, because they are fragmented more and more with each generation since interbreeding happened. The strands of Neanderthal DNA in the Siberian man were on average three times longer than those seen in people alive today. Working backwards, the scientists calculate that Neanderthals contributed to the man’s genetic ancestry somewhere between 7,000 and 13,000 years before he lived.

The findings, published in the journal Nature, suggest that humans and Neanderthals had reproductive sex around 50,000 to 60,000 years ago, though other couplings might well have happened later. Until now, estimates for interbreeding have varied enormously, ranging from 37,000 to 86,000 years ago.

“What we think may be the case is that the ancestors of the Ust’-Ishim man met and interbred with Neanderthals during the initial early admixture event that is shared by all non-Africans at between 50,000 and 60,000 years ago, and perhaps somewhere in the middle East,” Kelso told the Guardian.

But a small number of fragments of Neanderthal DNA in the man’s genome were longer than expected given how many generations had passed. Those might be evidence of his ancestors breeding with Neanderthals closer to the time he was born.

“Everyone outside Africa has about same amount of Neanderthal DNA. It seems to be something early on where one really mixed with Neanderthals in a serious way,” said Pääbo. “Since that happened I wouldn’t be surprised if, now and again, one did it here and there later on too.”

Prior to the latest study, the oldest modern human genome came from the 24,000-year-old remains of a boy buried at Mal’ta near Lake Baikal in easterbn Siberia.

Chris Stringer, head of human origins at the Natural History Museum in London, said the ancient DNA from the Siberian man sheds fresh light on the story of early human migrations out of Africa. In the 1920s and 30s, researchers found 100,000-year-old skeletons of modern humans in caves in Israel. The remains may have belonged to a group of humans that left Africa and ultimately went on to colonise southern Asia, Australia and New Guinea. But an alternative explanation is that they were from a migration that failed to go much further. According to that view, the more successful dispersal of humans out of Africa happened much later, around 60,000 years ago.

The latest findings suggest that the ancestors of modern Australians, who carry a similar amount of Neanderthal DNA to Europeans and Asians, are unlikely to have picked up their own Neanderthal DNA before 60,000 years ago. “The ancestors of Australasians must have been part of a late, rather than early, dispersal through Neanderthal territory,” Stringer said.

“While it is still possible that modern humans did traverse southern Asia before 60,000 years ago, those groups could not have made a significant contribution to the surviving modern populations outside of Africa, which contain evidence of interbreeding with Neanderthals,” he added.

Source: TheGuardian

Explain this…

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150,000-Year-Old Pipes Baffle Scientists in China: Out of Place in Time?

A file photo of a pipe, and a view of Qinghai Lake in China, near which mysterious iron pipes were found. (NASA; Pipe image via Shutterstock*)

The universe is full of mysteries that challenge our current knowledge.

In a mysterious pyramid in China’s Qinghai Province near Mount Baigong are three caves filled with pipes leading to a nearby salt-water lake. There are also pipes under the lake bed and on the shore. The iron pipes range in size, with some smaller than a toothpick. The strangest part is that they may be about 150,000 years old.

Dating done by the Beijing Institute of Geology determined these iron pipes were smelted about 150,000 years ago, if they were indeed made by humans, according to Brian Dunning of Skeptoid.com.

And if they were made by humans, history as it is commonly viewed would have to be reevaluated.

The dating was done using thermoluminescence, a technique that determines how long ago crystalline mineral was exposed to sunlight or heated. Humans are only thought to have inhabited the region for the past 30,000 years. Even within the known history of the area, the only humans to inhabit the region were nomads whose lifestyle would not leave any such structures behind.

Source: EpochTimes Read more

Chimps are making monkeys out of us

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Extraordinary research from Japan shows that chimpanzees are way ahead of humans in complex memory tests

Professor Tetsuro Matsuzawa plays with chimpanzee Ai at the Primate Research Institute of Kyoto University. Photograph: Justin McCurry

Tetsuro Matsuzawa begins his working day, conventionally enough, in front of a computer. He taps in a few commands, takes a seat and waits. Within minutes, the calm of his basement laboratory is pierced by the sound of excitable primates.

On cue, two chimpanzees appear through an opening in the ceiling, flash a look of recognition at Matsuzawa, and then aim an inquisitive stare at his unfamiliar companion from the Observer.

Matsuzawa feeds them a spoonful of honey each and wipes their hands and fingers – a near-daily ritual meant to reward them for arriving on time, and to encourage them to show up again the following morning.

After all, Ai, a 36-year-old chimpanzee, and her 13-year-old son, Ayumu, are free to stay in their nearby home, a re-creation of a west African rainforest they share with 12 other chimps. That they are such willing participants in Matsuzawa’s experiment is a tribute to the bond that has built up between the professor and the chimps during many years of research.

Over the course of more than three decades, Matsuzawa, a professor at Kyoto University’s Primate Research Institute in Inuyama, a historic town in central Japan, has gained unprecedented insights into the workings of the primate mind, and by extension, our own.

In a landmark test of short-term memory conducted in public in 2007, Ayumu demonstrated astonishing powers of recall, easily beating his human competitors, who had been in training for months.

The strength of Ayumu’s cognitive functions surprised even Matsuzawa, who has studied the mental dexterity of chimps for 36 years. He makes long annual visits to Bossou in south-eastern Guinea, where he witnesses chimps display in the wild the same powers of recognition and recall that Ayumu and other young chimps demonstrate on his computer screens.

“We’ve concluded through the cognitive tests that chimps have extraordinary memories,” Matsuzawa says. “They can grasp things at a glance. As a human, you can do things to improve your memory, but you will never be a match for Ayumu.”

The results stunned observers. In the tests, Ai and Ayumu, and two other pairs of a mother and offspring, were shown the numerals 1 to 9 spread randomly across a computer screen.

Their task was to touch the numbers in ascending order. To complicate matters, the game was altered so that as soon as the chimps touched the digit 1, the remaining eight were immediately masked by white squares. To complete the exercise, they had to remember the location of each concealed number and, again, touch them in the correct order.

In an even harder version, five numbers appeared on the screen before turning into white squares. The animals and their human counterparts displayed the same degree of accuracy – about 80% – when the numbers remained visible for seven tenths of a second. But when the time was reduced to four tenths of a second, and then just two tenths, Ayumu maintained the same level of accuracy, while his mother and the human volunteers floundered.

Given that humans share 98.8% of their DNA with chimpanzees, why do the latter have such vastly superior working memories?

The answer lies in evolution, says Matsuzawa. As humans evolved and acquired new skills – notably the ability to use language to communicate and collaborate – they lost others they once shared with their common simian ancestors. “Our ancestors may have also had photographic memories, but we lost that during evolution so that we could acquire new skills,” he says. “To get something, we had to lose something.”

For the chimps, the ability to memorise the location of objects is critical to their survival in the wild, where they compete for food with other, often aggressive, ape communities. To thrive, an individual chimp must be able to look up at, say, a sprawling fig tree and quickly note the location of the ripe fruit.

“They have to be able to think quickly because there are other hungry chimps behind them,” Matsuzawa says. “They have to grasp the situation as quickly as possible and decide where to go.”

Chimpanzee Ai tests her cognitive skills using Japanese kanji characters. Photograph: Justin McCurry

The same instincts kick in when confronted with a rival. “They have to see how many opponents are in front of them and decide whether to move forward or stay put. It can be a life-or-death decision.”

Six years after Ayumu first demonstrated his skills in public, the institute’s researchers are trying to find how far he can go before he falters badly. In the most recent tests, the number of digits has been increased from 1-9 to 1-19. The juxtaposition of two digits to form a single number is proving a worthy nemesis.

The chimps have a famously short attention span and have struggled to apply themselves to the lengthier tasks. Starting when they were aged about four, it took Ayumu and two other young chimps about six months to memorise the digits 1 to 9. In 2009, Matsuzawa and his team added the number 10, then 11.

“There might be a limit to how many things they can pay attention to at one time,” the professor says. “One to nine was easy, but one to 19 may be too much for them. In that sense, they’re like us. Numbers have infinite sequencing, which is why we developed the decimal system.

“Ayumu was amazing at remembering one to nine, and I know that’s not his limit. By increasing the numerals we want to discover her natural limit.”

To motivate the chimps, Matsuzawa programmes the computer to flash different numbers of digits on to the screen at any one time. “Motivation is the second most important thing after freedom,” he says. “It is totally up to them whether or not they show up in the morning, and if they actually start the tests. And I never scold them. I only ever offer them encouragement.”

As an extra inducement to persevere, each correctly completed task released a tiny chunk of apple or grape, or half a raisin, down a chute and into the windowed enclosure separating Ai and Ayumu from the watching researchers.

But Matsuzawa cautions against describing Ayumu as a genius. All three pairs of apes he works with at the institute can replicate his abilities to a certain extent. In fact, Matsuzawa believes he can bring any chimp up to speed: “All chimps potentially have the same capability; they just haven’t had it extracted by the computer tasks.”

Matsuzawa says our temptation to ascribe “super-chimp” status to the animals stems from a natural aversion to being thrashed at memory tests by primates. “Some humans are uncomfortable with the idea that beasts are cleverer than us, because we are supposed to be their intellectual superiors,” he says.

Now 13, Ayumu is being encouraged to produce offspring that, Matsuzawa hopes, will prove more serious rivals than his ageing mother. In chimps, as in humans, the ability to memorise complex scenes or patterns declines with age. In the 2007 experiment, Ai, then aged 31, did not perform as well as the human volunteers.

With the first morning session over, Ayumu climbs back out of the lab, while Ai stays behind to play with Matsuzawa, an almost constant companion since they met in 1977, when she was just a year old.

In the years since, Ai and her offspring have given Matsuzawa unprecedented access into the inner workings of the simian mind. “Until I met Ai, the only chimps I knew about were in Tarzan movies,” he says. “But she opened a window into the chimp world. She was my navigator. Studying the remains of our ancestors doesn’t tell us anything about how the mind works. But to know chimps is to know humans.”

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The 20 big questions in science

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From the nature of the universe (that’s if there is only one) to the purpose of dreams, there are lots of things we still don’t know – but we might do soon. A new book seeks some answers

What’s at the bottom of a black hole? See question 17. Photograph: Alamy

1 What is the universe made of?

Astronomers face an embarrassing conundrum: they don’t know what 95% of the universe is made of. Atoms, which form everything we see around us, only account for a measly 5%. Over the past 80 years it has become clear that the substantial remainder is comprised of two shadowy entities – dark matter and dark energy. The former, first discovered in 1933, acts as an invisible glue, binding galaxies and galaxy clusters together. Unveiled in 1998, the latter is pushing the universe’s expansion to ever greater speeds. Astronomers are closing in on the true identities of these unseen interlopers.

2 How did life begin?

Four billion years ago, something started stirring in the primordial soup. A few simple chemicals got together and made biology – the first molecules capable of replicating themselves appeared. We humans are linked by evolution to those early biological molecules. But how did the basic chemicals present on early Earth spontaneously arrange themselves into something resembling life? How did we get DNA? What did the first cells look like? More than half a century after the chemist Stanley Miller proposed his “primordial soup” theory, we still can’t agree about what happened. Some say life began in hot pools near volcanoes, others that it was kick-started by meteorites hitting the sea.

3 Are we alone in the universe?

science 3

Perhaps not. Astronomers have been scouring the universe for places where water worlds might have given rise to life, from Europa and Mars in our solar system to planets many light years away. Radio telescopes have been eavesdropping on the heavens and in 1977 a signal bearing the potential hallmarks of an alien message was heard. Astronomers are now able to scan the atmospheres of alien worlds for oxygen and water. The next few decades will be an exciting time to be an alien hunter with up to 60bn potentially habitable planets in our Milky Way alone.

4 What makes us human?

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Just looking at your DNA won’t tell you – the human genome is 99% identical to a chimpanzee’s and, for that matter, 50% to a banana’s. We do, however, have bigger brains than most animals – not the biggest, but packed with three times as many neurons as a gorilla (86bn to be exact). A lot of the things we once thought distinguishing about us – language, tool-use, recognising yourself in the mirror – are seen in other animals. Perhaps it’s our culture – and its subsequent effect on our genes (and vice versa) – that makes the difference. Scientists think that cooking and our mastery of fire may have helped us gain big brains. But it’s possible that our capacity for co-operation and skills trade is what really makes this a planet of humans and not apes.

5 What is consciousness?

We’re still not really sure. We do know that it’s to do with different brain regions networked together rather than a single part of the brain. The thinking goes that if we figure out which bits of the brain are involved and how the neural circuitry works, we’ll figure out how consciousness emerges, something that artificial intelligence and attempts to build a brain neuron by neuron may help with. The harder, more philosophical, question is why anything should be conscious in the first place. A good suggestion is that by integrating and processing lots of information, as well as focusing and blocking out rather than reacting to the sensory inputs bombarding us, we can distinguish between what’s real and what’s not and imagine multiple future scenarios that help us adapt and survive.

6 Why do we dream?

We spend around a third of our lives sleeping. Considering how much time we spend doing it, you might think we’d know everything about it. But scientists are still searching for a complete explanation of why we sleep and dream. Subscribers to Sigmund Freud’s views believed dreams were expressions of unfulfilled wishes – often sexual – while others wonder whether dreams are anything but the random firings of a sleeping brain. Animal studies and advances in brain imaging have led us to a more complex understanding that suggests dreaming could play a role in memory, learning and emotions. Rats, for example, have been shown to replay their waking experiences in dreams, apparently helping them to solve complex tasks such as navigating mazes.

7 Why is there stuff?

science 7

You really shouldn’t be here. The “stuff” you’re made of is matter, which has a counterpart called antimatter differing only in electrical charge. When they meet, both disappear in a flash of energy. Our best theories suggest that the big bang created equal amounts of the two, meaning all matter should have since encountered its antimatter counterpart, scuppering them both and leaving the universe awash with only energy. Clearly nature has a subtle bias for matter otherwise you wouldn’t exist. Researchers are sifting data from experiments like the Large Hadron Collider trying to understand why, with supersymmetry and neutrinos the two leading contenders.

8 Are there other universes?

Our universe is a very unlikely place. Alter some of its settings even slightly and life as we know it becomes impossible. In an attempt to unravel this “fine-tuning” problem, physicists are increasingly turning to the notion of other universes. If there is an infinite number of them in a “multiverse” then every combination of settings would be played out somewhere and, of course, you find yourself in the universe where you are able to exist. It may sound crazy, but evidence from cosmology and quantum physics is pointing in that direction.

9 Where do we put all the carbon?

For the past couple of hundred years, we’ve been filling the atmosphere with carbon dioxide – unleashing it by burning fossil fuels that once locked away carbon below the Earth’s surface. Now we have to put all that carbon back, or risk the consequences of a warming climate. But how do we do it? One idea is to bury it in old oil and gas fields. Another is to hide it away at the bottom of the sea. But we don’t know how long it will stay there, or what the risks might be. Meanwhile, we have to protect natural, long-lasting stores of carbon, such as forests and peat bogs, and start making energy in a way that doesn’t belch out even more.

10 How do we get more energy from the sun?

science 10

Dwindling supplies of fossil fuels mean we’re in need of a new way to power our planet. Our nearest star offers more than one possible solution. We’re already harnessing the sun’s energy to produce solar power. Another idea is to use the energy in sunlight to split water into its component parts: oxygen, and hydrogen, which could provide a clean fuel for cars of the future. Scientists are also working on an energy solution that depends on recreating the processes going on inside stars themselves – they’re building a nuclear fusion machine. The hope is that these solutions can meet our energy needs.

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Is it time to leave… again?

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I have read several accounts that strongly suggest we (humans) are not from this planet. There is some evidence and conjecture that we may have come here from Mars after we had made the planet inhabitable, but that we aren’t even from there, but further afield. Suggesting the possibility that we are in fact a race of space nomads.

If we are not from here, that would explain why they can’t find the so called ‘missing link’ between us and apes; there isn’t one.

We have succeeded in stripping this planet and making it uninhabitable, is this why we are searching so far and wide in the galaxies at great expense to find the next port of call?

solongandthanksforallthefish

Was Douglas Adams spoof ‘Hitchhiker’s Guide to the Galaxy‘ terribly far off the mark? “So long and thanks for all the fish!”

Maybe we’ve found our next home…

Star is crowded by super-Earths

An impression of what the sky might look like from the exoplanet Gliese 667Cd, looking towards the parent star and featuring, at top, the other super-Earths in the habitable zone

Scientists have identified three new planets around a star they already suspected of hosting a trio of worlds.

It means this relatively nearby star, Gliese 667C, now has three so-called super-Earths orbiting in its “habitable zone”.

This is the region where temperatures ought to allow for the possibility of liquid water, although no-one can say for sure what conditions are really like on these planets.

Gliese 667C is 22 light-years away.

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22 light-years, just next door really.

 

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