DNA analysis of ancient humans poses more questions than answers

DNA analysis of 400,000 year old bones found in Spain, the oldest known human remains, has yielded more questions than answers. The human family tree is now thought to have had many more branches than previously thought after the analysis which was the first time scientists could gain data from this period.

Originally it was thought the bones may have been Neanderthal but instead the bones have a closer relationship to Denisovans, a distinct human sub-species who lived in Siberia. The Denisovans interbred with the Neanderthals and Modern Humans, bones from the other human species found alongside their's, and traces of their DNA remains in humans today. Around 6% of the DNA in Melanesian people (living in places like Papua New Guinea) is shared with the Denisovans. Indeed around 4% of the DNA in non-Africans is Neanderthal.

Sirius object of worship in oldest known temple?

Its thought the oldest known temple in Göbekli Tepe, in Turkey, may have been dedicated to the Dog Star (Sirius). The site is 11,000 years old and consists of 20 enclosures though only a few have yet been excavated. Each enclosure is circular and surrounded by stone pillars on which are carved animals.

If the pillars were arranged as an astronomical observatory like Stonehenge may have been then by simulating the position of the stars at the time the temple was being used then Sirius may have been the object of worship. It is one of the brightest stars in the sky and would have started appearing on the horizon after 9300 BCE. Archaeoastronomer Giulio Magli believes the appearance of this new bright star may have sparked a new religion which the temple was built to serve.

The site in southern Turkey is also fascinating for how it goes against the idea of agriculture sparking human settlements and civilisation. There is no evidence of contemporary agriculture meaning the temple could have come first.

The milk revolution

An interesting article in Nature magazine on how Europeans around 7500 years ago developed a mutation that allowed them to drink milk and consume other dairy produce including early cheese, evidence of cheese making has been found in fragments of pottery with tiny holes in it. The ability to drink milk up until then was lost in adulthood and lactose intolerance remains true for many people around the world.

Early farmers learnt how to reduce the lactose in dairy produce so it was not hazardous to adult health but the main breakthrough came when a genetic mutation called LP allele allowed adults to drink milk without ill-effect. The mutation is thought to have happened around 7500 years ago in what is now Hungary.

Those with the mutation had an advantage over those who remained intolerant, milk was a vital source of nutrition when harvests were poor. Those with the mutation were also more fertile. Most people who can drink milk now can trace their ancestry to Europe though in a few other areas similar mutations occurred such as in West Africa.

Say hello to our earliest ancestor?

Fifty five million years ago in the palaeocene there lived a small mammal (which is now called Archicebus achilles) in what is now China. It may be this is the earliest known primate and thus the common ancestor to monkeys, apes and us!

Archicebus was rather small, being only 7cm long, and lived alongside tropical lake shores eating insects. The fossils of Archicebus show features now known in tarsiers, early primates which now live in South East Asia. Other features are common in other primate groups.

Near complete skeletons of Archicebus are known which is greatly aiding analysis. Archicebus lived about 7 million years earlier than the previous earliest known primates. Archicebus may also show the divergence point between tarsiers and modern monkeys and apes, a key point in human evolution.

Why did the Neanderthals die out?

Why did the Neanderthal variety of human die out? Its a mystery that will be discussed this week at a conference in London at which the results of a 5 year research programme will also be revealed. One major finding will be that modern humans arrived much earlier in Europe than previously thought (around 45000 years ago) and that Neanderthals died out earlier than thought too, within a few thousand years of the arrival of modern humans.

New techniques are said to be able to radiocarbon date fairly recent finds much more accurately. Thanks to these new techniques it is now thought that Neanderthals were largely died out by 39000 years ago, 10000 years earlier than thought.

The speed of their disappearance and the absence of any detected natural disaster (a major volcanic eruption in Europe occurred too late to have an effect) indicates that the arrival of modern man might be largely to blame. The Neanderthals were probably unable to compete with modern humans who, although not as strong, possessed superior social networks and connections and numbers, the Neanderthals remaining in small isolated groups.

The Neanderthals may have died out but some interbreeding took place, Neanderthal DNA lives on in European and Asian genes.

Aurornis xui beats Archaeopteryx as earliest bird?

The discovery of a fossil of Archaeopteryx in 1861 was one of the greatest fossil discoveries ever. The fossil showed the earliest known (at the time) bird and also a transitionary stage in the evolution of a branch of reptiles into birds, helping illustrate Darwin's theory of evolution too. Now finally an earlier stage in that evolution has been found.

Aurornis xui predates Archaeopteryx by 10 million years in the Jurassic period (about 150 million years ago). It shares many of the other early bird's features such as a long tail but is considered more primitive and the most primitive avian yet discovered. The fossil has preserved the outline of feathers along the body and tail though Aurornis was unlikely to have been able to fly.

Some scientists are not convinced Aurornis should be classified as a "bird" but rather was still a reptile but all agree it provides an important step in the evolution of the birds. Interestingly the discovery of Aurornis helps re-establish Archaeopteryx in the bird family tree after some scientists relegated it to a class of winged dinosaurs.

A common Euro-Asian language?

The idea of all languages having a common forebear is not a new idea (the Tower of Babel for example and has been considered by linguistic researchers for decades) but new research suggests that many languages spoken by people in Europe, Asia and America descend from a common language spoken during the Ice Ages 15,000 years ago.

Researchers have long used cognates (words that have a common etymological origin) as a kind of lingustic "DNA" to reconstruct ancient proto-words and have traced some common words back as far as 9000 years ago. This ancient Indo-European language later gave rise to languages like English, French, Hindi and Russian.

This is pretty much accepted, what is more controversial is tracing language back further. Some say this is too far back to meaningfully trace language roots as too many words would have changed over time. However researchers at Reading University have used statistical modelling to identify very common words have survived for thousands of years and which are shared across a number of ancient proto-languages across Europe and Asia linking Indo-European to other language groups like Altaic and Inuit-Yupik. Words which have survived include "I" and "We" (which might be no surprise) but also common are words like "bark" and "ashes". This is more surprising but then we should consider the cultural importance of such words to humans in the Stone Age.

Was it a comet and not an asteroid that finished the Dinosaurs?

Scientists examining the amount of rare metals released by the impact that caused the Chicxulub crater in Mexico (which scientists believe is where the object that hit the Earth to spark the mass extinction event at the end of the Cretaceous took place) now think that the Earth was hit by a smaller object than an asteroid but one traveling at a higher velocity, a comet in other words.

This is because the amount of debris deposited is less than would be expected if a larger asteroid struck the Earth. The object that hit the Earth is calculated to would need to be 5km in diameter to result in the rare metals like iridium detected however the size of the crater would indicate a much larger object, unless it was traveling fast. Other scientists say that it might not be possible to say conclusively from the metals detected and their displacement may not have been uniform.

However the strength of the impact was sufficient to send huge amounts of dust into the atmosphere and cause the "Nuclear Winter" that killed off the Dinosaurs and many other creatures, 70% of all species.

Did large eyes cause the demise of the Neanderthal?

A study of Neanderthal skulls has led scientists to suggest that the size of their eyes may have led to their demise and eventual extinction. Larger eyes meant that more of their brain was dedicated to seeing in the longer darker nights in Europe and the generally lower light conditions compared to Africa. Modern humans who stayed in Africa for longer (thus in better light) did not evolve this eye and brain adaptation and so their brains could develop higher level thinking, which enabled them to better adapt to the ice ages through improved clothing (for example evidence of needles and early tailoring has been found while Neanderthal clothing remained cruder) and to develop larger social groups.

However modern humans living at higher altitudes have also evolved larger vision processing areas in their brains and this has not resulted in reduced cognitive abilities. The findings seem to run counter to recent research that has dispelled the earlier view that Neanderthals were "stupid brutes" and instead were only slightly less intelligent than ourselves. Indeed although modern humans' advantage was only slight it was apparently just enough to tip the balance in their favour in the battle for survival during the ice ages.

John Hawks is among those sceptical.

The single most important correlate of orbit diameter is body mass. Neandertals were bigger on average. QED.
— John Hawks (@johnhawks) March 13, 2013

Mauritia

I've always found ancient continents and super-continents fascinating. Now scientists have found evidence of a now lost micro-continent called Mauritia which existed between 2000 and 86 million years ago. Mauritia was located between India and Madagascar but fragmented when India broke away and headed up towards its eventual collision with Asia.

Grains of sand off beaches in Mauritius were analysed (nice place to do some research) which were found to contain ancient minerals. Zirconium, a mineral commonly found in continental crust, were found in the sand and have been dated between 1,970 to 600 million years old.