Jamie Kendrick

We know that we shared Europe with them between 30 and 40 thousand years ago. We know they buried their dead and may have had primitive speech. We even know some of them had red hair like us. Now, genetic research has provided us with evidence that ancestral lineages of modern humans may also have been getting jiggy with the Neanderthals!

Scientists at the Max Planck Institute for Evolutionary Anthropology have announced a completed draft version of the Neanderthal – Homo neanderthalensis – genome with intriguing results and implications. It appears our mysterious relationship with the Neanderthals is set for further speculation.

The team led by Svente Pääbo, head of the Neanderthal genome project, have sequenced four billion base pairs – roughly 1.3 fold coverage of the genome or entire genetic code. The genome was compiled from amplified DNA, extracted from 21 Neanderthal bones taken from four European sites in Croatia, Germany, Russia and Spain.

Once mapped, the Neanderthal genome was then compared to five modern human genomes from individuals of French, Han Chinese, Papua New Guinean, Yoruban (east African) and San (southern African) origin for maximum variation.

Now for the revelation! Analytical tests show that the Neanderthal genome is significantly more similar to the genomes of non-African modern humans than Africans. The most plausible explanation for this is interbreeding between Neanderthals and non-African modern human ancestors, estimated to have occurred between 50 and 80 thousand years ago when populations of the two species overlapped in the Levant, Arabia and the Middle-East. One to four per cent of the Eurasian genome could be derived from Neanderthal sequences.

Pääbo commented that ‘Neanderthals fall into our variation and for some parts of the genome I might be closer to Neanderthals than you.’ Chris Stringer, Palaeoanthropologist from the Natural History Museum, London, reasoned that this could have been ‘small scale interbreeding’ with the signs ‘magnified in modern human populations after they increased in size’

In a currently accepted model called Out of Africa Two, modern humans – Homo sapiens – evolved in Africa in the last 200 thousand years and migrated from the continent some 60 to 80 thousand years ago, replacing remaining archaic populations. Neanderthals are known in the fossil record from around 400 thousand years ago when characteristic features such as their protruding nasal region and brow ridge, receding forehead, bell shaped rib cage and low cranial vault appear, to as recently as 26 thousand years ago from a site in Gibraltar. Out of Africa Two doesn’t predict gene flow between the two species but interbreeding dates following migration are compliant.

The scientists were also able to look for areas of the genome that are unique to modern humans and have been altered since our divergence with our so called ‘cousins’, the Neanderthals. It appears genes related to cognitive abilities, metabolism, cranial and upper body skeletal structure have been under positive selection in Homo sapiens since our split from the Neanderthals sometime within the last 500 thousand years.

Sarah Tishkoff, a geneticist at the University of Pennsylvania, claimed there was ‘no smoking gun – a gene or variant that distinguishes Neanderthals from modern humans, but I think there will be in the future’.

The research has certainly questioned the total replacement model of Out of Africa Two and has placed emphasis on the fossil record to provide us with palaeontological evidence of interbreeding. Contentious fossils showing a mosaic of Neanderthal and modern human characters are known but Stringer added that we should remain ‘cautious’ because they are ‘based on features that occur in low frequency today in modern humans’.

For the orginal paper see Green, R.E et al. 2010. A draft sequence of the Neanderthal genome. Science, 328(5979), pp.710-722. (http://sciencemag.org/special/neandertal/)

Kathryn Swindells

Scientists working at the University of Chicago have shown a mass extinction that occurred 360 million years ago helped reset Earth’s evolutionary clock and set the stage for the evolution of modern animals. 

This massive extinction known as the Hangenberg event occurred at the end of the Devonian Period of Earth’s history, 416 to 359 million years ago. What followed was a massive gap in the fossil record known as ‘Romer’s Gap’, which lasted 15 million years. Researchers Lauren Sallan and Michael Coates discovered this extinction effectively created a new evolutionary starting point at a time when the first vertebrates were making the transition from the sea to the land.

“The extinction was global” says Sallan, “It reset vertebrate diversity in every single environment, both freshwater and marine and it created a completely different world.” In the words of Coates, it is as if “something happened that almost wiped the slate clean.”

Prior to this event, life on earth was dominated by gigantic armoured fish such as Dunkleosteus in what was known as the Age of Fish. More modern creatures such as ray-finned fish and sharks existed but were very much in the minority. Some tentative attempts had also been made by creatures such as Tiktaalik and Ichthyostega towards life on land. Following the extinction, however, the armoured fish and the early land animals disappeared and were eventually replaced by the ancient ancestors of the majority of land animals today. The authors propose that modern vertebrate traits such as the five digit limbs shared by all mammals, bird and reptiles in the womb may have been set by an early ancestor which occurred at this time.

This work was made possible by using advances in modern analytical techniques to look at events that occurred millions of years ago. It explains why an event so catastrophic went undetected for so long.

As Sallan says, “It took the right methods to reveal its magnitude”. What is still unknown though is precisely what happened to wipe out the vast majority of life on earth. Other researchers have suggested that substantial glacial formation at the end of the Devonian may have lowered sea levels affecting life. Another mystery is why did those groups of animals that dominated before the extinction not recover? What is certain is that this event had major consequences for life on earth as we know it and remains as a pivotal moment in the history of the planet.

The work was published in the journal Proceedings of the National Academy of Sciences (PNAS).

Rosie Taylor

Tracks of a two-metre long giant ‘water scorpion’ discovered by a Sheffield lecturer are to be made into a silicon cast to enable further research on the creature.

Dr. Martin Whyte, from the University’s Geography department, came across the fossilised trackway when walking in Fife, Scotland.

The fossil shows the preserved footprints and tail track of an enormous eurypterid (or water scorpion) known as Hibbertopterus. 

It is the largest known walking trackway of any invertebrate animal.

Dr. Whyte’s discovery is considered internationally significant because it is the first piece of scientific evidence to show the Hibbertopterus was able to survive out of water and move between rivers.

He said: “The tracks show the animal was moving slowly and because there is a deep drag mark left by the tail it was not buoyed up and was, I believe, moving out of water.  

“This suggests that the hibbertopterids were able to survive in air; not in itself a new suggestion, but the first time that it can be backed up with scientific evidence.  

“The find adds significantly to our understanding of their ecology and also of Lower Carboniferous environments.”

Now that the fossilised tracks are in danger of disappearing due to years of weathering, Dr. Whyte’s discovery is being moulded in silicon in a project funded by Scottish National Heritage (SNH) and the Geologists Association. 

Richard Batchelor from Geoheritage Fife said: “The trackway is in a precarious situation. The rock in which it occurs is in danger of falling off altogether.

“Removing it and housing it in a museum would be prohibitively costly but moulding it in silicone rubber and making copies for educational and research purposes means that we can still see and research this creature’s tracks in years to come.”

Izzy Dean

A study conducted in the Netherlands has demonstrated that that Zebra finches can distinguish between different words, even when spoken by different people. Scientists believed that the formation of words evolved alongside the ability to understand the sounds which make up speech. However Verena Ohms and her team’s complex study reveals that this may not be true.

By giving the birds  food when they responded correctly to sounds, and plunging them into darkness when they did not respond or responded incorrectly, scientists were able to demonstrate that these birds could tell the difference between words such as “wit” and “wet”.  The experiment shows that these finches are able to clearly distinguish between different words, even when gender is altered or when listening to a person for the first time. 

Previously, the ability to recognise phonetics used in words when pitch or speaker is altered was thought to be a characteristic unique to our own species.   On the surface, this discovery may seem trivial, but scientists say it actually helps us understand the evolution of speech. 

Ohms, of the Institute of Biology at the University of Leiden, believes  we  evolved the ability to understand various sounds for similar reasons to other animals,  then later changed to use the meaningful phonetics we now recognise as speech.

The study implies that  that the ability to create and understand different tones in speech evolved not for talking , but for a different means of communication, and the ability to distinguish between tones was not used for speech until much later. 

Using noises to communicate information other than in speech occurs in other animals, such as deer and cranes, which can assess the size and gender of a member of their own species based on the noise they make. Some species of frogs have been shown to decide whether it is worth fighting another male for a female based on the pitch of its croak.