INDIGENOUS Australians and other Melanesian peoples have evolved in part from a hitherto unknown strain of Neanderthal-like Siberians.
German researchers using genetic material extracted from a 40,000-year-old finger bone and tooth discovered in a cave in Russia's Altai Mountains found their owners were part of a race of hominin distinct from both the ancestors of modern humans and the Neanderthals. They named them the Denisovans after the Denisova cave in which the bones were found.
Scientists believe Neanderthals and homo sapiens separated from a common ancestor about 500,000 years ago.
The discovery of the Denisovans, reported in the journal Nature today, showed that Neanderthal-like people were not confined to Europe, said the professor of human evolution at the Australian National University, Colin Groves. "What it now suggests is that the European branch, the Neanderthaloids, were actually a full Eurasian branch, not just European -- and that they had an eastern and a western subdivision," he said.
Furthermore, by comparing their genomes, the German scientists were able to show that homo sapiens inter-bred with the Denisovans while on their way to colonise south Asia and Australia.
"When homo sapiens expanded out of Africa around 100,000 years ago or less, obviously the east Asians incorporated a little gene flow from these Denisovans," Professor Groves said.
While the scientists who conducted the study had no Aboriginal Australian samples, Professor Groves said Melanesians, Papuans and Aboriginal Australians formed a group of related peoples.
"It does seem likely that if there were Aboriginal samples, they too would prove to have some gene flow from the Denisovans," he said.
Professor Groves suggested the remains unearthed at Denisova might be analogous to a skull discovered by farmers in China's Guangdong province in 1958.
The director of the Australian Centre for Ancient DNA at the University of Adelaide, Alan Cooper, said gene-sequencing technology was revolutionising the study of human evolution.
"We've moved from testing existing hypotheses that have been based on traditional science -- fossils and archeology, where we're just testing things that were already known -- to actually making new hypotheses ourselves," Professor Cooper said.
"This thing wasn't even supposed to exist -- there were no remains for it, no knowledge of it -- and yet the genetics is now demonstrating complete chunks of the human tree that were not even known."
Professor Cooper said this and other discoveries showed Asia had a " whole bunch of human history going on that we know nothing about". Asked whether gene-sequencing could redraw the tree of human evolution in the next five years, he replied: "I wouldn't be totally surprised."
Sexual relations between ancient humans and their evolutionary cousins are critical for our modern immune systems,researchers report in Science journal.
Mating with Neanderthals and another ancient group called Denisovans introduced genes that help us cope with viruses to this day, they conclude.
Previous research had indicated that prehistoric interbreeding led to up to 4% of the modern human genome.
The new work identifies stretches of DNA derived from our distant relatives.
In the human immune system, the HLA (human leucocyte antigen) family of genes plays an important role in defending against foreign invaders such as viruses.
The authors say that the origins of some HLA class 1 genes are proof that our ancient relatives interbred with Neanderthals and Denisovans for a period.
Getting these genes by mating would have given an advantage to populations that acquired them”
Peter Parham
At least one variety of HLA gene occurs frequently in present day populations from West Asia, but is rare in Africans.
The researchers say that is because after ancient humans left Africa some 65,000 years ago, they started breeding with their more primitive relations in Europe, while those who stayed in Africa did not.
"The HLA genes that the Neanderthals and Denisovans had, had been adapted to life in Europe and Asia for several hundred thousand years, whereas the recent migrants from Africa wouldn't have had these genes," said study leader Peter Parham from Stanford University School of Medicine in California.
"So getting these genes by mating would have given an advantage to populations that acquired them."
When the team looked at a variant of HLA called HLA-B*73 found in modern humans, they found evidence that it came from cross-breeding with Denisovans.
Scanty remains
While Neanderthal remains have been found in many sites across Europe and Asia, Denisovans are known from only a finger and a tooth unearthed at a single site in Russia, though genetic evidence suggests they ranged further afield.
"Our analysis is all done from one individual, and what's remarkable is how informative that has been and how our data looking at these selected genes is very consistent and complementary with the whole genome-wide analysis that was previously published," said Professor Parham.
A similar scenario was found with HLA gene types in the Neanderthal genome.
"We are finding frequencies in Asia and Europe that are far greater than the whole genome estimates of archaic DNA in modern humans, which is 1-6%," said Professor Parham.
The scientists estimate that Europeans owe more than half their variants of one class of HLA gene to interbreeding with Neanderthals and Denisovans.
Asians owe up to 80%, and Papua New Guineans up to 95%.
Uneven exchange
Other scientists, while agreeing that humans and other ancients interbred, are less certain about the evidence of impacts on our immune system.
"I'm cautious about the conclusions because the HLA system is so variable in living people," commented John Hawks, assistant professor of anthropology at the University of Wisconsin-Madison, US.
DNA from a tooth (pictured) and a finger bone show the Denisovans were a distinct group
"It is difficult to align ancient genes in this part of the genome.
"Also, we don't know what the value of these genes really was, although we can hypothesise that they are related to the disease environment in some way."
While the genes we received might be helping us stay a step ahead of viruses to this day, the Neanderthals did not do so well out of their encounters with modern human ancestors, disappearing completely some 30,000 years ago.
Peter Parham suggested a parallel could be drawn between the events of this period and the European conquest of the Americas.
"Initially you have small bands of Europeans exploring, having a difficult time and making friends with the natives; but as they establish themselves, they become less friendly and more likely to take over their resources and eliminate them.
"Modern experiences reflect the past, and vice versa."
DNA is the molecule that contains and passes on our genetic information. The publication of its structure on the 25th of April 1953 was vital to understanding how it achieves this task with such startling efficiency.
In fact, it's hard to think of another molecule that performs so many intelligent functions so effortlessly. So what is it that makes DNA so smart?
Multi-millennial survivor
For such a huge molecule, DNA is very stable so if it's kept in cold, dry and dark conditions, it can last for a very, very long time. This is why we have been able to extract and analyse DNA taken from species that have been extinct for thousands of years.
Scientists have 'resurrected' blood protein from preserved mammoths after harvesting their DNA
It's the double-stranded, double-helix structure of DNA that stops it falling apart.
DNA's structure is a bit like a twisted ladder. The twisted 'rails' are made of sugar-phosphate, which give DNA its shape and protect the information carrying 'rungs' inside. Each sugar-phosphate unit is joined to the next by a tough covalent bond, which needs a lot of energy to break.
In between the 'rails', weaker hydrogen bonds link the two halves of the rungs together. Individually each hydrogen bond is weak - but there are thousands of hydrogen bonds within a single DNA molecule, so the combined effect is an extremely powerful stabilising force.
It's this collective strength of DNA that has allowed biologists to study genes of ancient species like the woolly mammoth - extinct but preserved in the permafrost.
This short animation explains everything else you need to know about DNA.
Clever facsimile machine
Our cells need to divide so we can grow and re-build, but every cell needs to have the instructions to know 'how to be' a cell.
DNA provides those instructions - so a new copy of itself must be made before a cell divides.
It's the super-smart structure that makes this easy. The 'rungs' of the DNA ladder are made from one of four nitrogen-based molecules, commonly known as A, T, G and C. These form complementary pairs - A always joins with T and G always joins with C.
So one side of the double-stranded DNA helix can be used as a template to produce a new side that perfectly complements it. A bit like making a new coat zip, but by using half of the old zip as a template.
The original side and the new one combine together to form a new DNA double helix, which is identical to the original.
Cleverly, human DNA can unzip and 'replicate' at hundreds of places along the structure at the same time - speeding up the process for a very long molecule.
Molecular contortionist
Two metres of DNA coils like a telephone cord to fit into each cell
DNA is one of the longest molecules in the natural world. You possess enough DNA, stretched out in a line, to reach from here to the sun and back more than 300 times.
Yet each cell nucleus must contain two metres of DNA, so it has to be very flexible. It coils - much like a telephone cord - into tight complex structures called chromatins without corrupting the vital information within.
There are four different nucleotide bases in each DNA molecule:
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
These small molecules join DNA together and encode our genetic information.
And despite being packed in so tightly, the genetic material can still be accessed to create new copies and proteins as required.
Human cells contain 23 pairs of chromosomes, with each containing one long DNA molecule as well as the proteins which package it. It's no wonder DNA needs to be extremely supple.
Amazingly, this folded and packed form of DNA is approximately 10,000 times shorter than the linear DNA strand would be if it was pulled taut.
This is why we have the 'luxury' of having the plans for our entire body in nearly every cell.
A 26-second snippet of Martin Luther King's classic anti-racism address from 1963
A .pdf" of the seminal 1953 paper by Crick and Watson describing DNA' structure
The total data package was equivalent to 760 kilobytes on a computer drive. Physically, the DNA carrying all that information is no bigger than a speck of dust.
Genes are made up of stretches of the DNA molecule which contain information about how to build proteins - the building blocks of life which make up everything about us.
Different sequences of the four types of DNA bases make 'codes' which can be translated into the components of proteins, called amino acids. These amino acids, in different combinations can produce at least 20,000 different proteins in the human body.
Think of it like Morse Code. It too uses only four symbols (dot, dash, short spaces and long spaces), but it's possible to spell out entire encyclopaedias with that simple code.
Just one gram of DNA can hold about two petabytes of data - the equivalent of about three million CDs.
That's pretty smart, especially when you compare it to other information-storing molecules. Using the same amount of space, DNA can store 140,000 times more data than iron (III) oxide molecules, which stores information on computer hard drives.
DNA may be tiny but with properties including stability, flexibility, replication and the ability to store vast amounts of data, there's a reason why it must be one of the smartest known molecules.
With huge quantities of data being produced by ever-growing computer systems, traditional data storage solutions, like magnetic hard drives are becoming bulky and cumbersome. Researchers have now used DNA to store artificially-produced information, but could this be the future of data storage?
Autism affects male and female brains differently, a study has suggested.
UK experts studied brain scans of 120 men and women, with half of those studied having autism.
The differences found in the research, published in journal Brain, show more work is needed to understand how autism affects girls, the scientists say.
Experts said girls with the condition could be more stigmatised than boys - and it could be harder for them to be diagnosed at all.
Autism affects 1% of the population and is more prevalent in boys, so most research has focused on them.
In this study, scientists from the Autism Research Centre at the University of Cambridge used magnetic resonance imaging (MRI) to examine how autism affects the brain of males and females.
Male and female brains differ anyway - tissue volume is greater in males.
'Look-alikes'
The study looked at the difference between the brains of typical males and those with autism - and then females with and without autism.
There really needs to be more research and clinical attention toward females 'on the spectrum'”
Dr Meng-Chuan LaiUniversity of Cambridge
They found the brains of females with autism "look" more like - but still not the same as - typical male brains, when compared with the brains of females without autism.
But the same kind of difference was not seen in males with autism - so their brains did not show "extreme" male characteristics.
Dr Meng-Chuan Lai, who worked on the study said: "What we have known about autism to date is mainly male-biased.
"This research shows that it is possible that the effect of autism manifests differently according to one's gender.
"Therefore we should not blindly assume that everything found for males or from male-predominant mixed samples will apply to females."
He said future research may need to look at males and females equally to discover both similarities and differences.
Dr Lai added: "Lastly, there really needs to be more research and clinical attention toward females 'on the spectrum'."
Many girls go on to develop secondary problems such as anxiety, eating disorders or depression”
Carol Povey,National Austitic Society
Carol Povey, Director of The National Autistic Society's Centre for Autism, said: "Historically, research on autism has been largely informed by the experiences of men and boys with the condition.
"This important study will therefore help our understanding of how the condition differs between genders."
She added: "Girls can be more adaptive than boys and can develop strategies that often mask what we traditionally think of as the signs of autism.
"This "masking" can lead to a great deal of stress, and many girls go on to develop secondary problems such as anxiety, eating disorders or depression.
"It's important that we build on this study and more research is conducted into the way autism manifests in girls and women, so that we can ensure that gender does not remain a barrier to diagnosis and getting the right support."
A new contract for GPs will see the return of "proper family doctors," responsible for round-the-clock care and with dedicated help for the elderly, the Health Secretary says The deal agreed with the British Medical Association (BMA) has been heralded as the biggest shake-up since Labour introduced changes which allowed thousands of doctors to abandon responsibilty for out-of-hours care. Under the contract four million elderly patients and those with complex conditions will be given a named GP, personally accountable for their care at all times. Ministers say the change is crucial because the failure to care for older patients has causing a spiralling crisis in NHS emergency care, with millions of patients admitted to hospital because they could not get help in time from their GPs. Under a deal introduced by Labour, the majority of family doctors dropped responsibility for out-nstantly by almost one third. BMA negotiators later admitted the terms, which brought average GP incomes to more than £100,000 were so generous that they thought the Government was "having a laugh". Since then, there have been a succession of scandals in which patients were failed by locum doctors, including a notorious case when a pensioner was killed by an overdose of painkillers administered by an overseas medic working his first shift. The new deal will mean that GPs are personally responsible for the care of all patients aged 75 and over, around the clock, regardless of who delivers it - as well as for the care for younger patients with complex health needs. Older patients will also be promised same-day access to their doctors, via telephone consultations, while GPs will be instructed to draw up "personalised care plans" so all frail and elderly patients are properly looked after. Jeremy Hunt said last night: "Labour's 2004 GP contract broke the personal link between GP and patient. It piled target after target on doctors, took away their responsibility for out-of-hours care and put huge pressure on our A&E departments. This Government has a plan to sort this out. Today's announcement of a new GP contract is a vital step." Ofsted-style ratings measuring the performance of GP practices as outstanding, good, requires improvement or inadequate, will be published in every surgery by 2015, while data will be published scrutinising the quality of out-of-hours care for all patients. Government sources said the reports would be detailed and "unapologetically frank" informed by close observation and conversations with professionals and patients. Mr Hunt said: "We are bringing back named GPs for the vulnerable elderly. This means proper family doctors, able to focus on giving elderly people the care they need and prevent unnecessary trips to hospital. This is about fixing the long-term pressures on our A&E services, and freeing hardworking doctors to improve care for those with the greatest need." Since 2004, GPs pay has been dictated by hundreds of targets. Under the system - derided by critics as "points mean prizes" - income can be dictated by how many patients are weighed, asked about their alcohol intake or given lifestyle advice. Under the new deal, which will be introduced in April, more than one third of the indicators will be scrapped, which the BMA said would allow thousands of GPs to attend to their patients, instead of their computer screens. Dr Chaand Nagpaul, Chairman of the BMA's GP committee, said: "This is resurrecting what used to happen: it means tailored and personalised care." "The 2004 contract brought unprecedented bureaucracy and chasing of targets and box-ticking. We have removed a swathe of targets: what this is doing is giving GPs time - time to care. Doctors will be able to look at the patient in front of them, not the computer screen." Under the targets framework, doctors have been paid for improving their handwriting, or ensuring staff undergo training, or for asking patients how often they do activities such as DIY, cooking or gardening. Dr Nagpaul said: "Even today GPs up and down the land are asking these questions - how often patients cycle, garden or cook, how often they walk - and how quickly - checking the blood pressure of fit and healthy people, all the while measuring rather than providing care." The deal agreed yesterday involves some compromises, as ministers had orginally indicated that they wanted GPs to take back responsibilty for out-of-hours care for all patients, and further changes are likely to be negotiated in future years. Dr Nagpaul said: "Given the workforce crisis among GPs it's right to focus on the patients with the greatest need. I think the Government understsands that with a limited workforce GPs need to use their time wisely." The BMA said the terms would not increase funding for doctors - who on average earns £103,000, with more than 600 earning more than £200,000 - but would shift existing resources, so GPs could make better use of their professional judgement. Andy Burnham , Labour's Shadow Health Secretary, said: "No amount of spin can hide the fact that David Cameron has made it harder to get a GP appointment. There is nothing in this new contract to correct that." "David Cameron cut Labour's scheme of evening and weekend opening and the guarantee of seeing a doctor within 48 hours. "This announcement will not put an end to patients phoning the surgery at 9am and finding it impossible to get an appointment - many of whom, not happy with a phone consultation, will still turn to A&E."
