The Malaysian Insider :: Features
The Malaysian Insider :: Features |
| Brutish and short? DNA ‘switch’ sheds light on Neanderthals Posted: 17 Apr 2014 10:00 PM PDT How can creatures as different in body and mind as present-day humans and their extinct Neanderthal cousins be 99.84% identical genetically? Four years after scientists discovered that the two species' genomes differ by a fraction of a percent, geneticists said yesterday that they have an explanation – the cellular equivalent of "on"/"off" switches that determine whether DNA is activated or not. Hundreds of Neanderthals' genes were turned off while the identical genes in today's humans are turned on, the international team announced in a paper published online in Science. They also found that hundreds of other genes were turned on in Neanderthals, but are off in people living today. Among the hundreds are genes that control the shape of limbs and the function of the brain, traits where modern humans and Neanderthals differ most. "People are fundamentally interested in what makes us human, in what makes us different from Neanderthals," said Sarah Tishkoff, an expert in human evolution at the University of Pennsylvania, who was not involved in the new study. Discovering the differences in gene activation is "an amazing technical feat," she said, and goes a long way to answering that riddle. The discovery also underlines the power of those on/off patterns. Together, they add up to what is called the human epigenome, to distinguish it from the human genome. The genome is the sequence of 3 billion molecules that constitute all of a person's DNA while the epigenome is which bits of DNA are turned on or off even as the molecular sequence remains unchanged. In the last few years, research on the epigenome has shed light on how gene silencing leads to cancer, for instance, and how identical twins with identical DNA sequences can be very different. The epigenome exerts such powerful effects that it is often called the "second genetic code." Now it has offered clues to what makes modern humans distinct. Genes for stronger limbs For the new study, geneticists led by Liram Carmel of the Hebrew University of Jerusalem started with DNA from limb bones of a living person, a Neanderthal and a Denisovan, an extinct human that lived in Eurasia during the Stone Age and whose remains – a pinkie bone and a tooth, from a cave in Siberia – were not discovered until 2010. Geneticist David Gokhman and others on the Israeli team then examined the DNA's on/off patterns, identifying about 2,200 regions that were activated in today's humans, but silenced in either or both extinct species, or vice versa. When a gene is silenced, it does not produce the trait it otherwise would. Chief among the epigenetic differences, a cluster of five genes called HOXD, which influences the shape and size of limbs, including arms and hands. It was largely silenced in both ancient species, the scientists found. That may explain anatomical differences between archaic and present-day humans, including Neanderthals' shorter legs and arms, bowleggedness, large hands and fingers, and curved arm bones. Calling the work "pioneering," and "a remarkable breakthrough," paleoanthropologist Chris Stringer of the Natural History Museum in London said in an interview that the HOXD gene finding "may help to explain how these ancient humans were able to build stronger bodies, better adapted to the physical rigors of Stone Age life." One caveat about the research is that one person's epigenome can vary markedly from another's due to diet, environment and other factors. It is therefore impossible to know whether the on/off patterns found in Neanderthal genes are typical of the species overall or peculiar to the individual studied. Other DNA with big differences in on/off patterns between the extinct and present-day humans is associated with neurological and psychiatric disorders including autism, schizophrenia and Alzheimer's disease. More of the Neanderthal versions were silenced. In an interview, Carmel speculated that any given gene might "do many things in the brain." When dozens of brain-related genes became more active in today's humans, that somehow produced the harmful side effect of neurological illness. But the main effect might have been the astonishing leap in brain development that most distinguishes modern Homo sapiens from our extinct cousins. – Reuters, April 18, 2014. |
| Rave on: Londoners re-live dancing days with kids in tow Posted: 17 Apr 2014 08:27 PM PDT Dressed in a Spiderman outfit, the four-year-old boy runs to his dad by the bar to complain, before receiving a glow-stick as consolation. Such are the highs and lows of family raving, a new craze fuelled by London's ex-clubbers who still want to go dancing but now have kids in tow. "What a genius idea – beer, raving, children. What more could you want?" said Paul Crawley, 34, swaying slowly on the dance floor carrying his baby daughter Camille in a sling. "The worst thing is I was invited out last night, but I said no, I've got to stay sober for this party." This dingy bar in south London is normally the venue for all-night raves, but for two and a half hours on a Saturday afternoon, it is transformed into a playgroup with a difference. In the chill out area, mums breastfeed on low leather sofas to a soundtrack of soft rock, while older children paint and draw at a well-equipped craft table under moving projected images. The bar is well stocked and next door, professional DJs play chilled house music, funk and drum'n'bass at a surprisingly loud volume, although organisers insist it is safe for babies' ears. The undisputed king of the dance floor is Caelan, a fleet-footed five-year-old wearing impeccable white trainers. "Keep to the beat!" urges his dad, Michael Edie, while a little girl in a princess outfit looks on admiringly. Caelan has been taking dance lessons since he was three and this is a good place for him to get some practise in, offering a bit more space than at home. Edie, a DJ with London urban music radio station Rinse FM, is happy to stay seated, however. "You won't see me dancing. I'm no way as good as him," he laughs. We went raving here The toddlers staggering around in the half-light look disturbingly like small, drunk adults, while the waft of stale beer lends the party an authentic feel. It is a little too authentic for Jody Bullough, a 43-year-old from Burnley in northern England who is here with her six-year-old daughter Jasmine. "It's a scuzzy (grimy) venue. It's really dirty," said Bullough, who runs a manufacturing business, noting Jasmine's filthy hands after playing on the floor. The location has brought back fond memories, though. "I remember coming here years ago, when I lived in London and we used to go raving. It's a really good idea," she says. Nearby, Bullough's friend Rebecca Smith, a 40-year-old probation officer sporting a vest top and pixie haircut, does the funky chicken dance with her daughter. As the girls wander off to get tattoo transfers at the bar – they will wash off later – Smith breaks into some more impressive moves. "Normally it's a bit later and I've had a bit more alcohol, but this is OK, I can rave to this," she says, dancing off. No funny business Family discos and raves are increasingly common across London, as the clubbers who once packed world-famous venues such as Ministry of Sound get older and have children. "We haven't stopped being people with our own interests," said Hannah Saunders, a 45-year-old former civil servant who organised this party. Her events company, Big Fish Little Fish, is aimed at – and the pun is intended – "two-to-four hour party people" who like to strut their stuff before getting home for the kids' bedtime. Saunders used to spend her weekends at clubs and warehouse parties and her holidays in Ibiza. Now with two children under four, she found no shortage of family-friendly musical events but despaired at the chart-topping pop tunes that they played. "My kids are happy listening to my favourite drum'n'bass tracks, so I knew it would be fine," she said. Given the nature of the dance music scene, many of the parents here are likely to have indulged in recreational drugs in the past. But the only sign of nefarious behaviour is a group of children in a corner silently trading sparkly ribbons from the glitter cannon. By the end of the party there are empty plastic pint glasses piled up on tables, but most people are sober, fully aware of their responsibilities as parents. "The toxins we were pouring into our bodies (when we were younger) were neither here nor there – actually we still like music and dancing, and we can still do that," Saunders said. – AFP, April 18, 2014. |
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