55 posts tagged DNA
Baffling 400,000-Year-Old Clue to Human Origins
Scientists have found the oldest DNA evidence yet of humans’ biological history. But instead of neatly clarifying human evolution, the finding is adding new mysteries. In a paper in the journal Nature, scientists reported Wednesday that they had retrieved ancient human DNA from a fossil dating back about 400,000 years, shattering the previous record of 100,000 years. The fossil, a thigh bone found in Spain, had previously seemed to many experts to belong to a forerunner of Neanderthals. But its DNA tells a very different story. It most closely resembles DNA from an enigmatic lineage of humans known as Denisovans. Until now, Denisovans were known only from DNA retrieved from 80,000-year-old remains in Siberia, 4,000 miles east of where the new DNA was found. The mismatch between the anatomical and genetic evidence surprised the scientists, who are now rethinking human evolution over the past few hundred thousand years. It is possible, for example, that there are many extinct human populations that scientists have yet to discover. They might have interbred, swapping DNA. Scientists hope that further studies of extremely ancient human DNA will clarify the mystery. “Right now, we’ve basically generated a big question mark,” said Matthias Meyer, a geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a co-author of the new study. (via Baffling 400,000-Year-Old Clue to Human Origins - NYTimes.com)
Phobias may be memories passed down in genes from ancestors
Memories may be passed down through generations in DNA in a process that may be the underlying cause of phobias
Memories can be passed down to later generations through genetic switches that allow offspring to inherit the experience of their ancestors, according to new research that may explain how phobias can develop. Scientists have long assumed that memories and learned experiences built up during a lifetime must be passed on by teaching later generations or through personal experience. However, new research has shown that it is possible for some information to be inherited biologically through chemical changes that occur in DNA. Researchers at the Emory University School of Medicine, in Atlanta, found that mice can pass on learned information about traumatic or stressful experiences – in this case a fear of the smell of cherry blossom – to subsequent generations. The results may help to explain why people suffer from seemingly irrational phobias – it may be based on the inherited experiences of their ancestors. (via Phobias may be memories passed down in genes from ancestors - Telegraph)
DNA hint of European origin for dogs
The results of a DNA study suggest that dogs were domesticated in Europe. No-one doubts that “man’s best friend” is an evolutionary off-shoot of the grey wolf, but scientists have long argued over the precise timing and location for their emergence. The new research, based on a genetic analysis of ancient and modern dog and wolf samples, points to a European origin at least 18,000 years ago. Olaf Thalmann and colleagues report the investigation in Science magazine. It adds a further layer of complexity to the story. (via BBC News - DNA hint of European origin for dogs)
Scientists are starting to understand why one person’s face can look so different from another’s.
Working on mice, researchers have identified thousands of small regions of DNA that influence the way facial features develop. The study also shows that tweaks to genetic material can subtly alter face shape. The findings, published in Science, could also help researchers to learn how facial birth defects arise. The researchers said that although the work was carried out on animals, the human face was likely to develop in the same way. Professor Axel Visel, from the Joint Genome Institute at the Lawrence Berkeley National Laboratory in California, told BBC News: “We’re trying to find out how these instructions for building the human face are embedded in human DNA. “Somewhere in there there must be that blueprint that defines what our face looks like.” (via BBC News - Light shed on how genes shape face)
Scientists discover DNA body clock
Newly discovered mechanism could help researchers understand ageing process and lead to ways of slowing it down
A US scientist has discovered an internal body clock based on DNA that measures the biological age of our tissues and organs. The clock shows that while many healthy tissues age at the same rate as the body as a whole, some of them age much faster or slower. The age of diseased organs varied hugely, with some many tens of years “older” than healthy tissue in the same person, according to the clock. Researchers say that unravelling the mechanisms behind the clock will help them understand the ageing process and hopefully lead to drugs and other interventions that slow it down. Therapies that counteract natural ageing are attracting huge interest from scientists because they target the single most important risk factor for scores of incurable diseases that strike in old age. “Ultimately, it would be very exciting to develop therapy interventions to reset the clock and hopefully keep us young,” said Steve Horvath, professor of genetics and biostatistics at the University of California in Los Angeles. Horvath looked at the DNA of nearly 8,000 samples of 51 different healthy and cancerous cells and tissues. Specifically, he looked at how methylation, a natural process that chemically modifies DNA, varied with age. (via Scientists discover DNA body clock | Science | theguardian.com)
From biology class to “C.S.I.,” we are told again and again that our genome is at the heart of our identity. Read the sequences in the chromosomes of a single cell, and learn everything about a person’s genetic information — or, as 23andme, a prominent genetic testing company, says on its Web site, “The more you know about your DNA, the more you know about yourself.” But scientists are discovering that — to a surprising degree — we contain genetic multitudes. Not long ago, researchers had thought it was rare for the cells in a single healthy person to differ genetically in a significant way. But scientists are finding that it’s quite common for an individual to have multiple genomes. Some people, for example, have groups of cells with mutations that are not found in the rest of the body. Some have genomes that came from other people. “There have been whispers in the matrix about this for years, even decades, but only in a very hypothetical sense,” said Alexander Urban, a geneticist at Stanford University. Even three years ago, suggesting that there was widespread genetic variation in a single body would have been met with skepticism, he said. “You would have just run against the wall.” (via DNA Double Take - NYTimes.com)
Seven Molecules’ Claim to Fame Chemistry: These infinitesimal celebrities shape us and our world.
From drinking water to DNA, from caffeine to carbon dioxide, and from Lipitor to Viagra—that is from atorvastatin to sildenafil citrate—molecules define our personalities, regulate our abilities, and dictate our feelings. Invisible to the human eye, many of them are biological celebrities: They famously smell or stink, make us feel depressed or elated, pollute our planet or save our lives. Even the most destructive molecules are so essential to our civilization that modern industry wouldn’t exist without them. Here we describe seven of the most prominent corpuscular figures, without which our life would be completely different. In fact, without some of them, scientists say, there’d be no human life at all.
DNA study suggests hunting did not kill off mammoth
Researchers have found evidence to suggest that climate change, rather than humans, was the main factor that drove the woolly mammoth to extinction.
A DNA analysis shows that the number of creatures began to decrease much earlier than previously thought as the world’s climate changed. It also shows that there was a distinct population of mammoth in Europe that died out around 30,000 years ago. The results have published in the Proceedings of the Royal Society B. The view many researchers had about woolly mammoths is that they were a hardy, abundant species that thrived during their time on the planet. But according to the scientist who led the research, Dr Love Dalen of the Swedish Museum of Natural History, the study shifts that view. “The picture that seems to be emerging is that they were a fairly dynamic species that went through local extinctions, expansions and migrations. It is quite exciting that so much was going on,” he told BBC News. Dr Dalen worked with researchers in London to analyse DNA samples from 300 specimens from woolly mammoths collected by themselves and other groups in earlier studies The scientists were able to work out how many mammoths existed at any given time from the samples as well as tracing their migration patterns. They looked at the genetic diversity in their samples - the less diverse the lower the population (via BBC News - DNA study suggests hunting did not kill off mammoth)