Word: dna
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...this on anecdotal stuff ..." Recently, he was emailed pictures of a chimp with a pug-dog's head and a seal sprouting a gorilla's face. "Clearly, someone thinks we're a joke," he says. An analysis of hairs found in the ground nests identified their mitochondrial DNA (mtDNA) as East African chimpanzee. Williams counters that finding with three arguments: the DNA could have been contaminated, the use of human genetic markers might mask hidden differences, and mtDNA would not show variation in the paternal line. "Until we know the father's lineage...
...important new study shows that folk wisdom and subjective judgment may, in this case, be right. Writing in last week's Proceedings of the National Academy of Sciences, a team of scientists reported that long-term, unrelenting stress on mothers can damage the DNA of their immune-system cells in a way that may speed up the aging process. "It's an immensely exciting result," says Robert Sapolsky, a Stanford University cell biologist who wrote a commentary accompanying the report...
Even after the scientists corrected for factors such as age and body-mass index, those crucial cells looked different--in three important ways--in the women who reported the highest stress levels. First, the cells had shorter telomeres--bits of DNA that cap the ends of chromosomes. In lab experiments, scientists have shown that telomeres get a bit smaller every time a cell divides, and that when telomeres are worn out, cells can't divide anymore and ultimately die. In humans, older people tend to have shorter telomeres--and by this measure, the most stressed women in the study...
Finally, the stressed women's cells had higher levels of free radicals, a type of highly reactive molecule that can damage DNA. One might argue that women whose children were born with those disorders already had something wrong with their DNA and that stress wasn't the cause. But that wouldn't explain another crucial fact: the degree of cellular damage was highest in women who had been caring for a disabled child the longest. "We tried our hardest to make the result go away," says Blackburn, "because we wanted to make sure we weren't fooling ourselves...
Despite its intensity—the class studied DNA samples, excavated artifacts and performed four-hour labs every day—the course wasn’t all work...