Evolutionary dating how accurate
In particular, they may force a widespread re-examination of determinations about when one species split off from another, if that determination was based largely on genetic evidence.For years, researchers have been using their understanding of the rates of genetic mutations in cells to help date ancient biological samples, and in what’s called “phylogenetic comparison,” used that information along with fossil evidence to determine the dates of fossils and the history of evolution.These penguins live in massive rookeries, have inhabited the same areas for thousands of years, and it was comparatively simple to identify bones of different ages just by digging deeper in areas where they died and their bones piled up.For their study, the scientists used a range of mitochondrial DNA found in bones ranging from 250 years to about 44,000 years old. - Penguins that died 44,000 years ago in Antarctica have provided extraordinary frozen DNA samples that challenge the accuracy of traditional genetic aging measurements, and suggest those approaches have been routinely underestimating the age of many specimens by 200 to 600 percent.In other words, a biological specimen determined by traditional DNA testing to be 100,000 years old may actually be 200,000 to 600,000 years old, researchers suggest in a new report in Trends in Genetics, a professional journal.The findings raise doubts about the accuracy of many evolutionary rates based on conventional types of genetic analysis.
“We now think that many genetic changes were happening that conventional DNA analysis did not capture.
They were fairly easy to use and apply but also too indirect, and inaccurate as a result.” This conclusion, researchers said, was forced by the study of many penguin bones that were well preserved by sub-freezing temperatures in Antarctica.