Resurrecting Life in the "Valleys of the Dead"
A team of scientists led by Rutgers University's Paul Falkowski has identified signs of life in the oldest ice sample ever studied. After extracting ice from the Upper Beacon Valley in Antarctica, they used a range of dating techniques to show that the samples ranged from 100,000 years old to about 8 million years old — making the latter the oldest studied ice sample. The scientists were surprised to find live bacteria in both after they melted the samples and — after adding nutrients to the meltwater — noted that the bacteria began to grow again though the ones in the oldest ice grew much more slowly (doubling every 1-2 months versus every week).
They also found that the DNA present within the oldest microbes degenerated over time — an effect Falkowski attributes to cosmic radiation, which is especially strong at the Earth's poles. Comparing the DNA found within 5 ice samples from various ages, they discovered that while the bacteria in a 100,000-year-old sample contained fragments with an average length of 18,500 base pairs, those in the oldest sample had fragments with an average length of just 210 base pairs. If correct, Falkowski's theory would challenge the idea that life on Earth was sowed by extraterrestrial life forms — known as panspermia.More suprisingly, Falkowski and his colleagues found that there were few matches between the genetic sequences extracted from the bacteria in the ice and those from modern-day bacteria — which indicates that the former may have had novel genes. These genes may have been periodically reintroduced into the environment when the frozen microbes would thaw, affecting the evolution of modern microbes — leading Falkowski to hypothesize that the Antarctic ice served as a "gene Popsicle" that could be taken in by bacteria when the ice melts.
Could this study and others lead to the discovery of novel genes that could impart some new knowledge or ability as yet undiscovered in modern-day bacteria? If nothing else, these samples should help better elucidate what the conditions on Earth were like millions of years ago and, hopefully, shine some light on what we can expect to see in the future.
See also: ::Break-up Of Antarctic Ice May Expose Marine Life To More Sunlight, ::Antarctic Warming to Reduce Animals at Base of Ecosystem, Shift Penguin Populations
Image courtesy of adactio via flickr