Eggstracting ancient DNA

Scientists have successfully extracted ancient DNA from fossil eggshells for the first time, as reported this week in Proceedings of the Royal Society B.  The discovery has the potential to provide exciting new insights into the characteristics of some of the heaviest birds to have ever existed, including the Madagascan elephant bird and the New Zealand Moa – both now extinct.

While the idea that we could resurrect extinct creatures using fossilised DNA may be more science fiction that science fact, ancient DNA can nonetheless tell us a huge amount about a species’ diet and the kind of environmental conditions they lived in.  Recent studies have shown that DNA can be successfully extracted from ancient feathers, hair and nails, but up to now, nobody has ever extracted DNA from fossil eggshell.

The research team, led by Charlotte Oskam at Murdoch University in Australia, focused on the fossilised eggs of giant birds because their great size and thickness means that they are more likely to be preserved than other species’ eggshells.  It was previously thought that many Australian locations in particular had the wrong sort of climate for preserving ancient DNA, but the authors state that “bird eggshell has the potential for long-term DNA preservation in a number of often hostile environments that have not traditionally been conducive to long-term DNA survival”.

Eggshell acts as a natural barrier to water and oxygen which means that it’s excellent at preserving biomolecules, including DNA.  Furthermore, the authors of the study speculate that the anti-microbial properties of present-day eggshell may persist in its fossilised form, which greatly reduces the problem of bacterial DNA contaminating that of the species being studied.  The team now hope that future research will centre on refining the experimental procedures so that DNA can be extracted from eggshells in the most efficient way possible, as well being as undisruptive as possible to precious fossil specimens.