The Deep Seafloor Turns Out to Be a Treasure Trove for Ancient DNA

DNA preserved in the the ocean floor could provide a unique view of ancient animals that aren’t represented in the fossil record

A modern day foraminiferan species. Photo: Scott Fay

Researchers have discovered a jackpot of ancient DNA buried under 5,000 meters of Atlantic water and the sea floor, ScienceNOW reports. The genetic material once belonged to single-celled sea animals that lived around 32,500 years ago. This is the first time ancient DNA has been recovered from such oceanic depths.

The researchers uncovered the samples from silt and clay deposits. They analyzed their samples for traces of DNA specific to two groups of single-celled organisms—foraminifera and radiolarians—using genetic sequences from modern, related organisms to identify the DNA they were after. Their analysis turned up 169 foraminifera and 21 radiolarian species, ScienceNOW reports, many of which are new to science.

Where there is some DNA, the researchers reason, there must be more.  If they’re correct, the deep sea could constitute a treasure trove of long-buried DNA waiting to be discovered. Such DNA, the team told ScienceNOW, expands scientists’ ability to study ancient biodiversity.

Significantly, the existence of some of these newly discovered species isn’t well documented in the fossil record. Since fossils only preserve animals with hard structures—bones, shells, exoskeletons—DNA preserved in the vast stretches of the ocean floor could provide a unique view of animals otherwise lost to the millennia.

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