UW-Madison Scientists Help Confirm Oldest Fossils

University of Wisconsin-Madison scientists have helped confirm that tiny fossils detected in an Australian rock are the oldest fossils ever found.

The microscopic fossils were first identified nearly 25 years ago, in a rock that’s 3.5 billion years old.

Some scientists have questioned whether the fossils were just minerals. But researchers from UW-Madison and the University of California, Los Angeles have used a hi-tech device called a secondary mass ion spectrometer (SIMS) to determine the fossils are indeed ancient bacteria and microbes.

UW-Madison geology professor John Valley co-led the study.

“We’ve shown that they in fact have the exact geo-chemical fingerprint that we expect for life on earth,” Valley said Tuesday. “That really rules out the inorganic processes.”

Valley said the research took 10 years. But he still calls it very exciting.

He said the findings help show life has been around much longer than many thought possible.

“For a long time, it was believed life formed pretty recently on Earth, within the last 500 million years. And over the last really, 50 years, the earliest life has been pushed back, as we understand it’s formed earlier and earlier.” Valley says.

He added that more research he hopes to complete could show fossils that are even older than his recent discovery.

The study was published this week in the Proceedings of the National Academy of Sciences.