Scientists Discover Evidence of Oldest Life on Earth

To find life on other planets, scientists may want to search earth first.

Rusty tubes from northeastern Canadian hydrothermal vent deposits that represent the oldest microfossils and evidence for life on Earth.

Matthew Dodd

Science nerds are still giddy from last week’s discovery of seven earth-sized planets orbiting a nearby star, in part because it brings researchers closer to the most tantalizing question of all: How can we find life on other planets?

It would help if we had some idea of how life started on earth. A geological breakthrough announced on Wednesday in Nature makes that question slightly easier to answer. Scientists examining the chemical makeup of some of the Earth’s oldest rocks, located in northeastern Canada, may have found the oldest-known chemical fossils of bacteria. The team believes they are the remains of microbes that thrived near volcanic vents on the sea-floor from 3.8 to 4.3 billion years ago.

This patch of iron-rich rock found in northwestern Canada contains the oldest evidence of life on earth. The greenish rock (upper right) was formed from sea floor volcanic vents that gave microbes a place to thrive 3.8 billion years ago—and still do so today.

Dominic Papineau

Matthew Dodd, a Ph.D. student at the London Centre for Nanotechnology, and seven colleagues offered several lines of evidence to support their claim. The chemical patterns they found look just like known deposits of vent-loving microbes in much more recent samples from other locations. And the compounds they identified through laser imaging are consistent with the waste and remains of iron-eating bacteria that live near hydrothermal vents today.

The new discovery breaks the record for evidence of life on Earth by at least 300 million years. Previously, scientists dated microfossils found in western Australia to about 3.5 billion years ago.

As geologists push the proof of life farther back in time, and as astronomers pivot from finding planets to studying the chemicals they're made of, these far-flung fields of science will increasingly converge on the search for life elsewhere. The authors conclude their paper by inviting astronomers to join in their research. "Given this new evidence ... ancient submarine-hydrothermal vent systems should be viewed as potential sites for the origins of life on Earth, and thus primary targets in the search for extraterrestrial life."  

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