美国国家公共电台 NPR Tiny Fossils Could Be Oldest Evidence Of Life On Earth（在线收听）

STEVE INSKEEP, HOST:

We have news this morning about the origin of life. The news is about just how hard it is to find that news. NPR's Rae Ellen Bichell reports.

RAE ELLEN BICHELL, BYLINE: Things get hairy when you go looking for the earliest forms of life on Earth. Life forms would have been tiny, embedded in rocks that have been squished and cracked for billennia. But Matt Dodd, a bio geochemist at University College of London, thinks he's got it.

He and his colleagues write in the journal "Nature" that they've found tiny fossils in Canada wedged in rocks that are 3.7 billion years old. Some look like tubes, others like strings or spirals. Dodd says the shapes resemble bacteria alive today, like those that live on underwater vents near Hawaii. This life wouldn't have been much to look at.

MATT DODD: A spongy, kind of gloopy (ph) soup, if you like.

BICHELL: But if they really are fossils, the specimens could show that life got its start really early on.

DODD: The implications of this work have answers, not just to how life originated on Earth and when. But also, is there life elsewhere in the universe?

BICHELL: If life could start on Earth in those conditions, then why not in ancient oceans on Mars, too? But like other claims along these lines, the study has a lot of skeptics. Tanja Bosak, a geo biologist at MIT, isn't convinced. She says it's possible the shapes were just formed when minerals spewed out of hydrothermal vents.

TANJA BOSAK: The big problem is the understanding of what can create all sorts of very simple shapes in rocks.

BICHELL: Like similar fossils found in other parts of the world, these Canadian fossils are going to have to undergo the scrutiny of a lot of skeptical scientists. Rae Ellen Bichell, NPR News.

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