Life Traced to Hot Bacteria With Bad Smell

Every living thing on Earth is descended from bacteria that probably thrived in near-boiling water and raised a stench like rotten eggs, a new study suggests.

The organism, which apparently lived at least 3.5 billion years ago, was the last ancestor shared by all of today’s life forms, researcher James Lake said.

“What we’ve been able to do is get at the very bottom of the evolutionary tree that relates all known organisms,” said Lake, professor of molecular biology at UCLA.

While the organism was not the origin of life, he said, “it’s as far back as we’ve been able to get. Everything is related to it.”

‘The Deepest Branches’

His conclusions come from analyzing evolutionary changes in material found in every living cell. The effort required more than 1 million comparisons of material from different organisms.

The research, which produced a new evolutionary family tree, is reported in today’s issue of the British journal Nature.

“It just gives us a new picture of the deepest branches in the tree of life and how they’re related to one another,” said Allan Wilson, biochemistry professor at the University of California, Berkeley, who has used methods like Lake’s to trace human lineage.

Lake said the ancient ancestors probably resembled today’s one-celled organisms called eocytes, which live in geothermal hot springs.

Rotten-Egg Smell

Like eocytes, the organism probably lived in very hot water and got energy by processing sulfur, Lake said. That would produce hydrogen sulfide gas, giving a rotten-egg smell to the springs, he said.

The work also suggests that life may have begun in similarly high temperatures, he said.