Origins of Life Thermal Vents or Warm Ponds

Early on scientists thought that life probably first developed in warm ponds on land. Then, after hot thermal vents were found deep in the oceans, scientists started to think that they would be better candidates. Now, though, research is turning attention back to those warm ponds -- or more specifically, hot springs, which would be a sort of combination of the two earlier targets of research.

Armen Mulkidjanian at the University of Osnabruck in Germany says there is a fundamental problem with the ocean floor hypothesis: salt. The cytoplasm inside all cells contains much more potassium than sodium. Mulkidjanian thinks that reflects the chemistry ofthe water life first appeared in, yet seawater is sodium-rich and potassium-poor.

"The ancient sea contained the wrong balance of sodium and potassium for the origin of cells," says Mulkidjanian. Now, after extensive field studies, he claims to have found the one place on Earth where that balance is right: in the thermal springs of Kamchatka in far-east Siberia.

The theory solves another puzzle. Most biologists agree that the earliest life would have been little more than floating strands of DNA and RNA. The nucleotides that make up DNA and RNA are all surprisingly stable when exposed to UV light, suggesting they evolved in an environment where UV exposure weeded out all but the most photostable molecules. "You don't get UV light around deep-sea vents," says Mulkidjanian.

Others also believe recent evidence calls into question a marine origin for life. "I do not think the oceans were a favourable environment for the origin of life - freshwater ponds seem more favourable," says Nobel laureate Jack Szostak at Harvard University, a key player in the field. Szostak is trying to create artificial versions ofthe first cells, membranes and all. "Freshwater ponds," he says, "have lower salt concentrations, which would allow for fatty-acidbased membranes to form."

Source: New Scientist, February 18, 2012

There are some problems with this, of course -- the most obvious of which is the fact that finding "good" conditions somewhere on earth today doesn't tell us much about the early earth and what conditions existed then. At most it demonstrates that such an environment might have been possible somewhere, though the extreme overall conditions of the early earth have to render that questionable.

Not everyone involved in research on the origins of life agrees with Mulkidjanian. Quite a few find it intriguing, but others dismiss it. Many wouldn't even bother commenting on Mulkidjanian's research when contacted for the above story. But even if he turns out to be wrong, his ideas might lead scientists down a more fruitful path. So this is probably worth paying attention to and remembering.