One of the big unsolved problems inn science is how ‘life’, or more precisely, the first self-replicating molecular, came into being. Popular theories suggest, among other things, that life originated in deep underground thermal vents.
Via Machines Like Us I came across this article that suggests another possibility of how life began on Earth and possibly other planets. It says it might have happened in hollow tubes of ice called ‘brinicles’ that grow downward in the oceans near the poles, creating what the authors call a ‘chemical garden’ that has the ingredients necessary for producing life.
The origin of life is often proposed to have occurred in a hot environment, like the one found in hydrothermal vents. It is proposed that chemical-garden processes are involved in the mechanism. But there is a different school of thought that presents sea ice as a promoter of the emergence of the first life. Brine rejection in sea ice produces all the conditions that are considered necessary for life to appear.
The origin of life is a difficult problem and one should not think this is the solution. It could well be wrong. But the point is that people who think that scientists have no clue as to how life could have originated and that therefore a god must have done it are quite wrong. People are exploring all manner of avenues.
Earth’s crust solidified around 4.1 billion years ago. Life arose soon after that, between 3.9 and 3.6 BYa, while the planet was cooling but still quite hot. I’m not sure how water ice could have existed in the most likely conditions, even at the poles.
From what evolution shows us, nature doesn’t have any qualms about following different paths in parallel. It might be undersea vents that trigger life on one planet, and brinicles on another. Or even both. The universe is so big it’s probably reasonable to assume that every possible way life could arise has been done, repeatedly, and that some mechanism is probably more likely and therefore happens more often.
Right — the “answer” to the question could well be “yes”. Multiple pathways.
We know for sure that there’s probably no single least common ancestor. The amount of horizontal gene transfer (non-Darwinian) is likely to be substantial in any model.
From there, it’s more of a chemistry problem than a biology problem. What we do know is that RNA/DNA “won” over prior or competing self-replicating systems. And that there was a LOT of raw material to go around for all kinds of experiments. Hot experiments, cold experiments, experiments in clay, experiments in “warm ponds”, experiments with lightning, experiments without lightning. Some or many of them could have resulted in “a” solution — if not necessarily “the” solution.
Of course, you’d be hard-pressed to get anyone to commit to a clear definition of what “life” is — or how you would know “life” from “inanimate self-replicating molecule”. Like evolution, it’s likely to be a boundary-less country.
In case people haven’t seen one of these brinicles forming before, they are amazing:
When I first saw the Nova episode about life at thermal vents back in the 80’s I thought that life might have have started at thermal vents. I am quite happy with the idea that life might have had a Chthonic origin in the heat of Gaia and Hades, rather than an being born of Olympian lightning,
i know how life started. i was there. and i read Mano’s post on how to confuse creationists.
Do you have any more info on the claim that “we know for sure there is probably no single least common ancestor?” I’m assuming that term simply means last common ancestor for all life -- -- the proto cell, basically.