Study Puts Hole In Comet Theory Of Life's Origin

Astervitude writes "A new study by US and Japanese scientists has put a serious dent into one version of the popular panspermia theory that credits comets for bringing the seeds of life to Earth. Surveys conducted by the University of Arizona, the National Astronomical Observatory of Japan and others now show that objects from the main asteroid belt between Jupiter and Mars were largely responsible for the period of Late Heavy Bombardment that ended 3.9 billion years ago. UA Professor Emeritus Robert Strom believes that no more than 10 percent of the Earth's water comes from comets and any oceans then extant would have been 'vaporized by the asteroid impacts during the cataclysm.'" Interesting, because this directly contradicts the Nova mini-series Origins that just finished running on PBS. Science never stops moving.

Comments

Re:Why

[sbaker]

> Why would it be easier to believe that life began elsewhere
> than to assume that life started here on Earth?

Two reasons:

1) We have some idea of the early conditions on Earth - but maybe
      we have a hard time believing that those were conducive to
      forming life from scratch. If life started elsewhere then there
      is almost no limit to the range of concievable temperatures, pressures,
      gravity, radiation and chemical environments in which it might
      ultimately have formed.

2) Time: Is the Earth old enough for that very early phase of going
      from completely non-biological materials to DNA, cell walls, etc?
      If not - then panspermia explains that by saying that life was
      around in some other place LONG before the Earth was formed.

So panspermia allows for a scientific explanation of life's formation
that is perhaps more plausible than formation on early Earth.

Re:So why does this contradict panspermia?

[PakProtector]

Yes, but, as you point out, the Problem with the Idea of Panspermia is that it does not explain how life arose -- it just shifts the blame for it (as it were) elsewhere.

Re:Heh.

[Tatarize]

Personally I always hate panspermia. It seemed to fail Occams Razor pretty soundly. Yes, life on this planet came from an asteroid or comet from another planet. Well, if life can exist there to bring it here why can't it just develop here. Seemed like a big waste of time to me. I see no reason we cannot have a homegrown abiogensis on good old Earth. It's not like we hit some major hitch and need an alternate explanation that explains nothing.

Science never stops moving?

[jaymzter]

That's an interesting comment that glosses over many of the statements of science that are commonly excepted so much as "fact" that anyone that points out inconsistancies in them is labeled as anti-science or ignorant. Of course we are always learning more and yesterday's accepted theories have to adapt to new knowledge, but the virulence some people have for defending pet theories borders on intolerance.
A good case in point is evolution, where if you don't mention it in a glowing light on /. you get modded into oblivion. Please note I didn't relate it to Creationism or Intelligent Design, it's just that the theory of evolution itself has about as many holes as IE. Sure, right now it's the best idea going, but that doesn't mean it's the end of the conversation. Yet questioning it all usually does end the conversation.

Re:Genesis Therories

[Doc Ruby]

People have to understand what "we know" means. Adults have to take everything we hear with some number of grains of salt. Scientific statements of "we know" are more reliable than metaphysical statements of "we know", and adults should understand that for ourselves.

Which is why it's important for people to learn about science before tehy accept its knowledge. Just like it's important for us to learn about religion. Not just to learn the science, like reading it in _Discover_ magazine, or to learn the religion, like reading it in a bible. But we need to learn how the "knowledge system" works: its history, its failures, its successes, its alternatives and their histories. Just like we don't need to learn enough science to be scientists in order to appreciate science (and our world that it explains), we don't need to become experts in the discipline, to become scientists or clerics. We need to understand what the strengths and limitations are, and what it means when a scientist or a cleric says "we know", "I believe" or "this is". Otherwise, we're just faking it, and we will make all kind of mistakes, without ways to recover. And that's very dangerous, considering how powerful are these ways of knowing, whether they're right or (especially when) they're wrong.