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Did Sea Life Arise Twice?
eldavojohn writes "Dr. Adam Maloof has found fossils of sea sponges in Australia from 650 million years ago. You might think this is no big deal unless you consider that sea sponges were thought to have arisen 520 million years ago. These fossils predate the oldest hard bodied fossils we have by a hundred million years. Dr. Maloof is now wondering if life might have arisen twice after the first attempt was quashed 635 million years ago: 'Since animals probably did not evolve twice, we are suddenly confronted with the question of how some relative of these reef-dwelling animals survived the Snowball Earth.' So how is it that life survived the Marinoan glaciation? The BBC has a video on the topic and Wikipedia has a time line of the Proterozoic Eon into the Paleozoic Era."
You know how they say evolution would be falsified by a bunny in the pre-cambrian.
Well, it's not a bunny, but it's not in the stratum it's supposed to be.
Time to stop teaching the discredited theory of evolution.
...because this is Slashdot this story will arise twice for sure. ;)
More likely, this is evidence that there never was a Snowball Earth. We've never been sure whether the entire Earth froze up or just large areas of it. If creatures lived through the glaciation, that's a good indication that unfrozen regions still existed.
Genocide Man -- Life is funny. Death is funnier. Mass murder can be hilarious.
When I discuss evolution-vs-creationism with some folks, the discussion sometimes steers toward the notion that the coming together of amino acids to form life is this *incredibly* improbable thing, and that it certainly needed the hand of a creator to ensure that it happened on a planet which could support it.
I then point out to them that *all* we know is that life has been created on this planet *at least* once. It may have happened a million times, for all we know. Out in that vast ocean, there are countless chances for it to happen every day and it very well *may* be happening. Who the hell knows? Any life that we may find out there in the oceans gets attributed to being descended from the *first* occurrence of life... but that might not really be the case.
So, this notion that life may have arisen twice? I don't find it shocking at all. Okay, I guess I'm a little piqued by the fact that researchers think that they hold *evidence* of it (since that's a little harder to do) but, like I said, I have a hunch this has happened millions of times since the "first time".
But scientists can usually tell different species. They may look superficially identical, but they have unique organs which indicate if it's the same species, or a different species that discovered the same niche.
I think the likely explanation here is that (1) it's the same species at ~500 and ~600 million years ago, and it did survive the extinction because (2) Snowball earth wasn't as harsh as we believe.... there were probably warm zones around the equator for a few sponges to hang-on.
"I disapprove of what you say, but I will defend to the death your right to say it." - historian Evelyn Beatrice Hall
OK, since I took the two seconds necessary to RTFA, the summary's title is wrong. TFA specifically says NOT that life evolved twice, but that the date the Earth was inhabited was pushed back.
Now I have to read your links, at least the first one. But as to the second,
Does this mean that life on other planets arises identically or near-identically to our own, or that the origin of life on earth comes from elsewhere?
There is no proof at all that life exists anywhere else except on earth. When and if we find life elsewhere, than we can make conjecture about panspermia, until then it's just science fiction. Not even junk science.
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***Most dating methods that are used routinely are accurate***
True, but unhelpful. Dating techniques useful for dating rocks deposited millions of years ago mostly depend on the use of "index fossils" (fossils that are widely distributed but change enough over time to pin a date down fairly closely.) Less commonly, radiometric dating can be used, but that requires that an event (typically volcanic) reset the atomic clocks in the rocks in question to zero. Since pouring lava over a fossil tends to destroy it, radiometrically dateable fossils aren't all that common. There are a few fossils found between lava flows or buried in volcanic ash that can be dated with fair precision. One especially important set is a collection of difficult to interpret fossils from 595Ma at Fortune Head Newfoundland.
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