ASTEROID IMPACT PLAYED PIVOTAL ROLE IN RAPID PROLIFERATION OF LIFE

The Australian Centre for Astrobiology ^ | May 2003 | The Australian Centre for Astrobiology

[Junior]

Environmental stress. It can be a powerful evolutionary catalyst.

[CobaltBlue]

If true, where did the asteroid come from? I am under the impression that most, if not all, asteroids come from within our own solar system.

At work now so don't have time to research this.

[Mike Darancette]

Actually, birds kinda ran things for a short time after the demise of the dinosaurs.

Birds were top predator for a short time world wide and for quite a while in what was then a geographically isolated South America. But birds did not radiate many species to fill other ecological niches.

Mammals basically radiated to fill all ecological niches and quickly gained ascendancy.

When South America was finally connected to North America the Big Cats quickly gobbled up the Terror Birds.

[r9etb]

Environmental stress. It can be a powerful evolutionary catalyst.

But again -- the ice age they're talking about was an extreme environmental stress, too, and they note that diversification didn't occur afterwards. This particular claim seems to tie diversification the asteroid impact.

Which is fine, but let's just be clear about the underlying assumptions of the claim.

[Mike Darancette]

If true, where did the asteroid come from?

That is not relevant to the premise of the article.

[AppyPappy]

I guess we are all Triffids

[Junior]

There are a couple of ways of looking at this:

The ice age was a gradual thing and the various species extent at the time had plenty of time to adapt. The meteor impact threw that whole primordial paradise into a tizzy, stressing the environment and rendering some species extinct and opening up new ecological niches to the survivors.

Or, rapid speciation had already occurred in an isolated environment (a lake or small sea) while species in the outside world went on their fat, dumb and happy ways. When the asteroid hit it not only stressed the latter group but opened up the wider world (and new ecological niches) to the formerly isolated group.

Or, much like the last scenario, but with a group from the wider world being geographically isolated by the asteroid impact, and rapidly evolving in isolation (small groups evolve much more rapidly because changes are not as readily lost as they are in larger gene pools). Later this group rejoined the world at large.

[jlogajan]

That's not what the lady said. She said that after the ice age and before the impact, there were really simple things like algae and bacteria and stuff, and no evidence of diversification

There was no selection pressure favoring the new mutants. They were born and died out, ending their genetic influence, or limited to very small populations who didn't happen to leave a fossil record.

When conditions change, those few mutants who earlier may have had relatively expensive requirements compared to their simpler cousins, suddenly had a survival or re-population advantage.

I think you'll find that most higher complexity organism have initially higher "expenses" and therefore have a hard time getting a toe hold in a well settled niche. But when something comes along and upsets the apple cart, those few who've managed to pay that initial expense can now exploit that capital.

Complexity of organization requires an initial investment. Simpler organism can get into production quicker, and so tend to win the early races. But they are often less robust in the face of changing conditions. The more complex creature was paying for some unused abilities, and suddenly that is the difference between life and death -- or at least speed to repopulate.

[f.Christian]

To: f.Christian

fC ...

science (( no change )) vs the study of science (( change )) !

dh ...

That's a silly quibble. The universe does whatever it damn well pleases, and hasn't the slightest demonstrated notion of what a law is to constrain it. Insofar as what is demonstrable, natural laws are human inventions to help us think more effectively about nature. The claim that they are objectively existing things in and of themselves, is unproven and probably unprovable--as is likewise the claim that there is such a thing as "science" which exists independently of "the study of science".


1,398 posted on 05/14/2003 10:36 PM PDT by donh (u)

fC ...

reminds me of the oj juror lady ... "design (( dna )) --- what design (( dna ))" -- ? ? ? ?

[Mike Darancette]

Well said. Think of it as Mother Nature kicking over the poker table and shooting out the lights.

[colorado tanker]

They don't really come out and say it, but it almost sounds like they're supporting Hoyle's theories about extraterrestrial origins for life on Earth.

I thought that's where this article was going too - we're all space aliens.

I guess the theory of this article is that the asteroid slapped the earth out of it's torpor, kinda like the scene in B movies when the guy slaps the gal and yells "snap out of it"!

[f.Christian]

retro spin ...

Liberalism is unrestrained (( evolution )) ideology (( manmade reason -- feelings )) ...

neo democrats ---fascists !

Motivation ...

these gods (( experts )) are UN - questionable -- UN accountable to nothing (( changes // whims )) -- no other (( atheists )) !

Make it up to suit their needs -- desires !

[CobaltBlue]

>>That is not relevant to the premise of the article.<<

Oh, come on now. It's possible that life on earth came from somewhere else, hitching a ride on an asteroid or meteorite or whatever and you aren't a teensy bit curious as to where our ancestors were living and whether they are still alive, and what's become of them?

[Mike Darancette]

It's possible that life on earth came from somewhere else, hitching a ride on an asteroid or meteorite or whatever and you aren't a teensy bit curious as to where our ancestors were?

But there was life on Earth BEFORE the Impact Event and Ice formation described in the article, life that was ancesteral to life that existed afterward.

As to how life first formed upon this planet ......

[AndrewC]

Actually, birds kinda ran things for a short time after the demise of the dinosaurs.

Come now. Let's get our stories straight. Birds are dinosaurs are they not?

Are Birds Really Dinosaurs?

Ask your average paleontologist who is familiar with the phylogeny of vertebrates and they will probably tell you that yes, birds (avians) are dinosaurs. Using proper terminology, birds are avian dinosaurs; other dinosaurs are non-avian dinosaurs, and (strange as it may sound) birds are technically considered reptiles. Overly technical? Just semantics? Perhaps, but still good science.

Isn't this making up stories just so much fun!!?

[billbears]

It's possible that life on earth came from somewhere else, hitching a ride on an asteroid or meteorite or whatever and you aren't a teensy bit curious

No. Because that didn't happen

[AndrewC]

But there was life on Earth BEFORE the Impact Event and Ice formation described in the article, life that was ancesteral to life that existed afterward.

Oh bother, such petty details!

Speaking of details. How deep was the ice sheet over snowball earth and how large was its extent?

[jwalsh07]

Small Bang Theory.

[Junior]

Okay. Birds are avian dinosaurs. The birds kinda ran things for a short time after the demise of the non-avian dinosaurs.

Better?