US scientists may have resolved 'Darwin's dilemma'

Fox News ^ | 11/15/2014 | By Matt Cantor

[SeekAndFind]

Charles Darwin worried about a possible hole in his theory of evolution, but some American scientists may just have plugged it. For about a billion years after the dawn of life on Earth, organisms didn't evolve all that much.

Then about 600 million years ago came the "Cambrian explosion." Everything changed relatively quickly, with all kinds of plants and animals emerging—which doesn't quite seem to fit with Darwin's theory of slow change, hence "Darwin's dilemma." Now, within a few days of each other, two new studies have appeared that could explain the shift, ABC News reports.

One, by scientists at Yale and the Georgia Institute of Technology, suggests that oxygen levels may have been far less plentiful in the atmosphere prior to the Cambrian explosion than experts had thought.

The air may only have been .1% oxygen, which couldn't sustain today's complex organisms, indicating a shift had to happen before the "explosion" could take place.

In a separate study, a University of Texas professor explains where that oxygen burst may have come from: a major tectonic shift. Based on geological evidence, Ian Dalziel believes what is now North America remained attached to the supercontinent Gondwanaland until the early Cambrian period, in contrast with current belief, which has the separation occurring earlier.

[alexander_busek]

Fiddle. My question is why did some fish leave the ocean to become land mammals and some land mammals leave land to become fish mammals ..... as we were taught.

Are you disputing that they did? Are you questioning the fact that cetaceans possess a vestigial pelvis?

Regards,

[BroJoeK]

Big Red Badger: "So, my point is: Why has EVOLUTION Stopped ?"

Whoever told you that evolution has stopped should have known better.
The basic processes of evolution -- descent with modifications and natural selection -- continue with every newborn offspring.

[GeronL]

But even this article says there was no real evolution for 600 million years before the “Cambrian explosion”.

Isn’t that suppose to be impossible?

[mlo]

"Yea, that's science . . ."

Yes it is. Making hypothesis based on evidence and testing them. Not assuming certainty. That's how it works.

[BroJoeK]

SkyDancer: "My question is why did some fish leave the ocean to become land mammals and some land mammals leave land to become fish mammals ..... as we were taught."

Even today, some fish & other aquatic critters spend parts of their lives on land, and many land critters spend parts of their lives in water.
So why do they do it?
To find food.
To escape preditors.
And, that most powerful reason of all -- looking for love!

So once fish are spending some parts of their lives on land, then those which grow better lungs & legs get around better, find more food, and eventually, hey! Who needs that cold water anyway, why go back?

As for reptiles, birds & mammals which went the other way, the reasons were the same -- once you make your living in the water, then any new adaption to improve your swimming ability helps find more food, etc., etc....

Does that answer your question?

[BroJoeK]

freedumb2003: "This time, I’ll just grab some popcorn..."

;-)

[SkyDancer]

Nope - they all should have done it, not just a few ....

[SkyDancer]

Nope. Evolutionary scientists did. Why didn’t all creatures then flip? Why only some? And are you disparaging Kim Kardashian? Sexist.

[BroJoeK]

ClearCase_guy: "This is all conjecture.
Science has become the art of interesting guessing."

In scientific terminology, a "fact" is a strongly confirmed observation -- we know it's true because we've seen it, measured it, etc.
For examples, fossils are facts, and so is DNA.

The words "hypothesis" and "theory" describe explanations for those facts.
"Hypothesis" is a testable explanation -- testable by predictions which are confirmed or falsified through experiments or discoveries of new facts.
If a hypothesis gets confirmed, it's promoted up to "theory", but if falsified, then it remains as a discredited hypothesis.

Doubtless, the new facts this article reports on are evidence of suddenly higher oxygen levels during the Cambrian, and a different interpretation as to the splitting apart of Gondwanaland.
Others have also noted the Cambrian explosion came relatively soon after the melting of "snow-ball Earth", so now we are talking about, ahem, global warming and atmospheric pollution with, well, oxygen.

So don't tell me "climate change" is some kind of new phenomenon -- until they find fossilized SUVs from back then! ;-)

[Texas Eagle]

For about a billion years after the dawn of life on Earth, organisms didn't evolve all that much.

Ohhhhhhh. That explains it.

Who writes these "scientists" stuff? Jonathan Gruber?

This isn't science, this is theorizing.

Which I believe is Latin for, "throwing stuff against a wall and seeing what sticks".

[Texas Eagle]

two new studies have appeared that could explain the shift

Or it could not. This is why I hated science.

I guess I'm one of those weird people who want to KNOW why stuff happens.

[BroJoeK]

aimhigh: "One, by scientists at Yale and the Georgia Institute of Technology, suggests that oxygen levels may have been . . The air may only have been . . . . oxygen burst may have come from . . .Yea, that's science . . ."

No real scientist claims to have all the answers, or puts more weight on his hypotheses than they deserve.
Words like "may" and "suggest" tell us we are looking at interesting hypotheses, not confirmed theories or observed facts.

Taken with the appropriate understandings, I think it's all fine.

[ctdonath2]

6000 years is just a mere 60 hundred-year lifespans back to back. That’s not very long at all, plainly inconsistent with what’s around you.

[Big Red Badger]

Then Why do We wring our hands over endangered Species?

We should Celebrate the dodo Bird !

More room for Mutants!

Celebrate Obsolete Species!

[Hugin]

Assuming that eyeballs occurred in random placement all over, the organisms with them placed to give the maximum survival benefit would survive at a higher rate, and reproduce more, passing that trait on to more offspring. Those with eyeballs elsewhere would be eaten before they could reproduce.

[laweeks]

Those with eyeballs elsewhere would be eaten before they could reproduce.

The mere fact that they even had that design, times 2, and would be linked to a central processing area that would provide the overall organism with a method to "see" what's going on, makes Darwin look like a jackass

[Hugin]

Wrong. Jellyfish have eyes but no brain. The information collected by the eyes goes directly to the muscles which react without it being processed.

[arthurus]

That shift would have put more oxygen into the atmosphere, per a press release,

WOW! it was done with a Press Release! Obama must have made that happen.

[arthurus]

Poul Anderson wrote better than that.

[eartrumpet]

I could use an eyeball on my palm. It could be stuck up above tall grass and bushes to look around, it could be shoved in a hole, peek around a corner, slipped underwater. It would be a huge advantage. But no, when I stick my head in a cave, a tiger bites it off.