Posted on 10/16/2003 7:33:43 AM PDT by AntiGuv
The Cambrian Explosion - when life suddenly and rapidly flourished some 550 million years ago - may have an explanation in the reaction of primitive life to some big event.
The explosion is one of the most significant yet least understood periods in the history of life on Earth.
New research suggests it may have occurred because of a complex interaction between components of the biosphere after they had been disturbed by, for example, the break-up of a super-continent or an asteroid impact.
Scientists say the life explosion might just have easily occurred two billion years earlier - or not at all.
Dramatic events
All modern forms of life have their origin in the sudden diversification of organisms that occurred at the end of the so-called Cryptozoic Eon.
Scientists have struggled to explain what might have happened in the previous few hundred million years to trigger such a burst of life.
Certainly, it was a period of history that witnessed the assembly and break-up of two super continents and at least two major glaciation events. Atmospheric oxygen levels were also on the rise.
But what actually caused the Cambrian Explosion is unknown.
Writing in the journal Geophysical Research Letters, Dr Werner von Bloh and colleagues, from the Potsdam Institute for Climate Impact Research, present a new analysis of happened.
They suggest that "feedback" in the biosphere caused it to jump from one stable state without complex life to one that allowed complicated life to proliferate.
"We believe that there was a change in the environment - a slow cooling of the system - that caused positive feedback that allowed the conditions for complex life," Dr von Bloh told BBC News Online.
Self regulation
Using a computer model of the ancient Earth, the researchers considered three components of the biosphere, the zone of life.
These were single-celled life with and without a nucleus, and multicellular life. Each of these three groups have different environmental tolerances outside which they cannot thrive.
The computer model showed there were two zones of stability for the Earth - with or without higher lifeforms - and that 542 million years ago the planet flipped from one to the other.
What caused the flip is not clear. It might have been a continental break-up, or even an asteroid impact.
There is some indication that the Moon suffered a sudden increase in impacts about the same time as the Cambrian Explosion. If so, then the Earth would have been affected as well.
This latest analysis also provides some support for the Gaia hypothesis - the idea that the biosphere somehow acts as a self-sustaining and regulating whole that opposes any changes that would destroy life on Earth.
Intelligent beings
Dr von Blow says that after the Cambrian Explosion there has been a stabilisation of temperature up to the present, and that the biosphere is not playing a passive role.
He also adds that there is an intriguing implication from his research which suggests that had the conditions been only slightly different, the Cambrian Explosion could have occurred two billion years earlier.
An early explosion would have meant that by now the Earth could have developed far more advanced intelligent creatures than humans.
Alternatively it could still be inhabited by nothing more complex than bacteria.
Dr von Bloh says that it will be of great interest when we find other Earth-like worlds circling other stars to see if they have had their own Cambrian explosions yet.
The timing of such events has implications for the search for intelligent life in space, he says.
I suspect that the events that took place before the Cambrian were unique. History doesn't exactly repeat itself. Time doesn't move backwards.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=18260
There is, in fact a good deal of HOX gene diversity arising after the Cambrian. The vertebrate lineage in general has multiple HOX clusters which arose by gene duplication; thoise of fishes are quite different from mice and humans.
Some more evo 'fact free science'. They do not know what the earth was like before, during or after, so that's good, because it makes any nonsense they say possible.
Jeech, can't these people get a real job?
Yes indeed, and this article is not science, it is fantasy. The fact is that there is absolutely no way that gradual Darwinian evolution can explain the humongous variety of living things which appeared within the short span of less than ten million years or why no new animal living forms have arisen since. The Cambrian completely disproves Darwinian evolution, Gould and Eldredge thought so and no Darwinist has ever been able to refute it or give evidence for the gradual evolution of the Cambrian fauna.
Indeed, "time doesn't move backwards" from our 4D perception, but dimensionality is a whole 'nother subject.
Do you have a preferred view of what the special Pre-Cambrian conditions might have been?
Or God.
Sequoit 7 <<<<< 47 q36, b17ssd18.
n5 6b 22 j3.
A lot of the professional disagreements in this business are about just such issues.
Difficult, if not impossible, because we don't really know how the environment will change (except in the very long term, when everything dies). The best I could do is predict that as the environment changes, any life that survives will -- of necessity -- be adapted to the conditions in that changed environment. That's not much of a prediction, but it's consistent with the theory of evolution.
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