Life's lucky 'kick start'

BBC News ^ | October 13, 2003 | Dr David Whitehouse

[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.

[steve8714]

Do you mean Gaia?(sarcasm alert)

[js1138]

Whatever became of the hypothesis that the direction of life flipped due to the production of oxygen?

[pgyanke]

Well then, it seems that everyone in history is lost... except for you.

[pgyanke]

Sarcasm noted. :-)

[AntiGuv]

The Iliad and the Odyssey have never been proven any more inaccurate than have been the Hebrew Testaments, do you therefore believe in the existence of Zeus and Ares and Athena and Poseidon?

[pgyanke]

Probably the same thing that happened to the theory that explained "Global Cooling" in the '70s.

[dirtboy]

But what actually caused the Cambrian Explosion is unknown.

Personally, I think it's rather simple. I believe that all the oxygen sinks present on Earth were finally filled, allowing sufficient atmospheric oxygen for larger animals to form.

[Bigh4u2]

"Whatever became of the hypothesis that the direction of life flipped due to the production of oxygen? "

But the production of oxygen did not 'create' life. It just gave it the conditions necessary to survive.

The bigger question is where did 'life' come from in the first place?

[pgyanke]

Nice try... I'm was a Greek and Latin scholar in high school. The Greeks and Romans didn't believe in Zeus or Juno... they were stories they made up to explain the things they didn't understand (see "Big Bang Theory). They admitted as much. Their real religion was worship of their ancestors.

[<1/1,000,000th%]

Instead of working so hard to prove new ideas correct to change the historical record, it would be interesting to see how much we could learn by just examining the world around us and drawing conclusions.

This is the object of scientific activity.

[js1138]

life does not require free oxygen.

[<1/1,000,000th%]

Whatever became of the hypothesis that the direction of life flipped due to the production of oxygen?

One of Clinton's executive orders overturned that.

[asformeandformyhouse]

The difference between this and religion is that religion seldom admits uncertainty that might be resolved later by human inquiry. It either dictates the truth, or it claims the truth is some mystery beyond human understanding.

That makes as much sense as the guy who wants proof of God. If God can be proven, then he's not much of a God, is he? If God states something, then by the very definition of God, it must be so to that believer and a believer would be disingenuous to admit any 'uncertainty'. That may sound like a cop-out to you, but if you're honest with yourself and put away your disdain for 'religion', then you'll have to at least see that just as any religion is made up of it's 'believers', so is this doctor's.

[AntiGuv]

I see. Well, it appears that our perceptions of reality are too far removed from one another to make debate of any use. I'm disinterested in arguing over the accuracy of historical accounts describing Greco-Roman beliefs. My point has been made (irrespective of whether the Greeks actually believed those accounts which have never been proven any more inaccurate than have the Hebrew Testaments) and it suits me fine whether you acknowledge its relevance or not.

[js1138]

So that's why folks say the Clintons suck up all the oxygen.

[headsonpikes]

Your #7 is a good statement of the rational position.

It's the 'literal metaphysical tradition' that gets folks in trouble intellectually. These unfortunates imagine metaphysics to be a field of study not unlike physics, but with less math. ;^)

[pgyanke]

No, this is the goal of scientific objectivity. It's not the goal of scientists who will only accept conclusions that don't involve God.

God can't be proven by science, therefore God doesn't exist. Which of these two competing factions is God... the scientist or the supreme being?

[steve8714]

Life without Faith is thin, cold soup.

[pgyanke]

Don't forget your toys!

[js1138]

If God can be proven, then he's not much of a God, is he?

I dunno I've seen lots of freepers claim to have proofs of the existence of God.

The interesting thing would be to prove that God conforms to the beliefs of any particular church or denomination. Nailing down exactly which church has it right -- that would be interesting.

Personally I belong to the church of the seven blind men. None of us has the whole picture.