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.
That's part of the beauty of creationism- it allows its believers to be both an intellectual elite, privy to the real truth, and a persecuted minority, all at the same time.
Interesting that most of creationism's adherents belong to relatively new Protestant churches of the "snake-handling" varieties, while older, established Christian denominations (Catholic, Orthodox, Lutheran etc.) have no real issues with evolution.
A Freeper suggested this was due to the way the scientists think - some creatures might have just as easily been placed in a new phylum. Another said that all the possible body plans have been used.
Neither of these answers satisfy my curiosity. If bodies are being created randomly by mutation, I would expect body plans found in nature to be far more diverse than the SciFi creatures designed by Hollywood.
Any input???
Excerpted from a translation of Plutarch by John Dryden:
After this, Alcibiades, standing in dread of the Lacedaemonians, who were now masters both at sea and land, retired into Bithynia. He sent thither great treasure before him, took much with him, but left much more in the castle where he had before resided. But he lost great part of his wealth in Bithynia, being robbed by some Thracians who lived in those parts, and thereupon determined to go to the court of Artaxerxes, not doubting but that the king, if he would make trial of his abilities, would find him not inferior to Themistocles, besides that he was recommended by a more honourable cause. For he went not, as Themistocles did, to offer his service against his fellow-citizens, but against their enemies, and to implore the kings aid for the defence of his country. He concluded that Pharnabazus would most readily procure him a safe conduct, and therefore went into Phrygia to him, and continued to dwell there some time, paying him great respect, and being honourably treated by him. The Athenians, in the meantime, were miserably afflicted at their loss of empire; but when they were deprived of liberty also, and Lysander set up thirty despotic rulers in the city, in their ruin now they began to turn to those thoughts which, while safety was yet possible, they would not entertain; they acknowledged and bewailed their former errors and follies, and judged this second ill-usage of Alcibiades to be all the most inexcusable. For he was rejected without any fault committed by himself, and only because they were incensed against his subordinate for having shamefully lost a few ships, they much more shamefully deprived the commonwealth of its most valiant and accomplished general. Yet in this sad state of affairs they had still some faint hopes left them, nor would they utterly despair of the Athenian commonwealth while Alcibiades was safe. For they persuaded themselves that if before, when he was an exile, he could not content himself to live idly and at ease, much less now if he could find any favourable opportunity, would he endure the insolence of the Lacedaemonians, and the outrages of the Thirty. Nor was it an absurd thing in the people to entertain such imaginations, when the Thirty themselves were so very solicitous to be informed and to get intelligence of all his actions and designs. In fine, Critias represented to Lysander that the Lacedaemonians could never securely enjoy the dominion of Greece till the Athenian democracy was absolutely destroyed; and, though now the people of Athens seemed quietly and patiently to submit to so small a number of governors, yet so long as Alcibiades lived, the knowledge of this fact would never suffer them to acquiesce in their present circumstances.
Yet Lysander would not be prevailed upon by these representations, till at last he received secret orders from the magistrates of Lacedaemon, expressly requiring him to get Alcibiades despatched: whether it was that they feared his energy and boldness in enterprising what was hazardous, or that it was done to gratify King Agis. Upon receipt of this order, Lysander sent away a messenger to Pharnabazus, desiring him to put it in execution. Pharnabazus committed the affair to Magaeus, his brother, and to his uncle Susamithres. Alcibiades resided at that time in a small village in Phrygia, together with Timandra, a mistress of his. As he slept, he had this dream: he thought himself attired in his mistress's habit, and that she, holding him in her arms, dressed his head and painted his face as if he had been a woman; others say, he dreamed that he saw Magaeus cut off his head and burn his body; at any rate, it was but a little while before his death that he had these visions. Those who were sent to assassinate him had not courage enough to enter the house, but surrounded it first, and set it on fire. Alcibiades, as soon as he perceived it, getting together great quantities of clothes and furniture, threw them upon the fire to choke it, and, having wrapped his cloak about his left arm, and holding his naked sword in his right, he cast himself into the middle of the fire, and escaped securely through it before his clothes were burnt. The barbarians, as soon as they saw him, retreated and none of them durst stay to wait for him, or to engage with him, but, standing at a distance, they slew him with their darts and arrows. When he was dead the barbarians departed, and Timandra took up his dead body, and, covering and wrapping it up in her own robes, she buried it as decently and as honourably as her circumstances would allow. It is said, that the famous Lais, who was called the Corinthian, though she was a native of Hyccara, a small town in Sicily, from whence she was brought a captive, was the daughter of this Timandra. There are some who agree with this account of Alcibiades's death in all points, except that they impute the cause of it neither to Pharnabazus, nor Lysander, nor the Lacedaemonians; but they say he was keeping with him a young lady of a noble house, whom he had debauched, and that her brothers, not being able to endure the indignity, set fire by night to the house where he was living, and, as he endeavoured to save himself from the flames, slew him with their darts, in the manner just related.
Not true. Catholics acknowledge that God MAY have used an evolutionary process in creation. However, we have real issues where evolution gives credit for creation to happenstance.
No regular poster on FR regards abiogenesis to be a solved problem. Many evolutionists, including Darwin, accept the possibility that first life involves a miracle.
As for commom descent, go ahead and propose an altenative that makes sense.
I deal with the Big Bang the same way I deal with global warming. Here we are, 4-6 Billion years away from an event and we think that what we see here and now explains what happened then. Taking recent historical temperature data has allowed us to go from global cooling to global warming to whatever is next when the data adjusts again. Just as Earth's environment is in a constant state of flux and has shown wide diversity over time, I suspect the universe itelf could too. There are billions upon billions of sun-sized nuclear explosions every second across the galaxy (let alone the universe), that could give a bit of dynamism over the millenia.
I've seen your "evidence" but it's nothing but a snap shot of a water molecule and you're trying to explain Niagra Falls.
Fiction? Oh, my word.
If this had been an actual debate, you would have been instructed to go back and find additonal evidence to support your point. We now return you to your regularly-scheduled crevo thread.
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