Technognome
Professor of Ecognomics
Taika-Kim said:And about the waves of extinction (I had to check this from a book...)
There have been five previous times of great extinction, 440, 365, 245, 210 and 66 million years ago progressively. The biggest was 245 million years ago, when it's believed that almost all life on earth was destroyed due to some reasons not yet completely understood.
Despite all the past extinctions (during of which, maybe 10-20% of all species of life was destroyed) the level of biodiversity is now the highest it has ever been in the history of the world.
And some misc numbers:
It takes anything from 10 to 100 million years for the earth to recover from a big wave of extinction and new species evolve and take the place of the disappeared ones. So it's a long time to wait...
Cheers for that
However there is a bit of a lack of what I was after ie extinction rates at these previous times & presently. This I would imagine is important as addaptation to a changing environment presumably takes some time? Which would I assume be why some organisms, less suited to the changes, go extinct as they cannot make the greater adaptations required in the prevailing time scales.
Also I'm abit confused by your term 'recover from a big wave of extinction' if we only now have the higest level of biodiversity ever. Maybe due to limitations in the fossil record we only have a sketchy idea of levels biodiversity in the past?
I did abit of Googling as I was unsure about the number of extinction events;-
Link
It is often difficult to determine exactly when mass extinction events have occurred in the Earth's history - the fossil record is not perfect, and the poorer the record for a particular time frame, the more it is open to different interpretations. Some scientists have suggested that there is a cycle of mass extinctions, with a major die off every 26 million years or so. This would imply that there have been some 23 extinction events since the Cambrian, a figure which is at the upper limit of most estimates. While we remain unsure of the total number, there is general agreement over the existence of 6 major extinction events.
Good stuff here too
Some stuff on mass extinction rates here
From only a brief look about the whole subject seems to be abit of a factual & theoretical minefield.
What I do note is that extinction events do produce varying % levels of extinction. Thus I would hesitate to say that 100% could not be achived at sometime by some cause in the future.
Also it is my understanding that chaotic system are well buffered against sudden one off changes but behave differently when gradual and increasing changes occur?
Goz I'm not entirely sure that bacteria living on Lava constitute a biosphere sounds more like a biopool but then I could be described as Mr Picky
PHLUR :sun: