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Author Topic: How do we know how many species have gone extinct?  (Read 6177 times)

Emilio J. Romero J.(EJRM)

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Emilio J. Romero J.(EJRM)  asked the Naked Scientists:

Dear Chris:
We've all seen the commercials that state that "by the time you are finished watching this, xx species would have become extinct..."
 
Now, is that true? How can they forecast this in a time in which no one really knows how many species there are in our planet? How can they be accurate if every now and then we discover hundreds new species (recently in Vietnam and Australia )? Do the mathematics applied are sound? Can math be applied in such uncertain matters?

I've heard that there are actually less than 5 species that have "become extinct" in recent times (several considered extinct have reappeared).

I'm really curious about this. Can you shed some light, please?

Regards
Emilio

What do you think?


 

Offline yor_on

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How do we know how many species have gone extinct?
« Reply #1 on: 12/11/2008 13:11:26 »
Statistics my man.

First you get some idea of how many species that already are extinct.
Then you make an educated guess of how many there is known.
Then you follow up on them you know.
Then you make an even more educated guess on how many there might still be hidden, in the Amazons for example.
That you could base on, if you're serious, on how many new species that are found under ? a year, decade?
And there are other ways too I'm sure:)
As the rainforest's die, as well as the oceans, those numbers will change.

But as for knowing every species on this Earth?
That used to be Gods job, I think?

But we do know that they are shrinking rapidly with every year. So soon we might be able to know them all:)
As they mostly will be the kind that survive in acidic milieus as well as sulfurous.
Then you don't have to worry any more.
 

Offline Emilio Romero

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How do we know how many species have gone extinct?
« Reply #2 on: 12/11/2008 14:17:04 »
Agree... However, if we do not know how many there are... how can we know what percentage goes extinct every day/year/decade?
There is a red-list of threathened species that surprised me a lot a few years ago when I read it... there were very few species estinct (contrary to what they tell us)
Thank you
emilio

 

Offline atrox

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How do we know how many species have gone extinct?
« Reply #3 on: 12/11/2008 20:16:14 »
Hi Emilio!

As far as I know about 800 animal species are extincted since the 16th century.. (I bet,there are a lot of plant, too)

BUT these are only documented cases, means this are animals you did or do know (there are a lot of animals we wouldn´t notice if they go extinct) and you could really make clear, that there are no indvidues anywhere anymore... to consider a species as extincted in wilderness it could take decades of research. For example the Baiji (chinese river dolphin)... it took 4 years to consider him extincted...even if it was a pretty big animal...quite contrary to the overwhelming big part of all animals. So a lot of animals which are possibly extincted wouldn´t show on the ex-part of the red list yet.

bye
aj
 

Offline RD

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How do we know how many species have gone extinct?
« Reply #4 on: 12/11/2008 23:35:45 »
Quote
Extinction, though, is usually a natural phenomenon; it is estimated that 99.9% of all species that have ever lived are now extinct.
http://en.wikipedia.org/wiki/Extinction
 

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How do we know how many species have gone extinct?
« Reply #4 on: 12/11/2008 23:35:45 »

 

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