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Has the extinction rate increased 1,000 times?

Lots of journalists happily spread the "gospel" about a recent paper in the Science Magazine,

The biodiversity of species and their rates of extinction, distribution, and protection
by S.L. Pimm and 8 co-authors (U.S., U.K., Brazil). The abstract suggests it is a rather careful, conservative paper with some interesting statistics. The summaries in the media are not so careful, I think.



The eye-catching figure is that it's being estimated – and as far as I see, the paper assumes it is essentially right – that the "number of species that go extinct per year" has increased by three orders of magnitude. That's huge and I would surely count myself as someone who cares about the biodiversity problem if the truth were close to this number.

I have no doubts that people have exterminated numerous species – usually by clearly hostile tools such as guns, not so much by some esoteric, hypothetical, and convoluted methods such as carbon dioxide emissions which are OK for everyone – but are the numbers so bad?




However, I tried to figure out how this ratio "1,000" is being calculated and I have largely failed to find an argument. Is there a TRF reader who understands these issues and believes that there is some good enough evidence that the ratio may be this high?




Without the humans, one species typically lives for a few million years. This fact seems to be roughly hold for very diverse groups of organisms. If the "factor of 1,000 spedup" is real, an average species is destined to live for thousands of years only right now.

Are these numbers realistic? Can we estimate the number of species before humans emerged, their extinction rate, the number of species today, and their extinction rate? Or can we calculate the ratio without knowing the absolute numbers in the numerator and the denominator with any robust precision?

I think that because of the very basic rules of evolution, the very definition of a species may be fuzzy enough so that these questions don't admit any high-precision answers. In some types of organisms, the inter-species separation may be more significant than in others.

Over 100 years, the volume corresponding to the separation may very well grow by 10% in some measure which should mean that we should increase the number of species in this group by 10 percent, too. If it weren't politically incorrect, biologists might be forced to admit that the human population has split into several species, too. But I think that the conservationists are not really taking the evolution in their lifetimes into account. Along with their creationist friends, they still consider species to be fixed, unevolving boxes that were defined millions of years ago.

But the species are constantly and gradually being created by differentiation and this process has always competed against extinction. I don't see any discussion of this which is a part of the reason why I find it hard to accept these attempts to quantify the extinction rate as a good science.



Like the paper, this video shows where conservationist efforts may be most effective for biodiversity.

Moreover, as the authors of the paper are very well aware, the ranges of the species differ by many orders of magnitude in between the species, too. This correlation increases the risk of extinction for species with small ranges, and so on. So a particular definition of the extinction rate may very well be determined by some insanely small populations and whether or not we count them as separate species.

Also, I have a problem with the widespread assumption of the "universal background extinction rate". It seems likely to me that in various eras, the extinction rates were significantly different – even in the absence of meteoroids. Like earthquakes, extinctions are probably correlated with each other so they like to be grouped, much like earthquakes with smaller tremors that are linked to them. The recent centuries may experience a much higher extinction rate than the quietest centuries before the humans arrived but they may still be comparable to some rather normal centuries in which the extinction rate was higher – even though there were no meteoroid-like catastrophes.

What do you think?



Off-topic: Aquababes is what you get when Universal Music (with some visible help from the bottled water maker Aquila) organizes a casting and constructs a completely artificial girly band. They're cute and hot but the music ("Don't Call Me Baby") is sort of mediocre, isn't it?

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reader bodyguard agency in london said...

Let me say that I agree that it *is* painful, if Cheney has voted like that, and it certainly makes his ticket with Bush less appealing for people like me. On the other hand, it's not the only fact that will decide the elections.


reader BobSykes said...

Many, probably, most of the numbers given for extinction are probably made up on the spur of the moment, like Wilson's absurd fantasy (which he won't recant, he merely doubles down Paul Ehrlich-like).

However, there are some real efforts. For example, geological time-scale estimates by Robert May (a real scientist) and his colleagues

http://www.britannica.com/EBchecked/topic/133385/conservation/272660/Calculating-background-extinction-rates#ref959267

Also, from the historical record,

http://www.birdlife.org/datazone/sowb/casestudy/102

which gives an estimate of 151 bird species lost in 500 years. This is consistent with May's estimates above.


reader Luboš Motl said...

Thanks! Imagine that one believes that 150 out of 10,000 bird species died in 500 years.


What's the evidence that this hasn't been the normal refreshment in the past, i.e. that with this accuracy of defining species, most of the species are refreshed in 30,000 years?


reader RAF III said...

Lubos - This is the same Stuart Pimm who, about twelve years ago, reviewed Lomborg's book 'The Skeptical Environmentalist' in Nature. In that review, which was the most egregiously tendentious that I have ever read, he literally called Lomborg a nazi.
That review prompted me to review all of his work to that point and much of the work appearing in Nature which he referenced. I allowed my subscription to Nature to lapse shortly thereafter.
Pimm focused mainly on extinctions and based his work on island biogeography. I can assure you that both island biogeography and Pimm's work are utterly worthless in every respect, not science but pure propaganda. I still have the work work of several years to prove it.


reader Luboš Motl said...

Thanks for reminding me etc. - I forgot the name.


reader RAF III said...

It's a damn shame that anyone remembers his name, and that he is published in Science.
He is much like Paul Ehrlich - both remind me of something I occasionally scrape off my shoe


reader Curious George said...

Could Mr. Pimm kindly provide us with a list of 500 species which went extinct in 2013? He may not have data that recent but I would take any year in this century.


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reader Gordon said...

It looks like he is ignoring that well over 10 000 new species are being uncovered every year now (and that is just the eucaryotes). A 10*3 magnitude increase in extinctions may coincide with a 10*3 increase in the discovered new species, so not be a "real" increase. Craig Venter has been combing the seas in his sailboat collecting scads of new oceanic biota to get DNA sequences for novel proteins.
Stuart Pimm is a known alarmist in the Paul Ehrlich tradition.


reader Gordon said...

Yes, exactly---I wrote my reply without seeing yours :).


reader Mikael said...

"If it weren't politically incorrect, biologists might be forced to admit that the human population has split into several species, too." Seriously, Lubos?


reader Curious George said...

Imagine you are a 19th century biologist. You describe a species of a yellow butterfly from Asia. At the same time another biologist describes an otherwise similar red butterfly species in America. Would a difference in color, together with a geographic separation, be enough to keep them listed as two species even if they could interbreed?

This is not an idle speculation. Wikipedia: "The phylogeny of the Nymphalidae is complex. Several taxa are of unclear position, reflecting the fact that some subfamilies were formerly well-recognized as distinct families due to insufficient study."


reader Brady said...

It gets "worse" than that:
6 continental birds have gone extinct — 3 prolific terrestrial bird species hunted to extinction, and 3 single-habitat freshwater bird species hunted, drained dry, eaten by fish, and polluted to extinction. This historical record of 9 continental extinctions in 500 years contrasts starkly with Wilson’s predictions of over thirty continental bird and mammal extinctions per year, each and every year.”
http://wattsupwiththat.com/2010/01/04/where-are-the-corpses/
So the 151 birds translates into 6 birds on continents. The rest mostly from my home country Australia plus other islands. Please note in the above Birdlife International ref the words. "believed"; "suspected"; "appears" etc. Lack of falsifiability is the life blood of Environmentalism.


reader Jim Arndt said...

So when we find a new species is that a net positive?????


reader physicsnut said...

just wondering if they can count the number of new species that appear.


reader Honza said...

If they are right, we should see it soon. ;-) If you increase the rate of extinction 0.3 of bird species per year (150 in 500 years) thousand times, you will get 300 species per year. So given the 10,000 bird species out there, in ~30 years we should have remaining just turkey and chicken.(The turkey being Stuart Pimm, and chicken being Henny Penny AKA Chicken Little,)


reader lukelea said...

Here is an interesting background article from the NYT:

http://www.nytimes.com/gwire/2011/05/18/18greenwire-scientists-clash-on-claims-over-extinction-ove-96307.html?pagewanted=all

I especially noticed this sentence: "No ecologist disagrees that humanity has started, or will soon start, the Earth's sixth great wave of extinction, a process largely driven by destruction of natural habitats."


reader Carlos said...

Good News!
Humans will be able within the next couple of decades to bring back almost
every species that has been extinct. De-extinction is not science fiction. It
is science fact, species have already been brought back to life after all their
members have become extinct. Here is the 12 minute TED talk about the case. With resurrection biology being just a decade
or two down the road, there is really no need to spend all those millions to
save some beasts. With a few tissue samples, humans could bring back the famed
polar bear, not only that, but it could be genetically tailored to have
different color fur. Every environmentalists would be able to have a pink cuddly ¨bonsai¨of a bear in his own backyard
or as many as he or she wants. The animals fur could also be fluorescent so the
environmentalist can use the bear as a portable flash light and reduce his carbon
footprint. http://www.youtube.com/watch?v=5eMqEQw9Fbs


reader Alex said...

How sad. All the puppies and pussies are going to die (sob, sob).
Oh look! A pretty pink bow and some sparkly shoes.


reader Luboš Motl said...

Dear Mikael, are you denying that evolution is continuing and new species are splitting from any existing one?


I didn't mean just races. I meant real de facto barriers of reproduction, between most of the humans and some isolated tribes, for example.


reader Jim Z said...

Is it the sixth wave of extinctions, or the sixtieth wave of extinctions, or the six hundredth wave of extinctions?


reader Jim Z said...

How big will the number of extinct species be when the next glacial episode occurs?


I sure hope that another glacial episode doesn't occur.


Can we raise the global temperatures to prevent glaciation in the future?


reader Mark Luhman said...

If you leave out island and Australia we have lost just two spices in the continents in the last few hundred year, that the number I have read. Along with the number the total of spices lost that we know of is less than 800, most are due ti invasive spice taking up their habitat or directly kill them rat have devastated island birds since a majority nested on the ground. Now if you count subspecies the number would be larger how much I do not know.


reader Christoph said...

It's a hard question because we don't really know what's out there. For example, when researchers looked at 19 trees in Panama in the 1980s, they discovered about 1000 new species of beetle.

You could look into the 'red lists' published by the IUCN, which are available online at https://portals.iucn.org/library/dir/publications-list

The abstracts only list the number of species threatened with extinction and not the number of species actually having gone extinct, but the numbers for Europe (search term 'european red list') are 25% of amphibians, 9% of butterflies, 15% of dragonflies, 37% of freshwater fishes, 44% of freshwater molluscs and 20% of sampled terrestial molluscs, 20% of reptiles, 11% of sampledsaproxylic beetles, 25% of sampled vascular plants.


reader Mikael said...

Dear Lubos,
the question is not so much about the current situation but about the trend. I think mankind is getting more uniform both genetically and culturally and not less uniform. It is called globalization.


reader Luboš Motl said...

I don't believe it.


Globalization that I see is about the global trade, ability to sell goods and services very far. I don't believe that the people's genes are getting more uniform, quite on the contrary.


reader thejollygreenman said...

I have just finished reading a new book by Nicholas Wade called, “A Troublesome Inheritance: Genes, Race and Human history.” This author believes that we can see recent evolutionary changes in humans. I enjoyed reading the book.


reader John F. Hultquist said...

I recently read (cannot now find) there are an increasing
number of DNA variants and not enough time has passed to weed out the useful
from the damaging ones. Humans should,therefore, continue diversing.
Here is the idea (but not the one I recently saw):

http://articles.latimes.com/2012/dec/10/science/la-sci-human-genetic-variation-20121210