William M. Briggs

Statistician to the Stars!

Are We In The Midst Of A Global Extinction Event?

All Life Ends! Amphibians, Cartilaginous Fishes Hardest Hit.

That was the headline yesterday in newspapers all over the country as editors reacted to a press release from Science magazine which described a broad study of species loss. Even the Wall Street Journal, which is not known for overreacting, ran this: “A War Against Extinction: The Number of Species Keeps Falling, but Conservation Racks Up a Few Successes.” Golly! A war!

What makes this headline odd is that this same paper, and many others, not one month ago, announced to us: “Census of Marine Life unveils 6,000 new species.” That’s a lot of new species!

In an article announcing the many new species, the WSJ said:

Researchers participating in the census say they have now pinpointed about 250,000 species that live in the sea, but estimate that another 750,000 species still elude human discovery. And that’s without counting millions of microbe species, which constitute 90% of the ocean’s biomass.

So, which is it? Are the number of known species dwindling towards one (us, naturally), or are they proliferating out of control? The answer depends on what statistical method is used to count species. And in not making common errors the authors of the Science study appear to have made.

Suppose you have a list of Officially Tracked Species which are, obviously, known to you. There can be any number of species not known to you. At some point you go out in the field and try to count the number of each officially tracked species. Some time later, you venture out again and re-count. Only two things can happen: (1) the number of each species can go up or stay the same or (2) they can go down or become zero. But no matter what, the number of species on your official list can only decrease.

Why? Just think: your list of officially tracked species is set and, by definition, you are not adding to it. Your counting can only record extinction events. It is possible that since the official list was set, speciogenesis occurred somewhere, and we know with certainty that there are a large number of previously unknown species that could be added to the list. But the point is: these species are not on the list. So when you count, you can only be disappointed.

Thus, it should never shock a scientist to discover his list has shrunk. Poor Nicholas Dulvy, co-author to the Science study, evidently did not know this and was so upset after his counting that he fumed, “The reality is we’re still exporting degradation across the world.” See what I mean? Bad statistical thinking led US Citizen Dulvy to conjure up the image of his countrymen “exporting” some kind of species destruction engine.

The second error is this: the official list itself is incomplete. Dulvy and his brother scientists should have written an article announcing that the number of known species has increased since the last time they checked. And they should have acknowledged that it is likely to increase even further the next time. And they should have said that this will be so even if a few of the previously known species vanish.

Scientists do not have the power of King Herod and cannot order a census. They can only count a small sample, and are forced to use statistical modeling to estimate the extant number of any species. The models they use are error prone and cause over-certainty; and they often mistaken. How many times have we seen headlines like this? “‘Extinct’ Amphibians Rediscovered After Decades Lost to Science.” Amphibians! The very group said by Dulvy et alia to face the highest risk. Worse, as more people count, the bigger the chance that a species will be said to have gone extinct. (This is a form of observation bias.)

Now, it is true that some species since we have begun counting have gone extinct. This causes “biodiversity” to decrease, and that is said to be a bad thing. Sometimes, of course, the loss of a species is a bad thing. But not always. We can easily compile a list of killer microbes, creepy crawlys, and vermin that the world would be better off without. And what about the species thriving because of humanity? Dogs, cats, cows, pigs, and so forth are doing fine.

To say that some species are bad or good, or that some don’t count, or that diversity is important are moral judgments which have nothing to do with science.

Biodiversity is not to be desired just for the sake of diversity, either. Further, everybody believes this, even those who ever have that word on their lips. Prove it? Easily: suppose we create 10 new species, all of which are hostile or lethal to man. Biodiversity will have increased—hurrah!—but at the cost of human lives. Only the insane would say this is good.

Then, too, how many who worship biodiversity speak out against genetic modification of plants and animals, activities which can only increase, not decrease, diversity?


  1. A couple of other possibilities. You go out and count species. You get some and miss some. next time you do it, same thing happens, only this time you miss some on your list and add some that you didn’t see before.

    The question is whether the ones added were there the first time you counted and you just missed them or they are new, OMG New Species!

    Seems to me that the total number of species could be increasing or decreasing and we, so far, can’t know.

    But if you want to alarm people, which seems the current aim of the pseudo sciences, decrease must be the way to go.

  2. I suppose it’s unlikely that a new species could evolve in a year or two between surveys, so it must be more a case of them being missed in earlier surveys.

    One might ask how well the downside of fewer species has been appraised. If, indeed, we are becoming fewer, how can we be sure this is bad?

    Suspecting that this whole area of concern might be nonsense, has anyone compiled an encyclopedic listing of “nonsense” science – might make a weighty tome?

  3. If we were finding brand new species — species that had only existed for a space of decades, you would have a cogent point. We aren’t. You don’t.

    There is little (no) reason to believe that the discovery of new species is any reason to believe that the total number of species (known and unknown) is increasing. There is (good) reason to believe that it is shrinking. “Number of species” is silly talk, of course — a more useful term would be “shrinking phylogenic diversity.” “Species” is too ill-defined a term to be precisely numerical about, and some of us believe that losing a species with close relatives is less important than losing sole representatives of an evolutionary path.

    Human beings have been wiping out large mammal species ever since we left Africa. We’re simply more efficient hunters than the world has seen before (9/10 hunt success rate for modern hunter-gatherers compared to 1/10? for most comparable predators). Animals adapt on evolutionary timescales, humans adapt on individual and cultural timescales.

    Thus many large land mammals were wiped out before us moderns ever got on the scene. However, being agriculturists, we today are far better at wiping out species than puny hunter-gatherers ever were. Habitat destruction (something environmentalists should be harping on instead of their stupid climate change pseudo-millennialism) is the real name of the game.

    And no, we aren’t really wiping out the bad guys — “creepy-crawlies.” One of the big problems with the current extinction event is its phylogenic concentration. Many groups (like the evil germs and parasites we hate) have been mostly unaffected, while other groups have been hugely impacted (large mammals).

  4. Tman:
    Apart from aesthetics, the reduction to the point of extinction of certain unnamed large mammals, has what deleterious effects? I understand the possible and abstract ecological balance arguments, but for specific cases can you provide an empirical argument as to the effects.

  5. Darwin’s truly radical concept is Life is a continuum- and our naming process (taxonomy) merely artificial lines drawn at artificial points for and at our convenience. Taxonomy was initially used to group animals in a way to help in our understanding– Taxonomy is now used to group animals in such a manner as to sue other humans.

  6. Well, yes – and no.

    We do know of some “extinction” events – the passenger pigeon for example. OTOH, just yesterday there was an announcement of a “new” species of monkey being found. But while if only these two cases are considered the count of species does not seem to change, from what we know of the development of multi-cell organisms the actual total of both known and unknown decreased by one over the last 150 years as it is doubtful that an actual new species has developed. Note, doubtful – one or more may have, it is something else we do not know.

    What gets to me is that I am human-centric enough that, while I can understand the distress felt by some at the potential loss of the snail-darter, I wonder if saving it is important enough to justify destroying a sizeable part of the [US] human food supply. Perhaps it is – I do not know.

    What I do know is that the only way to keep humans from being a threat to other species is to make humans extinct, and I do not support that.

  7. Bernie,
    Surely you realize that the extinction of the mammoth had many impacts. With the loss of really large hides, an entire tribe could no longer sleep together protected from the cold. Monogamy was soon invented, not to mention sewing by the folks who were wistful about the loss of the tribal sleeping experience and wanted to fake it by assembling bear hides to the same coverage.

    Bear hides being more dangerous to accumulate in the needed numbers, some groups moved south inventing civilization when they got there.

    The development of baritone and bass horns was thwarted for millenia and likely the development of polyphonic music.

    Tman, I take your points. help me understand why you’ve found it unlikely that new (so far undiscovered) species are not evolving. Agreed, that we can wipe them out with alacrity, what about the ones that aren’t warm and cuddly?

    I agree that a “species count” is likely tangential to anything we should worry about, but is it possible that the species we are discovering now are only discoverable because they’ve prospered and increased in number?

  8. j ferguson:
    Now you have me walking with a limp!

  9. Yes, yes we are. Its called Evolution. In case environmentalists didn’t know the creatures we see around us were not created by Yahweh 6000 years ago in Iraq, they are all mutants in a perpetual extinction event that started with the first genetic differentiation.

  10. Here is a practical example. Pacific salmon are not in any danger of extinction as a species. But 100s of “distinct” populations are listed as threatened or endangered. Small genetic variations allow biologist to list these fish as an ESU (environmentally sensitive unit). What is left unsaid is that these small changes can occur in perhaps as few as two generations. . Given this broad definition every population in every small river is endangered– not only the river but the populations that spawn in certain sections of the river. If we can divided the total population in ever smaller subsets– everything becomes endangered. Once a defined population drops below some threshold number– genetic change occurs faster – thus the current mix of genetic material is threatened. To get more populations listed as threatened simply requires us to continually divide the total population into smaller and smaller subsets until we reach the magic number. It would actually be funny if we weren’t spending so much money and removing the focus we need to solve some of the more serious threats.

  11. SteveBrooklineMA

    28 October 2010 at 12:23 pm

    I am skeptical of these studies. How severe is the problem really?

    “On 29 January 2010, the IUCN Red List of Threatened Species identified 842 (746 Animalia, 96 Plantae) extinct species, subspecies and varieties, stocks and sub-populations.”


    So even going down to the “variety” and “sub-population” level, including all plants, insects, worms, etc, there have been 842 identified extinctions? As far as mammals go, here is a list


    seems like most of these are from before the first half of the last century.

    To put that 842 in perspective, estimates for the total number of species world-wide is around 1.8 million.

  12. intrepid_wanders

    28 October 2010 at 3:51 pm

    If you are REALLY bored and have 24mb to waste, check out the WWF Living Planet Report:

    As painful as it was looking and trying to understand the “makings” of a Planet Index, I laughed my butt off on the graphs past the first (without the “error-bars”). Apparently, the time series starts in 1970 with 100% confidence and the “error-bars” grow over time.

    I think somebody said “We need ‘error-bars’ like the IPCC report.”

    So they put in model projection “error-bars” in, with the lowest confidence, 2008.

  13. I wish you guys would agree on something. It’s becoming quite irksome dodging these falling skies all the time.

  14. TMan;
    Horse pucky, stem to stern.

    The astonishingly wrong and repercussion-free prediction of imminent doom that first riveted my attention was the claim of the impending mass extinction of the Earth’s species. In 1979, the biologist Norman Myers declared that a fifth of all species on the planet would be gone within two decades. This prediction was based upon . . . absolutely no evidence whatsoever. Myers acknowledged that the documented species extinction rate of animals was 1 per year; he then asserted that scientists had “hazarded a guess” that the actual rate was 100 per year; he then speculated that government inaction was “likely to lead” to several thousand or even tens of thousands a year, which would add up to as much as a million species over two decades. (This was when people thought there were 5 million species; the best guess now is at least 10 million.) It swiftly became conventional wisdom.

    Read more: http://budiansky.blogspot.com/2010/09/teflon-doomsayers.html#ixzz13PfNflG1

    You have no clue. You missed the point of the article entirely. In truth, the number of known species is increasing without visible limit.

    P.S. Next person to say or write “fragile ecosystem” goes up against the wall until they point out a robust ecosystem to emulate.

  15. A recent paper in Nature reported a global average wind speed drop of 10% between 1979 and 2008, http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo979.html

    Does this imply that there will be no wind in 300 years time?
    Of course not, it’s just a similar wrong linear malthusian extrapolation.

  16. What the heck is a “species”? And when you get that figured out, what are subspecies, evolutionarily significant units, evolutionary units, management units, metapopulations, distinct population segments, populations, and subpopulations?

    I hear the terror and moaning from the extinction-istas. OMG the world is coming to an end because we are extinctifying it!!!!! But are we? Briggs is right — the number of species is increasing every day.

    Take the jumping mouse, Zapus sps. There used to be one species. Now there are dozens. And it should come as some surprise to you sports fans to learn that many have been listed as Threatened Species under the Endangered Species Act.

    Here are just a few of the species and sub-species alleged to exist today (so far): Z. trinotatus orarius · Z. burti · Z. hudsonicus · Z. hudsonicus acadicus · Z. hudsonius (Jumping Mouse) · Z. hudsonius acadicus · Z. hudsonius alascensis (Alaska Jumping Mouse) · Z. hudsonius alscensis · Z. hudsonius americanus · Z. hudsonius campestris · Z. hudsonius canadensis · Z. hudsonius hardyi · Z. hudsonius hodsonius · Z. hudsonius hudsonicus · Z. hudsonius hudsonius · Z. hudsonius hudsonsius · Z. hudsonius intermedius · Z. hudsonius ladas · Z. hudsonius luteus (Meadow Jumping Mouse) · Z. hudsonius pallidus · Z. hudsonius preblei (Preble’s Meadow Jumping Mouse) · Z. hudsonius tenellus · Z. insignis · Z. orarius · Z. princeps (Pacific Jumping Mouse) · Z. princeps chrysogenys · Z. princeps cinereus · Z. princeps curtatus · Z. princeps idahoensis · Z. princeps kootenayensis · Z. princeps kootenayonsis · Z. princeps kootnayensis · Z. princeps luteus · Z. princeps major · Z. princeps minor · Z. princeps oreganus · Z. princeps oregonus (Big Jumping Mouse) · Z. princeps pacificus · Z. princeps palatinus · Z. princeps princeps (Western Jumping Mouse)

    Alleged, because there is some dispute. For instance, Z.h. intermedius (Mysterious MJM) is supposedly a cross between Z.h. campestris (Bear Lodge MJM) and Z.h. pallidus (Common Ordinary Everyday MJM), but nobody can say for sure. The reason for the confusion is the alleged sub-species look identical and interbreed like randy rodents if given half a chance. In addition, there is some dispute that Z.h. preblei (Preble’s MJM) even exists in a separate genetic way (DNA testing has been far from conclusive) from Z.h. campaestris (Bear Lodge, Room #4 MJM), Z.h. intermedius (Half-and-Half MJM), or Z.h. pallidus (Plain Old Run-of-the-Mill Backyard MJM).

    In the eternal battle between lumpers and splitters, the splitters are always victorious. Distinctions without differences are preferred over the indistinct and undistinguished. Hence the species count will continue to rise and may in fact be infinite.

  17. I meant “no” surprise, not “some” surprise. But you probably ARE surprised, so whatever.

  18. Great post, and very timely indeed. Thanks.

  19. Mike D.

    Are the Zapus variations you describe a production of runaway taxonomy or is it more likely that no one ever looked at jumping mice in detail before?

    I somehow sense the action of “make-work” science here.

    Many thanks for this instructive example. Zapus ???. What a great choice of names.

  20. Conservationists just don’t get it. Life IS war. It pits individual against individual and species against species. Only the fit survive.

  21. Alex Heyworth: “Only the fit survive”. Just for laughs, do you have a definition of “fit” that contains no reference to survival?

Comments are closed.

© 2014 William M. Briggs

Theme by Anders NorenUp ↑