Species going extinct 1,000 times faster than in pre-human times, study finds

September 18, 2014 by Beth Gavrilles
Credit: Wikipedia.

(Phys.org) —University of Georgia ecologists John Gittleman and Patrick Stephens are contributors to a major new study that finds that species are going extinct today 1,000 times faster than during pre-human times—a rate an order of magnitude higher than the previous estimate.

The study, which was led by Jurriaan M. de Vos of Brown University, appears in the journal Conservation Biology.

The researchers were able to establish the faster current extinction rate by pinning down a more accurate pre-human, or background, rate, explaining that estimating recent rates is straightforward, but establishing a background rate for comparison is not.

"Being able to look at the pre-human, or background, rate of extinction is important," said Gittleman, dean of the Odum School of Ecology and UGA Foundation Professor of Ecology. "We now know that the current rate of extinction is worse than we thought because the background rate is an order of magnitude slower than the original estimate. Having a real rate of extinction will allow us to look at causal mechanisms much more carefully."

They found that the background rate of extinction was slower before humans existed by comparing the number of that died out with the number of new species that emerged. The researchers calculated that the background rate of extinction was 0.1 extinctions per million species years-meaning that one out of every 10 million species on Earth became extinct each year during that time.

The previous estimate was one extinction per million species years, which skewed the current rate, making it appear to be only 100 times faster during human times. With the new data, the researchers hypothesize not only that current extinction rates are 1,000 times higher than natural background rates of extinction but that future rates are likely to be 10,000 times higher.

The earlier estimate was calculated by a team of researchers in 1995 that included Gittleman and was led by another co-author on the new study, Stuart Pimm of Duke University. It was based chiefly on an examination of the fossil record.

The current study makes use of new techniques and databases that were not available when the earlier estimate was made.

Like the previous study, it incorporates the fossil record, but also uses novel analytical computer models to estimate extinction rates from phylogenetic, or evolutionary, trees—essentially maps of the genetic history of a group of organisms. In this new, more rigorous study, both sets of evidence converge on the same—lower—estimate of the normal background rate of extinction.

"Twenty years ago, not to mention during Darwin's time, most evolutionary trees had missing branches and missing species," said Gittleman. "Now we've got much more comprehensive evolutionary trees where all the species are included, mainly due to much better molecular techniques."

One such tree, which Gittleman helped construct, traces the evolutionary history of the world's known mammal species. It was used in the new study as a source of high-quality data to ensure that the analytical models were accurate.

For Gittleman and Stephens, an assistant research scientist in the Odum School, the extinction rate study is a continuation of research focused on biodiversity conservation.

Gittleman recently co-authored a paper, published in Science, with Pimm and others looking at global rates of species , distribution and protection to learn where threats to species are expanding and help inform protection efforts. An earlier study analyzed information on international funding for biodiversity conservation and modeled its distribution to show which countries have major conservation finance shortfalls.

Explore further: Extinctions during human era worse than thought

More information: DE VOS, J. M., JOPPA, L. N., GITTLEMAN, J. L., STEPHENS, P. R. and PIMM, S. L. (2014), "Estimating the Normal Background Rate of Species Extinction." Conservation Biology. doi: 10.1111/cobi.12380

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cjn
4.1 / 5 (7) Sep 18, 2014
Punctuated Equilibrium. Humans and human activity are obviously a massive selective pressure on all the species of an ecosystem where we have a direct or indirect impact. I'm not sure it takes a scientific study to come to that conclusion. As our influence increases, one would expect that our behavior would have an increasingly negative impact on many other species. That said, I'm not sure that comparing it to a baseline, pre-human "extinction rate" is all that informative. Now, compare the modern species extinction rate to other punctuating events (long period of volcanic activity, glacial periods, etc...) and I'll think you have a real frame of reference for the scale of our damage to the bioshpere.

If I had to venture a guess, I'd say that we're probably statistically as catastrophic to other species as all but the mass extinction events.
antialias_physorg
4.4 / 5 (7) Sep 18, 2014
That said, I'm not sure that comparing it to a baseline, pre-human "extinction rate" is all that informative.

The information is in the fact that that -as with all rapid changes from a common baseline- it may be the last one. The more you deviate from the baseline the higher that risk. And at such an accelerated rate the risk is probably pretty high.
We should see the danger here and act accordingly to mitigate that risk.

Evolution is by now means a gurantee that life will continue indefinitely - no matter what you throw at it.
cjn
4 / 5 (6) Sep 18, 2014
antialias physorg:
The information is in the fact that that -as with all rapid changes from a common baseline- it may be the last one. The more you deviate from the baseline the higher that risk. And at such an accelerated rate the risk is probably pretty high.


Maybe I didn't make my point as clearly as I could have:

When in states of ecological equilibrium (the period between punctuating events), the rate of extinction will always be minimal, as there are no rapid, aggressive selective pressures -and so evolution and genetic diversity can maintain the status quo. Hence, equilibrium.

Our activity will intrinsically have adverse effects on some species throughout the biosphere, regardless of our intentions. Comparing our effects against the happy, Neverland world of equilibrium, where all species get to survive, just tells us that we have an adverse effect. As a "punctuating event", we have to compare our impact against other such events to know the relative scale.
antialias_physorg
3.4 / 5 (5) Sep 18, 2014
Our activity will intrinsically have adverse effects on some species throughout the biosphere, regardless of our intentions.

Why? Other animals seem not to have such devastating effect. What makes us so dumb...erm...special? Since we are not entirely instinct drioven we can choose to have an impact or not (or how much). So I think excusing ourselves by comparing our impact to times of mass exctinction through volcanic activity or meteorite impact isn't sensible.

Our impact is also a variable one. Humans tend to move on from one energy source to another (I use energy source in the loosest manner here for anything that we can exploit to further our aims. this can be also materials or actively making profit off of deteriorating environmental conditions for cheap production)
Past extinction spakes were not that variable (or targetted in actively seeking out new niches to destroy)
cjn
3 / 5 (5) Sep 18, 2014
Why? Other animals seem not to have such devastating effect. What makes us so dumb...erm...special? Since we are not entirely instinct drioven we can choose to have an impact or not (or how much). So I think excusing ourselves by comparing our impact to times of mass exctinction through volcanic activity or meteorite impact isn't sensible.


The "why" is because we must consume resources to survive as individual organisms, and as a society. Because humans are not particularly well adapted to survive alone, or without tools and structures, we are forced to shape the environment around us to meet our needs. We must consume trees, minerals, metals, and energy, even in our most basic states to survive (forging tools, constructing buildings to protect us). All these activities are destructive, and that is only for a few primitive lifestyles. We number 7,000,000,000 individuals, each requiring something from the environment to survive.
cjn
2.5 / 5 (4) Sep 18, 2014
(cont.)
Feeding this many people requires that we reduce the species diversity in arable land across to only the crops that we want grown, and animals that we want farmed. Keeping our agriculture in one place requires us to have to continually replenish the phosphorus and other resources, taken from other areas. Agriculture of this scale further requires the use of either modified crops or pesticides to address critical threats.

The industry required to maintain our populations requires continuous excavating our resources (petroleum, ores, salts, etc...). Processing of these requires further energy consumption, and results in waste released back into the environment. Even the production of "clean" energies requires that first the Earth and the environment be raided for raw minerals and the production of waste.

We cannot both grow and advance without further impacting the environment. We are what we are, and that is deleterious to any species not to our benefit.
tadchem
1.7 / 5 (3) Sep 18, 2014
All life consumes local resources and releases its own wastes. That is in the thermodynamics of non-dissipative structures. When a life form is successful and adaptable enough to proliferate on a global scale (as has happened many times in geological history) it becomes able to alter global conditions.
The diminishing of resources and accumulation of wastes provides niches for other life forms, and applies a Malthusian pressure to limit the population growth of the successful life form.
Populations do not grow exponentially, but according to the logistic equation; there are ALWAYS limiting factors in the equation.
Humans are currently in the growth stage of their population curve, and are altering the environment. The new paradigm for biology will include humans as the dominant life form in all land environments.
Already many species have evolved to coexist with humans. Other life forms will have to adapt ... or die.
aksdad
1 / 5 (6) Sep 18, 2014
This paper is an exercise in creative guessing. Using "novel analytical computer models" and "new techniques and databases" only makes it sound sciencey, but in fact it is not. If you lack data, no amount of novel analysis will make your estimates any closer to reality.

Now we've got much more comprehensive evolutionary trees where all the species are included, mainly due to much better molecular techniques.

Sure, but those "comprehensive evolutionary trees" contain a minute fraction of all prehistoric species. We only know of prehistoric species that no longer exist through physical evidence, mainly fossils. The fossil record is extremely sparse. On top of that, we're not even sure of rates of emergence and extinction of contemporary species. For example, insects are the largest class of animals; 6 to 10 million species accounting for perhaps 90% of the total variety of animal species. 6 to 10 million is a wide variance. How do you calculate extinction rates from that?
antialias_physorg
5 / 5 (5) Sep 19, 2014
The "why" is because we must consume resources to survive as individual organisms, and as a society.

So does every other living thing. No reason why this means humans must therefore be a cause of mass extinction why they can somehow do this without causing one. We can adapt our lifestyles to the point where we don't impact the environment unduly.
we are forced to shape the environment around us to meet our needs

Yes. But we can so in an sustainable manner. Long lasting structures. Low impact farming. Population control. Recycling/renewables instead of fossil/disposables. Water and energy conservation. (And we may even be on the brink of being able to adapt ourselves, but that's still too SciFi to have an impact).
antialias_physorg
5 / 5 (4) Sep 19, 2014
Feeding this many people requires that we reduce the species diversity in arable land across to only the crops that we want grown

No it does not. We are perfectly capable to produce agricultural machines that could pick out one agricultural product that is currently ripe for pickling in a field that is completely mixed. Mixed fields have all kinds of advantages
- less susceptibility to pests (using less pesticides)
- not depleting the land of available nutrients in a one-sided manner
- using less fertilizers
- less susceptibility of soil erosion because the field is never completely bare.
- higher variety of locally produced foods (i.e. less fuel needed for transporting products to the consumer as opposed to regional mono-cultures)

Even the production of "clean" energies requires that first the Earth and the environment be raided for raw minerals and the production of waste.

Only once. And the other kinds of fossil energy will run out. Then what?
cjn
1 / 5 (1) Sep 19, 2014
Even the production of "clean" energies requires that first the Earth and the environment be raided for raw minerals and the production of waste.

Only once. And the other kinds of fossil energy will run out. Then what?


@antialias: You're mistaken if you think I'm arguing about responsible stewardship; I'm not. I am, however, a realist. We cannot maintain a population of 7+bn individuals and still live in a manner which does not significantly impact the environment. Its impossible. Too many people live in denial of this fact.

The only way we could reasonably feed a population as large as we have is through the industrialization of modern agriculture that we've seen today. We need to get the most out of the land acreage we have dedicated to farming to sustain our populations, and that means that an overly-complex arrangement of mixed fields and extremely selective harvesting will not be an effective solution for the scale we need.
cjn
1 / 5 (2) Sep 19, 2014
(cont.)
Further, yes, we have to absolutely minimize species diversity in arable land for farming. We have to eliminate the native grasses and flowering plants, the herbivorous insects and animals, and the trees and shrubs. When you look at centuries-old farm land you can see and feel how homogenous the land is; a handful of grasses and insects.

To build the production capacity and infrastructure we need for a technological civilization we need to mine, need to smelt, need to transform raw material to components, components into devices, devices into systems, and systems into services. None of this can happen without first destroying some or all of the natural state in-which we found these resources.

Again, I'm am very much a proponent of "responsible" living, renewable energy, and reduced consumption, but that doesn't mean that my needs won't have an adverse impact on the environment.
antialias_physorg
5 / 5 (3) Sep 19, 2014
We cannot maintain a population of 7+bn individuals and still live in a manner which does not significantly impact the environment.

There's plenty of energy and plenty of food being created (we're just wasting much of it or feeding it to livestock which is a very inefficient way of creating food). We have the means to optimize this. Yes there will be some impact, but we don't need to drive other species to extinction at this rate.
...and having 7bn people is also not a 'must have', either. We do have the ability to have population control (or at the very least spread education and wealth more evenly which seems to have a population control effect by itself).
for a technological civilization we need to mine, need to smelt

We just need to reuse what we have. Ores aren't endless either.

We can reduce our oimpact considerably - and nature does have some resilience. Even with some impact no extinctions need to arise.
mooster75
3.5 / 5 (4) Sep 19, 2014
we are forced to shape the environment around us to meet our needs

Yes. But we can so in an sustainable manner. .

We can, but will we?
cjn
1 / 5 (2) Sep 19, 2014
@antialias
I don't think you can assume that people will embrace forced population reduction as a means to preserve other species, regardless of "education" or "wealth" spreading. We have a biological drive to reproduce, and to do it often; its what we were born to do. The only evidence we have is that population will grow when not under some sort of selective pressure. Moving forward to assess and mitigate our impact on the bioshphere, we have to be realistic about the baseline of what civilization consumes and how populations will behave.

Think for a second about what went into the electronic device you are using to interact on this forum, the energy required to maintain operation, and the infrastructure required to interface with others through the Internet. Its an incredible amount of resources and energy, all resulting in the destruction of something existing in its previous state, and its a tiny part of your impact on the world driven by your modest existence.
PacRim Jim
1 / 5 (5) Sep 20, 2014
In a few decades humans will fill the solar system with millions of novel species created with commercial biogenic equipment.
Will complaints about extinction stop then?
I suspect not. Some people live to complain.
Sinister1812
5 / 5 (2) Sep 20, 2014
It's frustrating how short-sighted a lot of us really are. It's going to catch up with us eventually.
antialias_physorg
4.2 / 5 (5) Sep 20, 2014
I don't think you can assume that people will embrace forced population reduction as a means to preserve other species, regardless of "education" or "wealth" spreading.

That's the fun thing: Education and security seem to accomplish this all on their own - without any coercion.
The only evidence we have is that population will grow when not under some sort of selective pressure.

Statistics say the exact opposite. The wealthier and the more educated a nation the less their population growth (to the point where the most wealthy/educated ones have already started a population decline).

the energy required to maintain operation, and the infrastructure

..both of which is already declining as efficiency goes up. The energy I required to go on the internet a scant 10 years ago was almost easily double than what I use now. And I see no reason whyt that trend should not continue.

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