Extinction events

[Earniel]

Originally Posted by EllethValatari

I'm going to annoy everyone and take the philosophical approach to this issue, which ironically is the simplest approach.

Personally I would consider it the most pointless approach, but then I never put much stock in philosophy. Too impractical for my taste.

Basically, if a scientist states that an animal is extinct, he is saying that "No (insert animal) is living on this earth." However, this fact cannot be proven unless someone were able to observe every inch of this earth at the same time, and thus deem the above statement correct. Debate proven unprofitable

You reach that decision a little too easily. Species don't get declared extinct without a lenghty process. For instance the Baiji isn't considered officially extinct just yet, it is noted as 'presumably extinct'. It hasn't been found during the two latest scientific surveys and there hasn't been any other sightings otherwise, which is quite telling for a sizable marine mammal.

But unless you can produce this instant say, a triceratops or a thylacine, -heck I'll happily take any golden toad- extinction is quite a reality whether it fits in one's philosophy or not.

Now, we can happily (and even productively) argue about the thylacine being effectively extinct or not, the same goes maybe for the golden toad. But I'd love to see someone willing to argue that the triceratops is not well and truly extinct.

[inked]

#18, Earniel, is what I was wanting to know.


link the first...
"Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from the threshold chosen for describing an extinction event as "major", and the data chosen to measure past diversity."

17-53% of all families, 48-84% of all genera, and 50-70% of all species diappearing rapidly seem to be the definition for all 5 major extinction events, if I read the article properly.

"The gaps between mass extinctions appear to be becoming longer, while the average and background rates of extinction are decreasing. Mass extinctions are thought to result when a long-term stress is compounded by a short term shock.[16] Over the course of the Phanerozoic, individual taxa appear to be less likely to become extinct at any time,[17] which may reflect more robust food webs as well as less extinction-prone species and other factors such as continental distribution.[17] However the taxonomic susceptibility to extinction does not appear to make mass extinctions more or less probable.[17]

The idea that mass extinctions are becoming less frequent is rather speculative – from a statistical point of view a sample of about 10 extinction events is too small to be a reliable sign of any actual trend."

Ergo, my question, aren't we being a wee bit overly dramatic?

"Arens and West (2006) proposed a "press / pulse" model in which mass extinctions generally require two types of cause: long-term pressure on the eco-system ("press") and a sudden catastrophe ("pulse") towards the end of the period of pressure.[23] Their statistical analysis of marine extinction rates throughout the Phanerozoic suggested that neither long-term pressure alone nor a catastrophe alone was sufficient to cause a significant increase in the extinction rate."

Multiple causation, hmmmm...............

link the second ...

"Background extinction rates are typically measured three different ways. The first is simply the number of species that normally go extinct over a given period of time. For example, at the background rate one species of bird will go extinct every estimated 400 years [5]. Another way the extinction rate can be given is in million species years (MSY). For example, there is approximately one extinction estimated per million species years [6]. From a purely mathematical standpoint this means that if there are a million species on the planet earth, one would go extinct every year, while if there was only one species it would go extinct in one million years, etc. The third way is in giving species survival rates over time. For example, given normal extinction rates species typically exist for 5–10 million years before going extinct. [7]"

The fact that we do not currently know the total number of species, in the past nor the present, makes it very difficult to accurately calculate the non-anthropogenicly influenced extinction rates. As a rate, it is essential to know not just the number of extinctions, but also the number of non-extinctions. This fact, coupled with the fact that the rates do not remain constant, significantly reduces accuracy in estimates of the normal rate of extinctions.

This inaccuracy was what my gut was responding to, by the way.

Thanks for the information.


I would say that your use of "extinction event" was, in my estimation, a poetic (indeed, hyperbolic formulation, to be precise) way of expressing your emotional response to the loss of amphibia you hold dear. It was not intended, I gather, to be a precise statement. Am I correct?

[EllethValatari]

Originally Posted by Tessar

Yes and no. One definition of extinction is "the act or process of becoming extinct; a coming to an end or dying out." Meaning that a species need not be entirely gone to be in the midst of extinction."

I was speaking of the moment in which an animal is declared to be extinct- the process or probability of extinction obviously being excluded.

Originally Posted by Tessar

This is not really a true statement.

You are simply stating that you don't think it's possible to call a species extinct, which in truth is not really the topic being debated. The topic being debated is about the event of extinction.

Another problem is that by saying such a debate is unprofitable you are basically saying, "Well we can't prove it 100% so we shouldn't bother." That's like saying, "I'm not sure that my dishwasher is getting every scrap of harmful bacteria off of my plate, so I wont bother washing it." There is a balance to be reached between "what's too much concern?" and "what is too little effort?" and that is part of what inspires this kind of debate. To just say that because we're not all scientists we shouldn't talk about it, or because even scientists can't prove it for sure, is not conducive to progress or balance.

I'm sorry I wasn't more sarcastic in how I worded my post. I should have remembered sarcasm is more easily noticed by the ear than the eye I don't agree with the philosophical approach to this issue; I was merely putting one out there. The problem with philosophy is it's location: it is closer to the heavens than it is to the earth. As G.K Chesterton once said,

The poet only asks to get his head into the heavens. It is the logician who seeks to get the heavens into his head. And it is his head that splits.

An imperfect world cannot be governed by perfect reasoning, and I don't expect it to.

[Gwaimir Windgem]

Originally Posted by inked

Ergo, my question, aren't we being a wee bit overly dramatic?

It's really not necessary to think that it's absolutely and definitively an extinction event. EV's point did have some validity: our awareness of the number of species in the world today is exponentially higher than it ever has been, and so it's really difficult to say definitively that what is going on now is equivalent to anything before which has been called an extinction event. However, it is possible that there seems to be a pretty good chance of this, based on the evidence we have; if our certainty is not absolute, it does seem to be enough that we should act as though it were, rather than taking a complacent inaction.

[EllethValatari]

Originally Posted by Eärniel

Personally I would consider it the most pointless approach, but then I never put much stock in philosophy. Too impractical for my taste.

I disagree. As I said in the post before this, logical philosophy (Isaac Watts, anyone?) can only work perfectly in a perfect setting, in the same way as how an accurate science experiment must have controlled variables. Not impractical, just seldom used, and used correctly.

[Gwaimir Windgem]

The difficulty is that we don't live in a perfect setting. In a perfect setting, the planets should trace out circular orbits, but they don't.

Don't get me wrong, I'm a fan of philosophy, and I believe that it is the greatest (or second greatest) human endeavour. I just think it's also important to be very aware of its inadequacies, and to not see in it a system that will infallibly describe the real world, as though we were able to completely grasp everything going on in reality. Don't think that there is no middle ground between simply dismissing philosophy and using it as a textbook to guide our interactions in the real world. Understanding philosophy as flawed does not in any way detract from the possibility of esteem, or even reverence for it.

[EllethValatari]

Originally Posted by Gwaimir Windgem

Understanding philosophy as flawed does not in any way detract from the possibility of esteem, or even reverence for it.

Is philosophy flawed, or is the world flawed and thus a mode of thought designed for a perfect circumstances rendered impractical?

[Gwaimir Windgem]

Both. Certainly, the world is too complex and multiform, and indeed flawed, for us to ever attain a full understanding of it. But at the same time, philosophy does not exist in a vacuum; it is the attempt of an intellect to engage the world rationally, and those intellects are themselves flawed.

[Earniel]

Originally Posted by inked

17-53% of all families, 48-84% of all genera, and 50-70% of all species diappearing rapidly seem to be the definition for all 5 major extinction events, if I read the article properly.

Major extinction events, yes. But there are several lesser extinction events recognised. One also has to keep in mind that 'rapidly' on a geological timeframe is not what we call rapid in day-to-day conversation.

This inaccuracy was what my gut was responding to, by the way.

The uncertainty and resulting inaccuracy are, as you see, noted and taken into account.

I would say that your use of "extinction event" was, in my estimation, a poetic (indeed, hyperbolic formulation, to be precise) way of expressing your emotional response to the loss of amphibia you hold dear. It was not intended, I gather, to be a precise statement. Am I correct?

Hm, no. there is little poetry to be found in the term extinction event. And while the current rate of extinction and decline of amphibians is deeply worrying, they're sadly not the only ones and are only part of the whole picture.

Nor am I the only one to consider modern-era extinctions as an extinction event. There have been many biologists from different fields saying the same thing. So I take my cue from several different sources. There is scientific concensus. The name 'anthropocene extinction' is even mentioned in several of places (although the definition and scientific acceptance of anthropocene as a new geological era is still under discussion.)

[Lief Erikson]

This is a cool thread .

Thanks for those sources, Eärniel, they're very interesting.

[Earniel]

You're welcome, Lief.

And ahem, moved all the welcomes to the Welcome thread.

[inked]

Frogs and suburbia ...

http://sciencenews.org/view/feature/...s_face_threats

Some rather unexpected findings, it seems.

[Earniel]

What did you find unexpected?

[Alcuin]

Does this link to the Voluntary Human Extinction Movement go here or in the Global Warming Thread?

[inked]

Originally Posted by Eärniel

What did you find unexpected?

"After almost a decade of hot debate over whether atrazine, a common agricultural weed killer (SN: 2/27/10, p. 18), is creating frogs with both male and female characteristics, some scientists have taken a step back to survey such intersex frogs in a wide variety of landscapes, including pristine woodlands, urban areas and suburbia. Ecologist David Skelly of Yale University, for example, has found that — counter to usual assumptions — percentages of mixed-sex green frogs may be higher in the suburbs than on agricultural lands."

The same the research showed: "COUNTER TO USUAL ASSUMPTIONS". You know, that data thingy screwing around with the hypothesis stuff.

[Earniel]

Originally Posted by inked

"After almost a decade of hot debate over whether atrazine, a common agricultural weed killer (SN: 2/27/10, p. 18), is creating frogs with both male and female characteristics, some scientists have taken a step back to survey such intersex frogs in a wide variety of landscapes, including pristine woodlands, urban areas and suburbia. Ecologist David Skelly of Yale University, for example, has found that — counter to usual assumptions — percentages of mixed-sex green frogs may be higher in the suburbs than on agricultural lands."

The same the research showed: "COUNTER TO USUAL ASSUMPTIONS". You know, that data thingy screwing around with the hypothesis stuff.

Well, one would assume more pesticides were being used in argicultural landscapes than urban ones, wouldn't you? The fact that the suburbs have maybe even a higher percentage of gender-bender frogs shows that the suburbs too must have a high level of endocrine disrupting subtances. Atrazine is a possible source still, but they point to waste-water with left-overs from birth control substances as a second possible source.

Besides, isn't science all about testing hypotheses?