Yes, that IS what I was thinking of. Thanks. Not 95% but still pretty high.
In fact, IS it proper to separate the two? You’re right, we are not alien visitors. We are of nature ourselves. So could the emergence of mankind be nature’s way of thinning out some species?
This is a simple matter of definition. “Natural” has two relevant and totally contradictory definitions. One definition is “not artificial”. The other is “in conformity with the observable world.” If you’re using the first one, “artificial” is roughly synonymous with “manmade.”
So nature either refers to everything in the cosmos except that which humans have influenced through artifice, or it refers to everything in the cosmos, period. Debates about whether humans are a part of nature are, in my opinion, totally boring, since the answer is entirely a matter of semantics.
Daniel
Can we agree on the “Combo Theory”?
A little bit of man, a little bit of nature…
Is that a song I’m unaware of?
I’d recommend David Quammen’s The Song of the Dodo to anyone who’d like to get a handle on the larger picture on evolution and extinction.
No. And in my post, that’s not what I meant. I suspect, however, that there’s an emergent property of complex systems, in that shocks tend to occur every so often. The “schedule” I was talking about merely indicates that die-offs have occurred every few hundreds thousand years, largely because after enough time some new species, evironment, or other change occurs. We happen to be the new one, but there doesn’t appear to be any causation behind it.
It was not really serious.
Was trying to edit:
If you think about it, it’s really just the odds. Over a long enough period of time, if the overall odds of certain disasters are roughly so much, you’ll tend to find they space them out. When you’ve got a standard deviation of a 100,00 years of so, it gets real easy to have a “schedule” pop up. After all, our science can’t really tell if you had die offs from two sources pop really close, or if it was just one.
You can tell that Siam Sam isn’t either,
because he never mentions Body Thetans; the alien presence within us.
Sure, but where are you taking this point? That is, I think, more important than the point itself.
It sounds almost like you’re arguing towards something like “Stuff like that would happen anyway, without us being here, so why care?”. I don’t mean to put words in your mouth - it’s just I can’t see where else you could be headed with such an argument.
No, that’s not where we were going. I was just making a point that as new species come and go, plants and critters move up and down the food chain naturally. What we have is not what we always had, and won’t be the end of the introduction of new species to the planet. He was simply saying that he believes we don’t see “natural” selection anymore because humans are always the cause of the destruction of a species.
No, really. We’re part of nature, aren’t we? So maybe it’s natural for us to kill off stuff.
I think this is basically the answer to the OP’s question: No, not all extinctions occurring are due to man but the overwhelming majority are as evidenced by the fact that the current extinction rate is a few orders of magnitude higher than the background rate.
Fair enough (and thanks for clearing that up). I agree that he’s wrong. We’re breaking things, but some things break without us.
There is an oddity about extinction rates. They are not happening where they have been predicted to happen.
All of the shouting has been about the predicted rise in extinction rates among dwellers in the tropical forests. However, here’s the oddity.
There have been no continental forest birds or forest mammals which have gone extinct in the last 500 years. By “continental” I mean those birds and mammals that live and breed on the continents, not on islands (including Australia).
On the islands and Australia, there have been a host of extinctions from predation by introduced species (including man). However, there have not been a corresponding host of extinctions on the continents. In fact, for continental forest birds and mammals, there have been none. In the last 500 years.
Don’t believe me? Go to the Red List search page. Put in “Animalia” for the Kingdom, “Chordata” for the Phylum, and “Mammalia” for the Class. Select “Terrestrial” for the “system this species is found in”. Select all “Regions of the World” except the Caribbean and Oceania, and select “Forest” for the habitat. Finally, select “Extinct” for the classification.
This will give us all of the extinct continental forest mammals … result? One island living rodent (from an island in the Gulf of Honduas), one island living bat (from Mauritius) … no forest mammals are recorded as ever going extinct. And the same is true for forest birds.
Now, over the last 500 years we have whacked down huge swaths of forest. But the birds and mammals there, I guess they hadn’t read the oh-so-impressive scientific studies that say that they should be extinct, so they just ignored the massive deforestation … damn impertinent of them, I’d say.
So before we get all hot and bothered about the destruction of the forests causing hundreds of thousands of species to go extinct, we should ask ourselves … where are the bodies?
w.
If you’re claiming that no continental birds have gone extinct in the past 150 years, how do you explain away the Passenger Pigeon?
A more theoretical response: the problem with looking at mammalian extinctions for the Mediterranean basin, the Indus valley, the Yangtze valley, and Central America is that all those areas have been settled by environment affecting civilizations for thousands of years. The causality of the various megafauna die-offs around the time that the ancestors of today’s Native Americans were showing up is pretty hard to prove. The best evidence lies for blaming man for the extinction of the giant sloth where middens have shown that the two species did actually share territory at the same time, and imply that some giant sloths ended up feeding human communities. But even there, things are hard to prove that it was human caused extinctions.
More recently lions, tigers, ostrich and bears had all been native to the Mediterranean basin during the Greco-Roman period. But, AIUI, if one looks at the records for the menagerie suppliers from the latter Western Roman Empire you’ll see that common animals for the circus were growing more and more scarce, and having to be brought in from further and further away. I believe it is a fact that many species that were in the Mediterranean basin, and Europe, two thousand years ago, are gone, now. And because of human activity.
Before one can start claiming that the larger mammal species that one would expect to be happening aren’t there, one should consider that for a lot of species there were reasons for our ancestors to see the removal of competing species as a good thing. Environmentalism is a concern that often goes unnoticed until a society has a food surplus. (Which is a crying shame, since a more aware and long-term view towards natural resources seems to go well with helping to keep food surpluses available.)
Or the Carolina Parakeet
This is covered under an evolutionary principle discussed by Darwin. Briefly, new species can insert themselves within an existing ecosystem and occasionally “wedge out” a pre existing species.
The concept of wedging is better explained in a brief and readable article extract “Tyres to Sandals” by the late Steven J Gould from Natural History magazine:
OK, but is it possible we’ve driven some to perhaps unrecoverable teetering on the brink of extinction?
You sound like you’re suggesting we can just continue to hack down forests and nothing bad happen. Is that what you’re saying?
First, you need to back up and read what I said, which was that no continental forest bird has gone extinct.
You and another poster are correct that both the Carolina Parakeet and the Passenger Pigeon went extinct … but not by the mechanism (cutting down forests) which has been proposed as the cause of the “6th wave of extinction” which is supposedly happening.
In fact, only six continental birds and three continental mammals have gone extinct in 500 years. This is indistinguishable from the background extinction rate.
Someone asks if I am saying that we should continue to cut down forests indiscriminately. No, absolutely not, that would be a bad idea for a host of reasons. It’s just that history has shown us that extinction is not one of those reasons.
Here’s the problem. In their 1963 seminal work “Theory of Island Biogeography,” Macarthur and Wilson explored the “species/area” relationship. This relationship, first stated mathematically by Arrhenius in 1920, relates the number of species counted to the area surveyed as a power law S = C a^z , where “S” is species count, “C” is a constant, “a” is habitat area, and “z” is the power variable (typically .15 to .3 for forests). In other words, the number of species found in a given area is seen to increase as some power of the area examined.
By surveys both on and off islands, this relationship has been generally verified. It also passes the reasonability test - we would expect to find more species in a state than we find in any county in that state, for example.
Does this species/area relationship works “in reverse” – if the habitat area is decreased, does the number of species decrease as well? And in particular, does this predicted reduction in species represent species actually going extinct? One of the authors of “Island Biogeography” thinks so. In 1992, E. O. Wilson wrote that because of the 1% annual area loss of (mainly tropical) forests worldwide, using what he called “maximally optimistic” species/area calculations, “The number of species doomed [to extinction] each year is 27,000. Each day it is 74, and each hour 3”. This claim was picked up, and has been spread around the world as fact rather than what it is … an unverified prediction.
If we have lost 27,000 species per year since 1992, that’s 430,000 species gone extinct. In addition, Wilson said that this rate of forest loss had been going on since 1980, so that gives us a claim of over three quarters of a million species lost in 28 years. Wilson also wrote, "Some groups, like the larger birds and mammals, are more susceptible to extinction than most.”
However, the facts don’t bear this out. You say that “Before one can start claiming that the larger mammal species that one would expect to be happening aren’t there, one should consider that for a lot of species there were reasons for our ancestors to see the removal of competing species as a good thing.” Well, no. That has nothing to do with whether forest reductions since 1980 have caused the loss of three quarters of a million species as is claimed.
There are about 8,400 continental bird species and about 4000 continental mammal species. Using Wilson’s figure of 10 million total species, he is claiming about 23 bird extinctions (27,000 X 8,433 / 10,000,000) and 11 mammal extinctions (27,000 X 3,921 / 10,000,000) per year, for a total of 34 continental bird and mammal extinctions per year. (I have used Wilson’s figure of 10 million species on earth, although modern estimates are around half that number. It makes no difference to the final result, as the total number of species cancels out of the equation.)
In 1988, Wilson said that a 40% reduction in forest and other habitats had already occurred. With the z value of .15 and the 1% annual forest loss as used by Wilson, at 40% habitat reduction the total species loss to up to 1998 should be about 32 times the annual loss. This means the total predicted bird and mammal extinctions are 32 x 34 extinctions per year, or 1,088 continental bird and mammal extinctions predicted by 1998. Over a thousand bird and mammal extinctions predicted by the turn of the century, and not one of them shows up in the record.
So y’all can ramble on about the huge extinction that is going on. Me, I’ve got this odd proclivity to look for that thing called “evidence” … I know that’s old-fashioned, but I’m just a reformed cowboy so I’m kind of old-fashioned myself.
Where is the evidence for the extinction? E. O. Wilson, backed by an army of environmentalists, says we should have seen three quarters of a million extinctions since 1980 occurring from forest reduction …
Can you name me one of them? There should be around a thousand birds and mammals among them. Can you name me one bird or mammal gone extinct from forest reduction? And if not … why do you believe this nonsense? A claim that we are in the middle of the “6th wave of extinction” is an extraordinary claim, which requires extraordinary evidence. But, far from having extraordinary evidence, you have no evidence at all …
If three quarters of a million species had actually gone extinct, you’d think someone could name at least one of them. I mean, we’re sure to have missed some of them. But birds are brightly coloured and loud and very visible, we wouldn’t have missed many of them … and supposedly, about 600 bird species have already gone extinct since 1980 from the cutting down of tropical forests, with 23 bird species gone extinct last year, and another 23 birds slated to go extinct this year.
Name me one of them.
w.
PS - it is critical to remember that none of this implies that habitat destruction, forest fragmentation, or loss of species diversity are incidental or unimportant issues. Diversity is vital to ecosystems: the more types of creatures there are in an ecosystem, the better the ecosystem works. Local extinctions can have large negative effects on the local area, and allowing for other species in our plans is essential.
Also, none of this implies that extinctions will either rise or fall in the future. This is an analysis of the historical record to date.
An examination of the historical extinction records does show, however, that
• Observed extinction rates on the continents are not significantly different from background rates.
• Although one continental bird species went extinct when its freshwater habitat was totally destroyed, the extinction of a bird or mammal species through habitat reduction has never been recorded on any of the continents.
• No continental forest bird or mammal has been observed to go extinct from any reason.
• The top, A number one reason for extinction is predation by other species, including man.
Dude while I agree with the major thrust of your post, you can’t just post nonsense like this. Many birds and mammals have become extinct though habitat reduction. For Australia alone I can name the paradise parrot, eastern hare wallaby and lessers stick nest rat. For Europe I can name the aurochs. For Asia the Himalayan Quail. All are species that have become extinct as a result of habitat reduction.
Are you saying that aurochs isn’t extinct, or that it wasn’t a forest animal?
And the thylacine was most certainly a forest dwelling species, and is certainly extinct. I’m guessing you are going to try for a true Scotsman by claiming that since it had been extemrinated on the mainland some time before the last island remnants were exterminated it isn’t amainland species, but it was mainland species before humans exterminated it from the mainland. However that kind of weaseling just won’t work around here.