I put this in Great Debates because…I’m debating it with Mr. K. He says that all species in the modern world that disappear do so because of man’s impact. I say that species are an ever-evolving thing with new ones cropping up and old ones dying off… and although we fuck up a lot of things, it isn’t solely man’s impact that make a critter or plant go bye-bye.
I’m not even sure how to look this up, so in addition to any debate that might be here (by the way, I’m fairly certain there isn’t a debate), if you could provide cites, I’d appreciate it. Anyone?
I’m with you, but I’m not sure how to “prove” anything like this. To me, it reads as an exercise in logic: if we have fossils of animals (and plants! Don’t forget that plants are specieses, too!) that went extinct before humans came along, then there were obviously forces in effect that were Not Us that caused extinction. So what’s changed to eliminate those causes? Nothing, that’s what. We may be causing the extinction of some species that wouldn’t be extinct without us, but we’re not impeding those other forces that have led to extinctions all along (habitat change where we aren’t, most likely).
Mankind is most definitely the cause of the extinction of some species, like the dodo, but then the dodo would probably have become extinct if any predator had introduced itself - like a pregnant cat getting washed ashore. Except for peculiar cases like the Smallpox virus, I think mankind is better viewed as an accellerant than a cause.
Well, the answer is you are right. Species can and do become extinct plenty free from human impact. Our presence has certainly caused an upswing in extinctions due to habitat loss and hunting. Extinctions can be caused rapidly, ( weather/geologic events that destroy a microhabitat) or slowly due to an inability to adapt. Human predation on habitat and direct hunting simply occurs at a faster rate that is difficult for natural processes to keep up with. In addition, human commerce has spread new species all over the place, where they displace existing ones.
We have a tendency to view ourselves as being immune from, or the sole cause of evolutionary change, but it is not correct.
It’d be peculiar as hell if the advent of man just happened to coincide with a drop in the background rate of extinctions, to zero.
AFAIK, volcanoes are still covering remote valleys in ash, earthquakes are draining pristine lakes, and pathogens are mutating to infect new host ranges.
The San Benedicto Rock Wren became extinct on August 1, 1952, at approximately 9 AM, when the volcanic island of San Benedicto exploded.
(Granted, it was technically only a subspecies; but there are shockingly few opportunities to cite this bit of trivia that are even remotely appropriate, so I figured I’d offer it for consideration here anyway. If you ever find yourself on one of those quiz shows, and the big jackpot question involves the extinction of the San Benedicto Rock Wren, you’re all set now.)
He’s not around at the moment, but I think maybe he’s saying that we don’t have a chance to see a “natural” extinction due to our impact. Meaning that we speed things up and maybe overtake the natural process by getting our big-ass carbon footprint in the way of the natural process that would take place if we weren’t a factor. I don’t think that’s correct, but it would be more believable than saying we’re the absolute cause of all of it.
Actually it turns out that dinosaurs still do roam the earth, as birds (except for the San Benedicto Rock Wren of course). So that may not be the best discussion-ending example.
The domestic dog is a subspecies of timber wolf these days, too.
Correct. But he did frame his argument within the confines of the modern world. By that, I think he means the Industrial Revolution to present day, as opposed when man actually came on the scene.
Besides dinosaurs, wasn’t there a major species extinction at one point in prehistory, maybe more than one? Something drastic, like 95% of all species at that time, according to the geologic record?
These days, sure it’s caused by humans; but something else would probably come along sooner or later to do the job.
I can sort of see what he’s saying - basically that we “extinct” them before “nature” has a chance to, but I still don’t think he’s right. There’s a whole lot of empty land out there where humans aren’t mucking about. I sometimes forget that, whatwith the 307 Starbuckses within a 10 mile radius around here.
Another term that has to be defined is just where do you put the limit on “human impact?”
It’s generally considered a good thesis that the giant sloth’s extinction was, in part, from the pressures of the newly arrived Native Americans who hunted it for food, but the climate that had favored megafauna prior to that point had already changed, and most of the recent megafauna extinctions took place with only minimal (if any) impact from human factors.
In more modern times, the solenodons are endangered (and the Cuban Solenodon had been considered extinct until a live specimen was found recently), not by deliberate human activity, but because they’re preyed upon by introduced species: cats, dogs, and rats. Which were all introduced (and with respect to the rats, introduced inadvertently) to the various Caribbean islands hundreds of years ago, and pre-dates the Industrial Revolution. So, when/if those species actually go extinct, would your husband consider them to be human caused extinctions, or not?
On preview: Siam Sam, I think you’re talking about the Permian-Triassic extinction.
Very good point. I think we’d have to consider it part of the human impact. They wouldn’t be there unless we introduced them, so it’s not only human, but in my opinion “direct” human impact. Just the same as new species being brought into lakes and eating all the other fish. It has to be attributed to man.
We are remarkably arbitrary about this type of thing though. Plenty of introduced plant species are just fine with us, regardless of their impact; while other are noxious weeds because they do nothing more than interfere with grazing land. Same goes for introduced animal species. Tokay geckos are mostly okay with us because they eat loads of bugs and baby mice. They also eat baby birds and native lizard species. Lizards are oogy though, so let’s just naturalize them. If they start eating the endangered Diesifyouevenlookatit bird chicks though, they’ll be war on the bastards. :rolleyes:
An oddity about the recent extinctions is that… they’re happening on schedule.
More or less, anyway. See, throughout all of history, there have been repeated die-offs every so often. These seem to occur at reasonably predictable intervals (granted, rounded to the nearest 10,000 years or so). And we’re just about properly timed for one. And along comes man, which in fact does the job nicely. We’re force other species to adapt or perish, just as with all previous extinctions. This time, instead of climate changes or huge meteors, the altering agent is alive and willful.
It makes you think. I’m not sure what about, though.
God really shouldn’t just leave these things lying around.
In a technical, pedantic sense, I might agree with your husband. As far as I know, every species on earth has felt the impact of human technology in one way or another, whether through reduced territory, minor climate changes, the introduction of pollutants into its food chain, or similar impacts. I suspect that a halfway decent biologist could show how at least one of these impacts has been harmful for the survival of each species, even if in a tiny way. Therefore, whenever any species goes extinct, you could say that it’s due in part to human influence.
This wouldn’t be a very interesting claim, though. If his claim is the more interesting one, that human influence is the primary cause of every extinction happening today, I’d want to see much stronger evidence for it. As others have said, that’d be a pretty remarkable claim: what has caused other causes of extinction to go extinct?
OTOH, keep in mind that humans have helped a number of species increase far beyond their original size. Think dogs, cats, and domesticated farm animals. Also, non-domesticated animals like pigeons, rats, and cockroaches. Some of the domesticated populations might not be able to survive without humans, but that’s another matter.
