Extinction Peeve

[Dancing David]

frequently i come across this little gem abou extinction. There were large land animals in the North American continent until homo sapiens arrived, then the land animals went away. Ergo the humans caused the extinction of the large land mammals.

I can stand this in Lopez's Artic Dreams which is an extended travlouge, but I read this in Morris's The Future of Life which is an op/ed piece about biodiversity, most of which is well cited.

But he even goes to say that the animals in Africa had a chance to co-evolve with homo sapiens which is why there are still elepahnts in Afrca.

Aaaaargh, the reason (most likely) that the large land mammals went extinct is post ice age (8,000 years before present) there were these tremendous temperature cycles where the average temperature fluctuated by a much as twenty degrees over a century. Large animals are not usually mobile enough to adjust to these changes.

Sigh, so these homos sapiens did something they didn't do in Asia and Africa?

 

[Phil]

Forgive my ignorance on this topic, but is there evidence to suggest that our kin had adverse impacts on any mammal population?

I would think that as we became better hunters and our numbers grew, we had to kill more food, and that would affect the populations of other species. But are there cases of adverse effects on any species?

 

[arcticpenguin]

Large mammals made it through quite a number of ice age cycles. Then man shows up and Boom!

Something similar happened in Australia as well. I think there is too much coincidence to write it off.

 

[Dancing David]

Forgive my ignorance on this topic, but is there evidence to suggest that our kin had adverse impacts on any mammal population?

I would think that as we became better hunters and our numbers grew, we had to kill more food, and that would affect the populations of other species. But are there cases of adverse effects on any species?

The most notable are the large land birds of polynesia, totaly gone within generations of the arrival of humans. Then there are the passanger pigeons.

 

[Dancing David]

Large mammals made it through quite a number of ice age cycles. Then man shows up and Boom!

Something similar happened in Australia as well. I think there is too much coincidence to write it off.

The efect of humans on the islands is fairly notable.

But my instructor at the U of I said that the extintion of the large land mammals in North America occured after the arrival of homo sap during the time that the temperatures were cycling so widely.

Why are there still elephants in Africa and Asia, killing a mammoth when there is no other game makes sense, but killing elephants, rhinos and camels, when there are deer is a strech. Why kill off the elephants and not the other game?

I just don't get it, it's not like there is any evidence that the homo sapiens in North America killed any elephants.

 

[Phil]

The most notable are the large land birds of polynesia, totaly gone within generations of the arrival of humans. Then there are the passanger pigeons.

So then why the peeve about the large land mammals?

Is it just because some throw our arrival around as the only cause with no evidence? Or is there something else that peeves you about it?

Playing devil's advocate: We had obvious impacts on the populations of smaller mammals. Couldn't we, along with the ice ages, indeed have played a part in the extinction of large mammals?

 

[Nucular]

Forgive my ignorance on this topic, but is there evidence to suggest that our kin had adverse impacts on any mammal population?

Well one such 'mammal population' upon which our kin - the white European 'settlers' - had what might be termed an 'adverse impact' were the Tasmanian aboriginals, though that's probably not quite what you meant.

Tactics for hunting down Tasmanians included riding out on horseback to shoot them, setting out steel traps to catch them, and putting out poison flour where they might find and eat it. Sheperds cut off the penis and testicles of aboriginal men, to watch the men run a few yards before dying. At a hill christened Mount Victory, settlers slaughtered 30 Tasmanians and threw their bodies over a cliff. One party of police killed 70 Tasmanians and dashed out the children's brains.
- Jared Diamond

I don't doubt that humans have had similar effects on other species, if this is how we treat our own.

On May 7, 1876, Truganini, the last full-blood Black person in Tasmania, died at seventy-three years of age. Her mother had been stabbed to death by a European. Her sister was kidnapped by Europeans. Her intended husband was drowned by two Europeans in her presence, while his murderers raped her.

 

[Dancing David]

So then why the peeve about the large land mammals?

Is it just because some throw our arrival around as the only cause with no evidence? Or is there something else that peeves you about it?

Playing devil's advocate: We had obvious impacts on the populations of smaller mammals. Couldn't we, along with the ice ages, indeed have played a part in the extinction of large mammals?

A large flightless bird does not have the same resources as an elephant or a rhino, especialy with the eggs. My main peeve is that people just assume that it must have been the humans, and not something else.

There could have been a half measure scenario, but again why still elephants in Asia and Africa.

Thanks for the comments , all.

 

[Eos of the Eons]

Haven't read everything. Have you seen those animals that went extinct? They aren't even anywhere else in the world. They were huge. Try feeding yourself when food gets scarce. Hmm...difficult, more difficult than a wolf hunting a mouse. Mammoths are a little hard to keep up. The smaller survive because they can find enough food to feed their smaller bodies.

The arrival of man only allowed for him to prey on the weakened masses. Saber tooth tigers were on the wane, and so was their main prey. Man was able hunt and take over the land. The strong survive.

Many animals don't survive severe weather changes. Even neanderthals went extinct.

Blame man all you want, but I feel it was still inevitable.
Man is to blame for mass extinctions of marsupials in Australia, but only because marsupials were extinct everywhere else already. Face it-placentals are better adapted. Rabbits and cats took over the habitats because they were stronger and quite possibly a lot 'meaner', etc.

Just do a google search on "marsupials, extinction, Australia"

 

[Hexxenhammer]

Paleo-indians stampeeded thousands of giant bison (the bigger, badder, pre-historic cousin to the regular bison) off of cliffs all the time. There is ample evidence of this. Did it cause their extinction? Couldn't have helped.

Also, African and paleo-indian diets would have been nothing alike. The paleo-indians would have needed a much higher energy, higher protein diet because of the climate. That means eating meat. And lots of it. Where's the best place to get meat? Big frickin' mammals.

 

[Dancing David]

Paleo-indians stampeeded thousands of giant bison (the bigger, badder, pre-historic cousin to the regular bison) off of cliffs all the time. There is ample evidence of this. Did it cause their extinction? Couldn't have helped.

Also, African and paleo-indian diets would have been nothing alike. The paleo-indians would have needed a much higher energy, higher protein diet because of the climate. That means eating meat. And lots of it. Where's the best place to get meat? Big frickin' mammals.

Ah the famous native americans driving the bison off cliffs story.

If there was taphonic evidence that they slaughetred the animals that would make sense, my intsrutor said there was not. Most likely just wild fire.

Meduium size mammals that can't trample you to death require less effort and danger than killing elephants.

Good point though.

 

[arcticpenguin]

My main peeve is that people just assume that it must have been the humans, and not something else.

Actually, there's been legitimate research done, not just assumptions. Here's an article: http://cas.bellarmine.edu/tietjen/images/debating_extinction.htm

Science Jan 8 1999: 182-183.

Over a century ago, Alfred Russell Wallace wrote that "we live in a zoologically impoverished world, from which all the hugest, and fiercest, and strangest forms have recently disappeared ..." (1, p. 150). Researchers seeking to explain this "marvelous fact," as Wallace called it, fall into two camps, one invoking global climatic change and the other human hunting as the cause. Over the past few decades, the debate has become deadlocked, in part because most researchers have focused their attention on the Americas and northern Eurasia, where the extinction of the huge, fierce, and strange creatures, such as mammoths and giant sloths, occurred between 12,500 and about 11,000 years ago. This was a time of rapid climatic change, but it was also when humans first arrived in these regions, making it difficult to discern causality. Australia provides the only separate, continent-sized natural laboratory in which dramatic Quaternary extinctions occurred. It is thus of exceptional importance as a testing ground for extinction theories, but until now problems with dating have limited its potential. As reported on page 205 of this issue, Miller et al. have now documented the extinction of the gigantic Australian bird Genyornis and so have broken new ground in dating megafaunal extinction in Australia (2). At the same time, these authors have broken the current deadlock in the great megafaunal extinction debate.
...
A new school of thought has recently established itself in the extinction debate. It advocates the idea that a combination of human impact and climate change was responsible for the extinction of the world's megafauna. The new Genyornis data (2) also weaken that argument, for the following reason. Fifty thousand years ago, Australia was experiencing mild cooling; 11,000 to 12,000 years ago, the Americas were experiencing rapid warming. These disparate climatic conditions, all coincident with megafaunal extinction, suggest that whatever was happening with climate, it was bad for the big animals. Under these conditions, the hybrid model becomes indistinguishable from the human-caused extinction model, for the influence of climate becomes extremely weak, and only the arrival of humans is important in predicting extinction.

Perhaps you are talking about popular perception, not the current state of the science.

 

[Eos of the Eons]

That article mentioned Moa, that lived in New Zealand

New Zealand was home to an equally impressive giant eagle (Harpagornis) capable of killing an adult moa.

So if people hunted moa into extinction-how did the eagle get extinct too?

http://digimorph.org/specimens/Dinornithiformes/


ALL the big animals died. Even our elephants, emus, and ostriches don't compare. The saber tooths are gone too. The predators and the prey that were huge are all gone.

What was all the plant life like when the big animals came to be and plentiful? What was it like when they started to become extinct? Were their food sources still plentiful when man arrived? Did man deplete their food sources and their numbers?

I still can't believe it was JUST humans that caused all those huge animals to go extinct.

Men didn't have guns back then. Guns were used to kill bison by the thousands. Try killing them by the thousands with spears and bows & arrows.

 

[Hexxenhammer]

Ah the famous native americans driving the bison off cliffs story.

If there was taphonic evidence that they slaughetred the animals that would make sense, my intsrutor said there was not. Most likely just wild fire.

Meduium size mammals that can't trample you to death require less effort and danger than killing elephants.

Good point though.

Did a little research...

Seems the paleoindians used natural features even if they weren't stampeeding bison off a cliff. They would herd them into arroyos and box canyons to mass slaughter them. These sites have the remains of 70-100 animals each. The bison on the bottom of the piles are never even butchered. Their skeletons are intact instead of scattered. This kind of hunting may not have been the sole cause of extinction, but like I said, sure couldn't have helped.

 

[Eos of the Eons]

Bison aren't extinct. I'm not sure even hundreds of Mammoths would be killed if cornered. It would be a horrible waste of meat. Noone can butcher hundreds of mammoths before they rot.

 

[neutrino_cannon]

The pleistocene and recent extinctions are not all a result of humans. Some animals, such as *many* (some ground sloths are known to have coexisted with humans. I don't know of any kill sites) species of ground sloth, and glyptodonts, as well as the last of the phorusrhacids, titanis walleri went extinct in South America, Central America and florida before there were even humans there. Same goes for notoungluates and liptoterns (bizzare, aberant mamals found only in South America). It is possible that relic populations of these animals were hunted by humans when they did reach South America. Most likely however, these animals went extinct as a result of North and South America joining at the end of the Pliocene, and were in trouble already.

However, many of the extinctions are very likely the result of man. Specifically, the moas of New Zealand, the various (and wonderful) marsupial megafauna of Australia, various bizzare (including a clam eating crocodile) forms from New Caledonia and most of the birds of Hawaii were all likely victims of human hunting, human introduced pests and habitat destruction. The Haast's Eagle (Harpagornis Moorei) mentioned earlier most likely went extinct as a result of habitat destruction and as a result of all the moas being killed off. I imagine it might have developed a taste for human flesh toward the end though, being that the maoris wore feather capes and must have looked a lot like moas to a diving harpagornis.

The best theory as to how the large mammals of Europe, Asia and the Americas died off is kalled overkill, i.e. that humans killed them. A more specialiezed branch of this theory is called blitzkreig hypothesis, which states that the animals were so easy for humans to kill, and that the humans killed them off so quickly as a result of a masive human population bloom that there would be no or little archeological evidence of such a fast slaughter.

So, in conclusion, there were some forms that could not have been killed off by humans because there weren't any humans there. Other animals were probably killed off by people this is the patern usualy seen in the case of the pacific islands, New Zealand being a model with it's extensive moa kill sites. The case for humans killing off the megafauna of the Americas is strong, but still debated. My personal opinion is that much of the megafauna there was already in trouble.

Finally, Africa sustained a number of genus extinctions, as well as a number of species going extinct from a still extant genus. look up a critter called sivatherium if you want more. The fossil record also shows that the ranges of the animals still alive in Africa were generaly larger than they are now. While it can be argued that Africa did not suffer the pleistocene as badly as other continents, the ecology is still far less diverse than it was at about the time humans were evolving there.

 

[Dancing David]

I agree that the humans may have been a factor, but when you read about 'animals innocent of man' it just makes me wonder, why are the elephants still in Asia and Africa, I am willing to believe that modern humans with rifles can extinct a species but why only here in North America for the large megafauna, thanks all, I am trying to open my mind.

 

[Eos of the Eons]

I imagine it might have developed a taste for human flesh toward the end though, being that the maoris wore feather capes and must have looked a lot like moas to a diving harpagornis.

I like that! Too funny!

Anyway. Is it possible that some just 'evolved'. Would you call the dissapearance of australopithecus (sp?) an extinction? We still have some forms of the large animals around. Rhinos, lions, tigers, etc. Were the bigger forms their ancestors?

Natural selection could have been for the smaller forms beause of several reasons. It seems big animals are at the highest risk for extinction too. Or they are the ones leaving the most fossils around. At one time there were wayyy more types of life inhabiting the planet. Are mammoths in the bison line anywhere far back? I know chimps aren't on our line, we just have a common ancestor. Did mammoths and bison have a common ancestor-or are bison a more direct off shoot?

What is the difference between extinction and just being the larger but now non-existant form of a more evolved member of the species (homo habilis to homo sapien)? Are homo sapiens extinct because we are now homo homo sapiens?

I hope this all makes sense.

 

[neutrino_cannon]

I agree that the humans may have been a factor, but when you read about 'animals innocent of man' it just makes me wonder, why are the elephants still in Asia and Africa, I am willing to believe that modern humans with rifles can extinct a species but why only here in North America for the large megafauna, thanks all, I am trying to open my mind.

My guess is that elephants are significantly different than mammoths in some aspect that made them more adaptable. I'll also guess (I need my reference, but I haven't got it) that elephants have suffered severe range reduction since the pleistocene.

Another possibility is that the climactic shifts, along with the extinctions of all their competators helped the elephants. I doubt it has anything to do with human over kill/blitzkreig being any less vigorous in Asia, asia lost plenty of other genera (e.g. megaloceros, cleodonta, elasmotherium, homotherium etc).

 

[neutrino_cannon]

I like that! Too funny!

Anyway. Is it possible that some just 'evolved'. Would you call the dissapearance of australopithecus (sp?) an extinction? We still have some forms of the large animals around. Rhinos, lions, tigers, etc. Were the bigger forms their ancestors?

Natural selection could have been for the smaller forms beause of several reasons. It seems big animals are at the highest risk for extinction too. Or they are the ones leaving the most fossils around. At one time there were wayyy more types of life inhabiting the planet. Are mammoths in the bison line anywhere far back? I know chimps aren't on our line, we just have a common ancestor. Did mammoths and bison have a common ancestor-or are bison a more direct off shoot?

What is the difference between extinction and just being the larger but now non-existant form of a more evolved member of the species (homo habilis to homo sapien)? Are homo sapiens extinct because we are now homo homo sapiens?

I hope this all makes sense.

There were several genera that evolved during the pleistocene, I did not think to check when elaphas and loxodonta first emerged. Certainly among ruminants, especially bovids there were a number of quickly emerging, and then dissapearing genera. Some are only known from one or two specimens, so i doubt we'll ever verify cause of extinction.

The only case I know of where one species that clearly evolved during the pleistocene displaced another into extiction, without any human assistance, was when Grizzlies emerged from China, followed the land bridge into North America and outcompeted arctodus, a specialized cursorial and predatory bear. Human artifacts and remains don't show up until after arctodus is gone, or at least very rare, and there's no way humans could have hunted arctodus anyway. I'd love to see them try, but picking up the resulting mess would be soooo time consuming. Think spagetti sauce.