The Big Debate

[worthy 55]

Were Mammoths and Mastodons all ready in North America before the land bridge ? If so could the heards from Europe have brought some type of disease that killed them off . Like when the European's came to South and North America and brought disease with them that all most killed off the native people ?

[Boesse]

Is it just me, or does it seem like someone came here just to argue for the sake of arguing? Eh... just a thought.

[Guest N.AL.hunter]

MarkGelbert

You are a troubled man. No where did I say that they would die off in one year. And you need to take lessons in reading comprehension. I didn't say Pandas were extinct. I was using them as an example of an animal with very specific dietary needs. This will be my last posting on this topic, but you really need to look at you original posting and you will see that you requested our input. When we give it, and it is different than yours, you call us "wrong" and take offense to our ideas. I am not here for that. My scenario is logical and the type of extinction I proposed has happened to geographically isolated species. Have a good day!

[MarkGelbart]

NA Hunter,

Man, there's no need to get huffy. The problem with your scenario is that there's no evidence to support it. You can't make up a theory with no evidence. Am I a troubled man just because I shoot down your scenario?

Ashcraft,

I forgot to respond to your point about the elephants. The savannahs and deserts of Africa are tropical--they're close to the equator. Populations in Africa remained lower than those in North America because disease was more prevalent.

There's no evidence that the moundbuilders died out as a race. It's commonly agreed that they were ancestors to later Indians who did die in large numbers upon contact with disease. The Spanish actually kept records of their decline.

Quit being obtuse. You know what I mean. Key deer could interbreed with northern white tails, if they were put in the same pen. And any breed of dog can interbreed with any other kind of dog. I've seen small poodles mating with German Shepherds.

Missouri's a big state. There's no evidence that the entire state ever became a desert. The study I read--Insularity and Mastodont Extinction--by King and Saunders (1984) examined the fossil evidence from Boney Spring, Jones Spring, and Trollinger Spring in western Missouri. It never became desert. We have cactus and hog nosed snakes in Augusta, Georgia. It's never been a desert here.

If you can't give a better source than Wikipedia, than you're wrong.

safossils,

I'm not sure I understand your point. I know my model is a theory. Why would that preclude me from defending it.

worthy55,

Yes, mastodons and mammoths were here before the land bridge. In fact one theory is a hyper-disease wiped them out. I don't agree with this theory. It's unlikely one disease could wipe out dozens of species.

[Guest N.AL.hunter]

OK I just have to respond to markGelbert:

First read this:

Food web structure and interaction strength pave the way for vulnerability to extinction

Patrik Karlssona,Tomas Jonsson and Annie Jonssona,

a Systems Biology Group, School of Life Sciences, University of Skövde, P.O. Box 408, SE-541 28 Skövde, Sweden

Received 13 February 2007; revised 25 June 2007; accepted 17 July 2007. Available online 20 July 2007.

Abstract

This paper focuses on how food web structure and interactions among species affects the vulnerability, due to environmental variability, to extinction of species at different positions in model food webs. Vulnerability is here not measured by a traditional extinction threshold but is instead inspired by the IUCN criteria for endangered species: an observed rapid decline in population abundance. Using model webs influenced by stochasticity with zero autocorrelation, we investigate the ecological determinants of species vulnerability, i.e. the trophic interactions between species and food web structure and how these interact with the risk of sudden drops in abundance of species. We find that (i) producers fullfil the criterion of vulnerable species more frequently than other species, (ii) food web structure is related to vulnerability, and (iii) the vulnerability of species is greater when involved in a strong trophic interaction than when not. We note that our result on the relationship between extinction risk and trophic position of species contradict previous suggestions and argue that the main reason for the discrepancy probably is due to the fact that we study the vulnerability to environmental stochasticity and not extinction risk due to overexploitation, habitat destruction or interactions with introduced species. Thus, we suggest that the vulnerability of species to environmental stochasticity may be differently related to trophic position than the vulnerability of species to other factors.

Earlier research on species extinctions has looked for intrinsic traits of species that correlate with increased vulnerability to extinction. However, to fully understand the extinction process we must also consider that species interactions may affect vulnerability and that not all extinctions are the result of long, gradual reductions in species abundances. Under environmental stochasticity (which importance frequently is assumed to increase as a result of climate change) and direct and indirect interactions with other species some extinctions may occur rapidly and apparently unexpectedly. To identify the first declines of population abundances that may escalate and lead to extinctions as early as possible, we need to recognize which species are at greatest risk of entering such dangerous routes and under what circumstances. This new perspective may contribute to our understanding of the processes leading to extinction of populations and eventually species. This is especially urgent in the light of the current biodiversity crisis where a large fraction of the world's biodiversity is threatened.

I found at least 250 more articles on the effects of climate and extinction. Many were about the Pleistocene Period. And that is just in one database ScienceDirect.

You also say you can't have a theory without proof. Tell that to Einstein.

Look my problem here is that you are dead set to say that any other idea/theory is wrong, and you dismiss others as illogical. You need to broaden your perspective. I am a science layperson. I taught college level chemistry, biology and physics as well as taught high school science for over 13 years. I am currently a research librarian at a college research library. I have access to thousands of articles on extinction theory. Why are there so many? Because there are a heck of a lot of theories out there about the extinction of past life forms. Debate is a good thing, but to completely dismiss that a changing climate can lead toward the extinction of organisms is, in my opinion, not a good way to think about the issue. Notice in past posting that I have never said your theory was incorrect. I just would like for you to understand that, again in my opinion, it seems too simplistic. Most scientist would agree that extinction is usually caused by several factors all happening to the organisms at the same time. I wish I could send you the complete texts of several articles, but by license agreements I am not allowed. If you are near a research library, please go in and use their databases, try ScienceDirect. You will find numerous examples of climate caused extinction articles, both on theory and about actual field investigations. Please, for the sake of us all, let this issue end.

[ashcraft]

All,

I apologize for my ramblings (and poor spelling dessert, desert augh), this will be my last response to this. The conversation was interesting, but it is getting to be regurgitation.

Ashcraft,

I forgot to respond to your point about the elephants. The savannahs and deserts of Africa are tropical--they're close to the equator. Populations in Africa remained lower than those in North America because disease was more prevalent.

There is no more human disease in the deserts of Africa then in other parts of the world, which is what I assumed you were talking about when you said tropical, yet elephants survive quite nicely there.

There's no evidence that the moundbuilders died out as a race. It's commonly agreed that they were ancestors to later Indians who did die in large numbers upon contact with disease. The Spanish actually kept records of their decline.

I said that is what I was taught, European explorers found vast fields of cane that were abandoned because of disease killing off the "owners". - the Mound Builder culture is now thought to have disappeared around 1350, several theories as to why, some theories suggest political reasons (untestable). However, it appears most of the mounds were completly abandoned long before the Europeans arrived. It is no longer widely accepted that they are the ancestors to who the Europeans found living here, it is one possibility, however.

Do you have references to these Spanish records? I would love to read them (seriously). In the "Prehistory of Missouri" the authors discussed a burial area down here in the "bootheel" with several hundred bodies. Average age was around 35, very high for those days and living conditions (so the author states), included with these bodies were Spanish trade goods.

The "diseae killed all the indians" theory is largely outdated, it sounded good at the time it was formulated, but the evidence is mostly antecdotal, at least that I have seen, little hard fact.

Quit being obtuse. You know what I mean. Key deer could interbreed with northern white tails, if they were put in the same pen. And any breed of dog can interbreed with any other kind of dog. I've seen small poodles mating with German Shepherds.

Grasshopper, you speak from ignorance. Geographical isolation is a key component to speciation. Coyotes and jackals can interbreed and produce viable offspring, but they don't. As far as chihuahuas and St. Bernards, show me a naturally occuring cross (meaning no artificial insemination). A female St. Bernard could carry a cross, but how would the male do his business? A female chihuahua could never carry the offspring of a St Bernard, not enough room, spontaneous abortion would occur. (The image of the attempts at breeding leave me queazy.)

Missouri's a big state. There's no evidence that the entire state ever became a desert. The study I read--Insularity and Mastodont Extinction--by King and Saunders (1984) examined the fossil evidence from Boney Spring, Jones Spring, and Trollinger Spring in western Missouri. It never became desert. We have cactus and hog nosed snakes in Augusta, Georgia. It's never been a desert here.

Never said (or at least intended to say) the whole state was a desert, where soil exists (Northern Prairie) enough water would have been retained to allow for grass growth. Ther xeric areas of the Ozarks and western priaire barely support plant growth now, any drying would lead to desert conditions.

Don't know much about Georgia, but it would be intersting to know did these harbingers of a dry environment got there? Do you think they leap-frogged the tundra of the ice-age, or the deciduous forests that came after?

If you can't give a better source than Wikipedia, than you're wrong.

Wikipedia wasn't the source, it is where I read it, I gave you the source. It is interesting that there is a difference of a factor of 10 though. Somebody lose a zero?

[Uncle Siphuncle]

Well guys, this has been an enlightening and entertaining discussion to help get me through the week. On that note, I'm going fossil hunting!

[Guest Nicholas]

Well guys, this has been an enlightening and entertaining discussion to help get me through the week. On that note, I'm going fossil hunting!

Good luck Dan.

I agree that this topic seems to be getting a tad bit over done, we probably should quit before it becomes heated.

[MarkGelbart]

NA hunter,

I have studied hundreds of papers that consider climate change as the cause of the extinction. I've been studying this topic for 20 years. The problem with them is this: there's no evidence to support them. The paper you cite is purely theoretical.

At the time the megafauna became extinct, the same species of plants that were abundant then are abundant now. If climate change caused the extinction, that necessarily means the plants they ate became extinct or rare. That just didn't happen, and there's no evidence it ever happened during the late Pleistocene.

It can't be a combination of climate change and overhunting, though that is the consensus of the majority of scientists these days. It was either one or the other. For example if man never came to North America, I believe just about every single species of megafauna would still be extant.

Of course, climate change and the accompanying extinction of plants has caused extinctions of animals in the past. I'm just saying that there's no evidence whatsoever that that's what happened in the late Pleistocene.

Do a google search of Dan Fisher's mastodon studies. He looked at the growth rings and isotope ratios of late Pleistocene mastodon tusks and compared them to those of African elephants. The tusk growth rings of late Pleistocene mastodons pretty much proves they were under stress from overhunting, not starvation.

You should apologize for calling me a troubled man simply because you disagree with my theory. That was uncalled for.

Ashcraft,

You goofed big time again. Jackals and coyotes can not interbreed--not only are they different species; they aren't even in the same genus.

I didn't think I would have to give a gender education lesson on this thread. In the same species the of the female will expand to the size of the male's . Any white tailed deer could theoretically breed with any other white tail deer and the same goes for dogs.

For you to continue to make the claim that disease didn't wipe out the Indians damages your credibility which in my opinion is pretty low, considering the number of factual errors on your posts.

I already gave you a source for the census figures--The Americas before and after 1492: Current Geographical Research. This is a pretty dry book but you can probably find it used on amazon.com for cheap. Another more accessible book is 1491: New Revelations of the Americas before Columbus by Charles Mann. He discusses the moundbuilders and why the culture disappeared and he gives evidence of how the Indians died because of disease.

Africa is the origin of most diseases now extant. Even the desert areas had devastating diseases found nowhere else on earth. Ever hear of the Tsetse fly?

Here's another book for you to read: Twilight of the Mammoths by Paul Martin. He discusses the extinction of the ground sloths on the Carribean Islands 6000 years BP. That's not an accidental extra 0. The disappearance there coincides with the colonization by the Indians. There's no fossil evidence of ground sloths there after that date. The wikipedia article was referring to an unreliable account...you know like a bigfoot sighting.

Stick to real science please.

[Necrocanis]

You goofed big time again. Jackals and coyotes can not interbreed--not only are they different species; they aren't even in the same genus.

Not that I have a real vested interest here, but I have to say that hybrids can occur even when not in the same genus. I know that sounds very wrong in the sense that the definition of a hybrid is the mixture of two animals within the same genus. I am also a fish hobbyist, and I collect mainly hybrids of catfish and different species of hybrids. I can give you some proof positive evidence of at least 8 different strains of hybrid catfish all pairings occured outside of their perspective genus. One is actually a hybrid between an african catfish that is considered an armored catfish in the family doridae, and the other was a species of south american pimelodid in the family pimelodidae. The cross was Pseudoplatystoma fasciatum x Oxydoras niger. That's not even in the same family. Two others also occured cross family. Pangasius pangasius x Pseudoplatystoma fasciatum, and also Hemioliopterus phractocephalus x Pangasius pangasius. I have several cross genus hybrids myself such as Hemioliopterus phractocephalus x Pseudoplatystoma fasciatum, and Hemioliopterus phractocephalus x Leiarius longibarbis. As far as I know these hybrids are not scientifically documented, but I can tell you without a shadow of a doubt that they are definitely cross family and cross genus hybrids.

Again this is not to ruffle any feathers, but I can provide evidence if required.

Cliff

[Boesse]

"Here's my model of Pleistocene megafauna extinction based on the latest scientific findings"

Have you collected any data or conducted any original research with regards to this topic? Otherwise, I am unclear on the concept of how you consider this your model.

However, if you mean that this is your perception of what other people have done, then I can accept that statement.

I guess I am unclear as to your scholarly connection with pleistocene extinction research.

Bobby

[ashcraft]

I said I would'nt add more, but I can't pass this by- domestic dogs, wolves dingos coyotes and jackals can all interbreed, and most crosses will produce viable offspring (golden jackal is an exception, it has 76 chromosomes).

It doesn't matter that they are in different families, they can't read.

Brent Ashcraft

[Guest Nicholas]

I said I would'nt add more, but I can't pass this by- domestic dogs, wolves dingos coyotes and jackals can all interbreed, and most crosses will produce viable offspring (golden jackal is an exception, it has 76 chromosomes).

It doesn't matter that they are in different families, they can't read.

Brent Ashcraft

This actually seems to be the case with many mammals of the same size, it is very possible although unlikely to occur in nature. There has been evidence and studies done on this for years now, perhaps the Zonkey (Zebra/Donkey) could be a viable example..

[Rain1950]

ScienceDaily (Apr. 1, 2008) — Does the human species have mammoth blood on its hands? Scientists have long debated the relative importance of hunting by our ancestors and change in global climate in consigning the mammoth to the history books. A new paper uses climate models and fossil distribution to establish that the woolly mammoth went extinct primarily because of loss of habitat due to changes in temperature, while human hunting acted as the final straw.

Science Daily

[MarkGelbart]

Boesse,

I never claimed to have done any original field work so your comment is unwarranted. My model (and it is original) is based on the hundreds of research papers and books I've read.

Ashcraft,

You're right about this one. I did some research and was surprised to learn that jackals can interbreed with dogs. In Russia they purposefully breed them because the hybrids reportedly make good sniffers.

Rain1950,

I'm familiar with models of late Pleistocene extinction on the mammoth steppe that theorize climate change caused the extinction of wooly mammoths.

Here's the problem I have with the logic.

In this abstract the researchers even admit that humans were the final straw. Well, if humans were the final straw, that means the wooly mammoths would still be around if not for us. Therefore, it was humans that caused the extinction.

Here's the problem I have with the facts.

The climate models of megafauna extinction in the mammoth steppe, an areas which stretched from Europe through Beringia into Alaska, say that an increase in precipitation caused the grass to turn into an environment of toxic mosses and spruce trees.

However, F. Chapin, a now retired scientist, conducted an experiment which casts doubt on this. He found that all one had to do to get steppe grasses growing again in Alaska was to dump fertilizer on the tundra. Apparently, mammoths and horses fertilized the steppe tundra with their dung and kept the grasses growing. When they died out, the grassy tundra converted to a mossy tundra with plants toxic to most herbivores.

They went a step further. In Siberia in conjunction with the Russian scientist Zimov they established a Pleistocene Park. They reintroduced herds of horses. In areas where the horses are kept the tundra is grassy and potentially able to support a megafauana. They're trying to get permission to introduce Siberian tigers as a substitute for Pantera Leo Atrox. Maybe some day they can clone a wooly mammoth and reintroduce it as well.

Here's an abstract from a study they did that was published in The American Naturalist in 1995.

Extinction of fauna played as great a role as climate in shift from steppe grass to tundra moss. Trampling and grazing by mammalian grazers caused the shift in dominance from grass to moss. The grass reduces soil moisture more than moss through higer rates of evapotranspiration. A model suggest moss became dominant when grazing is reduced below levels that are in equilibrium with climate and vegetation.