Overkill, Overchill, Overill? Megafaunal extinction causes

A couple of questions for Mammuthus.I'm wondering about why you are looking viruses or whether you have counted out bacteria for some reason I'm not picking up on. What about Anthrax? Has it been ruled out for any reason? Then what about diseases such as brucellosis, it may not kill the host, but may effectively render them sterile.I also have a few more questions about primers, but will serve them up later.Here is a link for anyone to consider the overkill hypothesis. It's only been around since the 1960s and the major proponent of it is Paul Martin at the U of Arizona. (Grayson and Martin are good friends incidently.)http://www.outriderbooks.com/ot10.html------------------
Bringer of fire, trickster, teacher.

I think you have to back up and consider that the examples that you are using are from agricultural settings. The use of optimal foraging technique would demand that a hunter be as opportunistic about getting kills, so if you have a species that is overhunted, the hunter switches to a more easily found prey simply because they go after things that are more easily found. In this way, you can see that a new equilibrium will be reached.For fun, try out this link for a classic model of predator-prey relationships: http://www.gypsymoth.ento.vt.edu/...PopEcol/lec10/lotka.htmlThere is no doubt that humans modified the environment, but whether and how this modification led to the extinction of species is something we should figure out soon because it seems to be a continuing problem.------------------
Bringer of fire, trickster, teacher.

Rei stated:

quote:

---

Completely true - in societies that are in equilibrium, in temperate climates (the number that I've typically heard is 80% from gathering, 20% from hunting in such environments). If the society is focusing heavily on hunting for calories, it is not in equilibrium. If we're not talking about a temperate climate, then gathering isn't as major of a percentage of calories. How many calories did the innuits traditionally get from plants, for example?

---

From Current Anthropology--Frank Marlowe, "Male Contribution to Diet and Female Reproductive Success among Foragers" Volume 42, Number 5, December 2001 pages 755-759:

quote:

---

Variation in male contribution to diet. Male contribution to diet varies from 25 to 100%, with a mean of 64%...Because there is less edible plant food for women to gather in colder climates, male contribution is higher at higher latitudes, where effective temperature is lower.

---

The difficulty with moving into a new territory is that you may not recognize food plants until many years have passed. You can recognize game animals quite easily.Then it should also be considered that when one game animal becomes scarce, you will switch to another prey that is more easily found and the unhunted species can recover in numbers. Humans are generalists when it comes to hunting, they do not rely on any one type of animal to meet their needs.Optimal Foraging Theory suggests that predators will simply go after the easiest prey available. In an environment where mammoths and bison were grazing side by side, the bison would quite easily be the animal of choice for most paleohunters. There is also some suggestion that hunting bison will actually increase their rate of reproduction. If this were to occur, they could outcompete the mammoths that they shared their habitat with. Prehistoric overgrazing might have selected against an animal that needed tall grass species to eat.Anyhow, that's my story and I'm sticking to it.------------------
Bringer of fire, trickster, teacher.[This message has been edited by Speel-yi, 10-17-2003]

quote:

---

The idea of Homo Sapiens Sapiens taking out Homo Sapiens Neanderthalensis is ridiculous, the average Neandertal could have taken the average Sapiens and twisted him into a pretzel. With greater brain capacity and much greater strength, Neandertal had a huge advantage, thinking otherwise is simply pure sapiens arrogance. Without the effect of the Pleistocene extinction event, I would have predicted the opposite out come, which means we may owe our very existence to this past event.

---

Modern man is build for speed, a Neanderthal would have had to catch the sapiens first. Then you have some other thing showing up like hafted weapons. Sapiens could kill from a distance, end of story.Anyway, just for grins. Try a Google on inca bone and/or shoveled inscisors for some comparisons about regional differences in populations. Wish I could show you guys some stuff about the Yuki from California, they definately had some Neanderthal features.

quote:

---

It is my understanding that Homo (Sapiens?) Neanderthalis has three major disadvantages when compared to Homo Sapiens Sapiens. We can run better. We have arms better suited to throwing. In other words we have range and mobility on our side should it come to a fight.

---

This is correct, Neanderthal reamins show a lot of evidence of close encounters with large animals. Lots and lots of broken bones. The modern design appears to have the advantage of speed on its side. A lot of recent focus has been in the structure of the cerebellum and its expansion in sapiens. Early erectus had a cerebellum that occupied 65 cc and moderns have about twice this capacity in that structure.

quote:

---

We eat a wider variety of food (from analysis of bone data from Neanderthals - they ate a higher proportion of meat, much closer to a pure carnivour diet).

---

Then it also appears that Neanderthal and Cro-Magnon may not have been in direct competition for resources. Yet another knock against replacement.------------------
Bringer of fire, trickster, teacher.

quote:

---

Hmm, I don't think that follows. While Neanderthals would require (almost) exclusively meat and Cro-Magnons wouldn't. Cro-magnon man still hunted, and probably the same kind of prey. That's pretty direct competition, and what's more only in one direction (a more successful Neanderthal would have limited impact on the more diverse diet of the Cro-Magnon while a successful Cro-Magnon would impact the main resource of a Neanderthal). I'd say that's a boon for replacement theory.

---

Isotopic anylysis does suggest that Neanderthals had an almost exclusively carnivorous diet. It does not mean that they could not eat anything else. Nor does it mean that either of the groups would have had much of an impact on game in any event. There would have been plenty to go around for both and apparently there was for at least 10,000 years since we find remains dated from the same time periods.But in order for competitive exclusion to work, we have to have two species that are incapable of interbreeding. There is nothing to suggest that the two populations could not mate and produce offspring other than a pet theory.If they were two separate species, there is no reason to think that both could not have coexisted for another 10,000 years together. They did occupy slightly different niches and neither one of their niches were seriously depleted by hunting.------------------
Bringer of fire, trickster, teacher.