The climatic change theory promotes the idea that the global warming, which brought about the end of the Ice Age, caused the animals to die off. The overkill theory states that humans over hunted the animals, and are thus responsible for the extinctions. It is likely that many of these animals became extinct at the end of the Ice Age due to a combination of climatic change and overkill.

The Ice Age, which began about one and a half million years ago, is also called the Pleistocene Epoch. The Ice Age consisted of a series of glacial advances and retreats called glaciations and deglaciations. The last glaciation in North America is called the Wisconsin. The Wisconsin glaciation began 122,000 years ago. The advance of the Late Wisconsin began 35,000 years ago.

The ice sheets, called the Laurentide and the Cordilleran gla

The land around the stream used to be desert grasslands, and Mammoth Kill Creek was probably a watering spot for the animals. At this spot the some of the mammoths may have died natural deaths and other were killed by humans. Both the case for climatic change and its role in extinction, and the case for overkill and its involvement, present some compelling evidence.

Most plants are characteristic of the environments they live in. By looking at a particular type of plant, we can tell a lot about where it came from and in what kind of conditions it lived. Because plants are so specific to their environment, they do not adapt well to climatic changes. Therefore, the changes mentioned above must have affected the Late Pleistocene vegetation environments. Mammoths and Mastodons were some of the largest mammals of the Ice Age, required large amounts of food. These and many other animals were herbivores. When there was not enough vegetation, or enough of the right kind of vegetation to eat, the animals had to either migrate or adapt. If they were not able to migrate or adapt quickly enough, they would die. In order for any species to survive, the population must grow faster than its members are dying. This means, for the Ice Age mammals to resist extinction, the birth rate would have to have been higher than the mortality rate, so any other factors increasing the rate of mortality would seriously jeopardize the existence of the animals. Gary Haynes studied the two living species of present day Proboscidea (Loxodonta africana and Elephas maximus) to find out more about their prehistoric counterparts (Haynes, 1991). First, he compared them to each other, finding them “...different in physical appearance, but very similar in social behavior and biology,” (Haynes, 1991). He then related them to the Mammut and Mammuthus of the Ice Age. He found, through allometric scaling, that elephants and mastodons seem to have similar biological histories. The larger bone structures indicate that the mammut, although it doesn’t differ much in actual size, would have weighed more than those of today. From this information, Haynes was able to deduce an assumption about reproductive patterns in the mastodon. The longer gestation periods in the prehistoric animals, because of their heavier weight, implies slower reproduction. Haynes also discovered useful information about the ability of these animals to subsist in specific conditions.

“As the glaciers receded, a profound reorganization occurred in hydrological, biological, and sedimentological systems. The world’s ice coverage changed from 30% of its surface to the current level of about 10%. This phase change of so much water from solid to liquid was the driving force behind much of the subsequent geological, climatic, and biotic transformation. As the ice melted, water and sediment choked the rivers; they altered the drainage of great lakes and, in breaking the ice dams that had formed some of these lakes, caused cataclysmic floods that themselves changed the face of North America (the channeled scab lands of Washington State and Idaho are examples). The continental shelves changed positions and depth as the shorelines migrated inward under rapidly rising seas. Rainfall patterns shifted; the seasons themselves were lengthened or shortened. Temperatures rose all over the earth. And of course, in the wake of so much physical perturbation to the environment, biotic systems changed. These great changes in the physical environment are at the heart of many scientists’ belief that the large-animal extinction at the end of the Ice Age was brought about by physical or environmental changes, not by human hunting. The extinction of many species in a broad environment must involve many variables in both biotic and physical spheres, because ecosystems are complex. Physical changes may bring about the death of one species, and its disappearance then affects other species

Some topics in this essay:
Ice Age, North America, Volkswagen Beetle, Mother Nature, Land Bridge, Peter Ward, Pedro Valley, University Arizona, Washington Idaho, Kill Creek, ice age, north america, mega fauna, climatic change, land bridge, grayson 1993, north america animals, america animals, mega faunal, change theory, sea levels, climatic change theory, mega faunal population, migrated north america, bering land bridge,