WHAT IS IT? ----------- This model illustrates the theory that Native Americans who arrived in the new world 10,000 years ago may have been responsible for the extinction of the large mammals of the Americas such as the American lion, tiger and mammoth. This theory is advanced by Jared Diamond in his book: "The Third Chimpanzee". The basic premise of the theory is that American large mammals evolved without human contact, so they were tame and unafraid of the migrating humans, allowing a high probability of successful hunting by the humans. This could account for the very rapid simultaneous extinction of all American large mammals at roughly the same time as the human arrival. HOW TO USE IT? ------------- SETUP initializes the mammoths and people. N-MAMMOTHS sets the initial number of mammoths. Note that the actual number of mammoths created is less than this, because the ones created in the oceans immediately die. The COUNT-MAMMOTH monitor shows that actual number of mammoths. N-HUMANS slider sets the initial number of human hunters. GO starts and stops the simulation. KILL-ODDS: the odds that when a human encounters a mammoth, it will die MAM-BR: the likelihood of a mammoth reproducing (at a given tick (or moon)) - the mammoth birth rate HUMAN-BR:the likelihood of a human reproducing (at a given tick (or moon)) - the human birth rate STAY-IF-PLENTY?: if this switch is TRUE (0), then the humans do not migrate if there are plenty of mammoths in their neighborhood. If the switch is FALSE, they migrate at the same rate regardless of the mammoth density. The definition of plenty is governed by the PLENTY slider. Monitors: YEARS displays elapsed years in the model. COUNT-HUMAN shows the current number of humans, and COUNT-MAMMOTH the current number of mammoths. These counts are also dynamically plotted in the Population Sizes plotwindow. THINGS TO NOTICE ---------------- Notice the rate of migration of the humans. How does that affect the population of mammoths? Notice the rate of mammoth decline. How many years does it take for them to go extinct? THINGS TO TRY ------------- Vary the KILL-ODDS. How deos that affect the mammoth population? Try both settings of the STAY-IF-PLENTY switch. How does the migration pattern of the humans affect the mammoths? EXTENDING THE MODEL ------------------- Make separate monitors for North and South America. What if Central America weren't so narrow? Do you think that it, or other geographical features, could block human hunters the way this model does? How would adding islands affect the model? STARLOGOT FEATURES ------------------ Note the use of nsum to calculate the number of mammoths in the neighborhood nsum mammoth-present mammoths-in-area REFERENCES & CREDITS -------------------- This model is based on the theory expounded by Jared Diamond in: Diamond, J. (1993). The Third Chimpanzee. Basic Books.