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Biological Anthropology Lab Human Population. Michelle Y. Merrill, Ph.D. Ernst Mayr Summarizes Darwin’s Argument for Evolution via Natural Selection. Fact #1: organisms reproduce exponentially Fact #2: population size generally constant Fact #3: resources limited
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Biological Anthropology LabHuman Population Michelle Y. Merrill, Ph.D.
Ernst Mayr Summarizes Darwin’s Argument forEvolution via Natural Selection • Fact #1: organisms reproduce exponentially • Fact #2: population size generally constant • Fact #3: resources limited • Inference #1: The Struggle for Existence • Fact #4: organisms vary • Fact #5: variation heritable • Inference #2: non-random survival and reproduction • Inference #3: accumulation of favorable characteristics adaptation
Fact #1: All organisms could increase population exponentially. “The greatest shortcoming of the human race is our inability to understand the exponential function.” -Albert A. Bartlett, Physicist Growth rate ’95-’00 = 1.37% ’00-’05 = 1.24% ’05-’10 = 1.17% (~198,000 years) 7% annual growth = doubles every decade!
Which would you rather? • $1,000,000.00 right now OR • A penny today, that would double every day for a month • Day 2: $0.02 • Day 3: $0.04 • Day 4: $0.08 • Day 5: $0.16 … • Day 30: $5,368,709.12 That’s the POWER of exponential growth!
Exponential Population Growth “19 Kids and Counting” At the Duggar’s reproductive rate, how many generations would it take for the Duggar population to exceed Earth’s present population? Duggar Family, Arkansas 19 Children 361 Grandchildren 6,859 Great-grandchildren 130,321 Great-great-grandchildren 2,476,099 – 5th generation 47,045,881 – 6th generation 893,871,739 – 7th generation 16,983,563,041 – 8th generation
The Lily Pond Parable If a pond lily doubles every day, and it takes 30 days to completely cover a pond… At what point would preventative action become necessary to prevent unpleasant events? On what day will the pond be 1/2 covered? 1/4 covered? How much would it help if we could double the size of the pond? With respect to human population and environmental degradation, what corresponding day is it for the world? Adapted from http://www.ecofuture.org/pop/facts/exponential70.html
Population Growth Explained with Ikea Boxes http://www.gapminder.org/videos/population-growth-explained-with-ikea-boxes/