Lecture 21

Lecture 21 - Bio 121 Lecture 21 Human population growth A....

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Bio 121 Lecture 21 – Human population growth A. Introduction a. Apply principles of last 2 lectures (population growth and demography) a.i. Growth over time a.ii. Growth today a.iii. Human future a.iv. Understand how r and attitudes and age distribuitions affect humans. B. Over 6 billion served – for very long time we had few people on earth (mortality, short life spans). Growth surge about 10000 years ago related to the replacing of huntergathers by agricultural societies a. Rate of increase a.i. Exponential a.ii. Currently have 6.9 billion, and we add about 78 million per year a.iii. Each minute on earth there about 146 net people added a.iv. B = (21/1000 per year)0.012, D = (9/1000)=0.009 a.v. r = 0.012 (1.2 % growth per year) a.vi. 2011 N=Noe^rt a.vi.1. N = 6billion e^(0.012)(12) b. Doubling time b.i. N=Noe^rt b.ii. N = 2No b.iii. 2=e^rt b.iv. Ln2=rt b.v. T=ln2/r b.vi. t~58 years C. Growth patterns a. Late 70s, r = 0.02 a.i. Doubling time was like 35 years a.ii. Rate of growth has slowed (but uneven)
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Lecture 21 - Bio 121 Lecture 21 Human population growth A....

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