Population Pressure
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The cultural transition from the romantic era of consumption to the era of tuberculosis derived not only from the germ theory of disease and the triumph of contagionism over anticontagionism, but also from political considerations. Worries over population decline and growing working-class militancy were aggravated by what now appeared to be a social disease, or a disease of poverty. One of the strategies deployed against the disease was...more
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European populations grew only slowly during the period 1200-1700; factors include disease and wars. Human feces and rotting animal remains were not sequestered and often contaminated drinking water. Cities were so filthy that more people died in them than were born. About a third of children died in infancy, many from abandonment and lack of care during wet-nursing. Children that survived were subjected to harsh discipline to control...more
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PV/T is a constant. Figuring out the volume of an ideal gas at standard temperature and pressure (STP).
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Figuring out the partial pressures of various gases in a container.
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World population will continue to rise until at least 2050. Environmental impact is the product of the number of people and how much of their income and technology is devoted to either consumption or conservation. So far, the balance is far at the consumption end and, globally, environmental problems are increasing. Environmentalism has not come close to counteracting the footprint of a billion extra people every dozen years. The only...more
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By 1950, in most of the underdeveloped world, mortality had fallen to about half its pre-modern rate. The birth rate, however, had remained high and, by 1950, was about twice the death rate. For the rest of the century, both rates fell dramatically and in parallel, maintaining the gap. The enormous excess of births over deaths in this period is known as 'the population explosion.' By 1990, the world population was growing at almost 90...more
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Genetics controls evolution. There are four major genetic systems, which are combinations of sexual/asexual and haploid/diploid. In all genetic systems, adaptive genetic change tends to start out slow, accelerate in the middle, and occur slowly at the end. Asexual haploids can change the fastest, while sexual diploids usually change the slowest. Gene frequencies in large populations only change if the population undergoes selection.
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Families lived together in traditional China and sons remained on the land; division of family land led to tiny plots and rural poverty. Because labor was so cheap, the country did not urbanize or mechanize. The Communist government started out with a pro-natal stance, but after experiencing the famine of the Great Leap Forward, moved strongly to fertility control. Fertility declined rapidly in the 1970s, but to counter momentum, the...more
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Mutations are the origin of genetic diversity. Mutations introduce new traits, while selection eliminates most of the reproductively unsuccessful traits. Sexual recombination of alleles can also account for much of the genetic diversity in sexual species. In some instances, population size can affect diversity and rates of evolution and fixation, but in other cases population size does not matter.
