Gord_in_Toronto
Penultimate Amazing
- Joined
- Jul 22, 2006
- Messages
- 26,162
That could well be the case. Maybe the main reason of the spreading of deserts (e.g. Sahara) after the last ice age is primarily caused be a lack of enough bio-mass. If the vegetation spreads to regions near the poles, then a shortage of needed psychons can be the result in regions near the equator, where survival conditions have become more difficult. Only 18'000 years ago, the location I sit now (Vaduz, Liechtenstein, Europe) was covered by hundreds of meters of ice.
BTW, the always changing climate on Earth has been a main driving force of evolution in general, and the last glacial period of around 100,000 years a main driving force of our evolution in special.
"The last glacial period was the most recent glacial period within the current ice age, occurring in the Pleistocene epoch. It began about 110,000 years ago and ended between 10,000 and 15,000 BP. During this period there were several changes between glacier advance and retreat." (Wikipedia)
"Unlike the psychons of atoms and simple molecules, the more complex psychons of enzymes, cells and animals evolved over billions of years on earth. Because of the limits in space and other resources, only a limited number of every kind of psychons could evolve. This limitation is empirically relevant. Unlike the output of chemical production processes, the output of biotechnological production processes cannot always be increased just as one likes." (Empirical Relevance of Psychons)
"The saturation thesis is relevant not only to humans but to all organisms. It can hardly be denied that many animal populations remain rather constant in size without Malthusian struggles for survival. There are also limits on animal breeding and plant cultivation. There is even a saturation for pathogens like bacteria and viruses. A pathogen of a local epidemic cannot be a threat to mankind, nor can genetically engineered pathogens." (The Demographic Saturation Theory)
Probability theory can easily resolve such questions.
"According to the saturation model, the endpoint of demographic transition is a fertility oscillating near direct-replacement fertility, resulting in a rather constant population. In reality, however, the effect of direct-replacement fertility after demographic transition can interfere with other effects. Despite being already saturated, populations of child-oriented countries or groups, having lower prevalence of contraception and abortion, can still increase at the expense of evolutionarily related less child-oriented countries or groups. The reason is simple: evolutionarily related countries or groups can be seen as subpopulations of a unit, having as a whole a maximum potential population. So if something hinders one subpopulation from replacing its deaths by births then another subpopulation can further grow at the expense of the first. The more evolutionarily-related subpopulations are, the easier they can grow at the expense of each other." (Classification in subpopulations and evolutionary relatedness)
"The most important long-ranging factor confounding the demographic saturation model is migration." (The effect of migration on direct-replacement fertility)
Cheers, Wolfgang
You know, I'm almost sorry I asked. But with a reply that concise, so elegant and explanatory . . . No, I am sorry I asked.
