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Category Archive: Theory of evolution

Aug 08 2007

Evolution-20: How selection advantage arises in evolution

(Please see here for previous posts in this series.) In the mathematics of evolutionary change, the selection advantage is a key mathematical quantity that determines the rate at which a favorable mutation spreads through the population. The selection advantage is a quantification of the net result of advantages that a variety of a species gains …

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Aug 06 2007

Evolution-19: The Boeing 747 in the junkyard

(Please see here for previous posts in this series.) As I have emphasized repeatedly in this series, the hardest thing to appreciate about evolution is how a cumulative sequence of very tiny changes can lead to big changes. The problem is that our senses can only detect gross differences between organisms and our minds can …

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Aug 03 2007

Evolution-18: Missing links

(Please see here for previous posts in this series.) About ten years ago, a group of engineering students came into my office. They were taking part in a scavenger hunt during Engineers Week and the one item that was very hard for them to find was a ‘slide rule’. They had little idea of what …

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Aug 01 2007

Evolution-17: How species diverge

(Please see here for previous posts in this series.) When my daughter was quite young, about five or so, the question of where people came from came up in a mealtime conversation. Naturally we told her that human beings had evolved from ancestors who were monkey-like and then became human-like. She sat there for a …

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Jul 30 2007

Evolution-16: The evolution of the eye

(Please see here for previous posts in this series.) The eye is one organ almost invariably brought out by creationists to argue against evolution. How could something so complex have possibly evolved incrementally, they ask? Darwin himself suggested the way that the eye could come into being. Due to the fact that eyes don’t fossilize …

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Jul 27 2007

Evolution-15: How species evolve

(Please see here for previous posts in this series.) The final feature that needs to be addressed is the probability of mutations cumulating to produce new organs and species. This question lies at the heart of many people’s objections to evolutionary ideas. They cannot envisage how infinitesimal changes, each invisible to the eye, can add …

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Jul 25 2007

Evolution-14: How a single mutation spreads everywhere

In the previous post, we saw that if we start with a trait that is present in just 0.1% of the population (i.e., f=0.001), and if this has a small selection advantage of size s=0.01, this will grow to 99.9% (F=0.999) in just under 1,400 generations, which is a very short time on the geological …

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Jul 23 2007

Evolution-13: Differential rates of survival

(Please see here for previous posts in this series.) Of the three stages of natural selection outlined before, the only one that occurs purely by chance is the first one, that of the occurrence of mutations. I discussed how although the chances of producing a favorable mutation by changes in any individual site in the …

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Jul 20 2007

Evolution-12: Population genetics and the Hardy-Weinberg law

(Please see here for previous posts in this series.) In the previous post, I discussed the puzzle posed by a na├»ve understanding of Mendelian genetics, which was that one might expect that organisms that displayed recessive gene traits would slowly disappear in a population while those with dominant gene traits would grow in number. But …

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Jul 18 2007

Evolution-11: The rise of population genetics and the neo-Darwinian synthesis

(Please see here for previous posts in this series.) The joining of Darwin’s theory of natural selection with the Mendelian theory of genetics is one of the great triumphs of biology, now called somewhat grandly the ‘neo-Darwinian synthesis’. It forms the basis of all modern biology, and was strengthened by the discovery of DNA as …

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