The story of evolution-6: The probabilities of natural selection

There are three mathematical ideas that one needs to come to terms with in order to get the full flavor of how natural selection works.

  1. One is the rate at which favorable mutations occur in organisms. These do occur by chance and the question is whether the frequency of such occurrences is sufficient to explain evolution.
  2. The second is the rate at which favorable mutations become more numerous in the population. It is not enough to produce a single favorable organism. The population of varieties with advantageous properties has to eventually grow to sufficiently high numbers that it dominates the population and can form the basis for yet further mutations.
  3. The third is whether the rate at which repeated small and favorable mutations build on each other is sufficient to produce major changes in complex systems (the eye, ear, and other organs for example) and even entirely new species.

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The story of evolution-5: How probability intuition can lead us astray

One of life’s ironies is that the difficulty in understanding the mathematics of Darwin’s theory of natural selection may actually be caused by natural selection itself.

As we saw earlier, natural selection does not try for maximum benefit but instead works on a ‘just good enough for now’ principle. Steven Pinker in his book How the Mind Works (1997) is a cognitive scientist who believes that natural selection has been the driver for most aspects of our bodies and our behavior, and that the brain, being just another organ, has evolved to do what it does to effectively meet the challenges it faced at various times in our somewhat distant past. Pinker points out that humans, when compared with other animals, have unusually large brains compared to body size but that this rapid expansion in brain size occurred more than 100,000 years (or about 5,000 generations) ago (Pinker, p. 198) and then leveled off after that. This means that the structure of our present brains has been largely determined by a time when humans were hunter-gatherers and foragers. [Read more…]

The story of evolution-4: Darwin gets an idea from Malthus

In Darwin’s travels to distant lands from 1831 to 1836 on the Beagle, the different climates and environmental conditions he encountered made him aware of the weakness of the existing theory of ‘special creation’, where god was assumed to have created creatures best suited for their environment. Darwin saw for himself that very similar climates could produce hugely different kinds of species, and that the nature of these species seemed to be more influenced by the species in nearby areas than by anything else. This seemed to him to suggest that new species arose from the modifications of the old.

The discovery that the Earth was much older than had been previously thought, and the evidence for which was in the geology book by Charles Lyell that he had read on the boat, told him that it may be possible for these changes to occur gradually by very small steps provided that there was enough time for the changes to accumulate.
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The story of evolution-3: Natural selection and the age of the Earth

It is clear that many people find it hard to accept Darwin’s theory of evolution by natural selection. One reason is of course because it completely undermines the need to believe in a creator, making god superfluous when it comes to explaining the nature and diversity of life, and thus people may have a negative emotional reaction that prevents them from seeing the power of the theory. As I have discussed earlier, people are quite able to develop quite sophisticated reasons to believe what they want and reject what they dislike.
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The story of evolution-2: The lack of evidence for perfect design

In the first post in this series, I showed with the example of a soap spray nozzle how natural design could come up with systems whose intricacy and complexity is such that it was superior to the efforts of intelligent human designers. But what about the argument that a god-like designer would be able to come up with an even better nozzle design? It is true that if we allow for the existence of such a designer, we could get the best possible design for a nozzle. The catch is that assuming that god is a perfect designer opens up a whole set of new problems, not the least of which is why if god is so powerful he would need any kind of nozzle at all and not simply create any kind of spray he/she needed.
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The story of evolution-1: The power of natural selection

We are rapidly approaching 2009, a year that marks a major scientific milestone that is going to be commemorated worldwide. It is both the 150th anniversary of the publication of the landmark book On the Origin of Species that outlined the theory of evolution by natural selection, and the 200th anniversary of the birth of its author Charles Darwin.

Darwin’s theory represents arguably one of the most, if not the most, profound scientific advances of all time, ranking well up with those scientific revolutions associated with the names of Copernicus, Newton, and Einstein. And yet it is widely misunderstood, or more appropriately, under-understood because most discussions of it remain on too high a level of generality, enabling critics to make statements about the theory that are not valid but yet seem plausible.

In order to create a better awareness of what the theory involves, today I will begin an occasional series of posts that looks at the details of the theory, including the mathematics that underlies it and which was developed later by people like J. B. S. Haldane, Sewall Wright, and R. A. Fisher.
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Guest post by Corbin Covault

My two posts on Taking offense and Taking offense (revisited) generated a lively discussion in the comments. One of the responses covered many of the issues raised by those who disagreed with some or all of my remarks and I felt that it should reach a wider readership so I asked the author to write it as a guest post. While it is a little longer than my own posts, I think readers will find that it provides an interesting perspective.

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Solving social problems the Confucian way

In writing my thoughts about Confucianism (here and here), one thing that struck me was the strong influence that its “Doctrine of the Mean” has, even down to this day. This is reflected in the “Chinese preference for negotiation, mediation, and the “middle man” as against resorting to rigid, impersonal statutes. Until recently, legal action has been regarded as something of a disgrace, a confession of human failure in the ability to work things out by compromises that typically involve family and associates. Figures are not available for China, but in the mid-1980s Japan in ratio to its population had one lawyer for every twenty-four in the United States.” (Huston Smith, The World’s Religions, p.191) [Read more…]

Taoism

The final religion that rounds out the major eastern religions is Taoism. Like Confucianism, it too is a rough contemporary of Buddhism. Its founder is named as Lao Tzu who is said to have been born around 604 BCE, which makes him the earliest of the three founders, but it is not clear if there ever really was such a person, or whether he was a later recreation to provide a single author for the book Tao Te Ching which translates as The Way and its Power and lays out the basic philosophy of Taoism. Huston Smith in his book The World’s Religions says that scholars do not think that the book was written by a single person although the coherence of the book suggests at least a strong single influence in shaping it. It is believed that the book took its final form around 250 BCE.
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Confucianism

Confucianism is an interesting religion that is little known or understood outside the countries where it is practiced. It is often portrayed merely as a bunch of fortune cookie type sayings, leading to jokes of the form “Confucius say. . .”

Although Confucius did say many things that can be quoted as aphorisms, the real religion is far more deep and interesting. (The source for my information is primarily the book The World’s Religions by Huston Smith (p. 154-195). This is an excellent book for anyone seeking to understand the essences of religions. The author takes a non-judgmental, non-comparative approach to each one, trying to simply summarize its basic principles and practices.)

Confucius was born around 551 BCE and lived to the age of seventy three, making him a contemporary of the Buddha. Like the Buddha, he too did not claim to be anyone special or have special powers, and just saw himself as a teacher. The Buddha’s teachings were not primarily social but instead focused inwards, on internal reflection and on what it takes for an individual to shed himself or herself from worldly entanglements and achieve enlightenment. Confucius’s teachings, on the other hand, were explicitly social and this-worldly, trying to teach people how to live in order to create a better society.

Whereas the Buddha turned away from worldly things and adopted the life of a monk and a mendicant, teaching his disciples his philosophy, Confucius earned his living as a tutor almost all his life, teaching his students “history, poetry, government, propriety, mathematics, music, divination, and sports.” Like Socrates, he was a kind of one-man university and taught in the Socratic style, with probing questions and dialogue rather than lecture, and he seemed to have been very modest, never claiming to be better than his students, although his reputation as a great teacher was huge.

To understand what Confucius was trying to achieve, we need to understand his times. Up to the eighth century BCE, China under the Chou Dynasty had been a more or less orderly society with a strong sense of custom and tradition and propriety that together kept the society cohesive and functioning. But this began to disintegrate, with self-interest beginning to predominate over group-interest and by the time Confucius came along, lawlessness had become rampant.

One response to this state of affairs was the Realist school which argued that what ‘people understand best is force.’ They believed that the ruler must maintain an “effective militia that stands ready to bat people back when they transgress. There must be laws that state clearly what is and is not permitted and penalties for violation must be such that no one will dare incur them. In short, the Realists’ answer to the problem of social order was laws with teeth in them. . Those who did what the state commanded were to be rewarded; those who did not were to be punished. . .[T]he laws had to be long and detailed. . .every contingency must be provided for in detail. . .Not only must the requirements of law be spelled out; penalties for infractions should likewise be clearly specified. And they should be heavy.” (p. 164)

The Realists, in short, were the Bush/Cheneys of that time. And like with the Bush-Cheney doctrine, they initially achieved some success in controlling society but created a mess thereafter. The Ch’in dynasty (221-206 BCE) fashioned its policy on Realist lines and succeeded in uniting China for the first time (and giving it its current name) but it collapsed in less that one generation.

Directly opposed to this was the philosophy developed by Mo Tzu, known as Mohism, which argued that the solution to China’s social problems was not force but universal love, where one should (he said) “feel toward all people under heaven exactly as one feels towards one’s own people, and regard other states exactly as one regards one’s own state.”

Confucius rejected both these extremes as unlikely to succeed in achieving the desired goal of social cohesion. He rejected the Realists use of force as clumsy and external. Smith summarizes Confucius’ critique of the Realists: “Force regulated by law can set limits to peoples’ dealings, but it is too crude to inspire their day-to-day, face-to-face exchanges. With regard to the family, for example, it can stipulate conditions of marriage and divorce, but it cannot generate love and companionship. This holds generally. Governments need what they cannot themselves provide; meaning and motivation.” (p. 167)

As for the Mohist philosophy, Confucius rejected it as utopian and unrealistic. He acknowledged that love has an important, even essential role to play in maintaining harmonious social relations but it is effective only if it is supported by the appropriate social structures and a collective ethos.

Confucius thus thought that the Realists were mistaken in their belief “that governments could establish peace and harmony through the law and force that are their domain” and that the Mohists were also mistaken because they “went to the opposite extreme; they assumed that personal commitment could do the job.”

Next: How Confucius set about creating a middle path.

POST SCRIPT: The Politics of Stem Cell Research

(Thanks to MachinesLikeUS for the link.)