Sunday, November 17, 2013

Evolution in texbook

I saw some sentences in the chapter on genetics and evolution in Sujit's textbook which I think are not correct. I am commenting here on only some of them. I am sure a professional  in the  field will spot a lot more errors than I did. My frustration with the system of education prevalent here is that you have to write exactly as given in the textbook even if it is wrong. If sujit writes what I tell him, he will fail in the exam.“Why create a generation of thinkers when what’s needed are workers?” seems to be the thinking behind education in most Indian schools. I will start with the  definition of evolution given in the textbook:

Evolution may be defined as a gradual development of more complex species from pre-existing simpler forms.

This definition is unhelpful. In biology, development refers to the changes in a single individual over its lifetime. Using this word confuses a basic idea:  individuals don't evolve, populations do. Also, it is not necessary that evolution always results in production of greater complexity. For eg., the tapeworm lost its digestive system when it became an intestinal parasite. It has no need for one. The most successful organisms on Earth -bacteria - did not evolve into multi cellular forms.

Some dimensions of an organism may become simple while other dimensions may become more complex. It all depends on its way of life. Eg., the tapeworm has adaptations that enable it to avoid the immune system of the human body. The minimal definition of evolution as given in this post is:

Evolution is a process that results in heritable changes in a population spread over many generations.

As Susan Blackmore says in this TED talk, (variation + selection + heredity) MUST result in evolution. The organism shaped by evolution is not the perfect, but the good-enough. It is not striving for anything. It just depends on the differential survival and reproduction of replicating units that have high copying fidelity with occasional errors. It is incredible to think that fungi and giraffe are different manifestations of the same simple process. When I first had a clear grasp of  this  idea., I had a similar reaction to what Keats had when he read Chapman's Homer.

The term 'survival of the fittest' appears in the chapter but is not explained. This is a much misunderstood term. The word 'fittest' is taken to mean 'strongest' and is often used to justify the Gordon Gekko-style 'greed is good' philosophy. Actually it just refers to an organism that best ' fits' its environment. A pusillanimous rabbit that takes flight at the slightest sign of danger is fitter than an intrepid rabbit that investigates every suspicious sound. The former will leave descendants while the latter will be lunch.

About speciation, the textbook says:

Thus speciation is arising of a new species from a sub-population of a species which is geographically or reproductively isolated over a long period of time from the other population of the same species.

The 'or' is confusing here. Though defining a species is not easy, speciation just means the evolution of different groups through reproductive isolation over a long period of time so that there is no gene flow between the two groups. These genetic differences gradually grow larger to the extent that the individuals of the two groups cannot interbreed. The most common way in which reproductive isolation occurs is by geographical isolation, a process known as allopatric speciation.

While discussing the formation of new species,it is mentioned at one point: "Then they would be ready to become two different species." This is not how evolution happens. It is not as if the best and the brightest of a species held a conference , decided that that they have had  enough of this practice business and that it is time for them to become new species. There is no conscious strategy involved. The language of conscious strategising is often used but that is only for expository convenience.

What actually happens is that because of the variation of individuals in a population, some individuals will have certain characters (morphological, anatomical, physiological or behavioral) that will give them an advantage over individuals that don't have them.Thus more of these individuals will survive and reproduce on average and leave copies of their genes to future generations. By this process, that particular character becomes more common in that species over many generations.

Tuesday, November 5, 2013

On Liberty

A good treatise for reading about freedom of speech and other personal freedoms would be On Liberty by John Stewart Mill. Bertrand Russell said, “On Liberty remains a classic . . . the present world would be better than it is, if [Mill’s] principles were more respected.” Here are some excerpts:
... there needs protection also against the tyranny of the prevailing opinion and feeling; against the tendency of society to impose, by other means than civil penalties, its own ideas and practices as rules of conduct on those who dissent from them; to fetter the development, and, if possible, prevent the formation, of any individuality not in harmony with its ways, and compel all characters to fashion themselves upon the model of its own.
The effect of custom, in preventing any misgiving respecting the rules of conduct which mankind impose on one another, is all the more complete because the subject is one on which it is not generally considered necessary that reasons should be given, either by one person to others, or by each to himself. People are accustomed to believe, and have been encouraged in the belief by some who aspire to the character of philosophers, that their feelings, on subjects of this nature, are better than reasons, and render reasons unnecessary.
If all mankind minus one, were of one opinion, and only one person were of the contrary opinion, mankind would be no more justified in silencing that one person, than he, if he had the power, would be justified in silencing mankind. Were an opinion a personal possession of no value except to the owner; if to be obstructed in the enjoyment of it were simply a private injury, it would make some difference whether the injury was inflicted only on a few persons or on many. But the peculiar evil of silencing the expression of an opinion is, that it is robbing the human race; posterity as well as the existing generation; those who dissent from the opinion, still more than those who hold it. If the opinion is right, they are deprived of the opportunity of exchanging error for truth: if wrong, they lose, what is almost as great a benefit, the clearer perception and livelier impression of truth, produced by its collision with error.
First: the opinion which it is attempted to suppress by authority may possibly be true. Those who desire to suppress it, of course deny its truth; but they are not infallible. They have no authority to decide the question for all mankind, and exclude every other person from the means of judging. To refuse a hearing to an opinion, because they are sure that it is false, is to assume that their certainty is the same thing as absolute certainty. All silencing of discussion is an assumption of infallibility. Its condemnation may be allowed to rest on this common argument, not the worse for being common.
But I must be permitted to observe, that it is not the feeling sure of a doctrine (be it what it may) which I call an assumption of infallibility. It is the undertaking to decide that question for others, without allowing them to hear what can be said on the contrary side.
 At present individuals are lost in the crowd. In politics it is almost a triviality to say that public opinion now rules the world. The only power deserving the name is that of masses, and of governments while they make themselves the organ of the tendencies and instincts of masses. 
The demand that all other people shall resemble ourselves, grows by what it feeds on. If resistance waits till life is reduced nearly to one uniform type, all deviations from that type will come to be considered impious, immoral, even monstrous and contrary to nature. Mankind speedily become unable to conceive diversity, when they have been for some time unaccustomed to see it.