Wednesday, December 17, 2008

Family Encyclopedia Gets Evolution All Wrong

The Dorling Kindersley Family Encyclopedia's chapter on evolution sucks.

I haven't ranted about the treatment of evolution in popular and educational literature for a while so here goes. I was at a friend's place the other day and found his son poring over the tome. I flipped over to the evolution chapter. This is supplementary educational material aimed at middle and high school students and for literate others.

Evolution is as well worked out a theory as any. Instead of impressing upon readers in unambiguous terms that the theory of evolution is a theory of immense explanatory and predictive power and is the only workable theory proposed that explains life, what I found was a disgraceful timidly written apology to creationists.

This is one of the most annoying aspects of many popular writings on evolution. Too much territory is ceded to creationists in an attempt to provide a 'balanced argument" so that people get to know "both sides to the story". Well, there isn't any "both sides to the story" as far as explaining the diversity of life is concerned. Evolution is it. Scientific educational materials need to say that clearly and loudly.

Here are some of the problems I found.

a) Trying to present a balance treatment:

Some scientists argue that by looking at the fossil record we can find out more about the past.

Some people believe that this can lead to a new species and that an animal or plant will adapt to its surrounding so that it has a better chance of survival (another big problem here which I will elaborate on later).

However, some people argue that all life forms on the Earth were created by design, in or close to the form in which they exist today.

So the impression given is that of a field vigorously debated between those who believe in evolution and those who believe in creation. This is totally disingenuous. For one, how does the vast majority of scientists translate into some people believe? In any case the merits of any scientific explanation is not decided on whether some, or many or few people believe in it. It is decided on evidence. All the evidence favors evolution as an explanation for life. This is never made explicitly clear.

b) Adaptations benefit individuals or groups?

Some animals choose their mates by means of sexual selection. A male may have elaborate features such as bright feathers, to attract a mate. Characteristics such as these, which may be beneficial to the species are passed on to the next generation.

There is a distinction to be made here that bears on one of the fundamental questions in evolution. Which entity do adaptations benefit? The individual organism or the species / group? One way to think about this is to consider the genetic relationship of organisms within a group. Organisms within a group vary genetically. The reproduction of individuals is independent i.e. it is not coupled to the reproduction of the group and so genes can increase their own reproduction independently of other genes in the group.

Natural selection will favor such genes that allow its bearer to reproduce more than other organisms in the group. Since differential survival and reproduction of individuals is a much faster process than the differential origin and extinction of groups, such genes will spread through the population even if they might be harmful to the group as a whole.

For example it might have been beneficial to the group if peacocks waste less energy developing an elaborate plumage and concentrate on gathering food and reproducing. An elaborate plumage also may expose the population to predators. Keeping plumage inconspicuous would have been a good group adaptation. Except that individual female choice for brightly colored plumage drives the evolution of bigger and brighter plumage, even though there may be a conflict between what is good for the individual and what is good for the group.

I can think of a simpler example to teach middle and high school students. In large penguin colonies or for that matter any large bird colony, Mama after grabbing food goes through an elaborate search among the thousands of squawking babies to find her own baby to feed. If individuals really strive for the benefit of the group, a more efficient group adaptation would have been for Mama to feed any child which is nearest to her. That way offspring are assured of getting food from some adult.

Such a hypothetical altruistic colony may do better than a colony full of selfish individuals. For example perhaps it is less likely to go extinct when scarcity strikes. But such a altruistic colony is unlikely to evolve in the first place since it is susceptible to invasion from a selfish mutant. A mutant parent with the ability to find and feed her own child will be able to produce more children than other altruistic parents, since she will also benefit from strangers feeding her children. The mutation will spread through the population (through her children) and destroy the altruistic group adaptation.

So natural selection will evolve adaptations that benefit the individual and not the species.

In only exceptionally rare cases such as eusocial insects, where only one individual in the group reproduces, and all other individuals are offspring of that founder will we see adaptations that benefit the group. In this case all the non-reproducing individuals share genes with the founder and the only way to pass on a proportion of one's genes is to selflessly help the founder reproduce more and maintain the group.

c) Inheritance of acquired characters.

The process of adaptation occurs when an organism evolves in a certain way to make it better suited to the environment. Some people believe that this can lead to a new species and that an animal or plant will adapt to its surrounding so that it has a better chance of survival

An organism may undergo change due to a number of processes, such as natural selection and adaptation, induced by the environment in which it lives.

No, No, No.

I am convinced that this is still the most popular perception of how evolution works. A lot of people I have talked to about evolution (not all of them with a science background) are familiar with the terms natural selection and adaptation but they understand it to mean the inheritance of acquired characters.

But individual organisms don't adapt that it has a better chance of survival. Evolution is not a teleologically process. And individual organisms during their lifetime don't adapt or change to changing conditions and then pass on those changes to their offspring. This inheritance of acquired characters doesn't work because of the separation of the somatic cells that make up the bulk of the body and the reproductive cells that are passed on to build the next generation.

Changes induced if any by the environment in the somatic cell lines don't get incorporated in the genetic material of reproductive cells.

Evolution is a process that takes place in populations. When the environment changes, those individuals who happen to possess traits that help them reproduce more than other individuals will produce more children. Those traits will then become more common in the population. Screening of these traits through successive filters of natural selection over generation results in a better and better fit between successive generations of descendants and the environment.

But it is critical to remember that these changes don't happen during the lifetime of an individual organism. Evolution takes place over generations. Organisms at any one time have different traits from those their ancestors possessed.

Evolution is not taught well if at all at the high school level in India. Biology teachers are not well versed in evolution, they being a product of a system without a comprehensive evolution syllabus at even the undergraduate college level. If an enterprising teacher does introduce the subject it will be by reading up of supplementary materials like this encyclopedia. That won't help students understand evolution any better. And for most students who give up the sciences after school this will be just about their only reading of evolution.

That may hurt us in the long run. Scientific American has an article on why knowledge of evolution can be useful to non-specialists too. Improved public understanding of the subject will have a significant influence on policy decisions on health care, ecology, agriculture.

What has been your experience with such large encyclopedia publications? Is the geology section for example worth referring to? Do you think it is written by experts in the field and can be relied upon?


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