(Copyright © 1999 Piero Scaruffi | Legal restrictions - Termini d'uso )
The British biologist Steven Jones delves into modern genetics not so much to trace the evolution of species but to trace the evolution of humans and their habits, from sex to language.
Jones reviews the birth of human genetics through Francis Galton's eugenetics (the discipline that studies how genius is passed on from father to offspring and how the human race can be improved through selective breeding) and Herbert Spencer's social darwinism.
Jones is particularly effective at pointing out the key role played by mutation in our ordinary lives:
Philosophically, the problem is that mutation is random. Evolution occurs by accident, by "genetic drift": by chance and time.
Jones reinterprets the "battle of sexes" from a biological point of view. Jones speculates on the biological role of sex (e.g., whether the male is just a parasite on the female), how casual the determination of sex is (some fish can switch sex at any time) and what the impact of female's choices of partners could be on evolution.
Jones also briefly discusses the different behavior of males and females, although he doesn't truly elaborate on, for example, why murder is almost exclusively male and it peaks at 25.
Jones also describes the dangers of inbreeding (how it increases the chances of inheriting bad genes), but doesn't really explain why India, where half of all marriages are between cousins or between uncle and niece, doesn't have a much higher rate of diseases than other countries.
The book, instead, dwells at length on the finding that genes have a sex: the impact of a gene depends on which parent gave it to us. The effects of the same gene can be quite different depending on whether it came from the father or from the mother (a phenomenon which is known as "genetic imprinting"). Jones speculates that this is due to the different goals of the male and female genes: male genes exhibit paternal irresponsibility (they have nothing to lose in exploiting the female genes as much as possible) whereas female genes exhibit maternal far-sightness (they have to preserve resources for further offspring).
Jones emphasizes that, while most genes seem pretty innocuous, one gene may be enough to cause major differences in abilities (after all, humans and chimps share 98.4% of their DNA).
In passing, Jones mentions facts about evolution that would deserve a longer treatment. For example, natural selection has (short-term) tactics, but no (long-term) strategy: that is why natural selection has never produced a clock or even a wheel. Tactics, on the other hand, can get to eyes and brains. Humans can build clocks, but not eyes. Nature can build eyes, but not clocks. Whatever humans build, it has to be built within a lifetime through a carefully planned design. Nature builds its artifacts through millions of years of short-term tactics.
After having analyzed the more or less abstract mechanism of mutation, Jones attacks the complementary aspect that together with mutation yields evolution: natural selection, i.e. the environment. Inheritance involves genes and environment working together. Jones projects this simple principle into our daily lives. Diseases which are dormant in our genes, for example, may be sparked off by environmental conditions. Diet is as important as genes in the development or the prevention of a disease. And pollution is as important as genes to the development of cancer. And so forth.
How of us is due to nurture (our experiences) and how much to nature (our genes)? The research on identical twins (who share all their genes) is, alas, still non conclusive.
Finally, Jones gives a perspective on "applications" of genetics to a variety of fields.
The similarity between biology and linguistics is well known. Languages evolved just like species, through little "mistakes" that were introduced by each generation. It is not surprising that the evolutionary trees drawn by biologists (based on DNA similarity) and linguists (based on language similarity) are almost identical. Jones concludes that language may date back to the beginning of mankind.
In general, genetics can help reconstruct the history of mankind from genetic "trails" left in various populations. As he notes,"everyone is a living fossil".
Of course, genetic engineering can be used for agricultural or medical purposes. But, unfortunately, it was born out of the desire to build a better race, and frequent historical detours show us the impact of biological ideas on evil or deranged politicians.
The book offers a comprehensive tour of the issues that surface in modern genetics and makes for a perfect companion to appreciate the moral dilemma facing society at the dawn of the cloning era.