Читать книгу The Handy Psychology Answer Book - Lisa J. Cohen - Страница 192

Jean-Baptiste Lamarck (1744–1829) was a French biologist who contributed to pre-Darwinian theories of evolution. In keeping with the ideas of Charles Darwin’s grandfather, Erasmus Darwin, Lamarck believed in the inheritance of acquired characteristics. In other words, an animal learns a new way to adapt to the environment and these changes are then passed onto the animal’s offspring via some form of heritability. Genetic change takes place because of the animal’s behavior. The classic example involves the long neck of the giraffe. It was thought that giraffes stretched their own necks by reaching up to eat the leaves off the top of tall trees. This trait was then passed on to later generations. Similarly, mountain goats grew a thicker coat in a cold climate and then passed this trait onto their offspring.

Although Lamarckian evolution has a kind of intuitive appeal, there has never been any evidence to support its central premise that learned behavior is directly coded into the genes, and it is not considered a scientifically valid theory. In modern evolutionary theory, genetic changes occur through random mutation. Some of these genetic mutations will improve the animal’s adaptation to the environment, though most will not. Those genes that do improve adaptation are more likely to be passed on to the next generation. Hence the environment influences reproductive success but does not act upon the genes directly.