INHERITANCE OF ACQUIRED CHARACTERISTICS

Toward the end of the eighteenth century, several naturalists suggested that life had evolved along with the evolution of earth. But only one of Darwin‟s predecessors developed a comprehensive model that attempted to explain how life evolves. Jean Baptiste Lamarck He (1744-1829) published his theory of evolution in 1809, the year Darwin was born. Lamarck was in-charge of invertebrate collection at the Natural History Museum in Paris. He presented a mechanism to explain how specific adaptations evolve.

Lamarckism.

This theory includes use and misuse of organs and inheritance of acquired characteristics. Use and misuse of organs. Lamarck argued that those parts of the body used extensively to cope with the environment become larger and stronger, while those that are not used deteriorate.

Example 1.

Among the examples Lamarck cited were the blacksmith developing a bigger bicep in the arm that works the hammer

Example 2.

Giraffe stretching its neck to new lengths is pursuit of leaves to eat. Inheritance of acquired characteristics. The second idea Lamarck adopted, was called the inheritance of acquired characteristics. In this concept of heredity, the modifications an organism acquires during its lifetime can be passed along to its offspring

Example.

Lamarck reasoned, the long neck of the giraffe, evolved gradually as the cumulative product of a great many generations of ancestors stretching higher and higher. Dismissal of Lamarckism. Weismann conducted the experiment of removing the tails of 68 white mice, repeatedly over 5 generations, and reporting that no mice were born in consequence without a tail or even with a shorter tail. These experiment clearly showed that acquired characteristics cannot be inherited.