NEET BIOLOGY

Detailed explanation-1: -Jean Baptiste Lamarck published his theory of evolution in 1809. In his theory, Lamarck proposed that traits like the long neck of a giraffe evolved over time by ‘use and disuse’. According to this idea, each giraffe stretched its neck over its lifetime to reach leaves on high branches.

Detailed explanation-2: -Lamarck is best known for his Theory of Inheritance of Acquired Characteristics, first presented in 1801 (Darwin’s first book dealing with natural selection was published in 1859): If an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring.

Detailed explanation-3: -Lamarck believed that the long necks of giraffes evolved as generations of giraffes reached for ever higher leaves. Lamarck was struck by the similarities of many of the animals he studied, and was impressed too by the burgeoning fossil record. It led him to argue that life was not fixed.

Detailed explanation-4: -This is ‘natural selection’. Consider the giraffe, for example. A Darwinian theory of evolution posits that it was through random variation that some giraffes had longer necks than others. Thanks to their long necks, they were able to reach leaves high up in the trees in their environment.

Detailed explanation-5: -According to Lamarck, organisms altered their behavior in response to environmental change. Their changed behavior, in turn, modified their organs, and their offspring inherited those “improved” structures.