Theories of evolution Lamarck vs Darwin | Evolution | Biology | FuseSchool

Lamarck's Theory of Evolution00:00:05

In the early 19th century, scientists lacked a mechanism for evolution. Jean-Baptiste Lamarck proposed that animals adapted to their environments throughout their lives, and these acquired characteristics were passed on to offspring. For instance, a giraffe's long neck was thought to be the result of continuous stretching and this trait was inherited by its young.

Darwin's Theory of Natural Selection00:01:27

Charles Darwin, having studied Lamarck's contemporaries, developed his own theory of "descent with modification" after observations during his voyage on the HMS Beagle. Darwin's key difference was that parental traits were passed on without being modified by the parent's life experiences. He emphasized that variations already exist within a population, and nature "selects" the fittest variants, a process called natural selection. Fitness, for Darwin, meant the ability to survive and pass on characteristics.

Natural Selection Explained00:02:26

Darwin proposed that changes in species occur slowly and gradually. In the case of the giraffe, natural selection would favor giraffes with longer necks, gradually increasing the average neck length in the population over time. Darwin published his ideas after more than 20 years of work, prompted by Alfred Russel Wallace, who had independently conceived of the same theory.