Biology · Evolution · NEET
| Proposed by | Jean-Baptiste Lamarck | Charles Darwin (and Wallace) |
| Core mechanism | Use and disuse of organs | Natural selection |
| Source of the trait | Environment creates a new trait in the lifetime | Variation already exists in the population |
| Inheritance | Acquired characters are inherited | Only pre-existing heritable variation passes on |
| Classic example | Giraffe stretches neck to reach tall leaves | Fitter variants survive and out-breed others |
| Status for NEET | Disproved ('nobody believes this any more') | Widely accepted foundation of evolution |
Lamarckism is rejected. NCERT clearly says about the giraffe long-neck idea: 'Nobody believes this conjecture any more.' Acquired characters (gained during one's lifetime by use or disuse) are NOT inherited. For NEET, treat Lamarckism as historically important but disproved.
The classic giraffe example belongs to LAMARCK. He said giraffes stretched their necks to reach tall leaves, this elongated neck was an acquired character, and it was passed to the next generation. Many students wrongly link giraffe with Darwin, which is a common trap.
Use-and-disuse (Lamarck): the environment forces a NEW character during life, then it is inherited. Natural selection (Darwin): variation ALREADY exists in the population, and nature simply selects the fitter variants who leave more progeny. Lamarck creates the trait; Darwin only selects among existing traits.
No. Darwin used variation and said fitter variants are selected, but he could NOT explain the SOURCE of variation. The origin of variation (mutation) came later with Hugo de Vries and genetics. This is a favourite NEET point.
NCERT states fitness refers ultimately and ONLY to reproductive fitness. The fittest individual is the one that leaves the most surviving progeny, not simply the strongest. This is Darwinian fitness.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Jean-Baptiste Lamarck was a French naturalist who, even before Darwin, said life forms had evolved, driven by the use and disuse of organs and the inheritance of acquired characters.
Charles Darwin, based on observations during his voyage on H.M.S. Beagle. Alfred Wallace independently reached a similar conclusion around the same time.
Branching descent and natural selection are the two key concepts of the Darwinian theory of evolution.
Changes gained in body cells during an organism's life (like a stretched neck) do not enter the germ cells, so they are not passed to offspring. Only inherited genetic variation is passed on.
Yes. NEET regularly tests you on WHO proposed WHAT and on comparing the two theories, so knowing Lamarckism and how it differs from Darwinism is essential even though it is rejected.
