Lamarck proposed two hypotheses: 1) that organs strengthened through frequent use and weakened through disuse, known as the law of use and disuse, and 2) that characteristics acquired by organisms during their lifetime to adapt could be inherited by their offspring. For example, as giraffes stretched their necks to reach higher tree branches, their stretched bodies would then be passed on genetically to subsequent generations, leading to the long necks of modern giraffes. Lamarck made significant early contributions to classifying invertebrate organisms as a founding professor at the Museum of Natural History in Paris in the late 18th century.

1. Lamrack’s Hypothesis
Use and Disuse
Inheritance and Acquired characteristics
By
Bo No.22
Lita No.24
MEP 611

2. Lamarck started his scientific career as
a botanist, but in 1793 he became one of
the founding professors of the Musee
National d'Histoire Naturelle as an expert on
invertebrates. His work on classifying worms,
spiders, molluscs, and other boneless
creatures was far ahead of his time.

3. Use and Disuse
• He proposed that if an organ is used a lot it will
develop and strengthen
• If it is not used it will atrophy
• He called this the law of use and disuse

5. Inheritance and acquired
characteristics
• if an organism developed a characteristic feature
through adapting to a new way of life during its
lifetime, it would pass this on to its offspring
• The classic example given is that of the giraffe’s
neck
• As the giraffe’s ancestors searched for a richer
food supply they stretched to reach higher
branches in trees
• Thus their stretched bodies were passed onto
their offspring

6. THANK YOU