Inheritance of Acquired Characteristics: Study Notes

For the complete syllabus, check out our PMDC MDCAT Syllabus 2025 article.

LAMARCK'S THEORY OF INHERITANCE OF ACQUIRED CHARACTERS

Jean Baptiste de of Lamarck proposed a new theory of organic evolution based upon the principle of use and disuse of organs in his book “PhilosphieZoologique”.

POSTULATES OF THEORY:

• When the living organisms live in a particular environment that has a great influence on them.
• When living organism migrates from one place to another in a different environment, their needs and habitats are gradually changed.
• When some changes are developed in body due to effect of environment by these changes some organs that are widely used become stronger and well developed while some other organs that are not properly used become weaker and degenerated.
• By use and disuse of organs, some new characters are developed in the body of organism called acquired characters that are transferred from one generation to another.
• After many generation the changes are accumulated to such extend, that a marked alternation occurs in the body and it results in the development of new species it is called evolution.

EXAMPLES

• Evolution of Giraffe
• Evolution of Snakes
• Kiwi- evolution of birds.
• Evolution of teeth in whale.
• Evolution of webbed feet of duck.

MAJOR OBJECTIONS:

• Absence of Mutilations in new Generation
• Boring of Holes are not inherited
• Circumcision in Males is not inherited

WEISMANN’S THEORY (GERMINAL CONTINUITY THEORY)

According to this theory:

• Zygote after fertilization of male and female gametes starts development and produce two kinds of cells called somatic and germ cells.
• When certain changes occur in a somatic cell of the body these are called acquired characters. These characters do not take part in reproduction.

​

Explore our MDCAT webapp for tests, video lectures, and complete prep resources.