Question

Which of the following are included in the four principles of Lamarckism?
A. Formation of rudimentary organs
B. Direct environment and new desire
C. Genetic drift
D. Inheritance of acquired characters
Choose the correct answer from the options given below:

• A. A and D only
• B. A, B and D only
• C. B, C and D only
• D. A, B and C only

Hint:

Remember the core of Lamarckism with the giraffe example: The environment (tall trees) creates a need (to reach leaves), leading to a change (stretched neck through use), and this acquired trait is inherited. Any concept involving modern genetics like "genetic drift" is not Lamarckian.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Lamarckism, or the theory of inheritance of acquired characteristics, was an early theory of evolution proposed by Jean-Baptiste Lamarck. It was based on several key principles that attempted to explain how species change over time.
Step 2: Detailed Explanation:
Let's analyze the given points based on Lamarck's theory:
- A. Formation of rudimentary organs: This relates to Lamarck's principle of "Use and Disuse." Lamarck proposed that organs that were not used would shrink and become vestigial or rudimentary over time. So, this concept is part of his theory.
- B. Direct environment and new desire: Lamarck believed that a change in the environment creates a new need or "desire" (besoin) in an organism, which drives it to change its behavior and, consequently, its physical form to meet that need. This is a core tenet of Lamarckism.
- C. Genetic drift: This is a mechanism of evolution that is part of the modern evolutionary synthesis, not Lamarckism. It describes random fluctuations in the frequencies of gene variants (alleles) in a population. It was proposed long after Lamarck.
- D. Inheritance of acquired characters: This is the most famous principle of Lamarckism. It states that the physical changes (characters) an organism acquires during its lifetime (e.g., a giraffe stretching its neck to reach higher leaves) are passed on to its offspring.
Step 3: Final Answer:
The principles of Lamarckism include the effects of the environment creating new desires (B), the principle of use and disuse leading to changes like the formation of rudimentary organs (A), and the inheritance of these acquired characters (D). Genetic drift (C) is not a part of Lamarck's theory. Therefore, the correct options are A, B, and D.