Question

Briefly summarize Lamarck’s hypothesis for evolution. What evidence rejects this hypothesis?

Answer 1

He came up with inheritance of acquired characteristics, organisms, by striving to meet the demands of their environments, acquire adaptations and pass them by heredity to their offspring. Now it is rejected because genetic studies show that traits acquired during an organisms lifetime, such as strengthened muscles, aren't transmitted to offspring....

Lamarckism, a theory of evolution based on the principle that physical changes in organisms during their lifetime—such as greater development of an organ or a part through increased use—could be transmitted to their offspring...

Lamarck's theory can be boiled down to two broad claims. First, new species evolved from previous species. Today, we know that each organism carries DNA that encodes the characteristics or traits that we associate with its species. This DNA is inherited from parent to offspring and small changes in the DNA over millions of years result in the diversity of species that we see today.Lamarck's second broad claim was, acquired traits are inherited by offspring. Lamarck's second tenet is that this evolution of species occurs by the inheritance of acquired characteristics......

Lamarck's theory suggested that the giraffe's original short-necked ancestor repeatedly stretched its neck to reach the higher branches to eat. Lamarck believed that the stretching elongated the giraffe's neck, which became a useful characteristic and was passed onto future generations. This resulted in the length of the giraffe's neck increasing over time...

It was rejwcted -

It is now commonly accepted that Lamarck's ideas were wrong. For example, simple organisms are still detected in all varieties of life, plus it is now known that mutations can create variation such as neck length.

Lamarck's theory of the inheritance of acquired characteristics was disputed by many biologists because more and more evidence demonstrated that traits and behaviors were the result of natural selection and controlled by genes..

Why was lamarckism was rejected after darwinism?

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4 Answers

Dipesh Chikane, Ph.D Scholar, Visiting Faculty, Project Assistant at Rajiv Gandhi Institute of IT and Biotechnology, Pune (20…

Answered April 28, 2018

Because all the postulates given by lamarck is criticise by Darwin and other scientist because all the postulates are become false because of the proof given by this peoples.

Lamarck statements - 1) During evolution body size of organism increased

Criticism = proressive evolution - simple to complex life, Retrogressive evolution - complex to simple.

2) Due to internal vital forces new characters evolved

Criticism = wing gene is present in human.

3) Environmental factors - Giraffe neck

Criticism = every organism is pre adapted.

4) use and disuse

Criticism = Human eye

5) Inheritance of acquired characters

Criticism = by weismann

Important point of Darwinism =

1. Evolution is not goal oriented or pre planned process.
2. Selection occur on given condition
3. Differential survival and diffrential reproduction are more important.
4. Adaptation is not accquired they are inherited.
5. Variation occur due mutation, mutation is random phenomenon, only beneficial mutation are selected. Hence, Darwinian theory is still accurate and accepted.