What was the problem with Lamarck's theory of inheritance of traits?

Answer 1

It's core principle is that individual organisms can pass characteristics acquired during their lifetime to offspring; for example, a thin man works out his whole life and develops large muscles, then has a son who will also have the large muscles. However current evolutionary theory dictates that only the genetic information that determines the genetic potential of an organism is passed on to offspring - in the example, his dad was thin so he will be too - so acclimation within this genetic potential (What Lamarckian theory would suggest is passed on) is not.

Of course as with most things within evolutionary theory that's just the current thinking, recent developments in Epigenetics for example suggest Lamarckian inheritance or aspects of it may actually exist within nature to some extent.

Answer 2

Lamarck believed that by using or not using a body part, then an individual may change its traits and then pass those traits on to it's offspring. For example, he believed giraffes were born with short necks. Then a giraffe stretched it's neck and made it longer. This giraffe then passed his long neck on to his offspring. Our understandings of genetics and how traits are passed on to our offspring through inheritance proves Lamarck's theory to be incorrect.

Answer 3

Lamarck hypothesized that the traits passed on to offspring were acquired through habit during the life of the parent. In his model, the stretching of the neck to reach higher leaves in the giraffe's short-necked ancestor would result offspring with longer necks.