Charles Darwin is recognised as the scientist most associated with the theory of evolution, however, a number of other scientists were influential in this field.
At the beginning of the 19th century Jean-Baptiste Lamarck was a French scientist who developed an alternative theory of evolution before Charles Darwin.
Lamarck's theory involved two ideas:
However, through modern science we now know that in the vast majority of cases this type of inheritance cannot occur.
Lamarck's theory cannot account for all the observations made about life on Earth. For instance, his theory implies that all organisms would gradually become complex, and simple organisms disappear.
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 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.