"This refers to all of the external factors which influence a creature during its lifetime.
For example, one person may have darker skin than another simply because she is exposed to more sunshine.
Or another may have larger muscles because he exercises more.
Such environmentally-caused variations generally have no importance to the history of life, because they cease to exist when their owners die; they are not passed on.
--In the middle 1800s, some scientists believed that variations caused by the environment could be inherited. Charles Darwin accepted
this fallacy, and it no doubt made it easier for him to believe that one creature could change into another.
He thus explained the origin of the giraffe’s long neck in part through ‘the inherited effects of the increased use of parts’ In seasons of limited food supply, Darwin reasoned, giraffes would stretch their necks for the high leaves, supposedly resulting in longer necks being passed on to their offspring."
CMI
