Why Do Cave Fish Lose Their Eyes

Scientific Evidence Proves Use it or Lose it is a Thing of the Past

Lamarck and Darwin both believed that giraffes developed long necks because that is what they use to consume the leaves high above trees Lamarck 's theory is that because their (giraffes ) forebears were continually stretching to reach the higher leaves in trees . The desire to reach higher leaves led to longer necks , and later on , the giraffe 's offspring inherited that physical trait (Natural History , 2005 ,

.46 Darwin disagrees with Lamarck when his theory of natural selection

stated that the giraffes with longer necks outlived the ones with shorter necks maybe because the more nutritious leaves were at the higher parts of trees . However , when Lamarck said that unused organs shrivel until they disappear (Natural History , 2005 ,

.46 ) Darwin was at a loss since his theory of natural selection cannot explain regressive evolution and he finally succumbed to Lamarck 's use it or lose it principle

Darwin , regardless of how great a scientist he is , is not infallible Robert Simmons has recently voiced out a contradictory view of both Darwin and Lamarck 's theory of why giraffes have long necks . Simmons believes that competition for mates and not stretching for treetop food is what drove the evolution of necks . According to his observations when male giraffes battle for mates , they swing their necks of over 6 feet long and weighs over 200 lbs . The momentum of these swings are often lethal , therefore , it is only natural that the victor is the one who possesses the longest and biggest neck . He goes on to say that if the competition for food is what spurred the elongation , then you would expect giraffes to eat the leaves from tall acacia trees rather than grazing on low shrubs (Discover , 1997 ,

.14

If Simmons ' theory disproves Lamarck 's conclusion that the stretching of the neck was due to food competition , then it can be said that the principle of Use it or Lose it ' can be disproved . To know if whether this principle is still steadfast , we have to consider both sides of the spectrum

The main proponent of Lamarck 's use it or lose it theory is the neutral-mutation hypothesis . According to this hypothesis , genes controlling the development of unnecessary structures become effectively neutral . Once the genes neither enhance nor hinder the organism 's survival , the forces that once maintained those genes in good working no longer operate . The genes accumulate mutation that impair their function , and so the unnecessary genes degenerate (Natural History , 2005 ,

.47 . Careful analysis of the use it or lose it scenario shall lead one to believe that if an organ is not anymore needed , it shall degenerate and sooner or later entirely disappear without any effect on the organism except for the loss of an unnecessary part

A group of scientists that holds a contrary view believes that the loss of one part is due to regressive evolution and not...