Monday, July 6, 2009

Lane: Movement a Great Invention of Evolution

Going back to the ancient Greeks motion has always been a profound problem. In his new book Life Ascending: The Ten Great Inventions of Evolution, evolutionist Nick Lane says that animal movement is one of the the ten great inventions of evolution, to go along with photosynthesis, DNA, the origin of life and the complex cell. Indeed animal movement is incredible, but the idea that it evolved is motivated more by the assumption that Darwin's idea is true rather than actual evidence for the evolution of movement.

Animal movement is accomplished by the contraction of muscles. When you raise up your hand to scratch your head, certain muscles are contracting to cause the motion. And when you then lower your hand, different muscles contract to make that happen. Needless to day, the body is fashioned with a dizzying array of muscles, precisely oriented and sized to give us the grace to dance across a stage or perform brain surgery.

Those muscles are controlled by a vast network of nerve cells. These long thin cells transmit electrical signals from the brain. They are fused to the right muscles, at the right places to cause the muscle to contract. But it is not a simple process. The nerve's electrical signal is transformed into complicated chemical signals that cross over from the nerve cell to the muscle. Ultimately, proteins in the muscle act to cause the contraction in a complex process.

So when you want to scratch your head, your brain lights up the right nerve cells to make it happen. The idea that all this evolved is, of course, not well supported by the scientific evidence. If we believe evolution is true we can conjure up speculative just-so stories about how it occurred. But they are not motivated by science.