Evolution according to Jean Baptiste Lamarck

Lamarck's ideas were educated and have some merit, but they do not include many answers to the questions that remain. The idea that using an organ more would determine its evolutionary change is only partially true. The variable in question would need to be considered more desirable to mates, and have the ability to genetically pass down the trait. There would need to be some pressure or benefit for the animal to change. The idea is there, but the mechanisms of how organisms evolve is not. This is where Darwins theory is able to fill in the educational gaps. Darwins theory was a more gradual process brought on by a selective pressure, and affirmed by natural selection. 

    Lamarck's first idea had a bit more grip than his second, increasing complexity.  Evolution can happen in both directions: complexity and simplicity. Depending on the reason for change, an animal might benefit from having a more simple digestive system, colored fur, etc. My final reason as to why Lamarck's idea is not steadfast is that animals don't need to change. There are many organisms that haven't changed for thousands and thousands of years, because they have what they need. Don't fix something that isn't broken! Lamarck had great ideas, but time and more research has given us better more definitive answers for evolution. This is why I love science, even the wrong answers can be helpful when attempting to understand our complex world.