Module 2.2: Lamarckism

   Jean-Baptiste Lamarck was one of the first scientist to develop and present a rational, comprehensible explanation for the process of evolution however, Charles Darwin is credited as the mastermind behind the theory of evolution by natural selection. Charles Darwin’s theory of evolution greatly impacts our current understanding of change in heritable traits of biological populations over successive generations. Unlike Darwin, who argued that all extinction is selective, that species not able to compete with other species die out, Lamarck claimed that species did not die out in extinctions, instead they improved into other species. He believed that living organisms evolved in a continuously upward direction. Simple life forms were raised from dead matter, that eventually became complex life forms with humans being the closest to reaching perfection. An ongoing spontaneous generation was what Lamarck used to explain how simple life forms could live along side more complex life forms in the same period. One of main reasons Lamarck’s ideas of evolution were dismissed was due his proposal that life forms could acquire information from the environment and pass it on in their genes (epigenetics). Lamarck illustrated the idea that organisms changed their behavior in response to environmental change with the extended necks of giraffes. Their changed behavior improved the structure of their organs which were inheritable traits. He claimed that giraffes developed their lengthened necks and front legs by generations of browsing on high tree leaves. Conversely, Darwin believed that giraffes with longer necks were able to reach higher branches and as a result, these giraffes were more reproductively successful since they persisted on an untouched food source while giraffes of lesser stature succumbed due to competition (sexual selection).

  Lamarck did not get it all wrong, like Darwin, they both suggested that life had changed gradually over time and was still changing. They agreed on the fact that living organisms develop traits that allow them to better suit and adapt to their environments. Lamarck and Darwin claimed that all species are related that is, that they are all descended from a common ancestor. Lamarck was also right about how complex organisms evolve from simpler ones through a gradual evolutionary process however, Darwin added the idea of selection that favored intermediate forms along the way. Yes, Lamarck might have gotten some aspects wrong, but he was one of the early evolutionists, and should be well recognized as such!