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Explanation:
Lamarck and Evolution
What do you think of when you hear the word evolution? Most people would mention Charles Darwin, the scientist who first proposed the theory of natural selection. But did you know that Darwin’s work was built on the ideas of another scientist? More than 50 years before Darwin’s voyage on the Beagle, French biologist Jean Baptiste Lamarck formulated ideas of evolution that attempted to explain changes he saw in living things.
Born in France in 1744, Lamarck served in the French army before he began to study botany and medicine. In 1778, he published Flore Française, a book on the plants of France. Later, he was appointed a professor at the National Museum of Natural History in Paris, where he studied invertebrates. What he saw in the specimens he classified intrigued him. He found that there were unexpected similarities among organisms, and he tried to find a way to explain them.
Inheritance of Acquired Characters
In 1801, Lamarck put forth a hypothesis that included several ideas very different from what we now know about evolution. His most well-known idea involves “inheritance of acquired characters.” He thought that during their lifetime, organisms could change in response to a changing environment and that they could pass on those acquired traits to their offspring. If organisms began to use part of their bodies in new ways, their bodies would change to accommodate these uses.
For example, Lamarck observed that giraffes had long necks and ate leaves from tall trees. He hypothesized that giraffes once had short necks. Individual giraffes stretched their necks to reach leaves on trees, and their necks grew longer in response. When these giraffes reproduced, he thought, their offspring inherited their longer necks. Lamarck also hypothesized that if organisms stopped using parts of their bodies, those parts would shrink and either become useless or cease to be part of the organism. He cited the human appendix as an example.
Evolving to “Perfection”
Lamarck thought that plants and animals came into being through spontaneous generation, or from nonliving substances. At first, he thought, they were simple organisms, but they had an innate urge to become more complex and “perfect,” and this is why they changed. Lamarck believed that because there were simple organisms and more complex organisms living side by side in the world, new simple organisms must be constantly coming into existence via spontaneous generation. Lamarck did not believe in extinction. He thought species that had disappeared had simply evolved into another type of organism.
In Lamarck’s view, giraffes developed long necks because they continually stretched their heads upward to eat leaves on tall trees.
Today, we know that organisms do not come into being via spontaneous generation. We also know that organisms cannot pass acquired traits to their offspring. Still, Lamarck can be credited for recognizing that organisms change through time through natural processes that can be explained. In addition, Lamarck recognized that offspring inherit traits from their parents. Both these ideas are important to our modern understanding of evolution.
