History of Evolution Theory

Evolution The process by which modern organisms have descended from ancient organisms. Change over time.

Darwin Made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time. He also collected fossils Preserved remains of ancient organisms Many resembled animals that were still alive.

Influential Scientists James Hutton Charles Lyell Jean-Baptiste Lamarck Thomas Malthus

James Hutton (1795) Proposed that Earth had to be much older than a few thousand years old Proposed that layers of rock form very slowly (millions of years)

Charles Lyell (1833) Processes occurring now have shaped Earth’s geological features over long periods of time.

Jean-Baptiste Lamarck (1809) One of the first scientists to recognize that living things have changed over time and that all species descended from other species Proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime Those traits could then be passed on to the offspring Over time, this process led to change in a species

Example In fiddler crabs, the males use their front claw to fight off predators and to attract a mate Because the front claw is used repeatedly, it becomes larger The larger claw trait is then passed on This theory was disproved If true, a man could work out every day and become muscular  when he has kids, they would be muscular.

Thomas Malthus (1798) Made the observation that babies were being born faster than people were dying He reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone. War, famine, and disease were the only things working against growth. Darwin applied this theory to plants and animals.