10.B BIO, C1 Ideas that Shaped Darwin's Thinking (PART B)

James Hutton

A geologist that proposed that forces beneath Earth's surface can push rock layers upward, tilting or twisting them in the process and eventually forming mountain ranges. Mountains, in turn, can be worn down by rain, wind, heat, and cold. Since most of these processes operate very slowly, Hutton concluded that our planet must millions and not just a few thousand years old.

Charles Lyell

A geologist that presented the idea that the geological processes we see in action today must be the same ones that shaped Earth millions of years ago. Ancient volcanoes released lava and gases, just as volcanoes do now. Ancient rivers slowly dug channels and carved canyons in the past, just as they do today.

Darwin's Understanding of Geology Led Him to Propose

If the Earth could change over time, life might change as well.

It would have taken many years for life to change the way Lyell suggested.

This would have been possible if the Earth was extremely old.

Jean-Baptiste Lamarck

A French naturalist that proposed a hypothesis about how organisms change over time through use and disuse of structures; suggested that organisms acquire traits through use and then pass them on to offspring

Lamarck's Theory of Evolution (Example)

A male fiddler crab uses its front claw to ward off predators and to attract mates; because the front claw is used repeatedly, it becomes larger; this characteristic (large claw) is passed onto its offspring

Comparing Lamarck's & Darwin's Theory of Evolution

Lamarck suggested that giraffe that stretch to reach food acquire long necks and pass long necks onto their offspring; Darwin suggested that some giraffe were born with short necks while some were born with long necks and those with long necks had a competitive advantage and would survive and pass the trait for long necks to their offspring so over time the trait for long necks would become more common in the population

Thomas Malthus

Studied populations and published a book in which he noted that babies were being born faster than people were dying. The only forces he observed that worked against this growth were war, famine, and disease. He reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone.

Thomas Malthus's Influence on Darwin's Thinking

Darwin read Malthus's work and realized that just like human populations that if all the offspring of almost any species survived for several generations, they would overrun the world; this information was central to Darwin's explanation of evolutionary change and contributed to his idea of survival of the fittest