16.2 Ideas That Shaped Darwin's Thinking

Knowing that Earth could change over time helped Darwin believe that life might change as well. Knowing that Earth was very old assured Darwin that there had been enough time for life to change

F: Older

F: slowly

F: THE SAME AS

T

Lamarack proposed that by selective use or nonuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. Over time this process led to change in a species.

Lamarack was one of the first to develop scientific hypothesis about evolution and to realize that organisms change over time.

Lamarack's ideas that evolution occurs and that an organism's trait are linked to its environment are true. His idea that acquired characteristics can be inherited is false. Also, his idea that species have an inborn drive to become more complex and perfect is false.

A giraffe could have acquired a long neck b/c it begun to stretch its neck upward to reach higher and higher on trees looking for leaves to eat. As the giraffe stretched toward leaves on higher branches, its neck would grow a little longer. Giraffes could then pass on their long neck to their offspring who could further lengthen their necks during their lifetime.

Human birth rate was higher than the death rate

If the human population grew unchecked, there wouldn't be enough living space and food for everyone

many more organisms are born than will survive and reproduce

Darwin stated that nature provides the variation among organisms, and humans select and breed for the variations they find useful or appealing

selective breeding

Find pigeons that naturally have larger than normal beaks. Mate the pigeons, then repeat this process over several generations until you achieve the desired beak size

He argued that Earth s many millions of yrs old. Knowing that Earth was very old convinced Darwin that there had been enough time for life to evolve.

He argued that the processes that changed Earth in the past were the same as the processes that are still changing Earth in the present. Knowing that Earth could change over time helped Darwin realize that life might change as well.

He was one of the first scientists to recognize that evolution has occurred and that organisms change to live more successfully in their environment. His general ideas about evolution and adaptation influenced Darwin.

He thought that if the human population continued to grow unchecked, it would run out of living space and food. Darwin realized that this was true of all organisms, not just humans.