Perhaps, more than any other face in biology, you should know and remember this one.

When polled, scientists said that of all the people who contributed to the vast body of scientific knowledge over the past 500 years, it was Darwin who impacted the world the most.

1809-1882

• Evolution is about change. Not a change in individual organisms, but a change in the overall population of organisms.

What is a population?

A group of organisms who can interbreed and produce viable offspring.

What are viable offspring?

Organisms who can survive, and produce offspring of their own.

This ability to produce viable offspring, is indeed what determines your fitness as an individual.

Evolution occurs on two levels:

• Microevolution:

• Macroevolution:

Evolution on a “micro” level, such as allelic frequencies.

Evolution on a larger scale, such as speciation over long periods of geologic time.

Macroevolution describes phylogeny, or evolutionary “relatedness” among groups of species.

Sometimes, however, allelic frequencies are very apparent.

Allelic frequencies for traits may never be noticeable in the phenotype of organisms, because some traits are not phenotypically apparent.

People of science, however, had difficulty explaining the “mechanism” that drove the process…or how it happened. The ideas first published by Charles Darwin in the mid 1800s are the basis of modern evolutionary theory.

Let’s find out about what some of the early “thinkers” thought...

The thought that evolution occurs, or that species change over time, has been around for a long time.

Some of the great early “thinkers” that you should be familiar with are:

• Aristotle: Great Chain

• Steno: Fossils, Superposition

• Linnaeus: Classification

• Hutton: Gradualism; Rock cycle

• Lyell: Uniformitarianism

• Malthus: Survival of the fittest

• Cuvier: Extinctions; Revolutions

Jean-Baptiste Lamarck

(1744-1829)

Lamarck should be noted for being one of the first to advocate early evolutionary theory, in a time when most believed in catastrophism, associated with biblical disasters, and creationism,.

Three Important Ideas:

• Use and Disuse

• Inheritance of Acquired Characteristics

• Natural Transformation

Fluida

Wallace, a contemporary of Darwin, is best known for independently developing a theory of natural selection which made Darwin publish his own more developed and researched theory sooner than intended.

Alfred Wallace 1823-1913

While Wallace is best known for “pushing” Darwin into publication, he is also known for developing the concept of “Aposematism”, (warning coloration) an added feature of evolutionary theory. The warning signal

may take the form of conspicuous colors, sounds, and even odors. Aposematic signals are beneficial for both the predator and prey, who each avoid damage.

Can you think of an organism that uses a “warning odor”?

The modern theory of evolution is a fundamental concept in biology, meaning that almost all other biological concepts build onto this one. As we go through this year, I will ask you to reflect on the following: “Does this content that we are learning now build on the theory of “Evolution through Natural Selection? ”

Darwin’s original theory, that of “Natural Selection” is called “Darwinism”.

Neo-Darwinism is the new theory that attempts to synthesize contemporary evolutionary concepts (microevolution) into Darwinism. 1809-1882

A. In nature, most organisms produce more offspring than can possibly survive.

B. In any population, individuals have variations.

C. Individuals with certain useful variations within their environments, such as speed, survive long enough to pass those variations on to their offspring in the next generation.

D. Over time, offspring with those advantageous variations make up most of the population and may look and act entirely different from their ancestors. Speciation has occurred.

Darwin's voyage, and eventual theory changed the world’s thinking and the course of science.

Darwin’s theory of Natural Selection wasn’t what really bothered most “God-fearing” people.

It was that Darwin had the audacity to implicate that humans were animals, and they shared a very real biological kinship and genealogy with the rest of the biological world. It bothers many still today!Cartoonists of the 19th Century portrayed Darwin as perhaps being more closely related to our primate relatives than is true!

"light will be thrown on the origin of man and his history".