WHO WAS CHARLES DARWIN AND WHAT DID HE REALLY SAY?

Charles Darwin was one of the most important biologist of the 1800’s and one of the most important biologist of all time. He proposed the theory of evolution by natural selection.

Charles Darwin was born in England in 1828 Charles Darwin was born in England in 1828. This was the Victorian Era when England was exploring the world bringing back scientific knowledge from the farthest reaches of the Earth.

He studied medicine and the ministry .

He met John Henslow, a professor of botany, who took him out on collecting trips in Scotland. These trips sparked his serious interest in science.

Henslow introduced Darwin to the renown geologist Adam Sedgwick Henslow introduced Darwin to the renown geologist Adam Sedgwick. On field trips with Sedgwick Darwin learned about modern geology.

Through the influence of these men and his father, Darwin accepted a position as naturalist aboard the H.M.S. Beagle.

The Beagle was commissioned for a five year voyage around the southern hemisphere

Darwin’s observations included the discovery of fossil mammals different from anything living today.

One of the Beagle’s stops was the Galapagos Islands off the coast of Ecuador.

While studying the organisms on the island, he made some amazing observations.

Although the iguanas on the Galapagos were similar to the iguanas in South America, there were also many differences.

He observed that the giant tortoises were different on each of the islands and theorized it was due to their environment

He noticed finches that were closely related, but had different bill structures depending on their habitat.

Later,Darwin began to think deeply about the observations he had made during the voyage. He consulted other scientists and conducted experiments to support his ideas.

Darwin published a book he had written about his ideas titled “Origin of Species”. (1853)

Darwin began the book by discussing how humans have “selectively bred” the wild rock pigeon into different varieties.

Darwin gives many examples of selective breeding such as broccoli, brussel sprouts, and cauliflower, which have all been selectively bred from wild cabbage.

By selecting certain plants for breeding humans have created many varieties, such as seen in roses.

In only a few thousand years, selective breeding has produced the vast varieties of dogs we have today. The ancestor of all these different breeds is the wolf.

Darwin hypothesized that the same thing happened in nature but over hundreds of thousands of years, such as the evolution of the horse.

Over time, mutations to the horse’s foot decreased the number of toes thus increasing speed. Since this adaptation was an advantage, the faster horse reproduced and past the trait down to its offspring

Natural selection takes place when variations give the organism, such as the checkered moth, a reproductive advantage.

Different variations are better suited for different environments, such as in members of the dog family.

If the new variation increases the ability of an organism to reproduce, then more genes are passed to the next generation

Just like with selective breeding, favorable variations are passed to the next generation resulting in new breeds.

During the billions of years of life on earth, little variations add up to big differences.

Natural selection is the process by which individuals whose genes are better adapted to the environment are more likely to survive and reproduce than other members of the species

Natural selection is the accepted scientific explanation for the evolution of life on earth.

Several Factors affect Natural Selection Over production Competition Variations Selection

Overproduction Most species produce more offspring than can possibly survive.

Competition: Offspring compete with others for limited food and other resources. Only a few will survive long enough to reproduce.

Variations: Differences between members of a species, which are controlled by genes.

Selection: Variations make some individuals better suited to the environment and, therefore, more likely to survive and reproduce. Helpful variations accumulate and unfavorable ones disappear

We see natural selection taking place today because of the chemicals we are adding to the environment.

When a pesticide is first applied, only a few insects survive When a pesticide is first applied, only a few insects survive. These survivors reproduce and on the next application many of the ofsprings of the original survivor survive.

Eventually, all the insects are offsprings of the original survivors and the pesticide has no effect on the entire population.

For Natural selection to take place the organism not only has to be better adapted to the environment, but also has to reproduce, thus passing the trait on to its offspring.

Over a period of time natural selection can lead to evolution.