182. Charles Darwin
"the theory of evolution by natural selection".
It was Darwin who first understood how it was that plants and animals evolved over time
to produce new and different species.
At first, this theory faced much opposition,
but since that time it has been supported by evidence from many areas of science.
Darwin was born in a small town in England in 1809.
When he was a young man, he went to university,
first to study medicine, and later to study religion.
However, Darwin found his schoolwork to be very boring.
Instead, he preferred outdoor activities and was very interested in nature.
While Darwin was at university,
the British navy was planning to send one of its ships, called the Beagle, on a voyage of exploration.
As part of this voyage, the ship would need a naturalist,
who could study the various plants and animals that might be found.
Darwin was recommended for this job by one of his professors, who had been impressed by Darwin.
Darwin was chosen as the naturalist of the Beagle,
and the ship left England in 1831.
The ship's voyage took Darwin around the world,
and he observed many species of plants and animals on his trip.
In one place near South America, known as the Galapagos Islands,
Darwin observed many unusual species of birds.
Several of these birds seemed closely related to each other, but they differed in interesting ways.
For example, some birds had long beaks that could reach insects hidden in the bark of trees,
but other birds had thick beaks that could break open the shells of nuts.
What Darwin realized was that certain characteristics could help an animal or a plant to survive and reproduce.
Individuals that lacked those characteristics would become more likely to die without reproducing.
Over many generations, the useful characteristics would then become more and more common,
as the surviving individuals passed the characteristics on to their offspring.
Eventually, after many generations,
the changes would be so great that a new species would exist.
In this way, a single species could divide into two or more new ones.
This was called the "process of evolution by natural selection".
When Darwin returned to England, he studied plants and animals in more detail.
After much research, he began writing a book about his theory of evolution by natural selection.
When the book, The Origin of Species, was published in 1859,
it was very popular and very controversial.
During the next twenty years, Darwin continued his scientific research,
and he wrote several more books.
By the time of his death, in 1882,
many biologists had realized that Darwin had made one of the most important scientific discoveries of all time.
For the first time, scientists could understand the origin of the many different species of plants and animals.