Charles
Darwin was
a scientist that lived from 1809-1882.
During his life he created
the most widely accepted explanation for evolution or why animals have
changed over time and why traits are passed on. When Darwin was a
young man he went on a long trip on a boat named "The Beagle" to the Galapagos
Islands where he watched many of the animals and plants. Like any
good scientist, Darwin began to ask questions. He wondered what made
certain animals survive while others died. He also wondered how different
species of animals have similar traits. Eventually, all this questioning
led Darwin to create his theory of Natural Selection.
What
is Natural Selection?
According to Darwin,
in any population, including human, there are certain characteristics that
are passed down. Some characteristics, like the ability to out-run
a predator, or to hide in tall grass, help members of a population to survive.
It would be important for a deer to run very fast if a bear was chasing
it. Those deer that don't run as fast as the others are easier targets
for the bear. So the deer that run fast survive, while those that
don't run as fast become the bear's dinner.
According to Darwin's
principle deer that run fast will have a greater chance for survival and
when they survive, they can pass those fast genes onto their children.
That's how traits are passed on to another generation÷strong traits survive,
weak traits don't.
What was
his Proof?
Darwin saw evidence
of this in his study of the animals on the island. He was most interested
in the finches that he found on Galapagos. The finches were almost
500 miles away from the mainland of South America. Although the finches
that Darwin found on Galapagos were very far away from the finches in South
America, they still had many of the same traits which lead Darwin to believe
that they were the same species. What Darwin found interesting was
that the finches on Galapagos had different characteristics than those
on the mainland. The finches of Galapagos had developed different
bills for feeding on the plants that were found on the island. The
two finches were obviously related, but they were definitely not the same.
This lead Darwin to conclude that the finches on Galapagos had evolved
to have the bills because having the different bills made it easier for
them to find food. Those finches that had the bills that were different
from the bills of the finches on the mainland were more likely to survive
because they could find more food. Because they survived, they passed
their new bills onto their children. Just like the deer that survived
because they ran faster than the bears, the finches with the new bills
found more food and were able to survive.
How
does Natural Selection explain family resemblance?
Natural Selection had
a few holes. How could strong traits get passed on if only one parent
had the strong trait and one had the weak trait? A scientist by the
name of Gregor Mendel took Darwin's ideas and made them work to explain
trait inheritance.
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