Why
did the chicken cross the road?
It
was the next step after coming down from the trees.
Evolution
Fifth Year biology students are currently studying one of
the most interesting-and indeed one of the most controversial topics in
Science- The Theory of Evolution.
The Theory of Evolution is most associated with the
famous English scientist Charles Darwin, who described it in his famous book of
1859: “On The Origin of Species”
You can read about Darwin’s life and discoveries here:
The theory states that there is a large genetic variation
within every population of organisms. Population size stays constant as the
organisms produce many offspring.
This then means that there is a lot of competition between the organisms for
resources within their environment. Only the organisms best equipped to get
these resources will survive in the long run...this is known famously as “Survival of the Fittest”
The better adapted organisms...e.g. the strongest and
fittest animals will survive longer then, as they will secure more and better
resources. The theory of Evolution states that these organisms or animals will
outbreed the weaker organisms in the population. Therefore, they will produce
more offspring who will share their parents’ stronger genetic makeup and
characteristics. This means then that each new generation of organisms will
become better adapted to their surrounding environment. This is also often
referred to as the principle of “Natural
Selection”
Darwin developed his ideas on Evolution after travelling
around different parts of the world. On a voyage to the continent of South
America, his observations led him to the hypothesis or theory that species
change slowly over time or Evolve-
to be better suited to their surroundings or Environment.
While travelling through the South American Grasslands or
‘Pampas’ he noticed a species of hare- (The Patagonian Hare) which was far
better suited to its environment than the rabbit. He concluded that over time
the Patagonian Hare had evolved differently to make better use of the resources
such as the plants it ate for nutrition in its environment. (Indeed, the native
Irish Hare is slightly different to Hares found elsewhere in Europe.)
Darwin believed further proof of his theory was to be
found on the Galapagos Islands of the coast of South America. He noticed that
tortoise species had long or short necks depending on how high the vegetation
was on each of the islands. On islands where the plants the tortoise ate had
high branches or stems, the tortoises had long necks, whereas the opposite applied
on islands where the plants were not as tall; here the tortoises had smaller
necks. An Adaption is a trait or
characteristic that helps organisms (plants and animals) become more suited to
their environments. Fitness is how
successful an organism can keep reproducing.
The Theory of Evolution argues that Variations can exist within a species’ population. Some individuals
within the species are better adapted so they can survive and reproduce. Extinctions occur when previous
adaptions are no longer suitable for the species to survive in their environment. Can you think of any
species or organisms that have become extinct?
Darwin examined other species, such as a bird called the
Finch. Check the link below to read an article on how scientists who
re-examined the Finch again recently explain why they can see new examples of evolution.
Darwin’s Theory was hugely controversial when he published
it. Many people took Bible accounts of creation very literally, and thought his
work was scandalous at the time.
When Darwin first told one of his friends about the idea
he was working on he said it was like ‘confessing a murder’!
This was because many people were extremely angry with
him because they believed that god had created all species of plants and
animals and that they always stayed the same.
Darwin’s ideas also meant that
human beings were not special creatures; they had evolved too just like every
other animal had. Darwin concluded in 1871 in another book “The Descent of Man”
that humans had evolved from the Ape; this really annoyed and upset many
people.
Read about reaction to his theories by clicking on the
links below:
Darwin went on to win many awards and prizes for his work.
His ideas are central to modern biology and science. Even though there are people
who still dislike his theories, it cannot be denied that he is still considered
to be one of the most important scientists of our times.
Play the Evolution game here and see if you can help a
species survive by adapting to their environment!
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