Theory of Evolution

Introduction

• Evolution refers to the progressive change of organisms as they descend from ancestral species.
• Important names in the history of theory of evolution are:
  • Jean Baptiste Lamarck
  • Charles Darwin
  • Alfred Russell Wallace
• There are four common mechanisms of evolution.
  1. Natural selection
  2. Genetic drift,
  3. Mutation,
  4. Gene flow

Jean Baptiste Lamarck

• Lamarck developed the fist comprehensive theory of evolution.
• Lamarck, a French Zoologist, proposed that organisms increased in complexity through time because of an innate tendency.
• He proposed that interactions of organisms and environment drove the process of evolution.
• He proposed that patterns of use and disuse drove the evolution of adaptations. 
• His theory states that every organism was continually striving for greater complexity.
• Lamarck’s theory was an important step to the studies on evolution, eventhough it was proved that acquired characters cannot be passed to offspring.

Charles Darwin

• Charles Darwin was born in 1809 – Shrewsbury, England.
• He was graduated in medicine from Cambridge University.
• Darwin used the term “descent with modification” for “evolution.”
• His theory states that all organisms – animals, plants, fungi, all organisms – are descended from a remote common ancestor.
• He stated that all species evolved from earlier species.
• Organisms change in time, usually very slowly, or evolve overtime to become a new species.
• He explained the mechanism of natural selection as members of a species possessing more desirable traits will have more offspring and survive to reproductive maturity.
• Other mechanisms of evolution include genetic drift and mutation, which were discovered after Darwin.
• The famous idiom Survival of The Fittest refers to:
  • Individuals whose characteristics are well suited to their environment survive.
  • Individuals whose characteristics are not well suited to their environment either die or leave fewer offspring or extinct.
• The term artificial selection refres to the intervention of humans ensures that only individuals with the more desirable traits produce offspring.
• He explained his theory in his publication On the Origin of Species - 1859.
• Darwin received several scientific awards in his life time.
• He died in April 1882.

Alfred Russell Wallace

• Alfred Russell Wallace, was naturalist and explorer lived in Europe during the time of Darwin.
• He developed the same theory of evolution by natural selection as Darwin.

Conclusion

• The idea of evolution has remained controversial for a long time.
• Lamarck proposed the fist comprehensive theory of evolution, which was a prelude to Darwin's theory.
• Darwin's theory has had tremendous impact on science, philosophy, and the way humans viewed the world.
• Alfred Russell Wallace was a contemporary of Darwin who also explained the same theory of evolution by Darwin.
• Antibiotic resistance is an evolutionary phenomenon of tremendous clinical significance.

References

1. Dr John van Wyhe, editor. 2002-. The Complete Work of Charles Darwin Online ( http://darwin-online.org.uk/)