Natural Selection Darwin’s Amazing Discovery

Evolution Evolution: Evolution is not just a theory It’s a FACT the process by which different kinds of living organisms have developed and diversified from earlier forms during the history of the earth Evolution is not just a theory It’s a FACT We see it taking place Not in Humans (we live too long) but in other living things that don’t live as long (e.g. bacteria)

Theories of Evolution But what made it happen? People noticed that evolution occurred way back in the 1700s (maybe even before that) But what made it happen?

Lamarck’s Theory In the late 1700s, French naturalist Jean-Baptiste Lamarck came up with the theory he called “Inheritance of Acquired Characteristics”

Lamarck’s Theory This theory stated that characteristics acquired during an organism’s lifespan would be passed on to its children For example, if a giraffe’s ancestor had a short neck but spent its life stretching to reach the leaves on the top branches of trees, it would stretch its neck and pass this trait on to its children As generations progressed the giraffe’s neck would get longer and longer

Lamarck This was a great theory. It explained how animals changed over time. Unfortunately, experimental tests did not support it

Charles Darwin and Natural Selection Charles Darwin was born in 1809, 10 years before the death of Lamarck He proposed a different mechanism for evolution He called his theory “The Theory of Natural Selection”

Natural Selection This theory states: Organisms better adapted to their environment tend to survive and produce more offspring. Darwin spent almost 30 years gathering evidence for this Theory. In 1859 Darwin published A book titled “The Origin of Species” that explained the theory to the general public.

Natural Selection It is based on 4 principles: Different members of a population have different traits These traits are heritable (can be passed on to the next generation) More offspring are produced than the environment can support Those members of the population with heritable traits are more likely to survive and pass their traits on to the next generation

Natural Selection While, like all revolutionary thinkers, Darwin was laughed at and ridiculed, in time, evidence proved that his theory was indeed correct and it is now believed to be the main way that desirable traits are passed down from one generation to the next