Before technology was available to show otherwise, the thought that Earth's natural surroundings changed was unimaginable and life forms were thought to be immutable (unchanged and unchanging)
By the 19th century, there was sufficient evidence that Earth was very old (billions of years) and that life forms on Earth had undergone and continued to undergo changes
Mutations
Changes in genetic information, the original sources of genetic variation
Types of mutations
Neutral
Harmful
Beneficial
Neutral mutations
Provide no benefit or harm to the individual
Harmful mutations
Reduce the reproductive success of an organism
Harmful mutations
Cystic Fibrosis
Huntington's Disease
Beneficial mutations
Produce a change in an individual's phenotype that gives the individual an advantage
Beneficial mutations
The sickle cell allele gives carriers a high degree of resistance to malaria
Changes as a result of human manipulation
Artificial selection
Directed breeding in which individuals that exhibit a particular trait are chosen as parents of the next generation, used to produce new breeds or varieties of plants/animals
Limitations of artificial selection
Breeders cannot create traits that do not already exist in some form within the population
If mutations arise, then breeders have new material to work with
In the past, Evolution was not accepted within the Catholic religion
With newer Popes, evolution has become accepted because they recognize that the Book of Genesis, and creation of all life in 7 days had to happen gradually over time
