Chapter 24 — Chapter 24 — Evolution

Creationism (theory of intelligent design): all organisms were created as they exist today, individually, without change. Spontaneous generation (life from non-living matter) was disproved by experiments, which however could not negate creationism. Evolution is the gradual change in the genetic makeup (allele frequencies) of a population over successive generations, which may lead to new species. Early speculations: the universe and organisms did not always exist in present form; organisms were not created at once; they result from innumerable changes from lower to higher forms. Evolution occurs due to variations and natural selection: organisms with beneficial traits are selected to produce the next generation, those with disadvantageous traits cannot, so the percentage of individuals with better traits increases.