Evolution

Evolution refers to biological change. Biological evolution involves change in the genetic constitution of populations over time such that complexity is achieved due to the formation of new genes or gene-encoded functions rather than harmful mutations. These changes are passed on from parents to their offspring, but biological evolution does not involve individual organisms. Individuals develop, but they do not evolve. The study of evolution encompasses two major facets: deducing the history of descent among living things (phylogenetic systematics), and investigating evolutionary mechanisms as revealed by laboratory and field studies of living organisms and their fossilized remains. Evolutionary change occurs as a result of beneficial mutation, migration, genetic drift and natural selection, and it is ultimately a passive process, devoid of any purpose or goal. As a scientific theory, it is an interconnected series of hypotheses, corroborated by a large body of evidence. Thus, biologists accept the historical reality of evolution, even though many details that are unclear continue to be investigated.