Evidence of common descent
Part of the Biology series on
Evolution
Introduction
Mechanisms and processes
Adaptation
Genetic drift
Gene flow
Mutation
Natural selection
Speciation
Research and history
Evidence
Evolutionary history of life
History
Modern synthesis
Social effect
Theory and fact
Objections / Controversy
Evolutionary biology fields
Cladistics
Ecological genetics
Evolutionary development
Human evolution
Molecular evolution
Phylogenetics
Population genetics
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The wide range of evidence of common descent of living
things strongly indicates the occurrence of evolution
and provides a wealth of information on the natural pro-
cesses by which the variety of life on Earth developed.
This evidence supports the modern evolutionary syn-
thesis, which is the scientific theory that explains why
life changes over time.
Fossils are important for estimating when various
lineages developed. As fossilization is an uncommon oc-
currence, usually requiring hard body parts and death
near a site where sediments are being deposited, the
fossil record only provides sparse and intermittent in-
formation about the evolution of life. Evidence of organ-
isms prior to the development of hard body parts such
as shells, bones and teeth is especially scarce, but exists
in the form of ancient microfossils, as well as impres-
sions of various soft-bodied organisms. Evolution with
common descent also provides the best explanation for a
variety of facts concering the geographical distribution
of plants and animals (biogeography), especially island
biogeography.
Comparison of the genetic sequence of organisms
has revealed that organisms that are phylogenetically
close have a higher degree of sequence similarity than
organisms that are phylogenetically distant. Further
evidence for common descent comes from genetic de-
tritus such as pseudogenes, regions of DNA that are or-
thologous to a gene in a related organism, but are no
longer active and appear to be undergoing a steady pro-
cess of degeneration. Since metabolic proce