Multiple sequence alignment (in this case DNA sequences) and illustrations of the use of substitution models to make evolutionary inferences. The data in this alignment (in this case a toy example with 18 sites) is converted to a set of site patterns. The site patterns are shown along with the number of times they occur in alignment. These site patterns are used to calculate the likelihood given the substitution model and a phylogenetic tree (in this case an unrooted four-taxon tree). It is also necessary to assume a substitution model to estimate evolutionary distances for pairs of sequences (distances are the number of substitutions that have occurred since sequences had a common ancestor). The evolutionary distance equation (

This hedgehog has no pigmentation due to a mutation.

Darwin's finches by Gould

A timeline demonstrating important dates in molecular paleontology. All of these dates are listed and specifically sourced in the History section under Timeline.

Neanderthal DNA extraction. Working in a clean room, researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, took extensive precautions to avoid contaminating Neanderthal DNA samples - extracted from bones like this one - with DNA from any other source, including modern humans. NHGRI researchers are part of the international team that sequenced the genome of the Neanderthal, Homo neanderthalensis.

Tyrannosaurus Rex Holotype