Table 2.

Some parallels between biological and linguistic evolution

Biological evolution	Language evolution
Discrete heritable units (for example, nucleotides, amino acids and genes)	Discrete heritable units (for example, words, phonemes and syntax)
DNA copying	Teaching, learning and imitation
Mutation (for example, many mechanisms yielding genetic alterations)	Innovation (for example, formant variation, mistakes, sound changes, and introduced sounds and words)
Homology	Cognates
Natural selection	Social selection and trends
Drift	Drift
Speciation	Language or cultural splitting
Concerted evolution	Regular sound change
Horizontal gene transfer	Borrowing
Hybridization (for example, horse with zebra and wheat with strawberry)	Language Creoles (for example, Surinamese)
Geographic clines	Dialects and dialect chains
Fossils	Ancient texts
Extinction	Language death