In a recent review Mark Pagel argues that language is a culturally transmitted replicator (Pagel, 2009).
Pagel starts by offering a useful update on phylogenetic methods and then uses a comparison between genetics and language phylogenetic trees to reveal similarities between cultural and biological evolution. He argues that borrowing and corruption, which could in principle be very important in the case of languages and make phylogenetic reconstruction difficult if not impossible, are, in fact, very limited. Pagel notes: “If languages are not the ‘closed shop’ to outside influences that we have come to expect of eukaryotic organisms with sequestered germ lines, the strength of descent with modification in language trees shows that the cultural processes of language teaching and learning that transmit language from one generation to the next can have a surprisingly high fidelity and can show resistance to outside effects.” To put it briefly, phylogenetic trees show, or so it is claimed, that languages are faithfully reproduced from one generation to the next.
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