from an L. L. Cavalli-Sforza paper, Genes, peoples, and
languages. The correspondence between gene families and language families is
clear. From the paper:

Most patterns found in the analysis of human living populations are likely to be
consequences of demographic expansions, determined by technological
developments affecting food availability, transportation, or military power. During
such expansions, both genes and languages are spread to potentially vast
areas. In principle, this tends to create a correlation between the respective
evolutionary trees. The correlation is usually positive and often remarkably high. It
can be decreased or hidden by phenomena of language replacement and also of
gene replacement, usually partial, due to gene flow.

Genetic variation and languages are both characteristics of individuals &
populations. One might imagine that gene flow between groups might be
modulated by linguistic affinity between groups, or, linguistic affinity between
groups might be modulated by gene flow between the groups. Cavalli-Sforza's
colleague Marcus Feldman has asserted that the correlation does indeed emerge
out of biases in mating patterns more explicitly of late.


Language and genes are passed from parents to offspring. But, there are clearly
differences in terms of the specific constraints on inheritance. When it comes to
genes we have both the Mendelian abstraction as well as DNA as a concrete
substrate. Parent-offspring transmission is symmetrical (from both parents),
subject to mutation, segregation, recombination, etc. Though there are attempts to
model language, to my knowledge there is not such robust theoretical
understanding of the inheritance of language from parents to offspring, in
particular the biological substrate which acquires language

(I do not class the arguments about deep structure in linguistics in the same class as Mendelian and DNA models of genetics).

Of course there is the reality of great differences in transmission of language and genes.

In the domain of language horizontal transmission is critical to understanding its distribution & evolution (I am aware that horizontal gene transfer is
important in biological evolution, but not so much in the scope and species we're talking about). One's parents may peak a different language because language acquisition and fluency is also dependent on peers in a way that genetic variation is not. Additionally, language transmission from parents need not be symmetrical, one may acquire the language of one parent but not the other. One may speak the same language as one's parents, but with a different accent (that one of one's peer group). Interestingly, the exception to this rule of accents are individuals with some socialization dysfunction, such as autism.

There are also similarities between languages and genes. The molecular clock has its analogy in the lexical clock. There is also lexical admixture between languages, for example the heavy load of French-derived terms in modern English, the
influence of Slavic upon the Baltic languages. A new paper in PLoS Biology leans on these last similarities to utilize the Structure framework to flesh out the relationships of the language of New Guinea & Australia, what was once "Sahul" during the last Ice Age.

The author's summary from Explaining the Linguistic Diversity of Sahul Using Population Models:

"About one-fifth of all the world's languages are spoken in present day Australia, New Guinea, and the surrounding islands. This corresponds to the boundaries of the ancient continent of Sahul, which broke up due to rising sea levels about 9000 years before present. The distribution of languages in this region conveys information about its population history. The recent migration of the Austronesian speakers can be traced with precision, but the histories of the Papuan and Australian language speakers are considerably more difficult to reconstruct. The speakers of these languages are
presumably descendants of the first migrations into Sahul, and their languages have been subject to many millennia of dispersal and contact. Due to the antiquity of these language families, there is insufficient lexical evidence to reconstruct
their histories. Instead we use abstract structural features to infer population history, modeling language change as a result of both inheritance and horizontal diffusion. We use a Bayesian phylogenetic clustering method, originally developed for investigating genetic recombination to infer the contribution of different linguistic lineages to the current diversity of languages. The results show the underlying structure of the diversity of these languages, reflecting ancient dispersals, millennia of contact, and probable phylogenetic groups. The analysis identifies 10 ancestral language
populations, some of which can be identified with previously known phylogenetic groups (language families or subgroups), and some of which have not previously been proposed.

From population genetics to linguistics : Gene Expression