  The similarity of the evolution of human languages (or alphabets, bird songs,
>...) to biological evolution of species is utilized to study with up to $10^9$
people the rise and fall of languages either by macroscopic differential
equations similar to biological Lotka-Volterra equation, or by microscopic
Monte Carlo simulations of bit-strings incorporating the birth, maturity, and
death of every individual. For our bit-string model, depending on parameters
either one language comprises the majority of speakers (dominance), or the
population splits into many languages having in order of magnitude the same
number of speakers (fragmentation); in the latter case the size distribution is
log-normal, with upward deviations for small sizes, just as in reality for
human languages. On a lattice two different dominating languages can coexist in
neighbouring regions, without being favoured or disfavoured by different
status. We deal with modifications and competition for existing languages, not
with the evolution or learning of one language.
