"Like other biological phenomena, language cannot be fully understood without reference to its evolution, whether proven or hypothesized," wrote Talmy Givón in 2002. As the languages spoken 8,000 years ago were typologically much the same as they are today and as no direct evidence exists for languages before then, evolutionary linguists are at a disadvantage compared to their counterparts in biology. Bernd Heine and Tania Kuteva seek to overcome this obstacle by combining grammaticalization theory, one of the main methods of historical linguistics, with work in animal communication and human evolution.