An interesting, albeit controversial Science magazine article by Quentin Atkinson, a researcher of the University of Auckland in New Zealand asserted that moderm human languages originated from Southern Africa. And by studying the phonemes (the smallest and barest sound component of languages) of 504 languages throughout the world, and applying statistical method in identifying patterns, Dr. Atkinson concluded that the farther humans move from South Africa, the lesser phonemes there are on the languages.
Dr. Atkinson's surmised, "This result, which is not explained by more recent demographic history, local language diversity, or statistical non-independence within language families, points to parallel mechanisms shaping genetic and linguistic diversity and supports an African origin of modern human languages." Thus, it follows the same pattern as genetic diversity which implies language is at least 50,000 years old, relative to the migration of modern humans from Africa.
The New York Times further states, "The finding fits well with the evidence from fossil skulls and DNA that modern humans originated in Africa" and added, "that languages increases with the number of people who speak it. This gave him the idea that phoneme diversity would increase as a population grew, but would fall again when a small group split off and migrated away from the parent group". So as the modern humans move from Africa, language diversity follow suit.
This study of Dr. Atkinson's instigated another source of debate. Many linguists are doubtful, especially to what it insinuates - that human languages arose only once, though can't be proven because the evolution of languages is so fast, making it considerably difficult to retrace.
Whether or not the claims of Dr. Atkinson is correct, the possible benefit of mathematical methodology in understanding language evolution should not be undermined.