<P> More recently -- in 2012 -- anthropologists Charles Perreault and Sarah Mathew used phonemic diversity to suggest a date consistent with this . `` Phonemic diversity '' denotes the number of perceptually distinct units of sound -- consonants , vowels and tones -- in a language . The current worldwide pattern of phonemic diversity potentially contains the statistical signal of the expansion of modern Homo sapiens out of Africa , beginning around 60 - 70 thousand years ago . Some scholars argue that phonemic diversity evolves slowly and can be used as a clock to calculate how long the oldest African languages would have to have been around in order to accumulate the number of phonemes they possess today . As human populations left Africa and expanded into the rest of the world , they underwent a series of bottlenecks -- points at which only a very small population survived to colonise a new continent or region . Allegedly such population crash led to a corresponding reduction in genetic , phenotypic and phonemic diversity . African languages today have some of the largest phonemic inventories in the world , while the smallest inventories are found in South America and Oceania , some of the last regions of the globe to be colonized . For example , Rotokas , a language of New Guinea , and Pirahã , spoken in South America , both have just 11 phonemes , while ! Xun , a language spoken in Southern Africa has 141 phonemes . The authors use a natural experiment -- the colonization of mainland Southeast Asia on the one hand , the long - isolated Andaman Islands on the other -- to estimate the rate at which phonemic diversity increases through time . Using this rate , they estimate that the world 's languages date back to the Middle Stone Age in Africa , sometime between 350 thousand and 150 thousand years ago . This corresponds to the speciation event which gave rise to Homo sapiens . </P>
when do most specialists conclude that language as we know it appeared
between 350 thousand and 150 thousand years ago