Spoken languages retain evidence of their origins
over thousands of years (see Box 1.1). The discipline of
historical linguistics seeks to trace the ancestry of all
~6500 languages currently spoken in the world. Many
of these languages can be traced to a number of
ancestral languages known as proto-languages. For
example, English, French, German, Russian and
Sanskrit all belong to the Indo-European language
family and share a common ancestral language known
as proto-Indo-European. Although the origins of
spoken languages can be traced back further than
historical records, a common ancestry for all human
languages cannot be identified, and some historical
linguists have suggested that languages do not retain
evidence of their origins over more than ~6000 years.
T