An interesting little read - Back in 2007, an NYU College of Dentistry research team mapped the migration of early humans by using tooth decay as a biomarker. The team collected over 600 samples of Streptococcus mutans (on six continents over the course of two decades). Streptococcus mutans is a common oral bacterium and significant contributor to tooth decay. By studying the DNA lineage of the bacterium strains, they were able to trace human evolution from a common African ancestor that existed over a hundred thousand years ago ("ancestral Eve"). From there, the team was able to create a family tree that extended, first, from Africa to Asia, then Asia to Europe. As humans migrated and evolved, so did the Streptococcus mutans.
It's fascinating how modern science can use a single-cell bacterium to trace the evolution of man. However, confirmation that Streptococcus is with us for the long haul - adapting as we adapt - is disheartening.
