Tracing Human Migration Through Dental Bacteria,


The team. . .discovered that Streptoccocus mutans, a bacterium associated with dental caries, has evolved along with its human hosts in a clear line that can be traced back to a single common ancestor who lived in Africa between 100,000 and 200,000 years ago. . .

In his analysis of the bacterium, Caufield used DNA fingerprints and other biomarkers that scientists have also employed to trace human evolution back to a single common African ancestor, known as “ancestral Eve.”

“As humans migrated around the world and evolved into the different races and ethnicities we know today,” Caufield said, “this oral bacterium evolved with them in a simultaneous process called coevolution.”

“By tracing the DNA lineages of these strains,” Caufield said, “We have constructed an evolutionary family tree with its roots in Africa and its main branch extending to Asia. A second branch, extending from Asia back to Europe, traces the migration of a small group of Asians who founded at least one group of modern-day Caucasians.”