About 40,000 years ago, bacteria in the stomachs of Japanese
people evolved to digest nori, the seaweed that's used to wrap
maki rolls. But the average person from North America doesn't
carry this version of the microbe. Some people will do a lot for
sushi. But at least one bacterium appears to have actually
altered its genetic code in order to feast on an ancient version
of the maki roll, scientists report in the journal Nature. The
bacterium, Bacteroides plebeius, lives in the human gut, along
with trillions of other microbes. And like many gut bacteria it
has acquired genetic sequences that allow it to produce lots of
different digestive enzymes. But B. plebeius apparently did not
have an enzyme capable of digesting seaweed 40,000 years ago,
when people first began to arrive in the Japanese archipelago,
says Jan-Hendrik Hehemann, the paper's lead author and a
researcher at the University of Victoria in British Columbia,
Canada. There was no need, because it appears "their continental
ancestors ate only hig