This is pretty much obvious because we already knew that...

 a) Intestinal flora varies quite a lot between different
    populations
 b) Antibiotics and industrial foods have already made
    parts of our gut flora extinct

But now some researchers have done the difficult legwork of
analyzing the intestinal flora of some genuine, minimal
contact hunter gatherers:


http://news.sciencemag.org/biology/2015/03/ancient-bacteria-found-hunter-gatherer-guts

Personally I've long been a paleo-skeptic... I believe that
a "modern paleo" diet has *some* health benefits and is useful
for weight-loss and to resolve some other specific issues, but
overall probably isn't the *healthiest* diet for modern
humans.  I think humans have cooked food much longer
than most paleo advocates admit, and also that evolution
works much more rapidly than paleo people give it credit for.
And our gut microbiomes evolve along with us (or you could
say that their changes *are* a way of us evolving) and are
part of us, and sad as it may sometimes seem, we can never
go back.

The real hardcore paleo nuts may now dream of getting a
fecal transplant from an Amazonian Indian, but I must warn
you that most Indians would kill you in a heartbeat if you
even suggest that you want to absorb some of their essence
in that way!

Cheers...