Well, it sounds like one to me, at any rate:
Dead guts spill history of extinct microbesExtinct microbes in fecal samples from archaeological sites across the world resemble those found in present-day rural African communities more than they resemble the microbes found in the gut of cosmopolitan US adults, according to research published December 12 in the open access journal PLOS ONE by Cecil Lewis and colleagues from the University of Oklahoma. ...
Aside: is everyone here taking the RSS feed for Eurekalert Archaeology? If not, you should be. :-)
Anyway, it would seem to follow, if you turn that the other way round, that the gut microbiome of a typical "present-day rural African communit[y]" is more like those actually extinct microbes from the remote past than it is like that of modern Americans. That seems huge to me. The time-depth seems not to matter so much here. Whether you lived 8,000 years ago or are alive today matter little. It's the mode of life that counts. In the broad historical sweep, modern Westerners are outliers.
It retrospect that's perhaps not surprising. How many people could have predicted that in advance is another matter. And to actually have confirmation is yet another.
I'm not looking at the data here; I'm reading someone else's summary of data that probably only means anything to specialists. But that seems to be the takeaway we're offered.
Link to the full article (which I haven't had a chance to look at yet):
PLOS ONE: Insights from Characterizing Extinct Human Gut Microbiomes