It's unlikely that the plants go back that far, but they could easily be descendents of the originals. The oldest plants I've heard of were about 50 years old. My neighbor has plants on his property that go back to the mid-1800s when his great-great grandfather was a hop farmer. But, again, I suspect they are descendents.
Most likely the plants didn't get enough nutrients. Hops are heavy feeders. It wouldn't hurt to dig them up, break off chunks about the size of your head and replant. Put 3-4" of composted manure over the bed and plan on a crop next year.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk