One of the traditional (note I did not say "true", just "traditional") criteria for demarcating humans from animals has been the assertion that animals act only out of instinct, while humans can decide to act out of other than pure instinct, and can transmit that kind of action to other humans, through teaching. In that way, certain practices become cultural.
A troupe of macaques in Koshima, Japan gave that assertion the lie when researchers watched one monkey take her sweet potatoes down to the ocean for washing. Other monkeys observed her, and began doing the same, finally transmitting this "cultural" behavior across generations. In my home, there is a similar phenomenon. Somewhere along the line, many years ago, my cat Momo began tapping or poking my hand when she wanted to be petted.
Momo is long gone now, but all the cats who knew Momo do the same--and even some who never knew Momo. I'll be lying on my side, and Cleo will come up behind me. Poke, poke, poke--non-stop, until I roll over and pet her. And if I stop before she's sated, she'll start poking again. Same with Bear and Diana (except they give up more easily than Cleo does). Only they understand the concept of "Soft paws, please!" (no claws) better than my little semi-feral rescue Cleo.
It's not as if it's the most profoundly abstract connection any animal ever made--they're simply demo'ing the behavior they want carried out. So it could possibly be a simple case of independent invention--but in 100% of the post-Momo cats up until now? It seems unlikely, though I have no idea how I'd figure out the p-value for that one.
Iain recently brought home a new cat, Andy, who is settling in just fine. I hypothesize that within a year of watching them poke or tap me to get a pet, he will be doing the same--they will have taught him what passes for culture in our little cat society.