Y'all seemed to like the genre of in-universe notices hastily thrown together in a word processor, so here's another one.
While the yinrih's nonsapient ancestors were social, they did not engage in social grooming. Yinrih pups give and receive gestures of physical affection such as kisses (from sires and dams) and tail thumps (from litter mates), but as they mature they begin rejecting these gestures. Deliberate physical contact between adults, including between sires and dams in a childermoot, is vanishingly rare. Of course medical exams are an exception, and there is a gesture similar to an embrace, where one person presses the top of his head against the chest or side of another, that indicates deep gratitude or relief, but we're talking "you literally saved my life" levels of gratitude.
In Futurama, that essentially happened to cats. They came to Earth because their planet was getting hard to live on, they landed in Ancient Egypt and were worshiped into house pets.