I read this story in the 1980s, but it may have been written prior to that. It was part of a collection of stories by the same author. In this story, a woman experiments with changing animals from one species to another, instantly. Her husband comes home after a long mission--the wife resents he is often gone for long periods. But just about the time they start to get along again, he is off on another mission. This time he goes to a distant planet where there is something called "the cliff" (I think). It forces him to crawl along towards it and turns out to be intelligent. Once his mission is complete, he returns home. At the very end, his wife pushes him off a cliff and into the sea below where he turns into a seal.
There was a another story in the same collection about a museum in which holographic images of people talked to each other. But they were slowly going more and more out of sync, as if their batteries were wearing down at not quite the same rate. The person seeing this had also observed that humans voices were becoming quieter and quieter, and speculated that we were all just holograms that were wearing down.