I think for humans (in the context of being crammed into an overbooked airplane) it just means a last grasp at personal space.
I used to commute to work by train and the train was set up with three seats in a row. My stop was early on the line and train was usually pretty empty when I would get on so choosing a seat was never a problem. I'm a bigger guy and, everyday, me and another bigger guy would sit next to each other in the same row. Sure, the middle seat was available but, more often than not, the seat remained empty. And you people think successful strategy only applies to planning a day at Disney