This behavioral trait has its origin in the evolutionary process and has been handed down for countless generations. The habit goes back to the ancient time when dogs were wild and lived in grasslands. To get a comfortable bed in such habitat, they had to turn round and round a few times so as to level the grass. Since those days, some of the species of dogs have been domesticated.
Today, these dogs sleep on a mat or the floor, but the old habit, possibly hardwired in their brain, still persists. Like their ancestors, they go round and round even though there is no longer any need to do so.
You might also like: