'Ron said if we bred rats from the rats that survived in pit, you know, the ones that dodged the dogs, well, we'd end up with bigger, better rats, see?'

In order to demonstrate that behavior had little effect on the genetically selectively bred rats, and lessen the chance of error when making his conclusions, Tryon cross-fostered the rats-that is, he had a "dull" mother raise "bright" children, and vice versa.

It won't breed big plants any more than a rat with his tail chopped off will breed tailless rats.

You can't breed rats to monkeys, Lark.

They can be handled easily, readily accept captive bred mice and rats for food, but are shy captives and do best when left alone.

Additionally, there are concerns as to whether or not breeding hairless and tailless rats is ethical.

They bred flies and rats by the million.

They've been breeding rats for the rat pit!

I mean, stealin' stuff and blaming it on the rats, yes, and breeding big tough rats for the rat pits and bringing back the ones that survive so we can breed even bigger rats, yes, but.

Belyaev and his successors also selectively bred wild rats for tameness, with similar results.