The albino Rattus norvegicus used in laboratories (photo above by Sarah Fleming) goes back to the Wistar Institute in Philadelphia. Physiologist Henry H. Donaldson took four pairs of albino rat with him when he joined the Institute in 1906, and work there by Donaldson, Helen Dean King, and others resulted in the development of a standardised “Wistar rat.”

In his 480-page tome The Rat: Data and reference tables for the albino rat (Mus norvegius albinus) and the Norway rat (Mus norvegius) of 1915 (revised in 1924), Donaldson notes: “In enumerating the qualifications of the rat as a laboratory animal, and in pointing out some of its similarities to man, it is not intended to convey the notion that the rat is a bewitched prince or that man is an overgrown rat, but merely to emphasize the accepted view that the similarities between mammals having the same food habits tend to be close, and that in some instances at least, by the use of equivalent ages, the results obtained with one form can be very precisely transferred to the other.”

What Donaldson means by the latter point is: “If the life span of three years in the rat is taken as equivalent to 90 years in man, it is found that the growth changes in the nervous system occur within the same fraction of the life span (i.e., at the equivalent ages) in the two forms.”

Since Rattus norvegicus has adapted to live with people (e.g. in tunnels under our cities), it makes for a perfect laboratory animal. Running rats through mazes of varying kinds has become an established way of studying learning, as in this video from the San Diego News Network: