From an historical perspective, I totally agree. Decades ago, when scientists settled on the mouse model, I don't believe that there was much (if any) solid evi

From an historical perspective, I totally agree. Decades ago, when scientists settled on the mouse model, I don't believe that there was much (if any) solid evidence about evolutionary relatedness. As you say, mice were used because they were the least-expensive mammalian option. Even so, it's arguable that predictive success for the mouse model helped drive its widespread adoption. Even so, just about all small mammals (e.g., rodents, shrews and moles) are more closely related to primates than large mammals. So maybe it was inevitable. > ... getting rarer ... Funny story. I was a grad student in the late 70s. And there was an animal-rights riot on campus. The primate lab was besieged. And some of us, whose thesis research depended on our building's mouse colony, were totally freaked.