animal experiment 1 animal model 1 article 1 artificial selection 1 avoidance behavior 1 basal metabolic rate 1 brain size 1 cognition 1 controlled study 1 encephalization 1 experimental evolution experimental mouse 1 gastrointestinal tract 1 human 1 long term potentiation 1 male 1 mouse 1 nerve cell plasticity 1 nonhuman 1 reward 1 trade-offs 1