BBC-LifeOfMammals/1.3_PlantPredators/#38:20 Bison 40:10 Bighorn Sheep 43:10 Topi fight
play: purposeless: not involved in survival/reproduction
play_bighorn: bighorn sheep who stayed close to their mothers play less often
play_brain Friedrich Froebel Kindergarten - building blocks self-directed activity, tactile/kinesthetic learning style.
Nova Family walks on all fours: reduced cerebellum
rat_dopamine: rats that played b4 are more likely to cross tube to find play partner;
dopamine (also hormone) cannot cross blood-brain barrier; L-DOPA precursor treat Parkinson.
raven.shtml: Tenebrio: Mealworm Beetle; Raja erinacea: Little skate (ray); Busycon: sea snail; Papilio: swallowtail
OMIT play_association: no correlation between play and phylogeny or sociality

1=D? 2=C  3=E  4=B  5=C
6=E  7=D  8=E  9=A  10=E

0. Muroidea superfamily of rodents: hamsters, gerbils, mice, rats.