Dogs Behave Jealously… in 1871

This chart appeared in “Mental Evolution in Animals” “Mental Evolution in Man”, both published in the 1880s; Romanes depicts the emotional and cognitive development starting with unicellular. On the left, at level 21, Romanes lists “Jealousy. Anger and Play.” On the right side, at level 28 we see “Anthropoid apes and dogs” at the same…