The latest contribution suggests that a sweet treat can change the way bumble bees make decisions, producing something akin — although perhaps distantly related — to optimism.

It’s like the way a chocolate bar might affect a human being, in terms of actions, if not subjective feelings.

Just to be clear, the scientists who did the experiment are not saying sugar makes the bees feel happy the way people might after eating something sweet. But a treat can change a bee’s brain state so that it is quicker to pursue a reward and to recover from a scare than it would be without a sugar boost.

Whether bees have some subjective experience of a positive feeling, the way a human might, remains an unanswered question. Some recent research argued that the structure of bee brains could allow for some subjective experience. That could be something as simple as a physical sensation, however, not something as general and elusive as, “I feel good!”

Clint Perry, a research fellow at Queen Mary University of London, who studied the bees with his colleagues, reported the results Thursday in the journal Science.

Other researchers have found something like pessimism in bees, something like anxiety in crayfish, and a defensive state that bears some relation to fear in fruit flies…