BALTIMORE (AP) _ As Valentine's Day draws nigh, the treacle begins to flow. Can anybody explain why lovers call each other ''sweetheart'' or ''sugar pie'' or ''honeybun'' or other sweet nothings?

Why not ''picklepuss'' or ''liverlips?''

Anthropologist Sidney Mintz of The Johns Hopkins University has some theories on why humans evoke the imagery of sweetness to express affection.

Possibly, our fondness for sweet talk can be traced genetically to our primate ancestors, who discovered the delights of juicy jungle fruits as they swung from tree to tree, he says.

Perhaps it is associated somehow with the infant's innate love for the sweetness of mother's milk, he says. In America, it might even be reinforced by the high sugar intake in our fast-food, candy-nibbling culture.

While lecturing in Paris on the link between sweetness and sensuality, Mintz says, ''it struck me as curious that all the words we use to describe love and warmth and good feelings are derived from the sweetness end of the spectrum of taste, not the sour, bitter, salty or hot.''

''Even the word 'sweet' has its root in the ancient Indo-European word for 'persuade,' so when we sweet-talk somebody, that's what it really is,'' he said.

Sweetness is associated with the language of love in the Bible and the Kama Sutra. Chaucer wrote of ''my sweet cinnamon.'' The clown in Shakespeare's ''As You Like It'' declares that ''honesty coupled to beauty is to have honey a sauce to sugar.''

And today, goodness is seen in the car engine that ''runs sweetly'' and or the triumphs of Walter ''Sweetness'' Payton, the great Chicago Bears running back.

''The candy associated with Valentine's Day brings together love and sweetness in a very striking way,'' says Mintz, who has written a book titled ''Sweetness and Power'' describing the role that sugar has played in modern history.

Sweets have an erotic nature that's undeniable, he says.

''What tends to be forgotten about sugar is its intensity, an intensity that our bodies are immediately aware of,'' Mintz says. ''What do you experience with your first mouthful of a hot fudge sundae? It's not surprising that we carry it over to describe the intensity of love and sex.''

The scrapbooks that Mintz keeps in his office document the bizarre twists that sugar-fueled passion can take.

There is a picture of Etienne Tholoniat, a master French baker, who created a lifelike female nude out of white chocolate with spun-sugar hair, lying on a bed of 600 sugar roses.

A clipping tells the story of a 30-year-old woman in Santa Cruz, Calif., who covered her body with a chocolate glaze and, posing as a chocolate Easter bunny, went ''hippity hoppity'' across the front yard of a neighbor who had spurned her affections, according to police. The neighbor called the cops, who took her into custody after what was described as a ''sticky altercation.''

Mintz, 67, says he's been happily married for 25 years to ''a beautiful, brilliant woman'' named Jackie. They met on the campus of Yale University, where he was teaching and she was a young graduate student.

He's called her ''sweetie pie'' ever since.