Cary Grant stars as Dr. Barnaby Fulton, an absent minded scientist toiling for a chemical company on a formula to reverse the effects of aging. His single minded dedication in this pursuit doesn’t seem to bother his wife Edwina (Ginger Rogers), but Barnaby is concerned the spice has gone out of their marriage.

Barnaby’s devotion to work does have one advantage: being able to ignore the advances of his boss’ secretary, played by starlet Marilyn Monroe. When one of the lab chimps masters the youth formula and mixes it into the water cooler, madcap hijinks ensue, with Barnaby regressing to a 20-year-old, and later a prepubescent teen.

I.A.L. Diamond adapted a story by Harry Segall called The Fountain of Youth, later retitled Darling, I Am Growing Younger and finally Monkey Business after Ben Hecht & Charles Lederer rewrote the script. Directed by Howard Hawks, it was an attempted return to the screwball comedies he mastered in the ’30s.

Hawks had wanted to cast a younger actress opposite Grant to show that he had “turned into a sort of fogey” who was later rejuvenated and remained young at heart. He had Ava Gardner in mind, but Grant resisted that idea and Ginger Rogers was cast instead. Though only 41, she was the oldest leading lady Hawks had ever directed and he was reportedly not happy about it.

The original script called for only Grant’s character to take the youth formula, but Rogers wanted her character to take part in the fun too. Hawks caved in and later complained that this ruined the film’s concept. ” I thought it was lousy and made her play badly throughout the picture.”

Monkey Business has its admirers, but there’s so much in the movie that plays bad that it’s impossible to blame to Ginger Rogers, who is all right. The jig she dances is one of the few pleasures in the movie. The rapid fire, sophisticated and wickedly funny dialogue that was a staple of films like Twentieth Century or His Girl Friday is missing in action here.

The great screwball comedies were driven by characters who were quick witted and highly intelligent and usually ahead of the audience. By regressing his cast in age, Hawks dumbs everything down: chimps running amok, an out of control car, or Grant dressing like an Injun and giving his wife’s admirer (Hugh Marlowe) a mohawk. Everything is overplayed, a failing common to body switch movies, where actors play kids by acting wild and crazy.

The film is more renowned for featuring Marilyn Monroe. This was before The Seven Year Itch made Monroe the female sex symbol of the 20^th century, but all the signs are here. She’s given nothing special to do in the script, but literally jumps off the screen and just has “it”. The actress has amazing screen presence and easily holds her own with Cary Grant. As Monroe would demonstrate when she had a good director, she was a gifted comic temptress.

Though hard to believe, Monroe’s legs only appeared on screen twice in her career: the iconic subway grating scene in The Seven Year Itch and here, where she models the indestructible pantyhose that Grant’s character has designed. Marilyn fans should enjoy that, otherwise, this is one of Hawks’ weakest efforts.