Since the ’90s, couples have turned to the theory of the five “love languages” to help navigate relationship pitfalls. But a new scientific paper suggests that the science behind the idea is shaky.Read more:If you’ve ever tried to improve communication in a relationship, you may have come across the concept of the five “love languages” — different ways of showing and receiving affection that have helped couples understand each other for decades. The theory comes from a Baptist pastor turned relationship counselor named Gary Chapman, whose 1992 book “The 5 Love Languages: The Secret to Love that Lasts” has been on and off the bestseller list for years.Now, a group of researchers at the University of Toronto and York University have set out to investigate the scientific underpinnings of the love languages — or lack thereof. They reviewed the theory, and came up with some relationship advice of their own. Richard Sima, who writes the Brain Matters column for The Washington Post, reports on their findings.Today’s show was produced by Emma Talkoff. It was mixed by Sean Carter. It was edited by Ariel Plotnick, Lucy Perkins, and Maggie Penman. Subscribe to The Washington Post here.