Most people carry an intact version of TAAR5, and easily recognize the fishy fragrance as mildly repulsive — an ability that might have evolved to help our ancestors avoid spoiled food. But a small number of the Icelanders in the study carried at least one “broken” copy of the gene that appeared to render them insensitive to the scent. When asked to describe it, some even mistook it for a sugary dessert, ketchup or something floral.
“They were really not even in the right ballpark,” Dr. Gísladóttir said.
A blunted sense for bad-smelling fish might sound maladaptive. But TMA doesn’t always spell trouble, especially in Iceland, where fish features prominently on many menus. The country is famous for nose-tickling dishes like rotten shark and fermented skate, which serve up about as much odor as you may imagine.
That might be why the TAAR5 mutation appears in more than 2 percent