Cameron Diaz has said it is not natural to be monogamous.
The Hollywood star, 41, who has never tied the knot, plays a single woman shocked to discover her boyfriend is married in the new film The Other Woman.
She told InStyle magazine: "A lot of people chase after it because they've been told, 'This equals happiness.' They chase it, they get it, and they find out, 'Why did I think this was going to make me happy? I'm miserable!'
"I don't know if anyone is really naturally monogamous. We all have the same instincts as animals.
"But we live in a society where it's been ingrained in us to do these things."
According to E! News, the star told the May issue of the mag that she had a good relationship with her exes, who include Justin Timberlake and Alex Rodriguez.
"I'm grateful for all of it - whether it was something quick and passing or something that lingered too long. There is not one thing I've been through that hasn't been a lesson that led me to this moment, and I can't believe how great life keeps getting."
Cameron, who has embraced getting older, said: "I'd love to go to space - it really is the next frontier."