Women are predisposed by their genetics to have affairs as "back-up plans'" if their relationships fail, according to a research paper.

Scientists at the University of Texas say they are challenging the assumption that humans have evolved to have monogamous relationships.

The team's research has put forward the "mate-switching-hypothesis" which says humans have evolved to keep testing their relationships and looking for better long-term options.

The senior author of the research, Dr David Buss, told the Sunday Times: "Lifelong monogamy does not characterise the primary mating patterns of humans.

"Breaking up with one partner and mating with another may more accurately characterise the common, perhaps the primary, mating strategy of humans."

For our distant ancestors – when disease, poor diet and minimal healthcare meant that few people lived past 30 - looking for a more suitable partner was necessary, researchers assert.

Despite anecdotal claims about cheatng, no study has shown that humans are predisposed to monogamy or non-monogamy.