A study of mobile phone calls suggests that women call their spouse more than any other person.

That changes as their daughters become old enough to have children, after which they become the most important person in their lives.

The study has been published in the journal Scientific Reports.

It also shows that men call their spouse most often for the first seven years of their relationship. They then shift their focus to other friends.

The results come from an analysis of the texts of mobile phone calls of three million people.

According to the study's co-author, Professor Robin Dunbar of Oxford University, UK, the investigation shows that pair-bonding is much more important to women than men.

"It's the first really strong evidence that romantic relationships are driven by women," he told BBC News.

"It's they who make the decision and once they have made their mind up, they just go for the poor bloke until he keels over and gives in!"

But the data shows that women start to switch the preference of their best friend from about the mid-30s, and by the age of 45 a woman of a generation younger becomes the "new best friend", according to Professor Dunbar.

http://www.bbc.co.uk/news/science-environment-17729478