Why do we fall in love? This universal feeling of attraction has posed one of the most baffling queries for scientists, who have struggled long to determine the biological purpose of love and why exactly we fall for one and other.

Now, a new study published in the journal Frontiers in Psychology, conducted by an international team from Poland, Germany and Russia, says that it has found evidence that humans fall in love based on an evolutionary response.

Earlier studies on love looked for answers in the genetic or neurological realms. 

Areas of study were shoehorned into studying the influence of these two factors on love in humans. But, the new research presents the first evidence that love influences reproductive success, as measured by the number of children people have.

The research was conducted on the Hadza people of Tanzania. They were selected as a control group because of their pristine, influence free relationships. They stay away from things that could influence the way we perceive love like in the civilized world. Factors such as contraception in the modern world disrupted the parameters for the study, which was the birth of children and the role reproduction plays in love.

The result showed that monogamous commitment to a partner in the case of both men and women was associated directly with the number of children they had. The research “may shed new light on the meaning of love in humans’ evolutionary past,” the authors wrote in the study.

That’s why the research team, led by Dr Piotr Sorokowski at the University of Wroclaw, Poland, chose to study the Hadzas. They reasoned that the Hadza lifestyle is more comparable to that of our prehistoric ancestors and could give us a better gauge of what love really is and what purpose it serves.

To gauge the love felt by married individuals who participated in the study, the researchers used a method called the triangular love scale. It is based on three components that scientifically help measure the depth of a person's love. They are intimacy, passion and commitment.

The team collected the response from each participant. They scored them on these three components only. Scientists compared these scores with the number of children born in their current marriages.

“We found that commitment and reproductive success were positively and consistently related in both sexes,” the scientists wrote in the study.

The study revealed a positive association between passion and reproductive success in women. This meant that reproduction success is influenced by the depth of the love one feels of their partner.

A negative correlation between intimacy and number of children was witnessed too. The dip was a result of a dip in intimacy between partners when there are lots of children around.

This would mean that “selection promoted love in human evolution,” the team said. Love was found to be a powerful motivator to reproduce in both men and women.