Falling in love is one of life's great mysteries, but now scientists believe this strange feeling could be key to our evolutionary success.

For the first time researchers have found evidence 'selection promoted love in human evolution' as it increased the chances of us having families.

Scientists studied the Hadza people of Tanzania, who don't use modern contraception, and found passionate partnerships were associated with having more children.

It follows previous research that found love may have evolved to stop male primates from killing their infants.

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Scientists have found the first evidence human love is related to reproductive success, therefore providing us with an evolutionary advantage (stock image)

LOVE STOPS MALE PRIMATES KILLING THEIR INFANTS This new study follows research from University College London in 2013 that showed infanticide in primates has consistently preceded monogamy. This is for the simple reason that when a male primate cares for his children he is less likely to kill them and love is an important emotion in driving this instinct. In species where males and females bonded strongly, the chance of their offspring surviving was much higher as the males had to help with parenting. As a result, monogamy was an evolutionary advantage. Robin Dunbar of the University of Oxford suggests this could have resulted in changes in the brain in order to keep the pair-bond together. This results in preference for your partner and rivalry with others which helped early human societies grow. This extra male care may have meant our brains started to expand as did our ability to care and cooperate with one another, therefore giving us an even greater capacity to love. Advertisement

In modern societies, factors such as contraction disrupt the link between love and number of children, which is why researchers looked at hunter-gatherers called the Hadza.

Their lives are believed to have changed little in the last ten thousand years and for this reason they could provide insight into the early evolution of love among our prehistoric ancestors.

'Our study may shed new light on the meaning of love in humans' evolutionary past, especially in traditional hunter-gatherer societies in which individuals, not their parents, were responsible for partner choice', researchers wrote in their paper published in Frontiers in Psychology.

Research led by Dr Piotr Sorokowski at the University of Wroclaw looked at three components in order to measure the depth of love - intimacy, passion and commitment.

This is referred to as the Sternberg Triangular Theory of Love created in 1985 by psychologist Robert Sternberg.

The theory defines passion as associated with physical and emotional stimulation - such as a strong enthusiasm, excitement, sexual and romantic feeling.

Commitment is the conscious decision to stick with another person and a promise to be loyal to them.

Intimacy is described as feelings of closeness and attachment which tends to strengthen the bond between two individuals.

They compared these measures of love with how many children couples had.

Researchers found there was a positive association between passion and reproductive success in both sexes.

This could be because passion increases the number of sexual encounters and is particularly high in the early stages of a relationship.

Commitment helps people maintain stable relationships and people often decide to stay together in order to have children. Pictured is a Hadza woman with her child

The lives of the Hadza are believed to have changed little in the last ten thousand years and for this reason they could provide insight into the early evolution of love among our ancestors

STERNBERG TRIANGULAR THEORY OF LOVE

The study looked at the Sternberg Triangular Theory of Love created in 1985 by psychologist Robert Sternberg. The theory defines passion as associated with physical and emotional stimulation - such as a strong enthusiasm, excitement, sexual and romantic feeling as well as strong feelings of anger that could make someone act in a dangerous way. Commitment is the conscious decision to stick with another person and a promise to be loyal to them. Intimacy is described as feelings of closeness and attachment which tends to strengthen the bond between two individuals. Advertisement

This means if a couple cannot have children they will realise that quite quickly and could decide to search for alternative mates.

Commitment helps people maintain stable relationships and people often decide to stay together in order to have children.

This means they are more likely create a good environment to bring them up.

However, there was a drop in intimacy with the number of children, which could be associated with the stress of raising a family.

This could be because women who take care of more children have less time to spend with their partners.

Mothers can also satisfy their need for intimacy with close contact with their children.

Scientists believe that passion and commitment are therefore the key ingredients.

'Despite some limitations, our research was the first empirical examination of a very important issue and should stimulate extensive works in this area', researchers wrote.

This follows research from University College London that showed many primates practised infanticide prior to some evolving to become monogamous.

This is for the simple reason that when a male primate cares for his children he is less likely to kill them and love is an important emotion in driving this instinct.

In species where males and females bonded strongly, the chance of their offspring surviving was much higher as the males had to help with parenting.

As a result, monogamy was an evolutionary advantage.

Robin Dunbar of the University of Oxford suggests this could have resulted in changes in the brain in order to keep the pair-bond together, writes BBC.

This results in preference for your partner and rivalry with others which helped early human societies grow.

This extra male care may have meant our brains started to expand as did our ability to care and cooperate with one another, therefore giving us an even greater capacity to love.