Theories of Love: Definition, Examples & Predictions

Theories of Love: Definition, Examples & Predictions
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  • 0:02 Love
  • 0:59 Evolutionary Theory
  • 3:57 Equity Theory
  • 5:55 Attachment Theory
  • 8:09 Lesson Summary
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Lesson Transcript
Instructor: Natalie Boyd

Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.

During early adulthood, many people fall in love. But why do people fall in love? And how can they be happy? Watch this lesson to learn more about theories on love, including the evolutionary, equity, and attachment theories.


Lena is in love. At least she thinks she's in love. Her boyfriend, Aidan, says that he loves her and that he wants to marry her, but Lena isn't quite sure. She wants to love Aidan, and sometimes she thinks that she does, but her feelings scare her, and she kind of wants to run away and hide. Lena and Aidan are both in their late 20s, which is part of the time of life known as early adulthood.

Early adulthood stretches from adolescence until middle age, or approximately age 20 to age 40. During early adulthood, many people fall in love. But why do people fall in love? And why do some, like Lena, experience difficulties with regards to romantic love? Let's take a closer look at three theories on love: evolutionary theory, equity theory, and attachment theory.

Evolutionary Theory

Lena isn't sure she even believes in love. Sure, Aidan makes her feel happy, and she's attracted to him, but what is love? And why do people fall in love? These are questions Lena doesn't know the answer to.

One theory to explain why people fall in love is the evolutionary theory of love. This theory looks at love as an extension of our evolution. Since the goal of evolution is to survive, the traits that insure survival are passed down from generation to generation.

Let's look at an example. Imagine Caveman Bill has great eyesight. He can spot a saber-tooth tiger from a mile away. His buddy, Caveman Dave, though, has horrible eyesight. Caveman Dave could be nose-to-nose with a saber-tooth before he even noticed!

Who do you think will survive long enough to have kids and grandkids? Chances are, Caveman Bill will see the tiger and move to safety, while Caveman Dave becomes the tiger's lunch. And because Caveman Bill survives long enough to have kids, his good eyesight is passed down to the next generation, while Caveman Dave's bad eyesight isn't.

That's the essence of evolution. But what does that have to do with love? According to evolutionary theory, there are two elements of love that have been passed down through evolution: sexual attraction and attachment.

Sexual attraction is that zing that you feel when you are faced with someone who you are physically attracted to. Lena definitely feels that for Aidan. Whenever he's around, her heart races and she feels all fluttery inside. According to evolutionary theory, sexual attraction is there to help us mate. After all, if Caveman Bill feels sexual attraction for his wife, he is likely to have kids and pass down his propensity for sexual attraction to the next generation.

But sexual attraction isn't the only element of love. Love is also defined by emotional attachment. When Lena is around Aidan, she feels happy. She wants to do things for him and wants to keep him around. What's the evolutionary purpose of that?

Well, think about Caveman Bill again. If he and his wife don't have attachment, they are likely to go their separate ways. And in the cold, hard world of cavemen (and the cold, hard world of today), survival is higher if you have a partner. After all, if Caveman Bill has a hard day hunting wooly mammoths and comes home with no food, his wife might have some berries and plants that she gathered for their dinner. Otherwise, he might starve.

So, according to evolutionary theory, love is all about surviving and passing our genes down to the next generation. We do that through sexual attraction and emotional attachment.

Equity Theory

But does evolutionary theory explain everything about love and relationships? To some people, talking about love as though it was just a way to make sure we have babies and pass our genes down seemed like a stretch. After all, human interactions are complex. For example, Lena could feel sexual attraction and emotional attachment to Aidan, but does that mean that she'll be happy with him? Does that mean that he's the right person for her?

Another theory on how love works is called the equity theory of love. This theory says that people want their input-outcome ratio to be roughly equivalent to their partner's input-outcome ratio. What does this mean?

Let's look at Lena and Aidan. They love to spend time together, but Lena feels like she always does the work. She plans their dates and chooses what to do. She remembers their anniversary, and while she will cancel plans with her friends for a special occasion, Aidan won't even miss watching his football game on television.

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