Ready to become an expert on falling in love? Here’s what the latest science says about the “hows” and “whys” of love, according to Dr. Helen Fisher, who wrote the book Why We Love: The Nature and Chemistry of Romantic Love.

First: Why do we need love at all? Dr. Fisher says at its most basic level, love is defined by our need to find mates and reproduce. But over time, we’ve developed three distinct systems to help us choose the right people to fall for. First, there’s the libido, the part of our brain that makes our hormones go crazy when we see someone attractive. We’ve also developed a romantic love system, which helps us focus our energy on one person at a time. And finally, we have an attachment system, which encourages us to seek long-term partners who are more likely to stick around and help us raise kids. So how do you know when you’re feeling REAL love and not just attraction? Dr. Fisher says when all three of our love “systems” are being satisfied, it triggers a rush of dopamine, the feel-good chemical. But where other feelings tend to come and go, true love doesn’t go away after a few hours or days. In fact, it tends to grow stronger when you’re around the person you love and makes you feel possessive. Okay, so let’s answer this burning “love” question: Does love at first sight really exist? Yes. According to Dr. Fisher’s research, all animal species need to feel “instant sparks” to get the reproductive ball rolling. So it makes sense that people can feel instant attraction too. And research shows that men are more likely to experience love at first sight because they tend to be more visual while women generally need time to develop trust with their partner. The last love question: Is it possible to make someone fall in love with you? Yes again. Dr. Fisher says whether you’re meeting someone new or trying to reignite the spark in a marriage lots of research shows that we’re more likely to feel a rush of romantic love when we’re trying new things. New experiences trigger the release of dopamine in the brain and make us feel the energy and elation most of us associate with falling in love.