Love is one of the most difficult topics to explain, both philosophically and scientifically. And while scientists have a lot more work to do in understanding the mechanisms behind love — examining the brain chemistry, hormones, and genetics behind initial attraction, deeper emotions, as well as timeless attachment — we do have some interesting facts about romance from past studies. A new Mental Floss video touches upon 26 of those facts, providing us with a bigger picture on how to view love and relationships.

Initial attraction and make-out sessions have a lot to do with body chemistry (quite literally), and our five senses. Research has shown that people tend to choose partners who have similar DNA to them; a person’s genetic makeup and physical health can be identified visually, as well as through smell, sound, and taste. Some studies found that kissing is a way of swapping millions of (typically good) bacteria between partners, as well as a way to find out whether a partner has a similar microbiome as ourselves. That being said, kissing has also been shown to lower stress, relieve pain, and boost our immune systems.

On the physiological side, love and falling in love has quite an impact on our bodies — from changing our immune systems to making our pupils dilated when gazing upon someone attractive. For example, the video cites a Finnish study in which participants were asked where they felt love and happiness in their bodies. People from different cultural backgrounds all agreed that love and happiness is felt throughout the whole body — likely because there’s a myriad of ways that emotion and feelings impact our physical health.

An increase in hormones, nerve growth factors, and changes in appetite and sleep during the start of a relationship all have an influence over a person’s physical health. Interestingly enough, one study found that love or the presence of a romantic partner had a pain-relieving effect on women. These positive health benefits can extend to long-term relationships too; research has shown that marriage is linked to better heart health, mental health, and longevity.

But it’s all about how healthy and happy your relationship is. If a relationship is healthy, the partners involved are probably more likely to be healthy, too. But when a couple is heading towards a breakup, relationship stress can lead to a weakened immune system, researchers have found.

On an emotional and mental level, we all know too well that love can often be associated with obsessive compulsions (thinking too much about a person you just met; checking your phone for texts way too often). And relationships have been compared to drug addiction due to the large release of dopamine in the “brain on love.” Watch the video for more facts and studies on the nature of love and attraction.