In the modern era of research there have been two key hormones that help increase the bond between loves. These are oxytocin and vasopressin. Oxytocin is the hormone released during sex, which allows the deepening and intensifying the overall feeling of attachment. It is also released during the time of labor, to help secure the bond between the baby and the mother. A study Pederan and Boccia by studies rats and found that the release of oxytocin cause a mothers focus to shit from grooming herself to her pups. Another study by Winslow et al found that when animals were injected with vasopressin, they had more tendencies to have more stable bonds and had more sex than necessary. When a drug was given to suppress the release of vasopressin, there was an immediate change in behavior. They lost devotion towards their mates and no longer had the urge to save their mate from potential suitor. Explaining the active and important role vasopressin plays in commitment of relationships. Both studies show that vasopressin and oxytocin are important hormones involved in bonding. However, because the study was conducted on humans, it is difficult to generalize to humans. Another condition would be that animals show love in many different ways and perceive love differently from humans.
Neurotransmitters also explain why humans at attracted to each other. The release of chemical substance in the brain make us addicted, obsessed, or in love with a specific person causing change in behavior. A study conducted by Mazaritti studying 60 individuals: 20 were women and 20 were men who had recently fallen in love in the last 6 months. 20 of the participants were suffering from obsessive compulsive disorder, there other 20 were healthy who were not in love and were used as the control variable. When the blood samples of the participants who were in love were taken Mazaritti discovered that low serotonin levels in new lovers were the same as the participants who suffered obsessive compulsive disorder.