To find out how long love will endure, all you need to do is test the blood levels of oxytocin. The high level of this hormone heralds a more permanent relationship, say the researchers, whose conclusions were presented in the journal Psychoneuroendocrinology.
Researchers from Bar-Ilan University in Israel interviewed 60 couples between 20 and 30 who had bonded within the last three months, and a control group of 43 unrelated people. They then compared the results of the blood tests taken at the start of the studies and six months later.
The level of oxytocin in the blood of people who recently mated with a new partner was on average twice as high as that of singles, regardless of factors such as gender, body weight, smoking, sexual activity or taking hormonal contraceptives.
Couples with a higher and stable baseline oxytocin level were more likely than others to remain in a relationship for the next six months. It was also observed that these people were more willing to show tenderness, which also increased the level of the love hormone.
On the biological level, the researchers note, the process of emotional attachment to a new partner resembles the process of creating a bond between mother and child.
Oxytocin is a peptide hormone that is synthesized in the hypothalamus and stored in the posterior pituitary gland. It plays an important role, among others during childbirth, accelerating uterine contractions, and also during the subsequent formation of the relationship with the baby. Moreover, studies show that this hormone promotes pro-social behavior and increases the level of trust in other people.