Humans by nature are intrigued by love and sex. In The Evolution of Desire, psychologist David M. Buss exposes to readers why we act the way we do in sexual situations/relationships based on evolutionary theories found through expansive experimental testing. One of the topics covered by Buss is that of sexual jealousy. Buss looks into the functions of sexual jealousy, the differences between women and men in relation to sexual jealousy, and the evolutionary cause of this trait.
As repeatedly mentioned throughout the chapters, humans act the way they do based on millions of years worth of successful adaptations. Every trait possessed by humans has been naturally selected for and serves some rationale in the ultimate purpose of human life: reproductive success. Buss starts out the book mentioning what women and men value in sexual partners and why. He then talks about why and when long-term relationships are desired versus casual-sex relationships and the functions each of these provide. But present in all types of relationships that humans face is jealousy.
According to evolution, this inevitable feeling of sexual jealousy is extremely beneficial. The ultimate evolutionary purpose of a both women and a men is to pass their genes on to offspring and raise these offspring to be successful and eventually reproduce themselves. Jealousy is a trait that has helped ensure this success over time. In men, as stated by Buss, sexual jealousy is found more when a mate is taking part in sexual/physical activities outside of the relationship. In women however, Buss states that sexual jealousy is based more on when a mate has emotional connections with another female.
These points, as backed up by various experiments and data mentioned by Buss, make sense. Men devote huge amounts of resources and time to raising their children, so they need to be sure that those children are in fact theirs (share their genetic makeup). Otherwise, the men