Explain the similarity-dissimilarity effect from the evolutionary perspective.

Our ancient ancestors might encounter other groups of hunter-gatherers. This situation provides three possible courses of action. First, two groups may move towards each other with friendly intent. This risks the danger of a surprise attack, but it also offers the possibility of mutual benefit to the two groups. Second, the two groups might move away from each other, acting out a self-protective fear intent. This may be a safer option, but it also ensures that beneficial opportunities are missed. Third, the two groups could move towards each other with aggressive intent based on fear or on the possibility of expanded opportunities. The risk is one of possible loss, but the potential benefits could be very great. The retreat and attack options both provide benefits and may have contributed to the survival of early humans or their ancestors. The attack option may be the most adaptive response in many situations. Supporting evidence can be seen in the genetic programming of male mice' reactions to strange mice entering their territory: "If it's a male, attack it; if female, seduce it."