Relationships between organisms require that individuals recognize one another. Such recognition is common even in early-evolved life.
At the cellular level, viruses know exactly where they are going. Among the variety of cell types, a virus recognizes its specific target. A virus makes its way via discrete inquiries with other cell types.
Plants recognize siblings with whom they share soil.
Social animals have especial need to recognize one another. Individuals are important where relationships exist for any duration, especially in any community with a social hierarchy.
The dark paper wasp, native to North America, is best known for making its paper nests below the roofs of houses (or in trees or foliage). A female founds her own colony. She’s no good at recognizing faces.
But her close cousin – the golden paper wasp – is. Goldie females form group colonies: building a joint nest and laying eggs there. Clustering queens squabble and determine a dominance hierarchy. So, it comes as no surprise that golden paper wasps, and other social wasps, remember and recognize individual faces; even human faces. While rigid exoskeletons disallow facial expressions, wasp heads do have different shapes, sizes, and features.
Birds recognize one another. Among a colony that can number up to half a million members, mated penguin partners find each other.
Ravens not only recognize each other, they long remember their affinity in individual relationships, even after being separated for years.
Practically all social mammals recognize each other individually. How they do so is sometimes surprising. Bats recognize one another by their echolocation calls, which have signature individuality.