Sociality

Some animals live in groups.

This helps them stay safe. Many parents also care for their babies. This is a way to help their young grow.

Some animals live apart but still share a home. Mouse lemurs do this. They find food alone. But they might sleep in the same spot.

Other animals live in very big groups. Bees live together in a nest. They all help care for the babies. It is amazing how animals work together.

Animals live in many different ways. Some live alone. Others live in big groups. This way of living is called sociality.

Many animals show parental investment. This means parents spend time and power to help their young. A mother wasp stays near her babies to keep them safe. This helps them survive.

Some animals are subsocial. They care for their young but do not live in large groups. Other animals are solitary but social.

Mouse lemurs are solitary but social. They look for food alone. But they may sleep in the same nest. Some dolphins also live this way. They live apart but interact with humans.

Some groups are more complex. These are called parasocial. They live in one home and help care for young. The highest level is eusociality.

Eusocial animals have many adult generations living together. They share the work of caring for babies. Bees and ants are eusocial. Some mole-rats may also be eusocial. They live in harsh places and help raise their siblings.

Animals live together in many different ways. This way of living is called sociality. It is a response to things like predators or parasites.

Some animals show gregariousness, which is the desire to be in groups. A big part of this is parental investment. This is when parents use time or energy to help their young. This helps the babies survive, but it uses up resources the parent might need for other things. Sociality can range from living alone to forming very complex societies.

There are different levels of how animals live together. Subsocial animals are those where parents care for their young for a short time. Some animals are called solitary but social.

Mouse lemurs are a good example of this. They hunt for food alone, but they might sleep in the same nest. Some dolphins also live this way by interacting with humans. Other groups are called parasocial. These animals live in one shared home and show parental investment. Within this group, communal animals live together but only care for their own babies. Quasisocial animals share the work of caring for the young. Semisocial groups even have a caste system to divide different jobs.

The highest level of sociality is called eusociality.

Eusocial groups have many adult generations living together at once. They share the work of caring for the newest babies. Some of these groups have a biological caste system. This means some members are born with physical traits for specific jobs. These traits do not change during their lives. This is seen in many insects like ants, bees, and wasps. It is also seen in termites and some beetles. Even some snapping shrimp live in eusocial groups to defend their home.

Scientists have worked hard to name these different ways of living. Suzanne Batra coined the words eusocial and quasisocial in 1966. Later, Charles D. Michener published a system for presociality in 1969. He studied bees to find new categories like communal and semisocial. He did not use these words for animals outside of insects. E. O. Wilson later helped refine these definitions. In 2005, Wilson and Bert Hölldobler made a big claim. They suggested that humans might actually be a eusocial species. This idea was very controversial among scientists.

Social living often links to how smart an animal is. Social predators like lions and spotted hyenas are very good at solving problems. They can use innovation to find new ways to do things. This is different from non-social predators like tigers or leopards. In some mammals, sociality helps them live in hard places. For example, naked mole-rats and Damaraland mole-rats live in harsh environments. They live in groups and help raise their siblings. This helps the whole group survive even when life is difficult.

Sociality describes the degree to which individuals in an animal population associate in social groups. This inclination to live in groups is known as gregariousness. Animals often develop social structures as a survival response to evolutionary pressures. For example, staying near offspring can protect them from predators or parasites. One fundamental driver of social behavior is parental investment. This is the expenditure of resources, such as time or energy, to benefit offspring. While this helps young survive, it reduces the parent's capacity to invest in future reproduction or other kin.

Scientists classify sociality into several distinct stages based on how animals interact. The most basic level is subsociality, where parents care for their young for a period of time. If animals associate only for courtship or mating, they are considered solitary. However, some species are described as solitary but social. These animals, such as the mouse lemur, forage separately but may share a nest or sleeping location.

Some cetaceans, like certain dolphins, also exhibit this behavior by interacting with humans while living apart from their own species.

Beyond these levels lies a meta-class called parasociality. Parasocial animals share two common traits: they show parental investment and live in a single, cooperative dwelling. This class includes communal, quasisocial, and semisocial groups. In communal groups, adults live in one nest but only care for their own young. Quasisocial animals live together and share the responsibility of brood care. Semisocial populations add a biological caste system to these traits. This system delegates labor based on whether an individual is able to reproduce.

The highest recognized degree of sociality is eusociality. Eusocial taxa exhibit overlapping adult generations and cooperative care of the young. They also feature a reproductive division of labor. In many cases, they possess a biological caste system. This means individuals are born with physical characteristics specific to a job. These traits remain unchanged throughout their lives. This level of organization is common in insects like ants, bees, and termites. Some species are called primitively eusocial if they lack these permanent physical differences.

Eusociality is not limited to insects. Certain mammals, such as the naked mole-rat and the Damaraland mole-rat, show primitive eusociality. These rodents live in harsh environments and help raise siblings born from a single queen. Even some crustaceans, like the snapping shrimp *Synalpheus regalis*, live in eusocial societies. These shrimp live in shared spaces in tropical reefs. A single breeding female is protected by many male defenders with large snapping claws. Scientists still debate if a species must have an irreversible sterile caste to be truly eusocial.

Our understanding of these classifications has evolved through significant scientific work. In 1966, Suzanne Batra coined the terms eusocial and quasisocial. Later, in 1969, the entomologist Charles D. Michener published a classification system for presociality. Michener studied bees and added the terms communal and semisocial to the system. While Michener focused on insects, E. O. Wilson later refined these definitions. In 2005, Wilson and Bert Hölldobler proposed a controversial idea. They claimed that humans might exhibit enough sociality to be considered a eusocial species.

Sociality is often linked to cognitive abilities and problem-solving. Social mammal predators, such as lions and spotted hyenas, show high levels of innovation. They are often better at solving problems than non-social predators like leopards or tigers. This suggests a connection between complex social structures and the ability to think in new ways. Whether through the complex hives of honey bees or the colonies of mole-rats, sociality remains a powerful tool for survival in the natural world.