Written by: Fatima Sajid
Exploring the Rich Tapestry of Animal Social Behavior
The animals of the world collectively are a different embroidery of life, from the littlest bugs to the biggest warm-blooded creatures, every species displays astounding evolution of social behaviors. These behaviors may range from simple aggregations to complex social orders, having a critical impact in forming the course of normal history.
In this article, we will discuss the intricacies and the importance of social behavior in animals throughout history and different parts of the world. From the seemingly unamusing solitary life forms to the mind-boggling social orders of eusocial animals and beyond, this article tries to solve the mystery of how social ways of behaving have developed and evolved in the animal world.
Many social behaviors of animals are adaptive, meaning that being social ultimately increases an animal’s fitness — its lifetime reproductive success. One example of how social behavior is adaptive is aggregation against predators. This concept applies to caterpillars feeding together on a leaf, a herd of wildebeest, schools of fish, and flocks of birds. One idea is that social behavior evolved because ancestral nonsocial neutral aggregates worked as cues for the quality or quantity of the resource being shared (e.g., food quality, mating opportunity, defense against predators). Such aggregates might have served as a basis for the subsequent evolution of social traits. This hypothesis, however, needs exploration from both theoretical and empirical
Figure 1. Caterpillars feeding on leaves
Figure 2. Mixed herd of topi and common zebra grazing on the savanna of tropical Africa.
Social behavior encompasses a wide variety of interactions, from temporary feeding aggregations or mating swarms to multigenerational family groups with cooperative brood care. Over the years, there have been many attempts to classify the diversity of social interactions and understand the evolutionary progression of social behavior.
Agonistic Behavior
Behaviors that produce, threaten to cause, or attempt to lessen physical harm are referred to as agonistic behaviors. Threats, aggressiveness, and capitulation are all parts of antagonism. Additionally, the behavior frequently shields either animal from significant harm in ritualistic or symbolic aggression.
Animals of all kinds frequently display antagonism. It can be defined as a group of interpersonal behaviors, excluding interactions between predators and prey, that are connected to any kind of aggressive or fighting behavior between two or more members of the same species. Both the life history of an individual in solitary species and the makeup of social groups in gregarious animals are significantly influenced by antagonistic actions. Threat, aggression, and submission are the three basic subtypes of these behaviors. All three are connected and are possible.
Altruistic Behaviors
Altruism refers to the circumstance in which some people put the interests of a wider group other than their own family before their own and their immediate offspring's. In animal societies, altruistic conduct is largely dependent on how individuals are assigned jobs based on their behavioral, cognitive, and social specializations.
The direct mechanism of altruism includes feeding, protection, and guarding, whereas the indirect mechanism includes alarming. The distribution of social duties can take many different forms, from the allocation of tasks within kin groups to the precarious balance between altruism and "parasitism" within groupings of genetically unrelated people. 'Kin selection' (also known as 'inclusive fitness') theory, proposed by Hamilton in 1964, and the idea of reciprocal altruism, both of which were developed in the 1960s and 1970s, attempted to explain the evolution of altruistic conduct. And the theory of reciprocal altruism is due primarily to Trivers (1971) and Maynard Smith (1974).
An example of altruism comes from ground squirrels, who may warn other members of their group about a predatory hawk overhead. This brings the hawk’s attention to the individual giving the warning call. This risky behavior benefits other individuals in the squirrel’s group. Other examples of altruistic behavior include sharing nesting space and helping to raise offspring of an unrelated individual.
Figure 3. A male red squirrel lets out a territorial call — called a rattle — at his neighbors.
Kin Selection
Kin selection, as opposed to natural selection, depicts how copies of an individual's genes are passed down through the survival and reproduction of their relatives. Natural selection indicates how an individual passes on copies of their genes through survival and reproduction. The principle of kin selection predicts that an individual will act altruistically to maximize the fitness of their relatives, just as the principle of natural selection predicts that an individual will act to increase their fitness.
When an animal sacrifices itself for the genetic fitness of its relatives, this is known as kin selection. Beyond the connection between parents and their children, the kin selection also includes other family members. The growth of altruistic conduct is facilitated when an individual's effort or risk is rewarded. It facilitates the development of altruistic behavior when the energy invested, or the risk incurred, by an individual is compensated in excess by the benefits ensuing to relatives.
Eusociality
In eusocial animals, social behavior has evolved to its most nuanced and intricate level. Colonies are home to eusocial species. The animals that do not reproduce make up the majority of the colony and are responsible for providing food, protection, and communal care for the young. Individuals in colonies are typically connected, and inbreeding (mating between closely related individuals) or the distinctive genetics of some groups of insects can cause relatedness to exceed 0.5. The phenomena are well-defined and almost only observed in insects, particularly ants, bees, wasps, and termites. Genetics through paleontology has all
contributed to the corpus of mostly specialist research on this phenomenon.
Figure 4. A subordinate female meerkat babysits her mother's young; an iconic example of cooperative behavior in mammals.
According to evolutionary biologists, the development of eusociality followed a path that began with solitary organisms learning the advantages of group behavior and eventually reached a "point of no return" (Wilson & Hölldobler 2005) where some individuals lost their ability to physically reproduce and could only benefit indirectly from evolution. It's also important to keep in mind that the selecting pressures at play at the time eusocial behavior first emerges may not be the same as those sustaining advanced eusocial colonies (Hölldobler & Wilson 2009).
Territoriality
To defend their territory from intruders of the same species, an animal or a group of animals engages in territorial behavior. Operational definitions of territory fall broadly into two categories—those that focus on animals’ behavior and those that focus on their ecological relationships. That said, the question of how to conceive of territory has long been a subject of contention, with widely varied opinions on how the term should be defined and whether and how it is useful for understanding animal behavior.
Smells like the pheromones released by the skin glands of various mammals can serve as a territorial boundary indicator, as can sounds like bird melodies. Combat and chases will start if such a warning does not stop intruders. Animals only defend their territories when it is economically feasible to do so. Territorial defense has both advantages and disadvantages. For instance, spotted hyenas (Crocutes crocuta) do not defend territories in the Serengeti plains where prey is more seasonal, despite the abundance and predictability of prey in the Ngorongoro crater. In the Serengeti, hyenas roam a large home range without defending territory.
Evolution of Mating Behaviors:
A mating system defines the procedures and patterns by which males and females successfully mate and create offspring, as well as how this connects to the reproductive ecologies of those species, including societal and environmental influences. In the past, it was believed that animals typically mated with a single partner. The rarity of strict genetic monogamy has now been exposed by growing evidence of multiple mating between the sexes and genomic evidence of mixed parentage within families.
Instead of focusing on extrinsic factors like defendable resources, a novel model for the evolution of mating systems emphasizes social interactions driven by genetically determined behaviors and how competition among various behavioral strategies plays out. According to this theory, social interactions can cause populations to split into two distinct species with different mating systems or even cause evolutionary transitions from one mating system to another. The model demonstrated that increases in the advantages of monogamous behaviors are a major driving force for evolutionary shifts in mating systems.
More rodents are monogamous than polygynous, and monogamy is the most frequent evolutionary transition from a promiscuous predecessor in this group of animals. This challenges previous assumptions and underscores the importance of considering the genetic and social dynamics that drive mating behaviors. Understanding these evolutionary shifts provides valuable insights into the diverse strategies employed by species to navigate the complex landscape of reproduction and ensure the survival of their genetic lineage.
Figure 5. Two gannets greeting each other on Bonaventure Island, Quebec.
Evolution of Dominance in Animal Kingdoms:
Understanding how behavior and physiology interact during social encounters is important if we are to understand how populations will respond to environmental change and to predict the welfare implications of hierarchy formation in captivity.
Dominance in animals refers to the establishment of hierarchical social structures within species living in social groups or communities. It evolves primarily due to competition for limited resources like food, mates, and shelter. Dominant individuals gain preferential access to these resources, enhancing their chances of survival and reproduction, which can be passed down to their offspring. Factors contributing to dominance include genetics, intrasexual competition among males, behavioral displays, sexual selection, environmental conditions, and the balance between cooperation and competition. The evolution of dominance varies across species and environments, shaping their social dynamics and survival strategies.
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