Sociality
Animal communities are not mere assemblages of species living together but form closely-knit communities or societies comparable to our own. ~ English zoologist Charles Elton
Conspecifics commonly congregate to be safer and live more productive lives. Microbes group to create biofilms – an elaborate communal form that offers a better life. Plants too can be gregarious, both with microbial mutualists and with each other.
Insects swarm. Birds flock. Mammals travel in herds and hunt in packs.
Each species has a typical group size at which it functions most efficiently. ~ English zoologist Desmond Morris
Sociality is a life-history variable, not an emblem of evolutionary advance. Living is mentally demanding, period. There is no shortage of problem-solving irrespective of lifestyle.
That said, social relations do tax the mind. In presocial animals, trade-off decisions must be made between self-interest and shared interest. Relationship history matters.
With no prospect of social climbing, eusocial animals may seem to have an easier time. But eusocial creatures typically have prodigious memory capacities, as there are many friends and otherwise much to remember. A life of colonial cooperation yields a rich social life.
Sociality is not just a set of behavior patterns. It is instead an integral part of an organism’s biology, woven into the fabric of being. Environment and life experience shape intelligence physiology as much as they impress upon the mind.
Prolonged isolation for individuals of any social species has profound biological diminishment as well as psychological impairment. Genetic quality deteriorates. Aging accelerates. In short, sociality is hardwired as an evolutionary adaptation.
Social ties promote survival. ~ English zoologist Lauren Brent
Sociality & Biochemistry
Biochemistry and sociality coincide. Zebra finches are known for being gregarious and loyal: happily congregating in groups and forming monogamous mating bonds. The level of the mesotocin in a zebra finch’s system makes a difference. Finches lacking mesotocin are not socially inclined.
Mesotocin is the avian hormone equivalent of oxytocin in humans. Isotocin is the fish variant. Both have similar effects to oxytocin. Overall, these hormones affect sociability, anxiety, pair bonding, orgasm, and maternal behaviors.
Highly social birds, such as those that travel in flocks, have more mesotocin receptors in parts of the brain related to social behaviors. Conversely, territorial birds have fewer mesotocin brain receptors.
The levels of oxytocin and vasopressin, another hormone associated with sociability, correlate with bonding behaviors in prairie voles, which are territorial during mating, but communal the rest of the year. Similar patterns of association between such brain hormones and social preferences have been found in many mammal species.
Sometimes smelling alike is enough to associate. Regardless of species, fish who like the same food and thereby smell similarly commonly congregate and forage together.
By associating with others that share the same preference for particular types of food, a fish ensures that it has enough to eat. Being surrounded by similar-smelling fish also protects an individual against predators that use certain chemical search patterns to detect prey. ~ Austrian ethologist Tanja Kleinhappel
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Vinegar Flies
Vinegar flies aggregate on rotten fruit; not as a social gala to show mutual attraction, but as a feast on a shared food source. Social interaction is not altogether absent. Vinegar flies react to the presence of others by spacing themselves out, giving each other personal space.
The correct culture of vinegar fly eggs laid in a fruit raises the odds of survival. One with too many eggs creates a group of larvae that become undernourished. Too few eggs also have consequence. There must be enough larvae to break up the food supply and engender yeast colonies that mush the food so that it is soft enough for all the larvae to feed.
This larval group dynamic makes it advantageous for a female to lay her eggs close to others. Most do.
Hermit Crabs
Hermit crabs have a soft underbelly that leaves them vulnerable to predators. For self-protection, hermit crabs tuck themselves into abandoned snail shells, of which there is a limited supply.
Those that live on the shoreline hollow out and remodel their shells. That sometimes doubles the volume, providing more room to grow. It also makes for a lighter mobile home to lug around.
The hermit crab is no hermit. Crabs regularly gather together for real estate swaps.
A crab that finds a suitable shell, albeit too large for it, waits nearby rather than walking away. Soon enough another crab comes by, then another.
A congregation of 3 will attract dozens more, all eager to trade up to a larger home. They typically form a conga line, small to large, each holding onto the crab in front of it.
Once the largest crab moves into the vacant shell, from large to the small, each queued crab quickly scuttles into the shell in front of it.
Crabs spend hours queuing up. Once swapping starts, a synchronous vacancy chain fires off in seconds, like a line of dominos.
Vacancies don’t just come via a convivial conga line. Hermit crabs sometimes gang up on one with a fine abode, prying it out of its home, and then competing for the better shell.
Having diligently worked to remodel its home, a crab is reluctant to leave it for any reason, including making love. Male hermit crabs have specialized private parts that help them keep their private property. Some males have penises that are 60% as long as the rest of their bodies.
Enlarged penises evolved to prevent the theft of property during sex. Species carrying more valuable, more easily stolen property have significantly larger penises than species carrying less valuable, less easily stolen property, which, in turn, have larger penises than species carrying no property at all. ~ American biologist Mark Laidre
Hermit crab funerals are well attended. Crabs come from all around, not to mourn the deceased, but in the hopes of a shell upgrade.
Some hermit crab species forgo shells for sea anemones. A crab plucks a young anemone off the sea floor and places it on its belly. The anemone attaches, attracted to free meals from scraps that float free when the crab eats.
The crab benefits because the anemone grows up and over the crab’s otherwise unprotected back. Meantime, the anemone’s fleshy foot provides protection to the crab.
Costs & Benefits
There are both costs and benefits to sociality: more competition for mates, more possibilities for mating; more competition for food, better information as to prime dining spots; more competition for everything material, but easier to relax in relative safety.
Being social is a time and energy sink. Social climbing is energetically expensive and stressful.
Pathogens and parasites love groups, though not of their own kind; only of their client base. Group living makes disease transmission and parasite propagation much easier.
Bird colonies are typical, in having all the costs and benefits of crowded conditions. Perhaps the biggest benefit of all is intangible: information.
Birds are nosy neighbors, as are most social creatures. Keeping one’s eyes and ears open garners tips on lifestyle as well as juicy gossip. Where to find food, the best spots to breed, and nest-building techniques are all on display to the careful observer.
A savvy female chickadee tunes into the dawn song contest between neighboring males to learn who is hot and who is not. She might then pay a visit to well-sung stud who will not mind a territorial intrusion for what she has in mind. You cannot blame a chickadee for wanting the best brood she can get.
Assistance for discomforts and illness may be offered by social living. Friendly grooming of each other is practiced by several mammal species, notably primates.
Animal sociality is often more than self-interest spread within a group and through time. Social interactions often exceed the struggle to survive, and reproduce, and entail a drive to thrive. Psychological satisfaction is a factor in the life of every animal.
Individuals in schools of fish, and flocks of birds, may stay together for months. Their social behaviors are as complex as any mammal.
Geese migrate as families. Most, if not all, birds recognize each other. Many have stable relationships for much of their lives. The same is true for most social species with lives that last for years.
Fish recognize their individual differences. Schooling fish take up different positions within a group according to their abilities. Fitter fish take the lead.
Female elephants may live as a family for more than 40 years. They know each other individually, with deep emotional bonds.
The line between group behavior and sociality is one of emotion. Bonds between individuals are emotional in nature. Social groups are of several individual bonds, each of varying affection.
Even intensely social creatures need personal space. This is readily observed in birds; a flock of which may sit in a line with precise spacing between them, as pigeons on a high wire illustrate.
The distance between varies by species. Wingspan is indicative of spacing, as shown in flock flight patterns, though other factors may weigh in. Rooks feed together but maintain enough distance that the earthworms that they feed upon are not given advance warning by another.
Coming too close results in aggression to prompt adjustment. Loved ones are different. Many nests are shared for long periods at very close quarters.
There are some birds so sociable that spacing is spurious. The affectionate small parrot known as the lovebird acquired its name by its lovey-dovey nature: huddling shoulder to shoulder in clusters, bathing and grooming each other, even occasionally feeding each other’s chicks.
Social facilitation is a change of behavior pattern when in the presence of others. Social facilitation affects practically all social species.
Birds and other animals commonly tend to eat more when in the presence of others, intrinsically driven by a sense of competition for limited resources. Solitary hens eat less than those with company.
Peer pressure is a natural phenomenon for every social species. A hungry fowl chick put in a pen with sated birds will not eat, even if food is available, simply because the others are not eating as they normally would. A hungry chick senses danger in unusual behavior and adheres to group behavior.
Practicing social facilitation isn’t always practical, sensible, or in an animal’s best interest. A minor disturbance within a group of animals sometimes cascades into a tizzy of panic. This discombobulation temporarily defeats the protective purpose which grouping affords. Predators count on such irrationality in herding animals to ease the task of nabbing something to eat.
Rooks roost colonially in the tops of trees, building their nests from twigs, typically of broken-off branches. Twigs are seldom plucked from the ground.
A bit of pilfering from each other’s nests is tolerated as business as usual. But pilfering can turn to pillaging if the stick supply runs thin. Unabashed thievery can become the norm in a rookery, ultimately resulting in the wholesale destruction of nests.
Protection
A group has a better chance against a predator than does an animal alone. The group can take concerted evasive action, scatter, confuse the predator, or even gang attack.
Groups are more conspicuous to predators, but individual risk is lessened. Cohesive groups respond to each other and provide better protection against predators, even if only by having more alert individuals nearby.
Solitary red-billed weaverbirds, or when congregated with other bird species, often fail to respond to a predatory goshawk flying overhead. When 2 or more weaverbirds are together, a hawk is much more likely to be seen and a response made.
Colonial nesting birds are known to form a formidable opposition. A fox coming into a group of nesting gulls is likely to be mobbed, to the point of the birds kicking the fox with their feet. A solitary bird has no such hope of intimidation.
Birds of prey rarely attack a close group. The most common stratagem is to make threatening swoops to try to get the group to scatter, so that the predator can single out an isolated individual.
Behavioral geometry favors close grouping. If each animal in a group tries to put one animal between itself and a predator, then a tight formation results.
Beside adding a margin of safety, protective grouping affords members more time for foraging and feeding, requiring less individual vigilance.
Protective grouping raises the issue of cheating: whether an individual can ride on the attentiveness of others. Slackers are more likely to be caught out as response time to danger slows.
A feeding-focused cheat is likely worse off than one that occasionally looks around. Hence, intermittent vigilance benefits both the individual and the group.
Food
Animals in a group often converge on a rich food source. When a tit flock member finds a morsel, the others alter their search to home in. While an individual may lose out in the instance that pickings are slim, the longer-term advantage benefits each member, as the odds of finding food are raised.
The jungle-runner is a whiptail lizard endemic to the tiny islet of Little Scrub, off the east coast of Anguilla. Their favorite foods include bird eggs and fruit, which is can be more than a single lizard can eat.
Lizards are normally territorial, as are jungle-runners when food is not abundant. Facing a surfeit, a jungle-runner invites others into the neighborhood to join the feast. A lizard signifies such abundance by performing pushups. This nonverbal communication works well in noisy environments and does not draw undue attention.
The invitational exercise not only works up an appetite, it can facilitate dining. By calling over more mouths, eating a bulky fruit like a prickly pear becomes a bit easier.
Pumas are large, secretive cats that reside in the mountains of the Americas. These territorial cats live largely solitary lives, but they reciprocally share food and water with neighbors.
First, pumas regularly kill prey many times their size and difficult to consume alone. Excess food reduces the costs associated with being close to conspecifics, thus increasing opportunities for social interactions and the development of more complex social strategies. Second, pumas live long lives in relatively stable territories, providing opportunities for repeated interactions with neighbors over time. ~ American zoologist Mark Elbroch et al
Group dynamics sometimes create favorable feeding conditions. Gannets and gulls are often group fishers. Diving together confuses the fish, making them more likely to be caught.
Dogs, hyenas, lions, and several other predators hunt in groups, with varying degrees of coordination, but consistently with better success than solitary individuals could hope for.
Though they hunt in groups, lion hunting behavior is typically individually opportunistic, not coordinated. The advantage of lion pack hunting comes after the kill, in keeping scavengers away from the carcass.
Hyenas pick their prey based on their group size, preferring zebra to wildebeest when in a plentiful pack. Zebra know this: ignoring a single hyena, and only becoming alarmed by the sight of a large pack.
Pair Bonds
Many animals form long-term partnerships. Pair bonding is seldom just about sex, even when that is part of the relationship.
Rabbitfish pair up for the long haul but mating has nothing to do with it. Rabbitfish migrate during the new moons of October, November, and December to mate in mass aggregations. Some rabbitfish couples are of the same sex.
Rabbitfish pairs are cooperative alliances, helping them better obtain resources than they could by themselves. Male cheetahs form lifelong alliances to defend territory.
The situation with fish is no different than our own. It’s easier to go through life with a partner and more fun.
Organization
Sociality is so useful to living beings it has been invented many different times in the insect world alone. ~ Caryl Haskins
Animal social organizations differ widely in complexity, and in the types of interactions between individuals. While the tendencies of social organizations are similar within a species, populations sometimes develop their own distinctive cultures.
One commonality of animal sociality is that a mother and her offspring are the foundation of social structure. In group-oriented animals, offspring inherit their mothers’ social connections, which generationally strengthens the resilience of the social network.
In birds and mammals, it is nearly always the female that cares for younglings by herself. Several fish reverse this, with paternal care, as with nest-building sticklebacks and pouch-carrying seahorses.
When parental duties are too much for 1 parent to bear, pair bonds become common. Nesting fish, such as cichlids, pair up to share parenting. Over 90% of bird species take care of their nestlings in pairs.
Although pair bonds are found in certain mammals, such as beavers, foxes, jackals, and gibbons, this not is not the typical mammalian grouping. Mother mammals are generally better off caring for their young without male assistance. Where parental assistance is necessary, there tends to be a larger group and alloparenting occurs.
Families are an extension of pairing. In animals with overlapping litters, older offspring sometimes assist with care of younger ones.
Harems – 1 dominant male exclusively mating with multiple females – is common among mammals. In polygamous monkeys, a male may have only a few females. With fur seals harems can be huge: up to 100 females. Male deer and some antelopes are also able to corral and control sizable numbers of females during breeding season.
The harem system means that many males are unmated during breeding season. It also means that overlords must constantly defend their hard-won breeding rights, which is often quite taxing.
The cost of harem-keeping may not be just from jealous rival males. In some polygamous species, such as the patas monkey, dominant males often become henpecked. A patas monkey harem may have a dozen females, who gang up and dominate the male.
While some harems last year-round, others dissolve at the end of the breeding season. When this happens, individuals may disperse or stay together.
At the end of the breeding season, red deer form separate male and female herds, each with dominance hierarchies. When breeding time comes around again, males make their move on the females and fight one another for harem possession.
With a shift in the balance of power between sexes, a harem system becomes a matriarchy: females are the center of society, with males on the periphery. During breeding periods, males are allowed in for mating, then dispatched. Coatis and elephants run matriarchies.
In an oligarchy, societal power is vested in an elite gang of dominant males. Baboons run oligarchical societies, as do humans. Oligarchies require restraint and cooperation among the dominant males or a society dissolves into discord. The history of men is replete with social dysfunctionality, much more so than other animals.
Social hierarchies are a norm among group-oriented presocial animals. Eusocial insects take the concept a significant step further with social systems that provide for efficient division of labor and a decent life for all in the colony.
Geladas
Dominance hierarchies are common among primates, as an evolved means to minimize conflicts. The behavioral byproducts of a stiff social order differ.
Geladas are Old World monkeys endemic to the Ethiopian highlands. Geladas are closely related to baboons and have a lifestyle like their savanna cousins. They live in a complex multi-tiered society like hamadryas baboons, though there are differences in their behavioral norms.
(Baboons are in the Papio genus, whereas Geladas comprise the Theropithecus genus (Greek for “beast ape”).)
Both male and female geladas have respective dominance hierarchies. Female geladas stay with their natal unit. In growing up they form strong social bonds and a dominance hierarchy among themselves that fits within the existing social order. Within a group, gelada females tend to be more aggressive than males.
Mature gelada males form or take over a family unit. As a group, females can exercise power over the dominant male. If a usurper tries to overthrow the resident male, the females may support or oppose him: an often-decisive decision. In contrast with hamadryas, a gelada male maintains his standing with family females by grooming them.
While there may be more than 1 male in a unit, only the dominant gelada male supposedly mates with the females. Conversely, a male may be monopolized by a dominant female.
Geladas social hierarchies create sexually monogamous relationships. If a male attempts to seduce another female, she is apt to publicly ignore him.
Geladas occasionally engage in infidelity: cheating on their partner and doing their best to cover it up by suppressing their normal mating cries to avoid being overheard. For instance, a non-dominant male may have consensual sex with a female. If the dominant male finds out, he will punish them both.
Alpha male geladas sometimes allow subordinate competitors into their reproductive unit. This fosters cooperation, which typically results in a 30% longer tenure for the leader. Such a magnanimous male may expect 3 more offspring during his lengthened leadership from being tolerant of some subordinate reproduction.
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Eusociality commonly comprises a breeding queen with a sterile colony of workers. Social insects – ants, bees, wasps, and termites – are the most well-known eusocial animals. There are a few others. An Australian weevil is the only beetle recognized as eusocial.
Snapping shrimp live in sponges on tropical reefs, in colonies of up to 300 individuals, but with only 1 reproductive female. Food is abundant. The main task of workers is to defend the home sponge from invasion. On a crowded reef, quality sponge real estate is sought by many species.
The sand puppy and the Damaraland mole rat are the only known eusocial mammals.
Though relatively few species have taken social living to the extreme of eusociality, many different animals have close cooperation, if not reproductive division of labor. Before flying off to their own lives, fledgling birds of many species stay with their parents a year or 2 to help rear the next generation. In over 200 species, including mammals, such as the dwarf mongooses and black-back jackals, young helpers assist their parents with younger siblings.
African Wild Dogs
They are the most enthusiastic animals. They live the life domestic dogs wish they could live. ~ English zoologist Rosie Woodroffe
The African wild dog is a long-legged canid that lives on the savannas and sparse woodlands of Africa. Its Latin name – Lycaon pictus: “painted wolf” – refers to the animal’s patchwork coat of red, black, brown, white, and yellow fur. Each dog has its own unique coat pattern, allowing instant recognition by others in the pack. These dogs have large rounded ears.
All other dogs have 5 toes on their feet. The African wild dog has only 4.
Wild dogs live in family groups of 6–20 adults. The dogs hunt as a pack in a very disciplined way: stalking with military grace and precision – steps synchronized, radio-dish ears cocked forward. Their attacks are similarly choreographed to cover all angles and ensure capture. If they tire in a long chase, initial leaders are replaced by 2nd-string dogs that lag early on. African wild dogs can run long distances, at speeds up to 55 kilometers per hour.
Targeted prey rarely escapes. Dogs will tear flesh until the animal falls.
Wild dogs’ relentless pursuit of prey is contrasted to their affability, civility, and generousness among themselves. Before a hunt, pack members practice a ritual bonding: circulating among the group, vocalizing, and affectionately touching each other, building enthusiasm.
Among most group-living carnivores, such as the big cats, dominant adults get first serving, leaving leftovers to their juniors. Wild dogs are exactly the opposite. Adults let puppies feed first. Pups still in the den, or injured pack members, are provisioned by regurgitation of the most recent meal.
The pack is typically dominated by a monogamous breeding pair. Other adults, which are related, serve as guardians and babysitters, and even wet-nurse the alpha pair’s pups.
Wild dogs are generous to a fault. Large packs with many offspring end up shortening the lives of nonbreeding adults, who gradually become malnourished from feeding the young.
They’re evolving into the mammalian equivalent of honeybees. ~ American ethologist Scott Creel
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The nature of a creature, its predators, and its habitat, present adaptive pressures that affect sociality and other facets of life. A lack of resources – food or mates – creates territorial instincts, or, conversely, may spur greater sociality. The great tit is alternately territorial or gregarious depending upon the season: territorial during mating season but wintering in large flocks with their own and other species.
Mating seasons often spur competitive and/or territorial behaviors, or alternately, may foster breeding colonies. Defending territory is energy expensive.
Social Dominance
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Male elephant seals and red dear spend much of the breeding season in battle: fighting for paternity of the next generation. The winner, either by aggressive negotiation or bloody fight, takes the spoils; at great cost.
Male elephant seal mortality is high. Few achieve the strength and size to hold a harem on a breeding beach.
A male lion may hold onto a pride of lions for very few years before being displaced by a younger and stronger rival. The reproductive life of a female red deer may be 20 years, but a stag’s breeding years are considerably fewer, as holding onto the privilege of paternity takes a heavy toll.
Conflicts arise in all social animals. The fiercest are often over mating rights and prime breeding spots. Yet few mating contests are so taxing as to be terminal to the loser. Such fighting in most species is ritualized.
A male mantis shrimp could easily kill a vanquished opponent. It seldom happens. A beaten combatant can signal his opponent that he has had enough. Specific submission gestures vary by species, though they typically involve putting oneself in a vulnerable position.
African wild dogs show an open-mouthed grimace, lower and turn the head, and even go belly up in a groveling motion. The winner permits the defeated to leave the field without further harm.
The Occam’s-razor explanation for letting an opponent live another day is that evolution generally favors success of a population, not just individuals. Nature does not intend to create murderous brutes as a norm.
Gall Aphids
A petiole is the stalk attaching the leaf blade to the stem of a plant. With the coming of spring, aphid eggs hatch on the petioles of cottonwood and poplar trees. The emerging aphids amble to leaves on the branches.
Of tens of thousands per tree, each female settles at the petiole of a selected leaf. There she chemically induces a hollow ball of leaf tissue – a gall – for her homestead, where she will bear offspring parthenogentically. Parthenogenesis is asexual reproduction without fertilization.
Once her daughters have matured, they either fly off to another host or stake a claim on the natal tree. Staking a claim to a choice leaf is not easy. Prize petioles can be hard to come by. There may be 20 aphids for every large leaf on the tree. Females may spend hours kicking each other for a preferred leaf, or a superior leaf site. They may fight for 2 days, to the death, for the right to grow a gall in a great location.
Lovely leaves are worth fighting for. Defeated females, and those disinclined to aggressive negotiation to death, are forced to accept inferior lodgings. The choices are a smaller unoccupied leaf or taking a secondary spot on a larger leaf: midrib, where the juices are not as nutritious. Both are equivalent in worth, but a significant step down in quality from a prime petiole.
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Dominance and deference are common components of presocial societies. There are many situations where social dominance enters in. First or best access to a meal is exemplary.
Territory is commonly critical. A dominant individual or pair take the choice spot, for whatever reason or whim. Might makes right in the animal world.
Chickens are unusual in develop a specific pecking order. In other species, particularly primates, the social hierarchy is much more complex, including alliances. 2 chimpanzee males may cooperate to share a top spot in their troop.
Conflicts recede when a social hierarchy has been achieved. Animals learn of other individuals’ capabilities and defer when appropriate to avoid losing a fight. Chickens are less aggressive once they get to know each other, as are other species.
Social stability lasts only as long as abilities remain static. A young male chimp or baboon that grows stronger may challenge the existing hierarchy. Other relationships in the group may change in that wake.
Some animal groups are too large for all to know each other. Such species use status badges to maintain hierarchy and avoid unnecessary conflict.
Male house sparrows have black bibs, which distinguish dominant birds from subordinates by size. Harris’ sparrows have black head feathers to the same effect: the blackest heads are the top birds.
Male African red-shouldered widowbirds wear epaulets. Territory holders have larger and redder shoulder patches than territory floaters, who are loiterers in other birds’ territories. These 2nd-place birds immediately concede defeat when challenged but are ready to assume a territory should a resident vacate.
Cheating is prevented because weak mimics would face constant challenges that they would lose. Deception would come with a heavy social cost. While status badges are more reliable than they may first appear, they are used primarily in species that constantly encounter large numbers of other individuals, such as sparrows and great tits.
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For most species social organization and individual interactions are too various to easily categorize. Many factors are in play. Changing seasons often alter social organization.
Male chaffinches tend to dominate females in winter flocks, displacing them at feeding sites. This is reversed in spring, when females displace males, as male flocks disperse to establish territories.
Feral chickens on an island off Queensland, Australia alternate between a hierarchical flock during the winter and a territorial regime in the breeding season.
The social structures of some mammals may shift by season. Red deer are a dramatic example. Other than the breeding season, red deer bucks and doe live apart. Red deer males live in loose bachelor herds, with a dominance hierarchy by body size. A higher-ranking stag may displace lower-ranked stags at a choice food patch by lowering his head and displaying his antlers.
Females (hinds) live in their own herds with the young of both sexes. Hinds seldom threaten or displace each other, even in winter, when food is scarcer.
Come April, stags shed their antlers. Male aggression takes a new form: rearing up on their hind legs and boxing with their hooves. As new antlers grow, the males become ever more aggressive: fighting head-to-head.
With a hierarchy established, male red deer herds break up in September. Each male heads to a favored display area, where he roars to gather hinds coming into estrous. So goes rutting season. Males defend the females they attract rather than any territory. Rutting season is but a few weeks, whereupon the different sexes return to their respective herds for the winter.
Sociality is commonly consistent for many mammals. Wolves hunt in packs, with a stable hierarchy based on their extended family group. Lion prides are similar in their social permanence.
Compared to wolves, elephant social order is more extended and complex. Females maintain immediate family groups of 5 to 15, which may also include young elephants of either sex. When a group gets too big, elder daughters form their own group, though the different herds remain aware of their family ties. Male adults are more solitary, though they do occasionally form friendships with other males, as well as establish dominance hierarchies for breeding rank.
Many primates maintain a uniform social organization regardless of season, characterized by complexity and subtlety in individual affections. Even lemurs have intricate mixed-sex social groups, with each troop maintaining a stable-boundary territory. Relationships are mostly friendly, except for males during the short breeding season, when dominance hierarchies play out. There are strong mother-offspring bonds. Play and mutual grooming are ubiquitous.
Each animal that lives in a complex social assemblage is critically dependent on cooperative interactions with others. This necessitates mental models of behaviors toward other individuals according to intimacy, biological relation, and social hierarchy.
A rhesus macaque mother may hold her own infant along with another of similar age. The other being held is most often the offspring of a dominant female.
The hope is for a social head start: to engender future association between one’s own offspring and high-ranking youngsters. Other primates behave similarly.
The social norms of different primate species vary, but monogamy is rare. Gibbons are a near-perfect exception to that rule. They have lifelong pair bonds between male and female, and a strict territoriality that is maintained by elaborate singing, especially at dawn. There are parallels between gibbons and songbirds in facets of their lifestyles.
Cooperation
Cooperation has posed a major problem to evolutionary biologists since Darwin, because although cooperation and altruism abound in Nature, Darwin’s theory of natural selection is based on the “survival of the fittest.” ~ English psychologist Andrew Colman
Living is an opportunistic exercise. Cooperation happens when it aligns with self-interest. The subtle issue inherent in such alignment is how self-interest is perceived.
While the exercise of cooperation is learned, its capacity is inborn. The innate basis for cooperation is similarity recognition: sensing a likeness between self and others.
High levels of animal cooperation are often found in very harsh and unpredictable places – from birds on African savannahs to bees in the Alps. ~ English evolutionary biologist Patrick Kennedy
From a genetic perspective, relatives are ready cooperators. Members of a group, even unrelated, tend toward cooperation when threatened or a mutual benefit is perceived.
Matabele ants only eat termites. It’s a hazardous food source, as the termites fiercely defend their nest, killing and maiming marauding ants. Ants injured in a foray are carried back to the nest by their comrades where they can recover. Many of the wounded ants wouldn’t otherwise survive. Knowing that the risk of the hunt is minimized helps sustain courage for the chancy endeavor.
Organisms are innately tribal, beginning with microbes cooperatively sharing genes to sustain the community.
Plants cooperate by warning others. These endeavors take energy, and so cannot be dismissed as incidental.
Many spiders make their way through life on their own, but some habitats are too harsh to do so. Lowland tropical rainforests offer tremendous prey potential, but the wind and rain are hard on spider webs, so they band together and help one another.
By living in groups, spiders can occupy spaces that they wouldn’t otherwise be able to. The spiders make dense webs that require a lot of silk. When the webs get damaged by strong rains or colonies are attacked by predators, some spiders can protect their offspring while others go and make repairs. ~ Ecuadoran evolutionary biologist Leticia Avilés
Likeness identification can have a softer side, especially when facing hard luck. Cooperation can be empathy in action. An animal may emotionally identify with another, which may be as simple as recognizing similarity in predicament.
Captive animals of different species tend to friendship from mutually facing eternal confinement. Life alone is lonely. Friendship is essentially emotional cooperation.
Regardless of species, individuals cooperate to mutual gain if the individuals involved can override their fear, which is most easily overcome by similarity recognition. If one animal can perceive a likeness in another, however that perception is taken, cooperation becomes a possibility.
There are several forms of cooperative behavior. Many behaviors, particularly intimate ones, are too nuanced or furtive to be observed in the wild and satisfy scientific rigor.
What has been repeatedly and variously observed as cooperative endeavor is predation.
Lionfish
Lionfish are venomous predators. When they hunt alone, they waste no time in devouring prey.
Lionfish savor the experience of having a hunting partner. A lionfish shimmies its tail and fans it fins to invite another lionfish to join him for a meal.
Hunting buddies are always polite to one another. The first one to strike takes a bite and backs off, allowing its partner to secure a mouthful.
Hunting together is more successful than solo endeavors. And it’s more fun to share dinner.
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Numerous predators hunt in groups.
Pseudoscorpions
Social behavior is rare among arachnids. ~ Brazilian ecologists Everton Tizo-Pedroso & Kleber Del-Claro
Pseudoscorpions are arachnids that look like scorpions in having flat, pear-shaped bodies and front pincers. Alas for them, they lack the scorpion’s stinging tail. There are over 3,300 species of pseudoscorpion in more than 430 genera. Pseudoscorpions emerged ~380 million years ago, during the Devonian.
After hatching, pseudoscorpions reach maturity in 10–24 months after molting a few times. Depending upon species, adults grow to 2–12 millimeters long, and may live 2–4 years.
Pseudoscorpions often practice phoresy: using another, larger animal as transport. Their pincers help them catch a ride.
Paratemnoides nidificator colonies are found under the bark of trees in the vast Brazilian Cerrado (tropical savanna). P. nidificator hunts in packs to bring down larger prey. They then share the spoils equitably, with hunters eating first, then younglings, and finally others in the colony.
Obligatory parental care favors the evolution of behavioral strategies that prioritize the feeding of juveniles. ~ Everton Tizo-Pedroso & Kleber Del-Claro
These pseudoscorpions take different work roles based upon their age and personality. Males and young females tend to hunt, while others spend time on home maintenance and caring for the young.
Division of labor is a strategy that maximizes foraging and reproductive success. ~ Everton Tizo-Pedroso & Kleber Del-Claro
Females will let their offspring eat them if food runs short. P. nidificator plan their breeding to avoid that.
Prey diversity and abundance seem to be the main factor limiting reproduction. ~ Everton Tizo-Pedroso & Kleber Del-Claro
P. nidificator live in tight-knit social communities. They are never aggressive toward one another.
Cormorants fish in different formations by group size. They vary their fishing tactics depending upon water turbidity and fish distribution.
Pelicans will form a tightly coordinated aerial crescent and dive for fish, closing the formation into a circle once in the water. This optimizes the odds of everyone getting something to eat.
Hawks and eagles sometimes cooperatively hunt. Harris’s hawk hunts in groups of 2 to 6, allowing them to snag jackrabbit, which, at over twice the size of single hawk, would be too much for a solitary hunter to take down. Coordinated hawk tactics vary depending upon the situation.
Crocodiles and alligators cooperatively collaborate during their hunts. Some swim in a circle around a shoal of fish, making the circle tighter until the fish are forced into a tightly woven bait ball. Then the crocodiles take turns cutting across the center of the circle, snatching prey.
These reptiles sometimes use their different sizes to advantage. Larger alligators drive fish out of deep lake waters into the shallows, where smaller, more agile ones are waiting.
The South American giant otter may grow to 1.7 meters and 32 kilograms. These otters eat mostly fish, principally caught solo; but they hunt cooperatively when pursuing large prey, including caiman and anaconda.
With obvious coordination, a caiman is attacked simultaneously from different directions. 2 or more otters will bite a large anaconda at different points, holding the snake fast, then bashing the body against fallen tree trunks floating in the water.
Dusky dolphins herd anchovies in the ocean using both coordinated chase and noise tactics;: a cooperative venture that creates a tight ball of anchovies, whereupon the dolphins take turns diving into the ball to grab bites while the others keep the anchovies balled.
Lionesses
Lionesses in a pride commonly cooperatively hunt, and when doing so enjoy greater success than solitary hunting, as a group can bring down bigger game. Their typical tactics, such as spacing, appear more opportunistically aware than intentionally coordinated: individuals taking advantage of a group endeavor.
Lionesses are quite capable of being thoughtful team plays. In one instance, 4 lionesses approached a herd of wildebeest with a businesslike gait. The wildebeest had split into 2 groups: one with about 50 to 60, the other group 100 or so. The hunting party kept enough distance not to startle the wildebeest. The ground was uneven, and the hunters diverged without the wildebeest being able to see the split.
As diversionary showpieces, 2 lionesses slowly climbed atop 2 adjacent mounds, where they sat upright, stationary but conspicuous. The wildebeest kept a wary eye on those 2. A 3rd lioness slinked her way into a ditch between the 2 groups.
A 4th lioness bolted from the forest behind the smaller group, driving those wildebeest toward the larger group and the showpiece lionesses, and over the ditch where 1 lioness lay in wait. As the wildebeest bounded over the ditch, the lioness there leapt up and grabbed 1, killing it. The 2 diversionary lionesses then joined the feast of 4, while the reunited wildebeest looked on in a line from the open plain.
In hunting gazelle, groups of lionesses form a U-shaped pattern, surrounding their prey on 3 sides, whereupon they close in.
Lionesses in a pride – often sisters or mother and daughters – hunt together for many moons. They know each other intimately. In group hunting, individual lionesses take consistent positions in strategic formations.
It was long thought that male lions were dependent upon lionesses for largesse. Instead, males are adept ambush hunters, relying upon the cover of darkness or vegetation. Male lions do not cooperatively hunt.
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Baboons are somewhat like lions in their hunting habits: one starts hunting and others join in. Whether a female that makes a catch can eat much of it depends on the aggressiveness of the dominant males in the group. Often female baboons are robbed of their prey. Baboons are not inclined to share.
Besides baboons, many monkeys cooperate with each other and generally possess a strong sense of fairness.
Comparatively, chimps play favorites: they cooperate in corralling game and share the spoils more easily if there are good relations between the parties. Chimps practice reciprocity with cooperative endeavor and share food.
Empathy & Altruism
Darwin’s initial conception of “survival of the fittest” was that competition was individual within a species, with the winners evolving the species. Darwin’s encounter with social insects created for him “one special difficulty, which at first appeared to me insuperable, and actually fatal to my whole theory.” That “special difficulty” was altruism. How to account for worker bees and ants toiling their lives away with no prospect of propagation?
Darwin’s “special difficulty” made him a family man: he expanded the survival competition concept to group selection, thus allowing for altruism among family members. Darwin came to think that the family that works together survives as the fittest: kin selection. That notion also proved inadequate to explain the widespread altruism between animals not related.
That said, relatedness does matter to animals. Honeybees are more likely to deliver food to their full sisters than half-sisters from a queen having mated with several drones. Ground squirrels are more likely to raise an alarm if family members are nearby. Individual animals of many species self-sacrifice for relatives, and not just offspring.
Coerced Altruism
Union gives strength. ~ Aesop
Manipulation of others is common in Nature, particularly by parasites. Examples abound. For one, parasitic roundworms cause the abdomen of their arboreal ant host to turn berry red, duping birds into eating it. This spreads the parasite via bird droppings.
Manipulation can also produce altruism. Eusocialism in insects evolved through coercion. The earliest queens purposely provided poor nourishment and/or aggressively kept their brood in check. Daughters had little choice but to help mother.
The sweat bee is an early-evolved eusocial insect. The 1st generation of a new nest are mostly small-bodied female workers which help the queen raise the next, larger generation. These 1st brood daughters could reproduce, either within the nest or after leaving to found their own colony. But the queen has diminished their likelihood of independent success by undernourishment – hence their small size. Meanwhile, the few 1st brood males are full sized; no difference between the 1st and succeeding generations.
Offspring may fail to resist manipulation if the cost of resistance exceeds the benefit. With largely selfsame genes, a queen can rather readily coercively co-opt cooperation from her children. But the temptation for a worker to get her own genes passed on never lets up, even in long-evolved colonial insects. An altruistic worker bee typically abstains from sex unless it gives her a shot at a royal baby.
4.2% of Western honeybee drones are the love child of worker bees. Just before virgin queens set out to establish their own colonies, worker-produced drones peak at over 6%. Breaking rank is worth the risk if it increases the chance of siring a hive.
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Vampire Bats
Vampire bats must feed on fresh blood at least once every 3 days or face starvation. Inexperienced young bats often fail. They then desperately beg for a drink from those who have fed. (As they are noticeably bloated, well-fed bats are obvious to the less fortunate. If not apparent, bats rub bellies to see who is in a position to share.) Engorged bats will often regurgitate blood to the benefit of their begging companions, related or not.
Bats remember such favors, and practice reciprocal altruism. If a bat gives to another, but the favor is not returned at a time of need, the ingrate will be ignored in the future.
Further, bats are sociable, and reputation matters. Selfish bats may be shunned when in need. Selfishness runs a considerable risk.
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Altruism has an even broader reach than kin, one that goes well beyond the facile competitive creed of “survival of the fittest.” Pure altruism has been observed in many animals, even the highly hierarchical dwarf mongoose. Stories are legion of dolphins of helping humans lost at sea.
Habitats and social dynamics differ, as does the way sharing occurs. The distinctions in altruism among all animals are only of degree, circumstance, and social norm, not of understanding.
Cichlids help defend or maintain shared territory depending on their personality: aggressive or risk adverse. As with many other creatures, personality plays out on a stage of sociality for cichlids.
Chimpanzees help others proactively simply because they understand that help is needed. The assist may be sharing food or joining a brawl. And the helper may not be related to the one(s) getting help.
Generous behaviour is known to increase happiness, which thereby motivates generosity. ~ Korean cognitive psychologist Soyoung Park et al
Cooperation and altruism are behavioral byproducts of need – if not in the moment, in recognition that the future is uncertain. Altruism is an exercise of empathy: a reaction from emotional identification and affinity. Rodents will liberate trapped cage mates even when they have nothing to gain.
Empathy is as innate as selfishness. The two are paradoxical twins that swap priority depending upon circumstance and personality.
Neonates will start crying in response to hearing another baby cry. Human infants offer comfort as an empathic initiative beginning at 1 to 2 years of age, after the necessary conceptual mental capacities develop.
Researchers have observed that mice show empathic response to other mice in pain, as demonstrated by writhing and licking their paws; more so when the pained one has been a cagemate. As emblematic of emotional contagion, mice are more sensitive to their own pain when in the presence of another mouse in pain, even if the pains are of a different sort.
Upon return to the den from a successful hunt, African wild dogs regurgitate a portion of partially digested meat for a female’s puppies and their babysitter. The babysitter beneficiary may not be related. These dogs will risk themselves to protect pups from powerful predators, such as a hyena or cheetah. The pups need not be a dog’s offspring.
At seasonal breeding grounds, unattached Adélie penguins help defend nests and nurseries belonging to other birds against attacks by skuas.
Social behaviors, including altruism, easily extend beyond one’s own species given common cause. Bird alarm calls are exemplary. At some risk to the caller, warnings benefit several other species that share the bird’s habitat.
Bird mobbing behavior is an even more overt example. When small birds of various species spot a hawk, owl, or other predator resting in their territory, they mob it, while uttering characteristic clicking sounds that attract other birds to the vicinity. A safer neighborhood benefits all.
Many species of birds, rodents, and primates practice altruism even if close relations are not involved. Capuchin monkeys are tolerant of friends coming by and taking some of their food. Caged capuchins will share food with another in an adjacent cage, especially if the sharing has been reciprocated in the past.
Zuni was a bonobo imprisoned at the San Francisco Zoo. One day a bird flew into Zuni’s enclosure, only to smack into a glass window in trying to fly out. Zuni gently picked up the stunned bird, stroked it, and carried it up to the top of a climbing frame. Placing the bird in position to escape, Zuni tried launching the bird. But the bird was too stunned and fell back to earth. Zuni retrieved the hapless bird, gently nestling it for the rest of the day. When the bird had sufficiently recovered, Zuni released it.
Chimpanzees selectively share the spoils of a kill. A successful chimp hunter will rip a carcass chunk off for a beggar, but the giving appears tactical. Giving is easy to other male hunting companions. A high-ranking male coming in after a kill is less likely to gain a piece of the prize than are lower-ranking fellow hunters. Chimp males also selectively share with female friends, and not just for sexual favors.
Friendship
Friendships between individuals are amply documented in people, chimpanzees, baboons, rhesus monkeys, rodents, horses, hyenas, lions, elephants, and dolphins. Elephants are notable for the lifelong bonding between a mother and her daughters. Sharing food, providing emotional support to others, comfort to the injured, and grieving upon the death of friends are all on display within the animal kingdom.
Numerous bird and mammal species are known to mate for life; beyond the needs of parenting, these couples are the most intimate of friends until death parts them.
Via sustained proximity, friendship comes naturally among relatives. But unrelated animals often have enduring bonds.
Males are particularly prone to have long-lasting buddies from relationships which typically formed as youngsters: playmates of the same age, not necessarily siblings. If a wolf leaves his pack, for whatever reason, his friends howl and howl from the loss. The departure of a less valued packmate does not elicit such a mournful reaction.
Generally, while females have friends, being a mother also brings strong emotional rewards and bonding with brood. Nature’s ruse for the sacrifices of breeding come in emotional payoff by attachment to offspring.
Among baboons, the strongest social bonds are between mothers and daughters, followed by sisters and other female relatives, including aunts, nieces, and cousins.
Females have more fluid bonds during their fertile years but tend to cherish tight bonds with a few other select females after the last possible offspring have been reared. Horse mares form long-lasting alliances, in part to keep aggressive stallions at bay.
Grooming is a common expression of friendship. It is both beneficial to the receiver and an act of intimacy, not to mention it feels good to receive and to give.
Ruby was a young, low-ranking baboon female who lost all of her kin in a leopard attack. Because baboon social support is commonly kin-based, Ruby’s prospects were poor.
But Ruby was gregarious. She spent hours grooming Sylvia, a high-ranking baboon who befriended her. By her temperament, Ruby was able to climb the social ladder, gaining access to the best food and most desirable resting places.
Friendship is as simple as seeking comfort or companionship from another to improve one’s own life experience. ~ American author Jennifer Holland
Interspecies Bonding
There are numerous stories of animals of different species forming social bonds. One is notably well-known.
In Kenya, a 1-year-old hippopotamus named Owen formed a close bond with a century-old tortoise named Mzee (Swahili for old man) after they came together at a wildlife sanctuary in Mombasa. They slept and ate together, inseparable friends.
2 baby red pandas born at Amsterdam’s zoo were abandoned by their mother. The zookeeper’s house cat, which had just given birth, let the 2 panda newborns nurse alongside her kittens.
Timur is a goat given as a live meal to Amur, a Siberian tiger at a Russian safari park. The stubborn goat refused to be eaten. Instead, the two became the best of friends. Amur gave up his sleeping spot to Timur, who, when awake, follows Amur wherever he goes.
In her captivating book Unlikely Friendships, Jennifer Holland chronicled 47 interspecies animal friendships of abiding affection. Many were quite unlikely, including: Sumatran tiger twin cubs and orangutan babies; a rat and a cat; a little Dorcas gazelle and a protective zebra (zebra are known to be aggressive toward antelope, even killing newborns, making this friendship especially surprising); an iguana and a house cat (lots of snuggling, not a known lizard proclivity); a leopard and a Brahmin cow (the leopard cuddled while being cow-licked); a sled dog pup and a polar bear (roughhousing play; such interspecies playfulness between sled dogs and polar bears has been seen numerous times; polar bears have even acted protectively toward the dogs); a baby oryx and a motherly lioness; a hamster and a rat snake; a rhinoceros, a warthog, and a hyena; a lion, a tiger, and a bear (oh my!).
Dogs figure regularly in interspecies relationships, numerically because they are so commonly around humans, but mostly because of their innate bonding sociality, which is what makes them a most popular pet in the first place. But then, the cat family too figures in prominently.
Many of these odd pairings came about in an environment of a nature park, wildlife sanctuary, or zoo. The wild is a different setting. Close contact between different species, where such friendships might arise, is seldom seen in the wild; though it does occur, and more often between social species. The awareness that comes with sociality affords realization that friends bring value to life regardless of their origin.
