6 Things About Capuchins

6 Things About Capuchins

Tool Usage

Tool usage is a rare, adaptable and intelligent behaviour often attributed to that of the great apes that can stand bipedally for much longer than monkeys. One of the few examples of monkey tool usage resides in capuchins. When sitting upright, the hands get freed up for extractive foraging techniques (providing more options in times of scarcity), with differing approaches between individuals.

For instance, cracking open nut shells such as palm nuts encasing fruit, with a combination of rocks that act as a hammer and anvil (some weighing as much or more than them) - if their jaws can't do the job. Or they can use sticks to probe for insects like termites in their mounds, as insects are the staple fallback food for capuchins despite being opportunistic omnivores.

Other instances could consist of utilising leaves as cups to retrieve/hold water, spreading millipede secretions superficially for mosquito, insect bite and parasite repellent; using sharp stones to dig through firm soil when their claws cannot, and having rocks plus sticks as 'ammo' for predators, territorial protection, disputes and even courtship.

Tool usage is more so reward-driven than by experimental curiosity (a psychologically invoked response towards a need or desire), and males usually exhibit the behaviour more often than females. Younger capuchins gradually adopt similar methods to that of more proficient and experienced adults via observation, yet taking numerous years to master (except they can live up to ~50 years).

More complicated tasks assumably require more tool modification and active trial and error attempts, e.g., combining sticks to reach further or trying to find the optimal sharpness, size and weight in a stone in order to strike a nut.

Still, tool usage in monkeys mostly doesn't seem to reach the level of the apes. The theorised difference between them and the great apes like chimps pertains to comprehension rather than performance. Capuchins have the capacity for experimentation and eventual success - but seeming aimless with no perception in comparison. The tools aren't necessarily tailored to be effective for a given task and might lack application of specificity. So discerning what makes one tool successful and another one not; makes the distinction (like random trial and error attempts with no recording or reflection of results).

For example, chimps can perceptually 'reorientate' to solve a problem, such as incorporating separate objects into one 'entity' - like moving boxes together to form 'stairs' out of them - perhaps to reach something when climbing is impossible. It's conceivably an implicit display of reasoning for the 'stairs' - with a particular aim to gain more height.

Intelligence

Capuchins are one of the cleverest monkey species. They have the capability to 'invent' new behaviours - spontaneous innovations/epiphanies that start out as idiosyncratic, then probably spreading throughout the group via observation, with slight individual differences.

It will likely exclusively represent that population, forming the 'tradition'/'culture' dictated by their 'toolkit'. The behaviours depend on ecological variation, where given traits, such as types of tool use, are present in some populations but absent in others.

The more skilled plus creative capuchins were more likely to survive, reproduce and teach descendants; therefore, given traits would become more prevalent with natural selection. Tool usage might not be as developed in wild habitats - as capuchins can imitate humans within captivity - yet it is still distinctly present regarding capacity for intellect.

Likewise, they seem to be super sentient and easy to train. When trained extensively since infantry as service animals in homes for paralysed people, they can help open drink bottles, microwave food, retrieve objects, flick light switches, wash the person's face, and probably open/close doors. Capuchins are 'nature's butlers' - like assistance dogs 2.0.

Insight

Insight, in this case, would be defined as one's capacity to gain a clear understanding through higher thought. Innate intuition, associative learning/conditioning, trial and error, habituation and observational learning are types of behaviours on the continuum that can intertwine to form the processes culminating in insight, the most advanced, specified and rarest type.

Insight is an intangible and abstract concept, basically being impossible to prove the distinctive phenomenologies of the mind. It emphasises the extent of convolutedness between 'what?' and 'how?' in a situation. The 'how?' of a query respects the specific type of approach, inferring an elaborate expression of intelligence, utilisation of gathered info and potentially implied reasoning (like with the 'stairs') - compared to just identifying said query - which is pretty instinctual.

The most outstanding behaviour of a capuchin's repertoire; is versatile tool usage/manipulation again, a type high up on the continuum. Adjustments can be made according to situational queries - including stone 'hammer' selection corresponding to the 'anvil' site variables, alongside the nut species and its maturation stage (if it's easier or tougher to crack).

They can try different stone shapes, sizes, masses; and alter dexterity to find the successful spatial and/or force relationship to solve the nut puzzle. Less powerful but smoother, more efficient/controlled striking movements save energy - precisely targeting certain parts of the shell surface and avoiding smashing the kernel. The motor skills get built up through repetition and muscle memory.

Sociality

Wild groups have thorough social structures; there are mainly females, and a few males, with one dominant and commonly the father of all babies (there can be a dominant female too). Allogrooming remains the universal action of intimacy/friendship. It's a sign of respect, group stabilisation, dispute resolution and keeps them clean.

Considering innovation in different groups, there are diverse social rituals like eye-poking, hand sniffing and ripping out a hair tuft to pass around (for some reason). These interactions function to 'feel each other out' - establishing, maintaining and testing social bonds.

There are also some different facial expressions that develop as infants get older. Some examples and their likely connotations include...

Open mouth, bared teeth = threat face

Relaxed open mouth = play/play reassurance

Scalp raise = active contact initiation/response

Lip-smack = passive contact and/or reassurance of association

Silent bared teeth = play in juveniles, but affiliation and/or submission in adults)

Lastly, there is cooperation and deception. Prosocial behaviour seems rewarding, stemming from intelligence and promoted by empathy and/or sympathy. Groups possess a sense of fairness, which upholds said sociality for harmony and function. With food, capuchins are the most kind concerning familiar kin and when items are deemed equal in worth.

Selfish capuchins get alienated as they're disruptive to the group's survival, so they're probably aware of when altruism is redundant, otherwise getting exploited easily. However, all can be a lot more selfish with strangers; if one finds a valuable item or when others aren't visible.

Locomotion

Primarily as tree-dwellers, capuchins naturally have incredible forearm strength, grip strength with claws, endurance and opposable thumbs + toes. They climb trees plus tree branches, swing and jump/leap as their salient forms of arboreal movement.

In response to strenuous physical locomotory demands, they can use more compliant and stable branches, minimising path length and managing energy costs. They can even wash urine on their hands and feet to improve grip with stickiness.

Capuchins also have a prehensile tail for grasping and coiling around branches while hanging underneath. It's 30-56cm long on average; and is as long as the body. It's like a 5th limb, balancing them and freeing up the others to reach for food, for example, since it can support the full bodyweight (a couple/few kilos or even less).

Gracile and Robust

It's speculated that population divergence occurred in capuchins via separation on either side of the amazon river - eventually altering the genetic make-up of each division. It is called the 'founder effect', where the subsets of the larger, more diverse population found a new, differentiated population.

The original population split into the now-known 'gracile' (untufted) and 'robust' (tufted) capuchin types. Untufted ones have longer limbs relative to the body, meaning they are presumably more mobile concerning climbing, swinging, leaping and general arboreal movement. However, tufted capuchins have stronger jaws and teeth to break open nuts.

Untufted types have rarely gotten observed using stones. Although environmental pressures/limitations of food scarcity have likely forced adaptations in the now tufted types, being typically more proficient and creative with tools to crack tough foods - maybe consequently becoming more intelligent, even though both populations have evolved similarly like humans (omnivory, larger brain size, social learning, cooperation and extractive foraging for instance). Perhaps untufted capuchins could afford to spend more time in trees due to higher food diversity and availability, thus becoming more equipped for locomotion suitable for it.

In general though, capuchins are better at breaking objects than other monkeys. They have complex enamel structures for crack/chip resistance, but tufted ones especially; are proposed to have intricate and dense formations residing in the front teeth and canines - since they specialise in breaking the more challenging foods.