“It is the hardest thing in the world to frighten a mongoose, because he is eaten up from nose to tail with curiosity. The motto of all the mongoose family is ‘Run and find out'” —Rudyard Kipling, Rikki-Tikki-Tavi
Cultural inheritance in banded mongooses
The banded mongoose is a bit of an anomaly in the mammal world. Instead of the offspring being raised by their parents (and behaving similarly to their parents), they instead inherit their behaviors from other adult mongooses. The adults are random, rather than closely related to the offspring, but take on a parental role in the sense that they sort of “adopt” a baby/juvenile (about one month old) and show it how to forage, hunt, stay safe from predators, and otherwise be a mongoose properly. These role models or “escorts” will carry around the pups and teach them closely for about two months. The plasticity of mongoose behavior is sufficient to allow for pups to behave more similarly to their role models than to their parents.
This kind of transmittance of behavior is known as cultural inheritance, and is actually quite common in the animal world– but the unique setup in mongooses provides an opportunity to easily decouple the direct genetic inheritance from parents and the cultural inheritance resulting from behavioral plasticity (social learning).
Cultural evolution is becoming one of the most popular topics in biology as more and more scientists are beginning to notice how new behaviors can sweep through a population in less than a generation. The classic non-human example of this would be humpback whale songs changing year to year.
While cultural evolution occurs more quickly than genetic evolution in one sense, it also allows for genetic diversity to persist. Higher behavioral plasticity results in higher variety of trait and higher variety of preference for those traits. It can actually slow down evolution towards physiological adaptation for an environment by slowing the adaptation of physiological change. That being said, it can allow for more rapid adaption and by relying on social learning, only one or a few members of a population need to “discover” a new behavior for it to spread through the population.
It’s possible the mongooses have evolved this escort system as a way to maintain diverse foraging methods and reduce competition in their groups. Maintaining plasticity in foraging behaviors would be useful for social animals that have a wide variety of food sources, as the mongoose does.
Timon and Pumbaa: based on a true story
So admittedly Timon is a Meerkat not a banded mongoose, but it’s the same family so it’s close. In a cool example of mutualism, Warthogs (which, by the way, are awesome animals and don’t get nearly enough love) can rid themselves of ticks and bugs by getting groomed by mongooses.
Warthogs–which should look kind of scary to a small mongoose, actually get along quite well with them. Wild pigs tend to have quite a few ectoparasites and bugs inhabiting their skin/fur which can provide an easy snack for the banded mongoose. Warthogs have learned to lay down when mongooses are nearby, so they can pick off the parasites. Besides allowing mongooses to groom them, they also welcome vervet monkeys to snack on their ticks.
Mutualism between mammals is somewhat rare, but wild pigs and mongooses (and vervets for that matter) are highly intelligent and it shouldn’t come as much of a shock that they are able to enjoy the company of other species.
Mutualistic foraging between dwarf mongooses and hornbills
In another species of mongoose, the dwarf mongoose of the Taru desert often cooperatively forages with large birds, particularly hornbills, who share the same prey. The hornbills will wait to start foraging around termite mounds if the mongooses are sleeping and the mongooses will wait for the hornbills to be nearby to begin their foraging. This is true mutualism, as, while many animals have instances of exploiting each other’s coincidental presence for their benefit, the hornbills and dwarf mongoose actually plan their foraging activities around the other.
The mongooses and the hornbills will warn each other of predators while they forage. The hornbills will even warn the mongooses when there are predators nearby that do NOT prey on the hornbills. The hornbills recognize predators specific to the mongoose as they will not warn against predators that do not prey on the mongoose. This is a pretty unique relationship as most cases of mutualism do not involve so much complex compensative behavior between species. The two species will communicate to one another with different vocalizations, and hornbills will sometimes wake up the sleepy mongooses when they’re impatiently waiting to start snapping up unfortunate insects.
Convergent evolution of neurotoxin resistance
Mongooses are mostly known for fighting cobras (partly because they’re exceptionally quick) but their resistance to the alpha-neurotoxin in cobra venom is what especially allows for this feat.
Acetylcholine is a very important neurotransmitter, so there are acetylcholine receptors all over your muscle cells that need to be free to bind (or not bind) acetylcholine, allowing your muscles to expand/contract. This neurotoxin, called alpha-bungarotoxin (alpha-BTX), works by binding to these acetylcholine receptors and blocking them up resulting in paralysis and eventually death. However the mongoose, the snakes themselves, and several other animals have independently evolved to alter the shape of their acetylcholine receptors so the neurotoxin, alpha-BTX, doesn’t bind.
Tweaks to the nicotinic acetylcholine receptor to prevent snake neurotoxin binding have been shown to have evolved at least four separate times in mammals (the honey badger, pigs, mongooses, and hedgehogs), but in the mongoose, the tweak involves a glycosylation site on the receptor matching the site present in snakes.
Syncing up birthdays
Despite being highly social and altruistic, meerkats are a more vicious member of the mongoose family and are especially well known to participate in infanticide. As meerkats live in a matriarchy with intense dominance hierarchies, many babies do not stand a chance from more dominant pregnant females. Banded mongooses however, have managed to evolve to sync up their birth so they’re all born on the same day. This prevents infanticide as all females are on essentially identical schedules (hormonally and in how they spend their time), so pups are never left alone with other females.
While most mammals have adapted to differentiate their own offspring very well, the banded mongoose benefits from having all pups be treated equally by the adult mongooses. Syncing up birth to the day or few days is a useful strategy, also seen in flamingos, where both male and female flamingos will even produce and feed crop milk to young who are not their own. However unlike flamingos, syncing up birthdays seems to be more about preventing infanticide and having a more lax dominance hierarchy.
This is a pretty unique strategy as usually species tend to fall on a continuum of high to minimal parental care. In this case, the banded mongoose receives a lot of “parental care” but not necessarily much from their parents. In almost all of nature, the level of paternal parental care is based on certainty of paternity, yet the mongoose has no idea who its close kin are. The behavior where a species mentors and takes care of young they know are not their own is, of course also seen in humans. Mongooses are exceptional in their array of cooperative behaviors– displaying reciprocity, altruism, cooperative breeding, and mutualism. But knowing humans, most will probably continue to believe we are special and entirely disconnected from these evolutionary adaptations.
- Dwarf mongoose and hornbill mutualism in the Taru desert, Kenya. O. Anne-E. Rasa – Behavioral Ecology and Sociobiology – 1983
- How the mongoose can fight the snake: the binding site of the mongoose acetylcholine receptor. D. Barchan-S. Kachalsky-D. Neumann-Z. Vogel-M. Ovadia-E. Kochva-S. Fuchs – Proceedings of the National Academy of Sciences – 1992
- Decoupling of Genetic and Cultural Inheritance in a Wild Mammal. Catherine Sheppard-Harry Marshall-Richard Inger-Faye Thompson-Emma Vitikainen-Sam Barker-Hazel Nichols-David Wells-Robbie Mcdonald-Michael Cant – Current Biology – 2018
- Reproductive competition and the evolution of extreme birth synchrony in a cooperative mammal. S. Hodge-M. Bell-M. Cant – Biology Letters – 2010