Animal culture involves the current theory of cultural learning in non-human animals, through socially transmitted behaviors. The question as to the existence of culture in non-human societies has been a contentious subject for decades, largely due to the lack of a concise definition for the word "culture". However, many leading scientists agree on seeing culture as a process, rather than an end product. This process, most agree, involves the social transmittance of novel behaviour, both among peers and between generations. Such behaviour can be shared by a group of animals, but not necessarily between separate groups of the same species.
The notion of culture in animals dates back to Aristotle in classical antiquity, and more recently to Charles Darwin, but the association of animals' actions with the actual word "culture" first originated with Japanese primatologists' discoveries of socially-transmitted food behaviours in the 1940s.
What is culture?
Culture
can be defined as "all group-typical behavior patterns, shared by
members of animal communities, that are to some degree reliant on
socially learned and transmitted information".
Organizational culture
One
definition of culture, particularly in relation to the organizational
aspect is the utilization of "involvement, consistency, adaptation, and
mission." Cultural traits that are indicators of a successful form of organization
are more likely to be assimilated into our everyday lives.
Organizations that utilize the four aforementioned aspects of culture
are the ones that are the most successful. Therefore, cultures that are
better able to involve their citizens towards a common goal have a much
higher rate of effectiveness than those who do not have a shared goal. A
further definition of culture is, "[s]ocially transmitted behavior
patterns that serve to relate human communities to their ecological
settings."
This definition connects cultural behavior to the environment. Since
culture is a form of adaptation to ones environment, it is mirrored in
many aspects of our current and past societies.
Cultural sociology
Other researchers are currently exploring the idea that there is a connection between cultural sociology and psychology.
Certain individuals are especially concerned with the analysis of
studies connecting "identity, collective memory, social classification,
logics of action, and framing."
Views of what exactly culture is has been changing due to the recent
convergence of sociological and psychological thought on the subject.
"Recent work depicts culture as fragmented across groups and
inconsistent across its manifestations. The view of culture as values
that diffuse other aspects of belief, intention, and collective life has
succumbed to one of culture as complex rule-like structures that
constitute resources that can be put to strategic use."
Culture is specific to region and not just one umbrella definition or
concept can truly give us the essence of what culture is. Also
referenced is the importance of symbols and rituals as cognitive
building blocks for a psychological concept of shared culture.
Memes and cultural transmission
Richard Dawkins argues for the existence of a "unit of cultural transmission" called a meme.
This concept of memes has become much more accepted as more extensive
research has been done into cultural behaviors. Much as one can inherit
genes from each parent, it is suggested that individuals acquire memes
through imitating what they observe around them.
The more relevant actions (actions that increase ones probability of
survival), such as architecture and craftwork are more likely to become
prevalent, enabling a culture to form. The idea of memes as following a form of Natural Selection was first presented by Daniel Dennett.
It has also been argued by Dennett that memes are responsible for the
entirety of human consciousness. He claims that everything that
constitutes humanity, such as language and music is a result of memes
and the unflinching hold they have on our thought processes.
Evolutionary culture
A
closely related concept to memes is the idea of evolutionary culture.
The validity of the concept of evolutionary culture has been increasing
recently due to the re-evaluation of the term by anthropologists.
The broadening scope of evolution from simple genes to more abstract
concepts, such as designs and behaviors makes the idea of evolutionary
culture more plausible. Evolutionary culture theory is defined as "a theory of cultural phylogeny." The idea that all human culture evolved from one main culture has been presented, citing the interconnectedness of languages as one of his examples has also been presented.
There is, however, also the possibility for disparate ancestral
cultures, in that the cultures we see today may potentially have stemmed
from more than one original culture.
Culture in animals
According to the Webster's dictionary definition of culture, learning
and transmission are the two main components of culture, specifically
referencing tool making and the ability to acquire behaviors that will
enhance one's quality of life.
Using this definition it is possible to conclude that animals are just
as likely to adapt to cultural behaviors as humans. One of the first
signs of culture in early humans was the utilization of tools.
Chimpanzees have been observed using tools such as rocks and sticks to
obtain better access to food.
There are other learned activities that have been exhibited by animals
as well. Some examples of these activities that have been shown by
varied animals are opening oysters, swimming, washing of food, and
unsealing tin lids. This acquisition and sharing of behaviors correlates directly to the existence of memes. It especially reinforces the natural selection component, seeing as these actions employed by animals are all mechanisms for making their lives easier, and therefore longer.
History of animal culture theory
Though the idea of 'culture' in animals has only been around for just over half of a century, scientists have been noting social behaviors of animals for centuries. Aristotle was the first to provide evidence of social learning in the songs of birds. Charles Darwin first attempted to find the existence of imitation
in animals when attempting to prove his theory that the human mind had
evolved from that of lower beings. Darwin was also the first to suggest
what became known as social learning in attempting to explain the
transmission of an adaptive pattern of behavior through a population of
honey bees.
The vast majority of cultural anthropological research has been
done on non-human primates, due to their being closest evolutionarily to
humans. In non-primate animals, research tends to be limited, and
therefore evidence for culture strongly lacking. However, the subject
has become more popular recently, and has prompted the initiation of
more research into the area.
Dawkins's meme theory
Evolutionary biologist Richard Dawkins made groundbreaking headway into the field of cultural transmission with his 1976 book entitled The Selfish Gene, which focused heavily on the move to evolution being understood primarily by genetic influence. Dawkins coined the term meme,
the primary unit of cultural transmission or imitation, to explain an
overarching mechanism of how animal behavior is shared and spread to
lead to cultural evolution. The use of the word meme was an intentional
phonetic derivation of the similar sounding word "gene", which Dawkins asserts to be the primary unit of selection as it lends itself to pathways of biological evolution:
"We need a name for the new replicator, a noun that conveys the idea of a unit of cultural transmission, or a unit of imitation. 'Mimeme' comes from a suitable Greek root, but I want a monosyllable that sounds a bit like 'gene'. I hope my classicist friends will forgive me if I abbreviate mimeme to meme." (Dawkins)
The analogy
between the gene and meme proposed by Dawkins as units of evolutionary
biology serves to reinforce the idea that there is a particular pathway
of transfer associated with each unit that lends itself either to the
evolution of genotypic, phenotypic, and/or behavioral patterns within
animal groups. Dawkins asserts that in order for cultural evolution to
take place, there needs to be (1) variation within the memes present,
(2) the capacity for meme replication between two or more parties, and
(3) fitness advantages and/or disadvantages with each meme that lead to
the selection or rejection of one meme over another.
Likewise, these three criteria in the context of genes are also
necessary for genetic evolution. However, with the meme unit, cultural
transmission has a distinct feature of being capable of taking place by
individuals developing varying interpretations of the meme without
exactly "copying" it to pass it on. These interpretations lead to the
creation of new memes, which are themselves subject to a cyclic process
of selection, rejection, or modification.
Whiten's Culture in Chimpanzees
Andrew Whiten, professor of Evolutionary and Developmental Psychology at the University of St. Andrews, contributed to the greater understanding of cultural transmission with his work on chimpanzees. In Cultural Traditions in Chimpanzees,
Whiten created a compilation of results from seven long-term studies
totaling 151 years of observation analyzing behavioral patterns in
different communities of chimpanzees in Africa (read more about it
below). The study expanded the notion that cultural behavior lies beyond
linguistic mediation, and can be interpreted to include distinctive
socially learned behavior such as stone-handling and sweet potato washing in Japanese macaques.
The implications of their findings indicate that chimpanzee behavioral
patterns mimic the distinct behavioral variants seen in different human
populations in which cultural transmission has generally always been an
accepted concept.
Cavalli-Sforza and Feldman models
Population geneticists Cavalli-Sforza & Feldman
have also been frontrunners in the field of cultural transmission,
describing behavioral "traits" as characteristics pertaining to a
culture that are recognizable within that culture.
Using a quantifiable approach, Cavalli-Sforza & Feldman were able
to produce mathematical models for three forms of cultural transmission,
each of which have distinct effects on socialization: vertical,
horizontal, and oblique.
- Vertical transmission occurs from parents to offspring and is a function which shows that the probability that parents of specific types give rise to an offspring of their own or of another type. Vertical transmission, in this sense, is similar to genetic transmission in biological evolution as mathematical models for gene transmission account for variation. Vertical transmission also contributes strongly to the buildup of between-population variation.
- Horizontal transmission is cultural transmission taking place among peers in a given population. While horizontal transmission is expected to result in faster within-group evolution due to the relationship building between peers of a population, it is expected to result in less between-group variation than the vertical transmission model would allow for.
- Oblique transmission is cultural transmission being passed from one generation to another younger generation, such as is done by teaching, and the result of reproducing information across generations is a rapid loss of variation within that specific population. Unlike vertical transmission, oblique transmission doesn't need to occur strictly between parent and offspring; it can occur between less-related generations (e.g. from grandparent to grandchild), or from an individual to a non-related younger individual of the same species.
Mechanisms of cultural transmission in animals
Cultural transmission, also known as cultural learning, is the process and method of passing on socially learned information. Within a species, cultural transmission is greatly influenced by how adults socialize
with each other and with their young. Differences in cultural
transmission across species have been thought to be largely affected by
external factors, such as the physical environment, that may lead an
individual to interpret a traditional concept in a novel way. The
environmental stimuli that contribute to this variance can include climate, migration patterns, conflict, suitability for survival, and endemic pathogens.
Cultural transmission can also vary according to different social
learning strategies employed at the species and or individual level.
Cultural transmission is hypothesized to be a critical process for
maintaining behavioral characteristics in both humans and nonhuman
animals over time, and its existence relies on innovation, imitation,
and communication to create and propagate various aspects of animal
behavior seen today.
Culture,
when defined as the transmission of behaviors from one generation to
the next, can be transmitted among animals through various methods.
The most common of these methods include imitation, teaching, and
language. Imitation has been found to be one of the most prevalent modes
of cultural transmission in non-human animals, while teaching and
language are much less widespread, with the possible exceptions of primates and cetaceans.
Recent research has suggested that teaching, as opposed to imitation,
may be a characteristic of certain animals who have more advanced
cultural capacities, though this is debatable.
The likelihood of larger groups within a species developing and sharing these intra-species
traditions with peers and offspring is much higher than that of one
individual spreading some aspect of animal behavior to one or more
members. This is why cultural transmission has been shown to be superior
to individual learning, as it is a more efficient manner of spreading
traditions and allowing members of a species to collectively inherit
more adaptive behavior.
This process by which offspring within a species acquires his or her
own culture through mimicry or being introduced to traditions is
referred to as enculturation.
The role of cultural transmission in cultural evolution, then, is to
provide the outlet for which organisms create and spread traditions that
shape patterns of animal behavior visibly over generations.
Genetic vs. cultural transmission
Culture,
which was once thought of as a uniquely human trait, is now firmly
established as a common trait among animals and is not merely a set of
related behaviors passed on by genetic transmission as some have argued.
Genetic transmission, like cultural transmission, is a means of passing
behavioral traits from one individual to another. The main difference
is that genetic transmission is the transfer of behavioral traits from
one individual to another through genes which are transferred to an
organism from its parents during the fertilization of the egg. As can be
seen, genetic transmission can only occur once during the lifetime of
an organism.
Thus, genetic transmission is quite slow compared to the relative speed
of cultural transmission. In cultural transmission, behavioral
information is passed through means of verbal, visual, or written
methods of teaching. Therefore, in cultural transmission, new behaviors
can be learned by many organisms in a matter of days and hours rather
than the many years of reproduction it would take for a behavior to
spread among organisms in genetic transmission.
Social learning
Culture can be transmitted among animals through various methods, the most common of which include imitation, teaching, and language.
Imitation is one of the most prevalent modes of cultural transmission
in non-human animals, while teaching and language are much less
widespread. In a study on food acquisition techniques in meerkats (Suricata suricatta), researchers found evidence that meerkats learned foraging tricks through imitation of conspecifics.
The experimental setup consisted of an apparatus containing food with
two possible methods that could be used to obtain the food. Naïve
meerkats learned and used the method exhibited by the "demonstrator"
meerkat trained in one of the two techniques. Although in this case,
imitation is not the clear mechanism of learning given that the naïve
meerkat could simply have been drawn to certain features of the
apparatus from observing the "demonstrator" meerkat and from there
discovered the technique on their own.
Teaching
Teaching is often considered one mechanism of social learning,
and occurs when knowledgeable individuals of some species have been
known to teach others. For this to occur, a teacher must change its
behavior when interacting with a naïve individual and incur an initial
cost from teaching, while an observer must acquire skills rapidly as a
direct consequence.
Until recently, teaching was a skill that was thought to be uniquely human.
Now, as research has increased into the transmission of culture in
animals, the role of teaching among animal groups has become apparent.
Teaching is not merely limited to mammals either. Many insects, for
example have been observed demonstrating various forms of teaching in
order to obtain food. Ants, for example, will guide each other to food
sources through a process called "tandem running", in which an ant will guide a companion ant to a source of food.
It has been suggested that the "pupil" ant is able to learn this route
in order to obtain food in the future or teach the route to other ants.
There have been various recent studies that show that cetaceans are
able to transmit culture through teaching as well. Killer whales are
known to "intentionally beach" themselves in order to catch and eat pinnipeds who are breeding on the shore.
Mother killer whales teach their young to catch pinnipeds by pushing
them onto the shore and encouraging them to attack and eat the prey.
Because the mother killer whale is altering her behavior in order to
help her offspring learn to catch prey, this is evidence of teaching and
cultural learning.
The intentional beaching of the killer whales, along with other
cetacean behaviors such as the variations of songs among humpback whales
and the sponging technique used by the bottlenose dolphin to obtain
food, provide substantial support for the idea of cetacean cultural
transmission.
Teaching is arguably the social learning mechanism that affords
the highest fidelity of information transfer between individuals and
generations, and allows a direct pathway through which local traditions
can be passed down and transmitted.
Imitation
Imitation can be found in a few members of the avian world, in particular the parrot. Imitation forms the basis of culture, but does not on its own imply culture.
Imitation
is often misinterpreted as merely the observation and copying of
another's actions. This would be known as mimicry, because the
repetition of the observed action is done for no other purpose than to
copy the original doer or speaker. In the scientific community,
imitation is rather the process in which an organism purposefully
observes and copies the methods of another in order to achieve a
tangible goal.
Therefore, the identification and classification of animal behavior as
being imitation has been very difficult. Recent research into imitation
in animals has resulted in the tentative labeling of certain species of
birds, monkeys, apes, and cetaceans as having the capacity for
imitation. For example, a Grey parrot by the name of Alex underwent a
series of tests and experiments at the University of Arizona in which scientist Irene Pepperberg
judged his ability to imitate the human language in order to create
vocalizations and object labels. Through the efforts of Pepperberg, Alex
has been able to learn a large vocabulary of English words and phrases.
Alex can then combine these words and phrases to make completely new
words which are meaningless, but utilize the phonetic rules of the
English language.
Alex's capabilities of using and understanding more than 80 words,
along with his ability to put together short phrases, demonstrates how
birds, who many people do not credit with having deep intellect, can
actually imitate and use rudimentary language skills in an effective
manner.
The results of this experiment culminated with the conclusion that the
use of the English language to refer to objects is not unique to humans
and is arguably true imitation, a basic form of cultural learning found
in young children.
Language
Language
is another key indicator of animals who have greater potential to
possess culture. Though animals do not naturally use words like humans
when they are communicating, the well-known parrot Alex demonstrated
that even animals with small brains, but are adept at imitation can have
a deeper understanding of language after lengthy training. A bonobo named Kanzi has taken the use of the English language even further. Kanzi was taught to recognize words and their associations by using a lexigram board.
Through observation of its mother's language training, Kanzi was able
to learn how to use the lexigrams to obtain food and other items that he
desired. Also, Kanzi is able to use his understanding of lexigrams to decipher and comprehend simple sentences.
For example, when he was told to "give the doggie a shot," Kanzi
grabbed a toy dog and a syringe and gave it a realistic injection.
This type of advanced behavior and comprehension is what scientists
have used as evidence for language-based culture in animals.
Primate culture
A bonobo fishing for termites using a sharpened stick. Tool usage in acquiring food is believed to be a cultural behavior.
The
beginning of the modern era of animal culture research in the middle of
the 20th century came with the gradual acceptance of the term "culture"
in referring to animals. Japan's leading primatologist of the time, Kinji Imanishi,
first used the word with a prefix as the term "pre-culture" in
referring to the now famous potato-washing behavior of Japanese macaques.
In 1948, Imanishi and his colleagues began studying macaques across
Japan, and began to notice differences among the different groups of
primates, both in social patterns and feeding behavior.
In one area, paternal care was the social norm, while this behavior was
absent elsewhere. One of the groups commonly dug up and ate the tubers
and bulbs of several plants, while monkeys from other groups would not
even put these in their mouths. Imanishi had reasoned that, "if one
defines culture as learned by offspring from parents, then differences
in the way of life of members of the same species belonging to different
social groups could be attributed to culture."
Following this logic, the differences Imanishi and his colleagues
observed among the different groups of macaques may suggest that they
had arisen as a part of the groups' unique cultures. The most famous of
these eating behaviors was observed on the island of Koshima,
where one young female was observed carrying soiled sweet potatoes to a
small stream, where she proceeded to wash off all of the sand and dirt
before eating. This behavior was then observed in one of the monkey's
playmates, then her mother and a few other playmates. The potato-washing
eventually spread throughout the whole macaque colony, encouraging
Imanishi to refer to the behavior as "pre-culture," explaining that, "we
must not overestimate the situation and say that 'monkeys have culture'
and then confuse it with human culture."
At this point, most of the observed behaviors in animals, like those
observed by Imanishi, were related to survival in some way.
A chimpanzee mother and baby.
The first evidence of apparently arbitrary traditions came in the
late-1970s, also in the behavior of primates. At this time, researchers
McGrew and Tutin found a social grooming handclasp behavior to be prevalent in a certain troop of chimpanzees in Tanzania, but not found in other groups nearby.
This grooming behavior involved one chimpanzee taking hold of the hand
of another and lifting it into the air, allowing the two to groom each
other's armpits. Though this would seem to make grooming of the armpits
easier, the behavior actually has no apparent advantage. As the
primatologist Frans de Waal
explains from his later observations of the hand-clasp grooming
behavior in a different group of chimpanzees, "A unique property of the
handclasp grooming posture is that it is not required for grooming the
armpit of another individual... Thus it appears to yield no obvious
benefits or rewards to the groomers."
Prior to these findings, opponents to the idea of animal culture
had argued that the behaviors being called cultural were simply
behaviors that had evolutionarily
evolved due to their importance to survival. After the identification
of this initial non-evolutionarily advantageous evidence of culture,
scientists began to find differences in group behaviors or traditions in
various groups of primates, specifically in Africa. More than 40
different populations of wild chimpanzees have been studied across
Africa, between which many species-specific, as well as
population-specific, behaviors have been observed. The researching
scientists found 65 different categories of behaviors among these
various groups of chimpanzees, including the use of leaves, sticks,
branches, and stones for communication, play, food gathering or eating,
and comfort.
Each of the groups used the tools slightly differently, and this usage
was passed from chimpanzee to chimpanzee within the group through a
complex mix of imitation and social learning.
Chimpanzees
In 1999, Whiten et al. examined data from 151 years of chimpanzee
observation in an attempt to discover how much cultural variation
existed between populations of the species. The synthesis of their
studies consisted of two phases, in which they (1) created a
comprehensive list of cultural variant behavior specific to certain
populations of chimpanzees and (2) rated the behavior as either
customary – occurring in all individuals within that population;
habitual – not present in all individuals, but repeated in several
individuals; present – neither customary or habitual but clearly
identified; absent – instance of behavior not recorded and has no
ecological explanation; ecological – absence of behavior can be
attributed to ecological features or lack thereof in the environment, or
of unknown origin. Their results were extensive: of the 65 categories
of behavior studied, 39 (including grooming, tool usage and courtship behaviors) were found to be habitual in some communities but nonexistent in others.
Whiten et al. further made sure that these local traditions were not due to differences in ecology,
and defined cultural behaviors as behaviors that are "transmitted
repeatedly through social or observational learning to become a
population-level characteristic".
Eight years later, after "conducting large-scale controlled
social-diffusion experiments with captive groups", Whiten et al. stated
further that "alternative foraging techniques seeded in different groups
of chimpanzees spread differentially...across two further groups with
substantial fidelity".
This finding confirms not only that nonhuman species can maintain
unique cultural traditions; it also shows that they can pass these
traditions on from one population to another. The Whiten articles are a
tribute to the unique inventiveness of wild chimpanzees, and help prove
that humans' impressive capacity for culture and cultural transmission
dates back to the now-extinct common ancestor we share with chimpanzees.
Similar to humans, social structure
plays an important role in cultural transmission in chimpanzees.
Victoria Horner conducted an experiment where an older, higher ranking
individual and a younger, lower ranking individual were both taught the
same task with only slight aesthetic modification.
She found that chimpanzees tended to imitate the behaviors of the
older, higher ranking chimpanzee as opposed to the younger, lower
ranking individual when given a choice. It is believed that the older
higher ranking individual had gained a level of 'prestige' within the
group. This research demonstrates that culturally transmitted behaviors
are often learned from individuals that are respected by the group.
The older, higher ranking individual's success in similar
situations in the past led the other individuals to believe that their
fitness would be greater by imitating the actions of the successful
individual. This shows that not only are chimpanzees imitating behaviors
of other individuals, they are choosing which individuals they should
imitate in order to increase their own fitness. This type of behavior is
very common in human culture as well. People will seek to imitate the
behaviors of an individual that has earned respect through their
actions. From this information, it is evident that the cultural
transmission system of chimpanzees is more complex than previous
research would indicate.
Chimpanzees have been known to use tools for as long as they have
been studied. Andrew Whiten found that chimpanzees not only use tools,
but also conform to using the same method as the majority of individuals
in the group. This conformity bias is prevalent in human culture as well and is commonly referred to as peer pressure.
The results from the research of Victoria Horner and Andrew
Whiten show that chimpanzee social structures and human social
structures have more similarities than previously thought.
Cetacean culture
Second only to non-human primates, culture in species within the order Cetacea, which includes whales, dolphins, and porpoises,
has been studied for numerous years. In these animals, much of the
evidence for culture comes from vocalizations and feeding behaviors.
Cetacean vocalizations have been studied for many years,
specifically those of the bottlenose dolphin, humpback whale, killer
whale, and sperm whale.
Since the early 1970s, scientists have studied these four species in
depth, finding potential cultural attributes within group dialects,
foraging, and migratory traditions. Hal Whitehead, a leading cetologist,
and his colleagues conducted a study in 1992 of sperm whale groups in
the South Pacific, finding that groups tended to be clustered based on
their vocal dialects.
The differences in the whales' songs among and between the various
groups could not be explained genetically or ecologically, and thus was
attributed to social learning. In mammals such as these sperm whales or
bottlenose dolphins, the decision on whether an animal has the capacity
for culture comes from more than simple behavioral observations. As
described by ecologist Brooke Sergeant, "on the basis of life-history
characteristics, social patterns, and ecological environments,
bottlenose dolphins have been considered likely candidates for socially
learned and cultural behaviors," due to being large-brained and capable
of vocal and motor imitation.[35]
In dolphins, scientists have focused mostly on foraging and vocal
behaviors, though many worry about the fact that social functions for
the behaviors have not yet been found. As with primates, many humans are
reluctantly willing, yet ever so slightly willing, to accept the notion
of cetacean culture, when well evidenced, due to their similarity to
humans in having "long lifetimes, advanced cognitive abilities, and
prolonged parental care."
Matrilineal whales
In the cases of three species of matrilineal cetaceans, including pilot whales, sperm whales, and killer whales, mitochondrial DNA nucleotide diversities are about ten times lower than other species of whale. Whitehead found that this low mtDNA nucleotide
diversity yet high diversity in matrilineal whale culture may be
attributed to cultural transmission, since learned cultural traits have
the ability to have the same effect as normal maternally inherited
mtDNA. The feeding specializations of these toothed whales are proposed to have led to the divergence of the sympatric
"resident" and "transient" forms of killer whales off Vancouver Island,
in which resident killer whales feed on fish and squid, and transient
whales feed on marine mammals. Vocalizations have also been proven to be
culturally acquired in killer and sperm whale populations, as evidenced
by the distinct vocalization patterns maintained by members of these
different species even in cases where more than one species may occupy
one home range. Further study is being done in the matrilineal whales to
uncover the cultural transmission mechanisms associated with other
advanced techniques, such as migration strategies, new foraging techniques, and babysitting.
Dolphins
By using a "process of elimination" approach, researchers Krutzen et al. reported evidence of culturally transmitted tool use in bottlenose dolphins (Tursiops
sp.). It has been previously noted that tool use in foraging, called
"sponging" exists in this species. "Sponging" describes a behavior where
a dolphin will break off a marine sponge, wear it over its rostrum, and
use it to probe for fish. Using various genetic techniques, Krutzen et
al. showed that the behavior of "sponging" is vertically transmitted
from the mother, with most spongers being female. Additionally, they
found high levels of genetic relatedness from spongers suggesting recent
ancestry and the existence of a phenomenon researchers call a "sponging
eve".
In order to make a case for cultural transmission as the mode of
behavioral inheritance in this case, Krutzen et al. needed to rule out
possible genetic and ecological explanations. Krutzen et al. refer to
data that indicate both spongers and nonspongers use the same habitat
for foraging. Using mitochondrial DNA
data, Krutzen et al. found a significant non-random association between
the types of mitochondrial DNA pattern and sponging. Because
mitochondrial DNA is inherited maternally, this result suggests sponging
is passed from the mother.
In a later study
one more possible explanation for the transmission of sponging was
ruled out in favor of cultural transmission. Scientists from the same
lab looked at the possibility that 1.) the tendency for "sponging" was
due to a genetic difference in diving ability and 2.) that these genes
were under selection. From a test of 29 spongers and 54 nonspongers, the
results showed that the coding mitochondrial genes were not a
significant predictor of sponging behavior. Additionally, there was no
evidence of selection in the investigated genes.
Rat culture
Notable research has been done with black rats and Norwegian rats.
Among studies of rat culture, the most widely discussed research is
that performed by Joseph Terkel in 1991 on a species of black rats that
he had originally observed in the wild in Palestine. Terkel conducted an
in-depth study aimed to determine whether the observed behavior, the
systematic stripping of pine cone scales from pine cones prior to
eating, was a socially acquired behavior, as this action had not been
observed elsewhere. The experimentation with and observation of these
black rats was one of the first to integrate field observations with
laboratory experiments to analyze the social learning involved. From the combination of these two types of research, Terkel was able to analyze the mechanisms involved in this social learning
to determine that this eating behavior resulted from a combination of
ecology and cultural transmission, as the rats could not figure out how
to eat the pinecones without being "shown" by mature rats.
Though this research is fairly recent, it is often used as a prime
example of evidence for culture in non-primate, non-cetacean beings. Animal migration may be in part cultural; released ungulates have to learn over generations the seasonal changes in local vegetation.
In the black rat (Rattus rattus), social transmission appears to be the mechanism of how optimal foraging
techniques are transmitted. In this habitat, the rats’ only source of
food is pine seeds that they obtain from pine cones. Terkel et al.
studied the way in which the rats obtained the seeds and the method
that this strategy was transmitted to subsequent generations. Terkel et
al. found that there was an optimal strategy for obtaining the seeds
that minimized energy inputs and maximized outputs. Naïve rats that did
not use this strategy could not learn it from trial and error or from watching experienced rats. Only young offspring could learn the technique. Additionally, from cross-fostering
experiments where pups of naïve mothers were placed with experienced
mothers and vice versa, those pups placed with experienced mothers
learned the technique while those with naïve mothers did not. This
result suggests that this optimal foraging technique is socially rather
than genetically transmitted.
Avian culture
The songs of starlings have been discovered to show regional "dialects," a trait that has potential to have a cultural basis.
Birds
have been a strong study subject on the topic of culture due to their
observed vocal "dialects" similar to those studied in the cetaceans.
These dialects were first discovered by zoologist Peter Marler, who noted the geographic variation in the songs of various songbirds.
Many scientists have found that, in attempting to study these animals,
they approach a stumbling block in that it is difficult to understand
these animals' societies due to their being so different from our own.
This makes it difficult to understand the animals' behaviors, let alone
determine whether they are cultural or simply practical.
However, despite this hindrance, evidence for differing dialects among songbird populations has been discovered, especially in sparrows, starlings, and cowbirds.
In these birds, scientists have found strong evidence for
imitation-based learning, one of the main types of social learning.
Though the songbirds obviously learn their songs through imitating other
birds, many scientists remain skeptical about the correlation between
this and culture: "...the ability to imitate sound may be as reflexive
and cognitively uncomplicated as the ability to breathe. It is how
imitation affects and is affected by context, by ongoing social
behavior, that must be studied before assuming its explanatory power."
The scientists have found that simple imitation does not itself lay the
ground for culture, whether in humans or birds, but rather it is how
this imitation affects the social life of an individual that matters.
Examples of culturally transmitted behaviors in birds
The complexity of several avian behaviors can be explained by the accumulation of cultural traits over many generations.
Bird song
In an experiment regarding at vocal behavior in birds, researchers Marler & Tamura found evidence of song dialects in a sparrow species known as Zonotrichia leucophrys.
Located in the eastern and southern parts of North America, these
white-crowned song-birds exhibit learned vocal behavior. Marler &
Tamura found that while song variation existed between individual birds,
each population of birds had a distinct song pattern that varied in
accordance to geographical location. For this reason, Marler and Tamura
called the patterns of each region a "dialect": however, this term has
since been disputed, as different types of in bird song are much less
distinct than dialects in human language.
By raising male sparrows
in various acoustic settings and observing effects on their verbal
behavior, Marler and Tamura found that sparrows learned songs during the
first 100 days of their lives. In this experimental setting, male birds
in acoustic chambers were exposed to recorded sounds played through a loudspeaker.
They also showed that white-crowned sparrows only learn songs recorded
from other members of their species. Marler and Tamura noted that this
case of cultural transmission was interesting because it required no
social bond between the learner and the emitter of sound (since all
sounds originated from a loudspeaker in their experiments). However, the
presence of social bonds strongly facilitates song imitation in certain
songbirds. Zebra finches
rarely imitate songs played from a loudspeaker, but they regularly
imitate songs of an adult bird after only a few hours of interaction. Interestingly, imitation in zebra finches is inhibited when the number of siblings (pupils) increases.
Innovative foraging
In
20th century Britain, bottled milk was delivered to households in the
early morning by milkmen and left on doorsteps to be collected. Birds
such as tits (Paridae) began to attack the bottles, opening the foil or cardboard lids and drinking the cream of the top.
It was later shown that this innovative behavior arose independently in
several different sites and spread horizontally (i.e. between living
members) in the existing population.
Later experimental evidence showed that conformity may lead to the
horizontal spread of innovative behaviors in wild birds, and that this
may in turn result in a lasting cultural tradition.
A spread of new foraging behaviors also occurred in an Argentinian population of kelp gulls (Larus dominicanus).
During the 20th century, individuals in this population began to
non-fatally wound the backs of swimming whales with their beaks, feeding
on the blubber and creating deeper lesions in areas that were already
wounded. Aerial photographs showed that gull-induced lesions on local
whales increased in frequency from 2% to 99% from 1974 to 2011, and that
this behavior was not observed in any other kelp gull populations other
than two isolated incidents. This implies the emergence and persistence of a local tradition in this population of gulls.
Migration
Juvenile
birds that migrate in flocks may learn to navigate accurately through
cultural transmission of route choice skills from older birds. Cultural inheritance of migration patterns has been shown in bustards (Otis tarda), and the pattern of inheritance was shown to depend on social structures in the flock.
Avian social networks
Social networks
are a specific mechanism of cultural transmission in birds. Information
learned in social contexts can allow them to make decisions that lead
to increased fitness.
A great deal of research has focused on the communication of new
foraging locations or behaviors through social networks. These networks
are currently being analyzed through computational methods such as network-based diffusion analysis (NBDA).
In wild songbirds, social networks are a mechanism for information transmission both within and between species.
Interspecific networks (i.e. networks including birds of different
species) were shown to exist in multispecies flocks containing three
different types of tits whose niches
overlapped. In this study, knowledge about new feeding areas spread
through social interactions: more birds visited the new area than the
number of birds that discovered the area independently. The researchers
noted that information likely travelled faster among members of the same
species (conspecifics), but that individuals did not depend solely on
conspecifics for transmission. Another study on army-ant-following birds
has also evidenced interspecific transmission of foraging information.
A recent study used RFID
identification transponders to experimentally manipulate avian social
networks: this scanner technology allowed them to restrict access to
feeders for some birds and not others.
Their data showed that individuals are more likely to learn from those
who were able to enter the same feeding area as them. Additionally, the
existing "paths" of information transmission were altered following
segregation during feeding: this was attributed to changes in the
population's social network.
Others have been able to predict the pattern information transmission among individuals based on a preexisting social network. In this study, social interactions of ravens (Corvus corax)
were first analyzed to create a comprehensive network. Then, the order
in which individuals learned task-solving behavior from a trained tutor
was compared with the network. They not only found that the pattern of
learning reflected the network that they had built, but that different
types of social connections (such as "affiliative interactions" and
"aggressive interactions") characterized different rates of information
transmission and observation.
Conformity in avian culture
Bartlett
and Slater observed call convergence (i.e. conformity) in budgerigars
introduced into groups with different flock-specific calls than their
own. They also found that the original calls of flock members did not change significantly during this process.
Conformity is one mechanism through which innovative behaviors
can become embedded in culture. In an experimental setting, tits
preferentially adopted the locally popular method of opening a
two-action puzzle box even after discovering the other possible way of
accessing the food. This formed diverging local traditions when different populations were seeded with birds specifically trained in one method.
Other research showed that although conformity has a strong
influence on behaviors adopted by birds, the local tradition can be
abandoned in favor of an analogous behavior which gives higher reward.
This showed that while conformity is a beneficial mechanism for quickly
establishing traditions, but that unhelpful traditions will not
necessarily be adhered to in the presence of a better alternative.
In some cases, conformity-based aggression may benefit
individuals who conform to traditions. Researchers used the framework of
sexual selection and conformism in of song types of songbirds to model
territorial aggression against individuals with non-conforming song
types.
Their model showed that aggressors won more frequently when targeting
non-conformers (than in un-targeted or random aggression). They also
found that alleles for conformity-enforcement propagated more
effectively than alleles for tolerance of non-conformity.
Finally, other species of birds have been observed to conform to
the personality of other individuals in their presence. Gouldian finches
(Erythrura gouldiae)
exist in red- and black-headed subtypes, and these subtypes have been
shown to have different levels of boldness (measured by the time taken
to explore new areas, and other similar tests). Experiments placing
black-headed birds (known to be less bold) in the company of red-headed
birds (known to be more bold) resulted in the black-headed bird
performing "bolder" behaviors, and red-headed birds became "shyer" in
the presence of black-headed ones. The experimenters hypothesized that this individual-level conformity could lead to stronger social cohesion.
Fish culture
Guppy mating behavior is believed to be culturally influenced.
Evidence for cultural transmission has also been shown in wild fish populations. Scientists Helfman and Schultz conducted translocation experiments with French grunts (Haemulon flavolineatum)
where they took fish native to a specific schooling site and
transported them to other sites. In this species of fish, the organism
uses distinct, traditional migration routes to travel to schooling sites
on coral reefs. These routes persisted past one generation and so by
relocating the fish to different sites, Helfman and Schultz wanted to
see if the new fish could relearn that sites' migration route from the
resident fish. Indeed this is what they found: that the newcomers
quickly learned the traditional routes and schooling sites. But when
residents were removed under similar situations, the new fish did not
use the traditional route and instead use new routes, suggesting that
the behavior could not be transmitted once the opportunity for learning
was no longer there.
In a similar experiment looking at mating sites in blueheaded wrasse (Thalassoma bifasciatum),
researcher Warner found that individuals chose mating sites based on
social traditions and not based on the resource quality of the site.
Warner found that although mating sites were maintained for four
generations, when entire local populations were translocated elsewhere,
new sites were used and maintained.
Controversies and criticisms
A
popular method of approaching the study of animal culture (and its
transmission) is the "ethnographic method," which argues that culture
causes the geographical differences in the behavioral repertoires of
large-brained mammals. However, this significantly downplays the roles
that ecology and genetics
play in influencing behavioral variation from population to population
within a species. Behaviors stemming from genetic or environmental
effects are not reliant on socially learned and transmitted information;
therefore, they are not cultural.
Culture is just one source of adaptive behavior an organism
exhibits to better exploit its environment. When behavioral variation
reflects differential phenotypic plasticity,
it is due more to ecological pressures than cultural ones. In other
words, when an animal changes its behavior over its lifespan, this is
most often a result of changes in its environment. Furthermore, animal
behavior is also influenced by evolved predispositions, or genetics. It
is very possible that "correlation
between distance between sites and 'cultural difference' might reflect
the well-established correlation between genetic and geographical
distances".
The farther two populations of a species are separated from each
other, the less genetic traits they will share in common, and this may
be one source of variance in culture.
Another argument against the "ethnographic method" is that it is
impossible to prove that there are absolutely no ecological or genetic
factors in any behavior. However, this criticism can also be applied to
studies of human culture. Though culture has long been thought to arise
and remain independent of genetics, the constraints on the propagation
and innovation of cultural techniques inevitably caused by the genome of
each respective animal species has led to the theory of gene-culture coevolution,
which asserts that "cognitive, affective, and moral capacities" are the
product of an evolutionary dynamic involving interactions between genes
and culture over extended periods of time. The concept behind gene-culture coevolution
is that, though culture plays a huge role in the progression of animal
behavior over time, the genes of a particular species have the ability
to affect the details of the corresponding culture and its ability to
evolve within that species.
We do not know every possible genetic or environmental effect on
behavior that exists, nor will we ever. In other words, it is
impossible to reject the notion that genes and ecology influence all
behaviors, to a degree. Culture can also contribute to differences in
behavior, but like genes and environments, it carries different weight
in different behaviors. As Laland and Janik
explain, "to identify cultural variation, not only is it not sufficient
to rule out the possibility that the variation in behavior constitutes
unlearned responses to different selection pressures [from the
environment], but it is also necessary to consider the possibility of
genetic variation precipitating different patterns of learning."
Gene-culture coevolution, much like the interaction between cultural
transmission and environment, both serve as modifiers to the original
theories on cultural transmission and evolution that focused more on
differences in the interactions between individuals.
Some scientists believe the study of animal culture should be
approached in a different way. Currently, the question being asked is,
"is this behavior learned socially (and hence is a result of culture
alone), or is it a product of genes and/or environment?" However, it is
impossible to find an absolute answer to this question, nor does one in
all likelihood exist. Therefore it seems as though scientists should
focus on examining how much variance in a behavior can be attributed to
culture. Performing field experiments is an excellent way to try to
answer this question: translocating individuals between populations or
populations between sites could help biologists distinguish between
culture, ecology and genetics. For example, if a newly introduced
animal shifts its behavior to mimic that of others in its new population, genetic difference as an effect on behavior can be ruled out.
Unanswered questions and future areas of exploration
In
the study of social transmissions, one of the important unanswered
questions is an explanation of how and why maladaptive social traditions
are maintained. For example, in one study on social transmission in guppies (Poecilia reticulata),
naïve fish preferred taking a long, energetically costly route to a
feeder that they had learned from resident fish rather than take a
shorter route. These fish were also slower to learn the new, quicker
route compared to naïve fish that had not been trained in the long
route. In this case, not only is the social tradition maladaptive, but
it also inhibits the acquisition of adaptive behavior.
