Evolution and Memes:
The human brain as a selective imitation device
This article originally appeared in Cybernetics and Systems, Vol
32:1, 225-255, 2001,
Taylor and Francis, Philadelphia, PA. Reproduced with permission.
"I memi e lo sviluppo del cervello", in KOS 211, aprile
2003, pp. 56-64.
"Evolution und Meme: Das menschliche Gehirn als selektiver
Imitationsapparat" , in: Alexander Becker et al. (Hg.): Gene,
Meme und Gehirne. Geist und Gesellschaft als Natur, Frankfurt:
Suhrkamp 2003 pp 49-89.
The new replicator
The meme is an evolutionary replicator,
defined as information copied from person to person by imitation.
I suggest that taking memes into account may provide a better understanding
of human evolution in the following way. Memes appeared in human
evolution when our ancestors became capable of imitation. From this
time on two replicators, memes and genes, coevolved. Successful
memes changed the selective environment, favouring genes for the
ability to copy them. I have called this process memetic drive.
Meme-gene coevolution produced a big brain that is especially good
at copying certain kinds of memes. This is an example of the more
general process in which a replicator and its replication machinery
evolve together. The human brain has been designed not just for
the benefit of human genes, but for the replication of memes. It
is a selective imitation device.
Some problems of definition are discussed
and suggestions made for future research.
The concept of the meme was first proposed
by Dawkins (1976) and since that time has been used in discussions
of (among other things) evolutionary theory, human consciousness,
religions, myths and mind viruses (e.g. Dennett 1991, 1995, Dawkins
1993, Brodie 1996, Lynch 1996). I believe, however, that the theory
of memes has a more fundamental role to play in our understanding
of human nature. I suggest that it can give us a new understanding
of how and why the human brain evolved, and why humans differ in
important ways from all other species. In outline my hypothesis
is as follows.
Everything changed in human evolution when
imitation first appeared because imitation let loose a new replicator,
the meme. Since that time, two replicators have been driving human
evolution, not one. This is why humans have such big brains, and
why they alone produce and understand grammatical language, sing,
dance, wear clothes and have complex cumulative cultures. Unlike
other brains, human brains had to solve the problem of choosing
which memes to imitate. In other words they have been designed for
This is a strong claim and the purpose
of this paper is first to explain and defend it, second to explore
the implications of evolution operating on two replicators, and
third to suggest how some of the proposals might be tested. One
implication is that we have underestimated the importance of imitation.
The essence of all evolutionary processes
is that they involve some kind of information that is copied with
variation and selection. As Darwin (1859) first pointed out, if
you have creatures that vary, and if there is selection so that
only some of those creatures survive, and if the survivors pass
on to their offspring whatever it was that helped them survive,
then those offspring must, on average, be better adapted to the
environment in which that selection took place than their parents
were. It is the inevitability of this process that makes it such
a powerful explanatory tool. If you have the three requisites -
variation, selection and heredity, then you must get evolution.
This is why Dennett calls the process the evolutionary algorithm.
It is a mindless procedure which produces "Design out of Chaos
without the aid of Mind" (Dennett 1995, p 50).
This algorithm depends on something being
copied, and Dawkins calls this the replicator. A replicator can
therefore be defined as any unit of information which is copied
with variations or errors, and whose nature influences its own probability
of replication (Dawkins 1976). Alternatively we can think of it
as information that undergoes the evolutionary algorithm (Dennett
1995) or that is subject to blind variation with selective retention
(Campbell 1960), or as an entity that passes on its structure largely
intact in successive replications (Hull, 1988).
The most familiar replicator is the gene.
In biological systems genes are packaged in complex ways inside
larger structures, such as organisms. Dawkins therefore contrasted
the genes as replicators with the vehicles that carry them around
and influence their survival. Hull prefers the term interactors
for those entities that interact as cohesive wholes with their environments
and cause replication to be differential (Hull 1988). In either
case selection may take place at the level of the organism (and
arguably at other levels) but the replicator is the information
that is copied reasonably intact through successive replications
and is the ultimate beneficiary of the evolutionary process.
Note that the concept of a replicator is
not restricted to biology. Whenever there is an evolutionary process
(as defined above) then there is a replicator. This is the basic
principle of what has come to be known as Universal Darwinism (Dawkins
1976, Plotkin 1993) in which Darwinian principles are applied to
all evolving systems. Other candidates for evolving systems with
their own replicators include the immune system, neural development,
and trial and error learning (e.g. Calvin 1996, Edelman 1989, Plotkin
1993, Skinner 1953).
The new replicator I refer to here is the
meme; a term coined in 1976 by Dawkins. His intention was to illustrate
the principles of Universal Darwinism by providing a new example
of a replicator other than the gene. He argued that whenever people
copy skills, habits or behaviours from one person to another by
imitation, a new replicator is at work.
"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. ... Examples of memes
are tunes, ideas, catch-phrases, clothes fashions, ways of making
pots or of building arches. Just as genes propagate themselves
in the gene pool by leaping from body to body via sperms or eggs,
so memes propagate themselves in the meme pool by leaping from
brain to brain via a process which, in the broad sense, can be
called imitation." (Dawkins, 1976, p 192).
Dawkins now explains that he had modest,
and entirely negative, intentions for his new term. He wanted to
prevent his readers from thinking that the gene was necessarily
the "be-all and end-all of evolution ... which all adaptations
could be said to benefit" (Dawkins, 1999, p xvi) and make it
clear that the fundamental unit of natural selection is the replicator
- any kind of replicator. Nevertheless, he laid the groundwork
for memetics. He likened some memes to parasites infecting a host,
especially religions which he termed viruses of the mind (Dawkins,
1993), and he showed how mutually assisting memes will group together
into co-adapted meme complexes (or memeplexes) often propagating
themselves at the expense of their hosts.
Dennett subsequently used the concept of
memes to illustrate the evolutionary algorithm and to discuss personhood
and consciousness in terms of memes. He stressed the importance
of asking Cui bono? or who benefits? The ultimate beneficiary
of an evolutionary process, he stressed, is whatever it is that
is copied; i.e. the replicator. Everything else that happens, and
all the adaptations that come about, are ultimately for the sake
of the replicators.
This idea is central to what has come to
be known as selfish gene theory, but it is important to carry across
this insight into dealing with any new replicator. If memes are
truly replicators in their own right then we should expect things
to happen in human evolution which are not for the benefit of the
genes, nor for the benefit of the people who carry those genes,
but for the benefit of the memes which those people have copied.
This point is absolutely central to understanding memetics. It is
this which divides memetics from closely related theories in sociobiology
(Wilson 1975) and evolutionary psychology (e.g. Barkow, Cosmides
& Tooby 1992, Pinker 1997). Dawkins complained of his colleagues
that "In the last analysis they wish always to go back to biological
advantage" (Dawkins 1976 p 193). This is true of theories
in evolutionary psychology but also of most of the major theories
of gene-culture coevolution. For example, Wilson famously claimed
that "the genes hold culture on a leash" (Lumsden &
Wilson 1981). More recently he has conceded that the term meme has
won against its various competitors but he still argues that memes
(such as myths and social contracts) evolved over the millennia
because they conferred a survival advantage on the genes, not simply
because of advantages to themselves (Wilson 1998). Other theories
such as the mathematical models of Cavalli-Sforza and Feldman (1981)
and Lumsden and Wilson (1981) take inclusive fitness (advantage
to genes) as the final arbiter, as does Durham (1991) who argues
that organic and cultural selection work on the same criterion and
are complementary. Among the few exceptions are Boyd and Richersons
Dual Inheritance model (1985) which includes the concept of cultural
fitness, and Deacons (1997) coevolutionary theory in which
language is likened to a parasitic organism with adaptations that
evolved for its own replication, not for that of its host.
With these exceptions, the genes remain
the bottom line in most such theories, even though maladaptive traits
(that is, maladaptive to the genes) can arise, and may even thrive
under some circumstances (Durham 1991, Feldman and Laland 1996).
By contrast, if you accept that memes are a true replicator then
you must consider the fitness consequences for memes themselves.
This could make a big difference, and this is why I say that everything
changed in evolution when memes appeared.
When was that? If we define memes as information
copied by imitation, then this change happened when imitation appeared.
I shall argue that should we do just that, but this will require
Problems of definition
If we had a universally agreed definition
of imitation, we could define memes as that which is imitated (as
Dawkins originally did). In that case we could say that, by definition,
memes are transmitted whenever imitation occurs and, in terms of
evolution, we could say that memes appeared whenever imitation did.
Unfortunately there is no such agreement either over the definition
of memes or of imitation. Indeed there are serious arguments over
both definitions. I suggest that we may find a way out of these
problems of definition by thinking about imitation in terms of evolutionary
processes, and by linking the definitions of memes and imitation
In outline my argument is as follows. The
whole point of the concept of memes is that the meme is a replicator.
Therefore the process by which it is copied must be one that supports
the evolutionary algorithm of variation, selection and heredity
- in other words, producing copies of itself that persist through
successive replications and which vary and undergo selection. If
imitation is such a process, and if other kinds of learning and
social learning are not, then we can usefully tie the two definitions
together. We can define imitation as a process of copying that supports
an evolutionary process, and define memes as the replicator which
is transmitted when this copying occurs.
Note that this is not a circular definition.
It depends crucially on an empirical question - is imitation in
fact the kind of process that can support a new evolutionary system?
If it is then there must be a replicator involved and we can call
that replicator the meme. If not, then this proposal does not make
sense. This is therefore the major empirical issue involved, and
I shall return to it when I have considered some of the problems
with our current definitions.
Defining the meme
The Oxford English Dictionary defines memes
as follows "meme (mi:m), n. Biol. (shortened
from mimeme ... that which is imitated, after GENE n.)
An element of a culture that may be considered to be passed on by
non-genetic means, esp. imitation". This is clearly built on
Dawkinss original conception and is clear as far as it goes.
However, there are many other definitions of the meme, both formal
and informal, and much argument about which is best. These definitions
differ mainly on two key questions: (1) Whether memes exist only
inside brains or outside of them as well, and (2) the methods by
which memes may be transmitted.
The way we define memes is critical, not
only for the future development of memetics as a science, but for
our understanding of evolutionary processes in both natural and
artificial systems. Therefore we need to get the definitions right.
What counts as right, in my view, is a definition that fits the
concept of the meme as a replicator taking part in a new evolutionary
process. Any definition which strays from this concept loses the
whole purpose and power of the idea of the meme - indeed its whole
reason for being. It is against this standard that I judge the various
competing definitions, and my conclusion is that memes are both
inside and outside of brains, and they are passed on by imitation.
The rest of this section expands on that argument and can be skipped
for the purposes of understanding the wider picture.
First there is the question of whether
memes should be restricted to information stored inside peoples
heads (such as ideas, neural patterns, memories or knowledge) or
should include information available in behaviours or artefacts
(such as speech, gestures, inventions and art, or information in
books and computers).
In 1975, Cloak distinguished between the
cultural instructions in peoples heads (which he called i-culture)
and the behaviour, technology or social organisation they produce
(which he called m-culture). Dawkins (1976) initially ignored
this distinction, using the term meme to apply to behaviours
and physical structures in a brain, as well as to memetic information
stored in other ways (as in his examples of tunes, ideas and fashions).
This is sometimes referred to as Dawkins A (Gatherer 1998). Later
(Dawkins B) he decided that "A meme should be regarded as a
unit of information residing in a brain (Cloaks i-culture)"
(Dawkins 1982, p 109). This implies that the information in the
clothes or the tunes does not count as a meme. But later still he
says that memes "can propagate themselves from brain to brain,
from brain to book, from book to brain, from brain to computer,
from computer to computer" (Dawkins, 1986, p 158). Presumably
they still count as memes in all these forms of storage - not just
when they are in a brain. So this is back to Dawkins A.
Dennett (1991, 1995) treats memes as information
undergoing the evolutionary algorithm, whether they are in a brain,
a book or some other physical object. He points out that copying
any behaviour must entail neural change and that the structure of
a meme is likely to be different in any two brains, but he does
not confine memes to these neural structures. Durham (1991) also
treats memes as information, again regardless of how they are stored.
Wilkins defines a meme as "the least unit of sociocultural
information relative to a selection process that has favourable
or unfavourable selection bias that exceeds its endogenous tendency
to change." (Wilkins 1998). This is based on Williamss
now classic definition of the gene as "any hereditary information
for which there is a favorable or unfavorable selection bias equal
to several or many times its rate of endogenous change." (Williams
1966, p 25). What is important here is that the memetic information
survives intact long enough to be subject to selection pressures.
It does not matter where and how the information resides.
In contrast, Delius (1989) describes memes
as "constellations of activated and non-activated synapses
within neural memory networks" (p 45) or "arrays of modified
synapses" (p 54). Lynch (1991) defines them as memory abstractions
or memory items, Grant (1990) as information patterns infecting
human minds, and Plotkin as ideas or representations "... the
internal end of the knowledge relationship" (Plotkin 1993,
p 215), while Wilson defines the natural elements of culture as
"the hierarchically arranged components of semantic memory,
encoded by discrete neural circuits awaiting identification."
(Wilson 1998, p 148). Closer to evolutionary principles, Brodie
defines a meme as "a unit of information in a mind whose existence
influences events such that more copies of itself get created in
other minds." (Brodie 1996, p 32), but this restricts memes
to being in minds. Presumably, on all these latter definitions,
memes cannot exist in books or buildings, so the books and buildings
must be given a different role. This has been done, by using further
distinctions, usually based on a more or less explicit analogy with
Cloak (1975) explicitly likened his i-culture
to the genotype and m-culture to the phenotype. Dennett (1995) also
talks about memes and their phenotypic effects, though in a different
way. The meme is internal (though not confined to brains) while
"the way it affects things in its environment" (p 349),
is its phenotype. In an almost complete reversal, Benzon (1996)
likens pots, knives, and written words (Cloaks m-culture)
to the gene; and ideas, desires and emotions (i-culture) to the
phenotype. Gabora (1997) likens the genotype to the mental representation
of a meme, and the phenotype to its implementation. Delius (1989),
having defined memes as being in the brain, refers to behaviour
as the memes phenotypic expression, while remaining ambiguous
about the role of the clothes fashions he discusses. Grant (1990)
defines the memotype as the actual information content
of a meme, and distinguishes this from its sociotype
or social expression. He explicitly bases his memotype/sociotype
distinction on the phenotype/genotype distinction. All these distinctions
are slightly different and it is not at all clear which , if any,
The problem is this. If memes worked like
genes then we should expect to find close analogies between the
two evolutionary systems. But, although both are replicators, they
work quite differently and for this reason we should be very cautious
of meme-gene analogies. I suggest there is no clean equivalent of
the genotype/phenotype distinction in memetics because memes are
a relatively new replicator and have not yet created for themselves
this highly efficient kind of system. Instead there is a messy system
in which information is copied all over the place by many different
I previously gave the example of someone
inventing a new recipe for pumpkin soup and passing it on to various
relatives and friends (Blackmore 1999). The recipe can be passed
on by demonstration, by writing the recipe on a piece of paper,
by explaining over the phone, by sending a fax or e-mail, or (with
difficulty) by tasting the soup and working out how it might have
been cooked. It is easy to think up examples of this kind which
make a mockery of drawing analogies with genotypes and phenotypes
because there are so many different copying methods. Most important
for the present argument, we must ask ourselves this question. Does
information about the new soup only count as a meme when it is inside
someones head or also when it is on a piece of paper, in the
behaviour of cooking, or passing down the phone lines? If we answer
that memes are only in the head then we must give some other role
to these many other forms and, as we have seen, this leads to confusion.
My conclusion is this. The whole point
of memes is to see them as information being copied in an evolutionary
process (i.e. with variation and selection). Given the complexities
of human life, information can be copied in myriad ways. We do a
disservice to the basic concept of the meme if we try to restrict
it to information residing only inside peoples heads - as
well as landing ourselves in all sorts of further confusions. For
this reason I agree with Dennett, Wilkins, Durham and Dawkins A,
who do not restrict memes to being inside brains. The information
in this article counts as memes when it is inside my head or yours,
when it is in my computer or on the journal pages, or when it is
speeding across the world in wires or bouncing off satellites, because
in any of these forms it is potentially available for copying and
can therefore take part in an evolutionary process.
We may now turn to the other vexed definitional
question - the method by which memes are replicated. The dictionary
definition gives a central place to imitation, both in explaining
the derivation of the word meme and as the main way
in which memes are propagated. This clearly follows Dawkinss
original definition, but Dawkins was canny in saying imitation "in
the broad sense". Presumably he meant to include many processes
which we may not think of as imitation but which depend on it, like
direct teaching, verbal instruction, learning by reading and so
on. All these require an ability to imitate. At least, learning
language requires the ability to imitate sounds, and instructed
learning and collaborative learning emerge later in human development
than does imitation and arguably build on it (Tomasello, Kruger
& Ratner 1993). We may be reluctant to call some of these complex
human skills imitation. However, they clearly fit the
evolutionary algorithm. Information is copied from person to person.
Variation is introduced both by degradation due to failures of human
memory and communication, and by the creative recombination of different
memes. And selection is imposed by limitations on time, transmission
rates, memory and other kinds of storage space. In this paper I
am not going to deal with these more complex kinds of replication.
Although they raise many interesting questions, they can undoubtedly
sustain an evolutionary process and can therefore replicate memes.
Instead I want to concentrate on skills at the simpler end of the
scale, where it is not so obvious which kinds of learning can and
cannot count as replicating memes.
Theories of gene-culture coevolution all
differ in the ways their cultural units are supposed to be passed
on. Cavalli-Sforza and Feldmans (1981) cultural traits are
passed on by imprinting, conditioning, observation, imitation or
direct teaching. Durhams (1991) coevolutionary model refers
to both imitation and learning. Runciman (1998) refers to memes
as instructions affecting phenotype passed on by both imitation
and learning. Laland and Odling Smee (in press) argue that all forms
of social learning are potentially capable of propagating memes.
Among meme-theorists both Brodie (1996) and Ball (1984) include
all conditioning, and Gabora (1997) counts all mental representations
as memes regardless of how they are acquired.
This should not, I suggest, be just a matter
of preference. Rather, we must ask which kinds of learning can and
cannot copy information from one individual to another in such a
way as to sustain an evolutionary process. For if information is
not copied through successive replications, with variation and selection,
then there is no new evolutionary process and no need for the concept
of the meme as replicator. This is not a familiar way of comparing
different types of learning so I will need to review some of the
literature and try to extract an answer.
Communication and contagion
Confusion is sometimes caused over the
term communication, so I just want to point out that
most forms of animal communication (even the most subtle and complex)
do not involve the copying of skills or behaviours from one individual
to another with variation and selection. For example, when bees
dance information about the location of food is accurately conveyed
and the observing bees go off to find it, but the dance itself is
not copied or passed on. So this is not copying a meme. Similarly
when vervet monkeys use several different signals to warn conspecifics
of different kinds of predator (Cheney and Seyfarth 1990), there
is no copying of the behaviour. The behaviour acts as a signal on
which the other monkeys act, but they do not copy the signals with
variation and selection.
Yawning, coughing or laughter can spread
contagiously from one individual to the next and this may appear
to be memetic, but these are behaviours that were already known
or in the animals repertoire, and are triggered by another
animal performing them (Provine 1996). In this type of contagion
there is no copying of new behaviours (but note that there are many
other kinds of contagion (Levy & Nail, 1993; Whiten & Ham,
1992)). Communication of these kinds is therefore not even potentially
memetic. Various forms of animal learning may be.
Learning is commonly divided into individual
and social learning. In individual learning (including classical
conditioning, operant conditioning, acquisition of motor skills
and spatial learning) there is no copying of information from one
animal to another. When a rat learns to press a lever for reward,
a cat learns where the food is kept, or a child learns how to ride
a skateboard, that learning is done for the individual only and
cannot be passed on. Arguably such learning involves a replicator
being copied and selected within the individual brain (Calvin
1996, Edelman 1989), but it does not involve copying between
individuals. These types of learning therefore do not count
as memetic transmission.
In social learning a second individual
is involved, but in various different roles. Types of social learning
include goal emulation, stimulus enhancement, local enhancement,
and true imitation. The question I want to ask is which of these
can and cannot sustain a new evolutionary process.
In emulation, or goal emulation, the learner
observes another individual gaining some reward and therefore tries
to obtain it too, using individual learning in the process, and
possibly attaining the goal in quite a different way from the first
individual (Tomasello 1993). An example is when monkeys, apes or
birds observe each other getting food from novel containers but
then get it themselves by using a different technique (e.g. Whiten
& Custance 1996). This is social learning because two individuals
are involved, but the second has only learned a new place to look
for food. Nothing is copied from one animal to the other in such
a way as to allow for the copying of variations and selective survival
of some variants over others. So there is no new evolutionary process
and no new replicator.
In stimulus enhancement the attention of
the learner is drawn to a particular object or feature of the environment
by the behaviour of another individual. This process is thought
to account for the spread among British tits of the habit of pecking
milk bottle tops to get at the cream underneath, which was first
observed in 1921 and spread from village to village (Fisher and
Hinde 1949). Although this looks like imitation, it is possible
that once one bird had learned the trick others were attracted to
the jagged silver tops and they too discovered (by individual learning)
that there was cream underneath (Sherry & Galef 1984). If so,
the birds had not learned a new skill from each other (they already
knew how to peck), but only a new stimulus at which to peck. Similarly
the spread of termite fishing among chimpanzees might be accounted
for by stimulus enhancement as youngsters follow their elders around
and are exposed to the right kind of sticks in proximity to termite
nests. They then learn by trial and error how to use the sticks.
In local enhancement the learner is drawn
to a place or situation by the behaviour of another, as when rabbits
learn from each other not to fear the edges of railway lines in
spite of the noise of the trains. The spread of sweet-potato washing
in Japanese macaques may have been through stimulus or local enhancement
as the monkeys followed each other into the water and then discovered
that washed food was preferable (Galef 1992).
If this is the right explanation for the
spread of these behaviours we can see that there is no new evolutionary
process and no new replicator, for there is nothing that is copied
from individual to individual with variation and selection. This
means there can be no cumulative selection of more effective variants.
Similarly, Boyd and Richerson (in press) argue that this kind of
social learning does not allow for cumulative cultural change.
Most of the population-specific behavioural
traditions studied appear to be of this kind, including nesting
sites, migration routes, songs and tool use, in species such as
wolves, elephants, monkeys, monarch butterflies, and many kinds
of birds (Bonner 1980). For example, oyster catchers use two different
methods for opening mussels according to local tradition but the
two methods do not compete in the same population - in other words
there is no differential selection of variants within a given population.
Tomasello, Kruger and Ratner (1993) argue that many chimpanzee traditions
are also of this type. Although the behaviours are learned population-specific
traditions they are not cultural in the human sense of that term
because they are not learned by all or even most of the members
of the group, they are learned very slowly and with wide individual
variation, and - most telling - they do not show an accumulation
of modifications over generations. That is, they do not show the
cultural "ratchet effect" precluding the possibility of
humanlike cultural traditions that have "histories".
There may be exceptions to this. Whiten
et al. (1999) have studied a wide variety of chimpanzee behaviours
and have found limited evidence that such competition between variants
does occur within the same group. For example, individuals in the
same group use two different methods for catching ants on sticks,
and several ways of dealing with ectoparasites while grooming. However,
they suggest that these require true imitation for their perpetuation.
True imitation is more restrictively defined,
although there is still no firm agreement about the definition (see
Zentall 1996, Whiten 1999). Thorndike (1898), originally defined
imitation as "learning to do an act from seeing it done".
This means that one animal must acquire a novel behaviour from another
- so ruling out the kinds of contagion noted above. Whiten and Ham
(1992), whose definition is widely used, define imitation as learning
some part of the form of a behaviour from another individual. Similarly
Heyes (1993) distinguishes between true imitation - learning something
about the form of behaviour through observing others, from social
learning - learning about the environment through observing others
(thus ruling out stimulus and local enhancement).
True imitation is much rarer than individual
learning and other forms of social learning. Humans are extremely
good at imitation; starting almost from birth, and taking pleasure
in doing it. Meltzoff, who has studied imitation in infants for
more than twenty years, calls humans the consummate imitative generalist
(Meltzoff, 1996) (although some of the earliest behaviours he studies,
such as tongue protrusion, might arguably be called contagion rather
than true imitation). Just how rare imitation is has not been answered.
There is no doubt that some song birds learn their songs by imitation,
and that dolphins are capable of imitating sounds as well as actions
(Bauer & Johnson, 1994; Reiss & McCowan, 1993). There is
evidence of imitation in the grey parrot and harbour seals. However,
there is much dispute over the abilities of non-human primates and
other mammals such as rats and elephants (see Byrne & Russon
1998; Heyes & Galef 1996, Tomasello, Kruger & Ratner 1993,
Many experiments have been done on imitation
and although they have not been directly addressed at the question
of whether a new replicator is involved, they may help towards an
answer. For example, some studies have tried to find out how much
of the form of a behaviour is copied by different animals and by
children. In the two-action method a demonstrator uses one of two
possible methods for achieving a goal (such as opening a specially
designed container), while the learner is observed to see which
method is used (Whiten et al. 1996; Zentall 1996). If a different
method is used the animal may be using goal emulation, but if the
same method is copied then true imitation is involved. Evidence
of true imitation has been claimed using this method in budgerigars,
pigeons and rats, as well as enculturated chimpanzees and children
(Heyes and Galef 1996). Capuchin monkeys have recently been found
to show limited ability to copy the demonstrated method (Custance,
Whiten & Fredman 1999).
Other studies explore whether learners
can copy a sequence of actions and their hierarchical structure
(Whiten 1999). Byrne and Russon (1998) distinguish action level
imitation (in which a sequence of actions is copied in detail) from
program level imitation (in which the subroutine structure and hierarchical
layout of a behavioural program is copied). They argue that other
great apes may be capable of program level imitation although humans
have a much greater hierarchical depth. Such studies are important
for understanding imitation, but they do not directly address the
questions at issue here - that is, does the imitation entail an
evolutionary process? Is there a new replicator involved?
To answer this we need new kinds of research
directed at finding out whether a new evolutionary process is involved
when imitation, or other kinds of social learning, take place. This
might take two forms. First there is the question of copying fidelity.
As we have seen, a replicator is defined as an entity that passes
on its structure largely intact in successive replications. So we
need to ask whether the behaviour or information is passed on largely
intact through several replications. For example, in the wild, is
there evidence of tool use, grooming techniques or other socially
learned behaviours being passed on through a series of individuals,
rather than several animals learning from one individual but never
passing the skill on again? In experimental situations one animal
could observe another, and then act as model for a third and so
on (as in the game of Chinese whispers or telephone). We might not
expect copying fidelity to be very high, but unless the skill is
recognisably passed on through more than one replication then we
do not have a new replicator - i.e. there is no need for the concept
of the meme.
Second, is there variation and selection?
The examples given by Whiten et al. (1999) suggest that there
can be. We might look for other examples where skills are passed
to several individuals, these individuals differ in the precise
way they carry out the skill, and some variants are more frequently
or reliably passed on again. For this is the basis of cumulative
culture. Experiments could be designed to detect the same process
occurring in artificial situations. Such studies would enable us
to say just which processes, in which species, are capable of sustaining
an evolutionary process with a new replicator. Only when this is
found can we usefully apply the concept of the meme.
If such studies were done and it turned
out that, by and large, what we have chosen to call imitation can
sustain cumulative evolution while other kinds of social learning
cannot, then we could easily tie the definitions of memes and imitation
together - so that what counts as a meme is anything passed on by
imitation, and wherever you have imitation you have a meme.
In the absence of such research we may
not be justified in taking this step, and some people may feel that
it would not do justice to our present understanding of imitation.
Nevertheless, for the purposes of this paper at least, that is what
I propose. The advantage is that it allows me to use one word "imitation"
to describe a process by which memes are transmitted. If you prefer,
for imitation read "a kind of social learning which is capable
of sustaining an evolutionary process with a new replicator".
This allows me to draw the following conclusion.
Imitation is restricted to very few species and humans appear to
be alone in being able to imitate a very wide range of sounds and
behaviours. This capacity for widespread generalised imitation must
have arisen at some time in our evolutionary history. When it did
so, a new replicator was created and the process of memetic evolution
began. This, I suggest, was a crucial turning point in human evolution.
I now want to explore the consequences of this transition and some
of the coevolutionary processes that may have occurred once human
evolution was driven by two replicators rather than one. One consequence,
I suggest, was a rapid increase in brain size.
The big human brain
Humans have abilities that seem out of
line with our supposed evolutionary past as hunter-gatherers, such
as music and art, science and mathematics, playing chess and arguing
about our evolutionary origins. As Cronin puts it, we have a brain
"surplus to requirements, surplus to adaptive needs" (Cronin,
1991, p 355). This problem led Wallace to argue, against Darwin,
that humans alone have a God-given intellectual and spiritual nature
(see Cronin 1991). Williams (1966) also struggled with the problem
of "mans cerebral hypertrophy", unwilling to accept
that advanced mental capacities have ever been directly favoured
by selection or that geniuses leave more children.
Humans have an encephalisation quotient
of about 3 relative to other primates. That is, our brains are roughly
three times as large when adjusted for body weight (Jerison 1973).
The increase probably began about 2.5 million years ago in the australopithecines,
and was completed about 100,000 years ago by which time all living
hominids had brains about the same size as ours (Leakey, 1994; Wills,
1993). Not only is the brain much bigger than it was, but it appears
to have been drastically reorganised during what is, in evolutionary
terms, a relatively short time (Deacon 1997). The correlates of
brain size and structure have been studied in many species and are
complex and not well understood (Harvey & Krebs 1990). Nevertheless,
the human brain stands out. The problem is serious because of the
very high cost (in energy terms) of both producing a large brain
during development, and of running it in the adult, as well as the
dangers entailed in giving birth. Pinker asks "Why would evolution
ever have selected for sheer bigness of brain, that bulbous, metabolically
greedy organ? ... Any selection on brain size itself would surely
have favored the pinhead." (1994, p 363).
Early theories to explain the big brain
focused on hunting and foraging skills, but predictions have not
generally held up and more recent theories have emphasised the complexity
and demands of the social environment (Barton & Dunbar 1997).
Chimpanzees live in complex social groups and it seems likely that
our common ancestors did too. Making and breaking alliances, remembering
who is who to maintain reciprocal altruism, and outwitting others,
all require complex and fast decision making and good memory. The
"Machiavellian Hypothesis" emphasises the importance of
deception and scheming in social life and suggests that much of
human intelligence has social origins (Byrne & Whiten 1988;
Whiten & Byrne 1997). Other theories emphasise the role of language
(Deacon 1997, Dunbar 1996).
There are three main differences between
this theory and previous ones. First, this theory entails a definite
turning point - the advent of true imitation which created a new
replicator. On the one hand this distinguishes it from theories
of continuous change such as those based on improving hunting or
gathering skills, or on the importance of social skills and Machiavellian
intelligence. On the other hand it is distinct from those which
propose a different turning point, such as Donalds (1991)
three stage coevolutionary model or Deacons (1997) suggestion
that the turning point was when our ancestors crossed the "Symbolic
Second, both Donald and Deacon emphasise
the importance of symbolism or mental representations in human evolution.
Other theories also assume that what makes human culture so special
is its symbolic nature. This emphasis on symbolism and representation
is unnecessary in the theory proposed here. Whether behaviours acquired
by imitation (i.e. memes) can be said to represent or symbolise
anything is entirely irrelevant to their role as replicators. All
that matters is whether they are replicated or not.
Third, the theory has no place for the
leash metaphor of sociobiology, or for the assumption, common to
almost all versions of gene-culture coevolution, that the ultimate
arbiter is inclusive fitness (i.e. benefit to genes). In this theory
there are two replicators, and the relationships between them can
be cooperative, competitive, or anything in between. Most important
is that memes compete with other memes and produce memetic evolution,
the results of which then affect the selection of genes. On this
theory we can only understand the factors affecting gene selection
when we understand their interaction with memetic selection.
In outline the theory is this. The turning
point in hominid evolution was when our ancestors began to imitate
each other, releasing a new replicator, the meme. Memes then changed
the environment in which genes were selected, and the direction
of change was determined by the outcome of memetic selection. Among
the many consequences of this change was that the human brain and
vocal tract were restructured to make them better at replicating
the successful memes.
The origins of imitation
We do not know when and how imitation originated.
In one way it is easy to see why natural selection would have favoured
social learning. It is a way of stealing the products of someone
elses learning - i.e. avoiding the costs and risks associated
with individual learning - though at the risk of acquiring outdated
or inappropriate skills. Mathematical modelling has shown that this
is worthwhile if the environment is variable but does not change
too fast (Richerson and Boyd 1992). Similar analyses have been used
in economics to compare the value of costly individual decision
making against cheap imitation (Conlisk 1980).
As we have seen, other forms of social
learning are fairly widespread, but true imitation occurs in only
a few species. Moore (1996) compares imitation in parrots, great
apes and dolphins and concludes that they are not homologous and
that imitation must have evolved independently at least three times.
In birds imitation probably evolved out of song mimicry, but in
humans it did not. We can only speculate about what the precursors
to human imitation may have been, but likely candidates include
general intelligence and problem solving ability, the beginnings
of a theory of mind or perspective taking, reciprocal altruism (which
often involves strategies like tit-for-tat that entail copying what
the other person does), and the ability to map observed actions
onto ones own.
The latter sounds very difficult to achieve
- involving transforming the visual input of a seen action from
one perspective into the motor instructions for performing a similar
action oneself. However, mirror neurons in monkey premotor cortex
appear to belong to a system that does just this. The same neurons
fire when the monkey performs a goal-directed action itself as when
it sees another monkey perform the same action, though Gallese and
Goldman (1998) believe this system evolved for predicting the goals
and future actions of others, rather than for imitation. Given that
mirror neurons occur in monkeys, it seems likely that our ancestors
would have had them, making the transition to true imitation more
We also do not know when that transition
occurred. The first obvious signs of imitation are the stone tools
made by Homo habilis about 2.5 million years ago, although
their form did not change very much for a further million years.
It seems likely that less durable tools were made before then; possibly
carrying baskets, slings, wooden tools and so on. Even before that
our ancestors may have imitated ways of carrying food, catching
game or other behaviours. By the time these copied behaviours were
widespread the stage was set for memes to start driving genes. I
shall take a simple example and try to explain how the process might
Let us imagine that a new skill begins
to spread by imitation. This might be, for example, a new way of
making a basket to carry food. The innovation arose from a previous
basket type, and because the new basket holds slightly more fruit
it is preferable. Other people start copying it and the behaviour
and the artefact both spread. Note that I have deliberately chosen
a simple meme (or small memeplex) to illustrate the principle; that
is the baskets and the skills entailed in making them. In practice
there would be complex interactions with other memes but I want
to begin simply.
Now anyone who does not have access to
the new type of basket is at a survival disadvantage. A way to get
the baskets is to imitate other people who can make them, and therefore
good imitators are at an advantage (genetically). This means that
the ability to imitate will spread. If we assume that imitation
is a difficult skill (as indeed it seems to be) and requires a slightly
larger brain, then this process alone can already produce an increase
in brain size. This first step really amounts to no more than saying
that imitation was selected for because it provides a survival advantage,
and once the products of imitation spread, then imitation itself
becomes ever more necessary for survival. This argument is a version
of the Baldwin effect (1896) which applies to any kind of learning:
- once some individuals become able to learn something, those who
cannot are disadvantaged and genes for the ability to learn therefore
spread. So this is not specifically a memetic argument.
However, the presence of memes changes
the pressures on genes in new ways. The reason is that memes are
also replicators undergoing selection and as soon as there are sufficient
memes around to set up memetic competition, then meme-gene coevolution
begins. Let us suppose that there are a dozen different basket types
around that compete with each other. Now it is important for any
individual to choose the right basket to copy, but which is that?
Since both genes and memes are involved we need to look at the question
from both points of view.
From the genes point of view the
right decision is the basket that increases inclusive fitness -
i.e. the decision that improves the survival chances of all the
genes of the person making the choice. This will probably be the
biggest, strongest, or easiest basket to make. People who copy this
basket will gather more food, and ultimately be more likely to pass
on the genes that were involved in helping them imitate that particular
basket. In this way the genes, at least to some extent, track changes
in the memes.
From the memes point of view the
right decision is the one that benefits the basket memes themselves.
These memes spread whenever they get the chance, and their chances
are affected by the imitation skills, the perceptual systems and
the memory capacities (among other things) of the people who do
the copying. Now, let us suppose that the genetic tracking has produced
people who tend to imitate the biggest baskets because over a sufficiently
long period of time larger artefacts were associated with higher
biological success. This now allows for the memetic evolution of
all sorts of new baskets that exploit that tendency; especially
baskets that look big. They need not actually be big, or
well made, or very good at doing their job but as long as they trigger
the genetically acquired tendency to copy big baskets then they
will do well, regardless of their consequence for inclusive fitness.
The same argument would apply if the tendency was to copy flashy-looking
baskets, solid baskets, or whatever. So baskets that exploit the
current copying tendencies spread at the expense of those that do
This memetic evolution now changes the
situation for the genes which have, as it were, been cheated and
are no longer effectively tracking the memetic change. Now the biological
survivors will be the people who copy whatever it is about the current
baskets that actually predicts biological success. This might be
some other feature, such as the materials used, the strength, the
kind of handle, or whatever - and so the process goes on. This process
is not quite the same as traditional gene-culture evolution or the
Baldwin effect. The baskets are not just aspects of culture that
have appeared by accident and may or may not be maladaptive for
the genes of their carriers. They are evolving systems in their
own right, with replicators whose selfish interests play a role
in the outcome.
I have deliberately chosen a rather trivial
example to make the process clear; the effects are far more contentious,
as we shall see, when they concern the copying of language, or of
seriously detrimental activities.
Whom to imitate
Another strategy for genes might be to
constrain whom, rather than what, is copied. For example, a good
strategy would be to copy the biologically successful. People who
tended, other things being equal, to copy those of their acquaintances
who had the most food, the best dwelling space, or the most children
would, by and large, copy the memes that contributed to that success
and so be more likely to succeed themselves. If there was genetic
variation such that some people more often copied their biologically
successful neighbours, then their genes would spread and the strategy
"copy the most successful" would, genetically, spread
through the population. In this situation (as I have suggested above)
success is largely a matter of being able to acquire the currently
important memes. So this strategy amounts to copying the best imitators.
I shall call these people meme fountains, a term suggested by Dennett
(1998) to refer to those who are especially good at imitation and
who therefore provide a plentiful source of memes - both old memes
they have copied and new memes they have invented by building on,
or combining, the old.
Now we can look again from the memes
point of view. Any memes that got into the repertoire of a meme
fountain would thrive - regardless of their biological effect. The
meme fountain acquires all the most useful tools, hunting skills,
fire-making abilities and his genes do well. However, his outstanding
imitation ability means that he copies and adapts all sorts of other
memes as well. These might include rain dances, fancy clothes, body
decoration, burial rites or any number of other habits that may
not contribute to his genetic fitness. Since many of his neighbours
have the genetically in-built tendency to copy him these memes will
spread just as well as the ones that actually aid survival.
Whole memetic lineages of body decoration
or dancing might evolve from such a starting point. Taking dancing
as an example, people will copy various competing dances and some
dances will be copied more often than others. This memetic success
may depend on whom is copied, but also on features of the dances,
such as memorability, visibility, interest and so on - features
that in turn depend on the visual systems and memories of the people
doing the imitation. As new dances spread to many people, they open
up new niches for further variations on dancing to evolve. Any of
these memes that get their hosts to spend lots of time dancing will
do better, and so, if there is no check on the process, people will
find themselves dancing more and more.
Switching back to the genes point
of view, the problem is that dancing is costly in terms of time
and energy. Dancing cannot now be un-evolved but its further evolution
will necessarily be constrained. Someone who could better discriminate
between the useful memes and the energy-wasting memes would leave
more descendants than someone who could not. So the pressure is
on to make more and more refined discriminations about what and
whom to imitate. And - crucially - the discriminations that have
to be made depend upon the past history of memetic as well as genetic
evolution. If dancing had never evolved there would be no need for
genes that selectively screened out too much dance-imitation. Since
it did there is. This is the crux of the process I have called memetic
driving. The past history of memetic evolution affects the direction
that genes must take to maximise their own survival.
We now have a coevolutionary process between
two quite different replicators that are closely bound together.
To maximise their success the genes need to build brains that are
capable of selectively copying the most useful memes, while not
copying the useless, costly or harmful ones. To maximise their success
the memes must exploit the brains copying machinery in any
way they can, regardless of the effects on the genes. The result
is a mass of evolving memes, some of which have thrived because
they are useful to the genes, and some of which have thrived in
spite of the fact that they are not - and a brain that is designed
to do the job of selecting which memes are copied and which are
not. This is the big human brain. Its function is selective imitation
and its design is the product of a long history of meme-gene coevolution.
Whom to mate with
There is another twist to this argument;
sexual selection for the ability to imitate. In general it will
benefit females to mate with successful males and, in this imagined
human past, successful males are those who are best at imitating
the currently important memes. Sexual selection might therefore
amplify the effects of memetic drive. A runaway process of sexual
selection could then take off.
For example, let us suppose that at some
particular time the most successful males were the meme fountains.
Their biological success depended on their ability to copy the best
tools or firemaking skills, but their general imitation ability
also meant they wore the most flamboyant clothes, painted the most
detailed paintings, or hummed the favourite tunes. In this situation
mating with a good painter would be advantageous. Females who chose
good painters would begin to increase in the population and this
in turn would give the good painters another advantage, quite separate
from their original biological advantage. That is, with female choice
now favouring good painters, the offspring of good painters would
be more likely to be chosen by females and so have offspring themselves.
This is the crux of runaway sexual selection and we can see how
it might have built on prior memetic evolution.
Miller (1998, 1999) has proposed that artistic
ability and creativity have been sexually selected as courtship
displays to attract women, and has provided many examples, citing
evidence that musicians and artists are predominantly male and at
their most productive during young adulthood. However, there are
differences between his theory and the one proposed here. He does
not explain how or why the process might have begun whereas on this
theory the conditions were created by the advent of imitation and
hence of memetic evolution. Also on his theory the songs, dances
or books act as display in sexual selection, but the competition
between them is not an important part of the process. On the theory
proposed here, memes compete with each other to be copied by both
males and females, and the outcome of that competition determines
the direction taken both by the evolution of the memes and of the
brains that copy them.
Whether this process has occurred or not
is an empirical question. But note that I have sometimes been misunderstood
as basing my entire argument on sexual selection of good imitators
(Aunger, in press). In fact the more fundamental process of memetic
drive might operate with or without the additional effects of sexual
The coevolution of replicators with their replication
Memetic driving of brain design can be
seen as an example of a more general evolutionary process. That
is, the coevolution of a replicator along with the machinery for
its replication. The mechanism is straightforward. As an example,
imagine a chemical soup in which different replicators occur, some
together with coenzymes or other replicating machinery, and some
without. Those which produce the most numerous and long lived copies
of themselves will swamp out the rest, and if this depends on being
associated with better copying machinery then both the replicator
and the machinery will thrive.
Something like this presumably happened
on earth long before RNA and DNA all but eliminated any competitors
(Maynard Smith & Szathmáry 1995). DNAs cellular copying
machinery is now so accurate and reliable that we tend to forget
it must have evolved from something simpler. Memes have not had
this long history behind them. The new replicator is, as Dawkins
(1976 p 192) puts it, "still drifting clumsily about in its
primeval soup ... the soup of human culture". Nevertheless
we see the same general process happening as we may assume once
happened with genes. That is, memes and the machinery for copying
them are improving together.
The big brain is just the first step. There
have been many others. In each case, high quality memes outperform
lower quality memes and their predominance favours the survival
of the machinery that copies them. This focuses our attention on
the question of what constitutes high quality memes. Dawkins (1976)
suggested fidelity, fecundity and longevity.
This is the basis for my argument about
the origins of language (Blackmore 1999, in press). In outline it
is this. Language is a good way of creating memes with high fecundity
and fidelity. Sound carries better than visual stimuli to several
people at once. Sounds digitised into words can be copied with higher
fidelity than continuously varying sounds. Sounds using word order
open up more niches for memes to occupy and so on. In a community
of people copying sounds from each other memetic evolution will
ensure that the higher quality sounds survive. Memetic driving then
favours brains and voices that are best at copying those memes.
This is why our brains and bodies became adapted for producing language.
On this theory the function of language ability is not primarily
biological but memetic. The copying machinery evolved along with
the memes it copies.
The same argument explains why our brains
seem especially adapted to soaking up some kinds of memes rather
than others. For example, most people find mathematics and reading
difficult, but adopting religious rituals, retelling stories and
singing songs easy. This argument parallels an important argument
in evolutionary psychology. It has become increasingly clear that
the human brain is not a general purpose learning device but is
adapted to learn some things more readily than others, based on
genetic advantage in past environments (Pinker 1997, Tooby &
Cosmides 1992). The equivalent for memes is that the brain is not
a general purpose imitation machine, but one honed by memetic and
genetic evolution to be good at copying some kinds of memes and
bad at others. Songs, stories and rituals have long taken part in
gene-meme coevolution while maths and reading are relative newcomers,
using machinery that was not designed for them.
These newcomers have brought with them
further opportunities for the improvement of memes, and with that
further steps in the design of replicating machinery - but this
time outside of the brain. Writing improved the longevity of language
memes and ensured the success of slates, pens, pencils and libraries.
Printing improved fecundity, and the spread of printed books ensured
the survival of printing presses, factories and book shops. Communications
by road, rail, ship and aircraft, served to spread more memes faster
and they in turn encouraged the creation of ever better means of
We can see this process happening very
fast now as communication technologies improve. The mobile phone
is a good example. A decade ago few people would have predicted
its phenomenal penetration. From the preserve of rich business people
it has become a commonplace teenage accessory. Why? Biological advantage
is hardly relevant, and benefit to the individual is arguable when
mobile phones reduce privacy and increase stress and noise pollution.
From the memes point of view it makes perfect sense. With
a mobile phone people can transmit more memes than with a phone
tied to one place. As these memes spread they carry with them the
idea of using the mobile phone, which thrives along with the memes
it transmits. This suggests the testable prediction that the success
or failure of new technologies is closely correlated with their
effectiveness as meme spreading devices.
Another general principle is the shift
from what I have called "copy-the-product" to "copy-the-instruction"
(Blackmore 1999). In terms of fidelity, fecundity and longevity
it is preferable to copy the instructions for making something rather
than copying the product itself. Copying a product (like a wheel,
a dance or a verbal story) inevitably allows for the introduction
of errors (as in the soup discussed above) and those errors are
cumulative over sequential copying. Higher fidelity copying is therefore
achieved by copying the instructions, especially if they can be
easily copied, and safely stored. In this case any errors made in
building the product affect only one product and not a whole lineage.
A further reduction in error rates can be achieved by digitising
the instructions. As Dawkins (1995) points out, this is why digital
codes have evolved in both biology (in the form of the digital genetic
code) and in human technologies such as telephones, hi-fi systems
Copying the instructions also leads to
higher fecundity because the same set of instructions can be used
again and again. Finally, many products are necessarily ephemeral,
such as soups, songs, music and speech, but the instructions for
making them can potentially be stored for ever (whether in human
memory or in cultural artefacts).
This suggests that copying the instructions
is a better evolutionary strategy. In fact this is an empirical
issue that, at least in limited domains, could be tested. But, assuming
it is correct, we ought to find a shift from one mode of copying
to the other throughout evolution, as the products of the better
system out-performed those of the inferior system. This could be
why we now find in biology the distinction into genotype and phenotype,
and why Lamarckian inheritance does not occur in sexually
Many human inventions can be seen as shifts
from copy-the-product to copy-the-instruction. For example writing
made it possible to recreate the same stories, myths and social
contracts again and again from the same stored instructions. Printing
made possible the storage of type that could be used to produce
multiple copies of the same book. More recently high technology
products are produced with enormous accuracy from instructions for
building them and we see the appearance of systems that look very
much like genotypes and phenotypes. For example, the instructions
for storing and displaying text in the program Word 97 are faithfully
copied every time it is installed in a new computer (even if they
do not always perform identically), but it is the products made
by users (letters, books and so on) which act like phenotypes or
interactors in that their success determines how many more copies
of Word 97 are made.
All these are examples of a powerful and
general evolutionary principle. Higher quality replicators spread
at the expense of poorer quality competitors, and as they do so
they spread the replication machinery that copied them. Most simply
put, we have coevolution between replicators and their copying machinery.
Not only is this is how technology evolves, it is how we humans
got our brains.
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