The Law of
the Jungle: Moral Alternatives and Principles of Evolution
J. L. Mackie
people speak of ‘the law of the jungle’, they usually mean unrestrained
and ruthless competition, with everyone out solely for his own advantage.
But the phrase was coined by Rudyard Kipling, in The Second Jungle
Book, and he meant something very different. His law of the
jungle is a law that wolves in a pack are supposed to obey. His
poem says that ‘the strength of the Pack is the Wolf, and the strength
of the Wolf is the Pack’, and it states the basic principles of
social co-operation. Its provisions are a judicious mixture of individualism
and collectivism, prescribing graduated and qualified rights for
fathers of families, mothers with cubs, and young wolves, which
constitute an elementary system of welfare services. Of course,
Kipling meant his poem to give moral instruction to human children,
but he probably thought it was at least roughly correct as a description
of the social behaviour of wolves and other wild animals. Was he
right, or is the natural world the scene of unrestrained competition,
of an individualistic struggle for existence?
not unlike those of Kipling have been presented by some recent writers
on ethology, notably Robert Ardrey and Konrad Lorenz. These writers
connect their accounts with a view about the process of evolution
that has brought this behaviour, as well as the animals themselves,
into existence. They hold that the important thing in evolution
is the good of the species, or the group, rather than the good of
the individual. Natural selection favours those groups and species
whose members tend, no doubt through some instinctive programming,
to co-operate for a common good; this would, of course, explain
why wolves, for example, behave cooperatively and generously towards
members of their own pack, if indeed they do.
this recently popular view has been keenly attacked by Richard Dawkins
in his admirable and fascinating book, The Selfish Gene.
He defends an up-to-date version of the orthodox Darwinian
theory of evolution, with special reference to ‘the biology of selfishness
and altruism’. One of his main theses is that there is no such thing
as group selection, and that Lorenz and others who have used this
as an explanation are simply wrong. This is a question of some interest
to moral philosophers, particularly those who have been inclined
to see human morality itself as the product of some kind of natural
is well, however, to be clear about the issue. It is not whether
animals ever behave for the good of the group in the sense that
this is their conscious subjective goal, that they aim at
the well-being or survival of the whole tribe or pack: the question
of motives in this conscious sense does not arise. Nor is the issue
whether animals ever behave in ways which do in fact promote the
well-being of the group to which they belong, or which help the
species of which they are members to survive: of course they do.
The controversial issue is different from both of these: it is whether
the good of the group or the species would ever figure in a correct
evolutionary account. That is, would any correct evolutionary account
take either of the following forms?
The members of this species tend to do these things which assist
the survival of this species because their ancestors were members
of a subspecies whose members had an inheritable tendency to do
these things, and as a result that sub-species survived, whereas
other sub-species of the ancestral species at that time had members
who tended not to do these things and as a result their sub-species
did not survive.
The members of this species tend to do these things which help the
group of which they are members to flourish because some ancestral
groups happened to have members who tended to do these things and
these groups, as a result, survived better than related groups of
the ancestral species whose members tended not to do these things.
other words, the issue is this: is there natural selection by and
for group survival or species survival as opposed to selection by
and for individual survival (or, as we shall see, gene survival)?
Is behaviour that helps the group or the species, rather than the
individual animal, rewarded by the natural selection which determines
the course of evolution?
when Dawkins denies that there is selection by and for group or
species survival, it is not selection by and for individual survival
that he puts in its place. Rather it is selection by and for the
survival of each single gene - the genes being the unit factors
of inheritance, the portions of chromosomes which replicate themselves,
copy themselves as cells divide and multiply. Genes, he argues,
came into existence right back at the beginning of life on earth,
and all more complex organisms are to be seen as their products.
We are, as he picturesquely puts it, gene-machines: our biological
function is just to protect our genes, carry them around, and enable
them to reproduce themselves. Hence the title of his book, The
Selfish Gene. Of course what survives is not a token gene: each
of these perishes with the cell of which it is a part. What survives
is a gene-type, or rather what we might call a gene-clone, the members
of a family of token genes related to one another by simple direct
descent, by replication. The popularity of the notions of species
selection and group selection may be due partly to confusion on
this point. Since clearly it is only types united by descent, not
individual organisms, that survive long enough to be of biological
interest, it is easy to think that selection must be by and for
species survival. But this is a mistake: genes, not species, are
the types which primarily replicate themselves and are selected.
Since Dawkins roughly defines the gene as ‘a genetic unit which
is small enough to last for a number of generations and to be distributed
around in the form of many copies’, it is (as he admits) practically
a tautology that the gene is the basic unit of natural selection
and therefore, as he puts it, ‘the fundamental unit of self-interest’,
or, as we might put it less picturesquely, the primary beneficiary
of natural selection. But behind this near-tautology is a synthetic
truth, that this basic unit, this primary beneficiary, is a small
bit of a chromosome. The reason why this is so, why what is differentially
effective and therefore subject to selection is a small bit of a
chromosome, lies in the mechanism of sexual reproduction by way
of meiosis, with crossing over between chromosomes. When male and
female cells each divide before uniting at fertilization, it is
not chromosomes as a whole that are randomly distributed between
the parts, but sections of chromosomes. So sections of chromosomes
can be separately inherited, and therefore can be differentially
selected by natural selection.
issue between gene selection, individual selection, group selection,
and species selection might seem to raise some stock questions in
the philosophy of science. Many thinkers have favoured reductionism
of several sorts, including methodological individualism. Wholes
are made up of parts, and therefore in principle whatever happens
in any larger thing depends upon and is explainable in terms of
what happens in and between its smaller components. But though this
metaphysical individualism is correct, methodological individualism
does not follow from it. It does not follow that we must always
conduct our investigations and construct our explanations in terms
of component parts, such as the individual members of a group or
society. Scientific accounts need not be indefinitely reductive.
Some wholes are obviously more accessible to us than their components.
We can understand what a human being does without analysing this
in terms of how each single cell in his body or his brain behaves.
Equally we can often understand what a human society does without
analysing this in terms of the behaviour of each of its individual
members. And the same holds quite generally: we can often understand
complex wholes as units, without analysing them into their parts.
So if, in the account of evolution, Dawkins’s concentration upon
genes were just a piece of methodological individualism or reductionism,
it would be inadequately motivated. But it is not: there is a special
reason for it. Dawkins’s key argument is that species, populations,
and groups, and individual organisms too, are as genetic units too
temporary to qualify for natural selection. ‘They are not stable
through evolutionary time. Populations are constantly blending with
other populations and so losing their identity’, and, what is vitally
important, ‘are also subject to evolutionary change from within’
abstract general proposition may seem obscure. But it is illustrated
by a simple example which Dawkins gives (pp. 197—201).
species of birds is parasitized by dangerous ticks. A bird can remove
the ticks from most parts of its own body, but, having only a beak
and no hands, it cannot get them out of the top of its own head.
But one bird can remove ticks from another bird’s head: there can
be mutual grooming. Clearly if there were an inherited tendency
for each bird to take the ticks out of any other bird’s head, this
would help the survival of any group in which that tendency happened
to arise - for the ticks are dangerous: they can cause death. Someone
who believed in group selection would, therefore, expect this tendency
to be favoured and to evolve and spread for this reason. But Dawkins
shows that it would not. He gives appropriate names to the different
‘strategies’, that is, the different inheritable behavioural tendencies.
The strategy of grooming anyone who needs it he labels ‘Sucker’.
The strategy of accepting grooming from anyone, but never grooming
anyone else, even someone who has previously groomed you, is called
‘Cheat’. Now if in some population both these tendencies or strategies,
and only these two, happen to arise, it is easy to see that the
cheats will always do better than the suckers. They will be groomed
when they need it, and since they will not waste their time pecking
out other birds’ ticks, they will have more time and energy to spare
for finding food, attracting mates, building nests, and so on. Consequently
the gene for the Sucker strategy will gradually die out. So the
population will come to consist wholly of cheats, despite the fact
that this is likely to lead to the population itself becoming extinct,
if the parasites are common enough and dangerous enough, whereas
a population consisting wholly of suckers would have survived. The
fact that the group is open to evolutionary change from within,
because of the way the internal competition between Cheat and Sucker
genes works out, prevents the group from developing or even retaining
a feature which would have helped the group as a whole.
is just one illustration among many, and Dawkins’s arguments on
this point seem pretty conclusive. We need, as he shows, the concept
of an evolutionarily stable strategy or ESS (p. 74 et
passim). A strategy is evolutionarily stable, in relation to
some alternative strategy or strategies, if it will survive indefinitely
in a group in competition with those alternatives. We have just
seen that where Cheat and Sucker alone are in competition, Cheat
is an ESS but Sucker is not. We have also seen, from this example,
that an ESS may not help a group, or the whole species, to survive
and multiply. Of course we must not leap to the conclusion that
an ESS never helps a group or a species: if that were so we could
not explain much of the behaviour that actually occurs. Parents
sacrifice themselves for their children, occasionally siblings for
their siblings, and with the social insects, bees and ants and termites,
their whole life is a system of communal service. But the point
is that these results are not to be explained in terms of group
selection. They can and must be explained as consequences of the
selfishness of genes, that is, of the fact that gene-clones are
selected for whatever helps each gene-clone itself to survive and
now we come to another remarkable fact. Although the gene is the
hero of Dawkins’s book, it is not unique either in principle or
in fact. It is not the only possible subject of evolutionary natural
selection, nor is it the only actual one. What is important about
the gene is just that it has a certain combination of logical features.
It is a replicator: in the right environment it is capable of producing
multiple copies of itself; but in this process of copying some mistakes
occur; and these mistaken copies
mutations - will also produce copies of themselves; and, finally,
the copies produced may either survive or fail to survive. Anything
that has these formal, logical, features is a possible subject of
evolution by natural selection. As we have seen, individual organisms,
groups, and species do not have the required formal features, though
many thinkers have supposed that they do. They cannot reproduce
themselves with sufficient constancy of characteristics. But Dawkins,
in his last chapter, introduces another sort of replicators. These
are what are often called cultural items or traits; Dawkins christens
them memes - to make a term a bit like ‘genes’ - because
they replicate by memory and imitation (mimesis). Memes include
tunes, ideas, fashions, and techniques. They require, as the environment
in which they can replicate, a collection of minds, that is, brains
that have the powers of imitation and memory. These brains (particularly
though not exclusively human ones) are themselves the products of
evolution by gene selection. But once the brains are there gene
selection has done its work: given that environment, memes can themselves
evolve and multiply in much the same way as genes do, in accordance
with logically similar laws. But they can do so more quickly. Cultural
evolution may be much faster than biological evolution. But the
basic laws are the same. Memes are selfish in the same sense as
genes. The explanation of the widespread flourishing of a certain
meme, such as the idea of a god or the belief in hell fire, may
be simply that it is an efficiently selfish meme. Something about
it makes it well able to infect human minds, to take root and spread
in and among them, in the same way that something about the smallpox
virus makes it well able to take root and spread in human bodies.
There is no need to explain the success of a meme in terms of any
benefit it confers on individuals or groups; it is a replicator
in its own right. Contrary to the optimistic view often taken of
cultural evolution, this analogy shows that a cultural trait can
evolve, not because it is advantageous to society, but simply because
it is advantageous to itself. It is ironical that Kipling’s phrase
‘the law of the jungle’ has proved itself a more efficient meme
than the doctrine he tried to use it to propagate.
far I have been merely summarizing Dawkins’s argument. We can now
use it to answer the question from which I started. Who is right
about the law of the jungle? Kipling, or those who have twisted
his phrase to mean almost the opposite of what he intended? The
answer is that neither party is right. The law by which nature works
is not unrestrained and ruthless competition between individual
organisms. But neither does it turn upon the advantages to a group,
and its members, of group solidarity, mutual care and respect, and
co-operation. It turns upon the self-preservation of gene-clones.
This has a strong tendency to express itself in individually selfish
behaviour, simply because each agent’s genes are more certainly
located in him than in anyone else. But it can and does express
itself also in certain forms of what Broad called self-referential
altruism, including special care for one’s own children and perhaps
one’s siblings, and, as we shall see, reciprocal altruism, helping
those (and only those) who help you.
now I come to what seems to be an exception to Dawkins’s main thesis,
though it is generated by his own argument and illustrated by one
of his own examples. We saw how, in the example of mutual grooming,
if there are only suckers and cheats around, the strategy Cheat
is evolutionarily stable, while the strategy Sucker is not. But
Dawkins introduces a third strategy, Grudger. A grudger is rather
like you and me. A grudger grooms anyone who has previously groomed
him, and any stranger, but he remembers and bears a grudge against
anyone who cheats him - who refuses to groom him in return for having
been groomed - and the grudger refuses to groom the cheat ever again.
Now when all three strategies are in play, both Cheat and Grudger
are evolutionarily stable. In a population consisting largely of
cheats, the cheats will do better than the others, and both suckers
and grudgers will die out. But in a population that starts off with
more than a certain critical proportion of grudgers, the cheats
will first wipe out the suckers, but will then themselves become
rare and eventually extinct: cheats can flourish only while they
have suckers to take advantage of, and yet by doing so they tend
to eliminate those suckers.
is obvious, by the way, that a population containing only suckers
and grudgers, in any proportions, but no cheats, would simply continue
as it was. Suckers and grudgers behave exactly like one another
as long as there are no cheats around, so there would be no tendency
for either the Sucker of the Grudger gene to do better than the
other. But if there is any risk of an invasion of Cheat genes, either
through mutation or through immigration, such a pattern is not evolutionarily
stable, and the higher the proportion of suckers, the more rapidly
the cheats would multiply.
we have two ESSs, Cheat and Grudger. But there is a difference between
these two stable strategies. If the parasites are common enough
and dangerous enough, the population of cheats will itself die out,
having no defence against ticks in their heads, whereas a separate
population of grudgers will flourish indefinitely. Dawkins says,
‘If a population arrives at an ESS which drives it extinct, then
it goes extinct, and that is just too bad’ (p. 200). True: but
is this not group selection after all? Of course, this will
operate only if the populations are somehow isolated. But if the
birds in question were distributed in geographically isolated regions,
and Sucker, Cheat and Grudger tendencies appeared (after the parasites
became plentiful) in randomly different proportions in these different
regions, then some populations would become pure grudger populations,
and others would become pure cheat populations, but then the pure
cheat populations would die out, so that eventually all surviving
birds would be grudgers. And they would be able to recolonize the
areas where cheat populations had perished.
name for grudgers is ‘reciprocal altruists’. They act as if on the
maxim ‘Be done by as you did’. One implication of this story is
that this strategy is not only evolutionarily stable within a population,
it is also viable for a population as a whole. The explanation of
the final situation, where all birds of this species are grudgers,
lies partly in the non-viability of a population of pure cheats.
So this is, as I said, a bit of group selection after all.
is worth noting how and why this case escapes Dawkins’s key argument
that a population is ‘not a discrete enough entity to be a unit
of natural selection, not stable and unitary enough to be "selected"
in preference to another population’ (p. 36). Populations can be
made discrete by geographical (or other) isolation, and can be made
stable and unitary precisely by the emergence of an ESS in each,
but perhaps different ESSs in the different regional populations
of the same species. This case of group selection is necessarily
a second order phenomenon: it arises where gene selection has produced
the ESSs which are then persisting selectable features of groups.
In other words, an ESS may be a third variety of replicator, along
with genes and memes; it is a self-reproducing feature of groups.
might reply that this is not really group selection because it all
rests ultimately on gene selection, and a full explanation can be
given in terms of the long-run self-extinction of the Cheat gene,
despite the fact that within a population it is evolutionarily stable
in competition with the two rival genes. But this would be a weak
reply. The monopoly of cheating over a population is an essential
part of the causal story that explains the extinction. Also, an
account at the group level, though admittedly incomplete, is here
correct as far as it goes. The reason why all ultimately surviving
birds of this species are grudgers is partly that populations
of grudgers can survive whereas populations of cheats
cannot, though it is also partly that although a population of suckers
could survive - it would be favoured by group selection, if this
possibility arose, just as much as a population of grudgers - internal
changes due to gene selection after an invasion of Cheat genes would
prevent there being a population of suckers. In special circumstances
group selection (or population selection) can occur and could be
observed and explained as such, without going down to the gene selection
level. It would be unwarranted methodological individualism or reductionism
to insist that we not merely can but must go down to the gene selection
level here. We must not fall back on this weak general argument
when Dawkins’s key argument against group selection fails.
conclude, then, that there can be genuine cases of group selection.
But I admit that they are exceptional. They require rather special
conditions, in particular geographical isolation, or some other
kind of isolation, to keep the populations that are being differentially
selected apart. For if genes from one could infiltrate another,
the selection of populations might be interfered with. (Though in
fact in our example complete isolation is not required: since
what matters is whether there is more or less than a certain critical
proportion of grudgers, small-scale infiltrations would only delay,
not prevent, the establishing of pure populations.) And since special
conditions are required, there is no valid general principle that
features which would enable a group to flourish will be selected.
And even these exceptional cases conform thoroughly to the general
logic of Dawkins’s doctrine. Sometimes, but only sometimes, group
characteristics have the formal features of replicators that are
open to natural selection.
on an earlier version of this paper, Dawkins agreed that there could
be group selection in the sort of case I suggested, but stressed
the importance of the condition of geographical (or other) isolation.
He also mentioned a possible example, that the prevalence of sexual
reproduction itself may be a result of group selection. For if there
were a mutation by which asexual females, producing offspring by
parthenogenesis, occurred in a species, this clone of asexual females
would be at once genetically isolated from the rest of the species,
though still geographically mixed with them. Also, in most species
males contribute little to the nourishment or care of their offspring;
so from a genetic point of view males are wasters: resources would
be more economically used if devoted only to females. So the genetically
isolated population of asexual females would out-compete the normal
sexually reproducing population with roughly equal numbers of males
and females. So the species would in time consist only of asexual
females. But then, precisely because all its members were genetically
identical, it would not have the capacity for rapid adaptation by
selection to changing conditions that an ordinary sexual population
has. So when conditions changed, it would be unable to adapt, and
would die out. Thus there would in time be species selection against
any species that produced an asexual female mutation. Which would
explain why nearly all existing species go in for what, in the short
run, is the economically wasteful business of sexual reproduction.
implications for human morality have such biological facts about
selfishness and altruism? One is that the possibility that morality
is itself a product of natural selection is not ruled out, but care
would be needed in formulating a plausible speculative account of
how it might have been favoured. Another is that the notion of an
ESS may be a useful one for discussing questions of practical morality.
Moral philosophers have already found illumination in such simple
items of game theory as the Prisoners’ Dilemma; perhaps these rather
more complicated evolutionary ‘games’ will prove equally instructive.
Of course there is no simple transition from ‘is’ to ‘ought’, no
direct argument from what goes on in the natural world and among
non-human animals to what human beings ought to do. Dawkins himself
explicitly warns against any simple transfer of conclusions. At
the very end of the book he suggests that conscious foresight may
enable us to develop radically new kinds of behaviour. ‘We are built
as gene machines and cultured as meme machines, but we have the
power to turn against our creators. We, alone on earth, can rebel
against the tyranny of the selfish replicators’ (p. 215). This optimistic
suggestion needs fuller investigation. It must be remembered that
the human race as a whole cannot act as a unit with conscious foresight.
Arrow’s Theorem shows that even quite small groups of rational individuals
may be unable to form coherently rational preferences, let alone
to act rationally. Internal competition, which in general prevents
a group from being a possible subject of natural selection, is even
more of an obstacle to its being a rational agent. And while we
can turn against some memes, it will be only with the help and under
the guidance of other memes.
is an enormous problematic area. For the moment I turn to a smaller
point. In the mutual grooming model, we saw that the Grudger strategy
was, of the three strategies considered, the only one that was healthy
in the long run. Now something closely resembling this strategy,
reciprocal altruism, is a well known and long established tendency
in human life. It is expressed in such formulae as that justice
consists in giving everyone his due, interpreted, as Polemarchus
interprets it in the first book of Plato’s Republic, as doing
good to one’s friends and harm to one’s enemies, or repaying good
with good and evil with evil. Morality itself has been seen, for
example by Edward Westermarck, as an outgrowth from the retributive
emotions. But some moralists, including Socrates and Jesus, have
recommended something very different from this, turning the other
cheek and repaying evil with good. They have tried to substitute
‘Do as you would be done by’ for ‘Be done by as you did’. Now this,
which in human life we characterize as a Christian spirit or perhaps
as saintliness, is roughly equivalent to the strategy Dawkins has
unkindly labelled ‘Sucker’. Suckers are saints, just as grudgers
are reciprocal altruists, while cheats are a hundred per cent selfish.
And as Dawkins points out, the presence of suckers endangers the
healthy Grudger strategy. It allows cheats to prosper, and could
make them multiply to the point where they would wipe out the grudgers,
and ultimately bring about the extinction of the whole population.
This seems to provide fresh support for Nietzsche’s view of the
deplorable influence of moralities of the Christian type. But in
practice there may be little danger. After two thousand years of
contrary moral teaching, reciprocal altruism is still dominant in
all human societies; thoroughgoing cheats and thoroughgoing saints
(or suckers) are distinctly rare. The sucker slogan is an efficient
meme, but the sucker behaviour pattern far less so. Saintliness
is an attractive topic for preaching, but with little practical
persuasive force. Whether in the long run this is to be deplored
or welcomed, and whether it is alterable or not, is a larger question.
To answer it we should have carefully to examine our specifically
human capacities and the structure of human societies, and also
many further alternative strategies. We cannot simply apply to the
human situation conclusions drawn from biological models. Nevertheless
they are significant and challenging as models; it will need to
be shown how and where human life diverges from them.
University College, Oxford.
1 R. Dawkins, The Selfish Gene (Oxford, 1976).
2 I am among these: see p. 113 of my Ethics:
Inventing Right and Wrong (Penguin, Harmondsworth, 1977).
3 This suggestion is made in a section entitled
‘The paradox of sex and the cost of paternal neglect’ of the following
article: R. Dawkins, ‘The value judgments of evolution’, in M. A.
H. Dempster and D. J. McFarland (eds) Animal Economics (Academic
Press, London and New York, forthcoming).
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