Download Bowles, S. and Gintis, H.: A cooperative species—human reciprocity

J Econ (2011) 104:191–194
DOI 10.1007/s00712-011-0237-5
BOOK REVIEW
Bowles, S. and Gintis, H.: A cooperative
species—human reciprocity and its evolution
288pp, Princeton University Press, Princeton and Oxford 2011,
Hardback, e24.35
Werner Güth
Published online: 27 August 2011
© Springer-Verlag 2011
The authors consider homo sapiens as “A Cooperative Species”. What I like about this
is that it allows for continuity in the sense that also ape species, our close relatives in
the animal kingdom, are “cooperative species”. Thinking of genocides, e.g. in the form
of building concentration camps to murder millions of people, should make it clear
that “cooperative” is a rather neutral quality—we often “cooperate” in doing good as
well as in causing harm. The book offers a rich account of biological, anthropological,
experimental findings which render its reading undoubtedly worthwhile. The question
is, however, whether the authors are rather eclectic in reporting evidence and when
explaining what they report. And one is left alone when asking oneself how is “cooperation” related to specialization and labor division which is so highly developed in
homo sapiens, what, of course, presupposes some trading group exceeding the size of
families. But let us first describe what the book offers.
Chapter 1 elaborates on what is actually meant by “A Cooperative Species”, namely
that we “are genuinely concerned about the well-being of others, try to uphold social
norms, and value behaving ethically for its own sake” (p. 1) and that this is so because
our (human) ancestors lived in habitats where such qualities were fitness enhancing. Actually, the main idea is that they existed in groups of “individuals who were
predisposed to cooperate and uphold ethical norms” (p. 1).
Inclinations to care for group welfare are justified as being evolutionarily stable
since phenotypes with such inclinations protect themselves by ostracizing those without such inclinations, since such inclinations become intrinsic once over a lifetime,
and since groups compete with other groups in order to maintain or even enlarge their
habitat. What is less clear is whether such structural aspects also apply to some other
species. We should be afraid of a hindsight bias, e.g. in the sense of assuming that
what we know has happened, had to happen?
W. Güth (B)
Max Planck Institute of Economics, Jena, Germany
e-mail: [email protected]
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After briefly mentioning the normative approach to decision making, based on
preferences, beliefs and constraints (action space), Chapter 2 propagates the idea of
social preferences, specifically altruism. As experimental evidence, the authors mention results of one-shot prisoners’ dilemma games for which appropriately defined
altruism can render mutual cooperation an equilibrium outcome. What “evolution”
means is then more clearly discussed in the section on “Genes Culture, Groups, and
Institutions”. The authors refer to gene-culture coevolution where, of course, genetic
adaptation is slow compared to the tremendous speed of cultural evolution in mankind. “The parallel between cultural and biological evolution” (p.15) is more difficult
to buy, especially since cultural adaptation often relies on institutional prerequisites
(schools, universities,. . .). Regarding genetic evolution one would have liked to see a
convincing argument how and why human intelligence could evolve and why we use
this intelligence to bother about the well-being of those in the same group and to harm
those in other groups.
Chapter 3 propagates “Social preferences” in the sense of reciprocity inclination
or responding in kind. The concept was studied in (social) psychology long before
its more recent discussion in experimental economics employing punishment games
or trust-and-reward games. The evidence is often very interesting, especially when
cross-cultural effects are reported (Section 3.8) where—as often in so-called crosscultural/country studies—one misses the comparison with intra-cultural/country variance.
Interestingly enough, when played repeatedly using a partners design, the evidence
is rather uncomforting since cooperation is declining. What this shows is that without
punishment institutions like veto power in the ultimatum game, cooperation is endangered. Could one not argue: we are not intrinsically concerned about others’ well-being
but we are clever enough to develop emotional reactions that make us reciprocate?
Actually, when in an ultimatum experiment having to wait before reacting to an
unfair proposal, the rejection rate is smaller than when responding impulsively. It very
much depends on circumstances how reciprocal we are. Couldn’t it be that we have
developed a very flexible behavioral repertoire of which “cooperativeness” is only one
option? Social preferences in the narrower sense of neoclassical economics can easily
be shown (analytically) to be evolutionarily stable when certain conditions prevail: if
changing the own preference type is somehow noticeable by others, this change does
not only affect the own behavior but also that of others who are noticing this change.
Partitioning society such that “group” sizes are small could imply such effects.
Chapter 4 discusses the “socio-biology” of evolution. What it essentially propagates is to give up the standard assumption of unbiased random matching. It is well
known that in case of sufficiently strong associative matching cooperative behavior
can evolve. Although associative rather than random matching is the generic case,
assuming that a species is substructured in groups may mean to throw out the baby
with the bath water. To maintain one species of all, there has to be migration. To justify
the claim of methodological individualism, one would like to hear a story how such
a group structure results from individual choices, e.g. by individuals establishing or
severing links with others (as studied in strategic network formation).
Chapter 5 strangely begins with presenting Folk Theorems for infinitely often
repeated base games, e.g. the prisoners’ dilemma game on p. 81. One argument—
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see also the own criticism by the authors in section 5.6—against this is that nearly
every outcome can be justified by a subgame perfect equilibrium. Why do the authors
focus on cooperative outcomes? Another objection is that requiring subgame consistency (all isomorphic subgames must have the same solution) avoids Folk Theorems.
Most importantly, however, human life is finite (in the sense of a commonly known
upper bound for human life). Viewing the infinite horizon as the limit of large finite
horizons is another way to avoid Folk Theorems. Note also that one does not need
an infinite horizon when the base game has multiple equilibria with different payoffs
(one can threaten to switch to a worse equilibrium in case of a deviation from solution
play). Here the criticism would be only that the subgame perfect equilibria which
condition on past moves are not subgame consistent. So what remains is the insight
that by not just looking at future implications but reacting to some forgone events,
we can stabilize cooperation. This again postulates reciprocity inclinations. For this
there exists ample evidence—experimentally, however, based on scenarios where a
finite horizon is unavoidable. We probably observe a lot of initial cooperation in finite
horizon games because of punishment incentives, similar to ultimatum experiments.
In Chapter 6 the interesting idea of reputation formation in repeated interaction
meaning that human life unfolds in a more or less stable group is elaborated. Note that
this allows a cooperative type not only to display own cooperativeness but also the
conditional co-operators in his group to behave cooperatively, i.e., we are outside the
realm of habitats for which general theorems (of evolutionary selection) predict own
material opportunism (assuming that material success is the relevant fitness measure).
Such reputation formation requires limited group sizes allowing that everybody learns
more or less about all others. The authors try to justify this by referring to anthropological, genetic, and prehistoric warfare evidence. Of course, it is a bit questionable how
representative the evidence about which we can learn now is for the circumstances of
our ancestors. And should we not more explicitly incorporate the genetic and cultural
inheritance of the ancestors (primates) of our (human) ancestors because the evolution
of human cooperation did not start from scratch.
The coevolution of institutions and behaviors can and should be studied theoretically especially since the efficiency of institutions will depend on the reliability of
the individuals implementing them. So, for instance, witness evidence will be rather
questionable in a society where lying is common practice. The authors first describe a
broad impression about such coevolution by reporting some finding and then formally
justify their interpretation by explicitly modelling intergroup interaction: “the model
works because altruists confer fitness advantages on insiders, while inflicting fitness
costs on outsiders” (p. 113).
“Selective Extinction” (Section 7.1) is mathematically formulated and formally
analyzed (in Sections 7.2 to 7.4) and applied in Sections 7.5, 7.6 by imposing calibrated parameters before simulating “Gene-Culture Coevolution” (Section 7.7).
Chapter 8 continues with simulation findings, this time with simulating “Parochialism, Altruism, and War”, first illustrated by rather special games (Tables 8.1 and
Figure 8.1). The authors then go on to discuss what they call “Strong reciprocity”
(Chapter 8), namely a “predisposition to cooperate and a willingness to punish defectors” (p. 148). They begin with a little analytical exercise or some complex simulation
and then draw rather general and mostly intuitive conclusions which are additionally
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supported by field or experimental evidence. “Socialization” (Chapter 10) and “Social
Emotions” (Chapter 11) are analyzed in the same way. A special service for the reader
is the Appendix with altogether 12 subsections giving the formal details and illustrations of altruism, agent based models, “game theory” (only a glimpse of it), dynamical
systems, etc.
Reading the book is an exciting experience, mainly because it
• is very informative by reporting findings from different sciences like archaeology,
eth(n)ology, evolutionary theory, experimental research and relating them to each
other,
• offers a specific approach relying on partitioning mankind in subgroups allowing
altruists to survive in spite of their disadvantage, and reputation formation in small
sub-societies,
• but also provokes the reader with their approach, e.g. by letting her decide for herself how subgroup structuring results from individual (non)migration tendencies,
how to actually imagine the dynamics of genetic and cultural adaptation, how to
compare the evidence, generated by archaeologists and eth(n)ologists with those
produced by analytic exercises, numerical simulations, and recent experiments.
It is this impressive courage of drawing major conclusions from so far still very
specific evidence which impresses the reader most. This is not just a selling story but,
in my view, the deep conviction of Samuel Bowles and Herbert Gintis how mankind
could evolve as a cooperative species due to its strong reciprocity inclinations. Like
me, readers might not follow their reasoning in some aspects. But these do not question
that the broad picture which they describe is an appealing one. Like me, most readers
will finally say: “Dear Herb, dear Sam, I am very impressed and thank you both for
this most inspiring book!”
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