The Pleistocene Social Contract: Culture and Cooperation in Human Evolution

189 Pages·2021·0.922 MB·English

by  Kim Sterelny

The Pleistocene Social Contract

The Pleistocene
Social Contract
Culture and Cooperation
in Human Evolution
KIM STERELNY
Philosophy
RSSS Australian National University
1
3
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Library of Congress Control Number: 2020043282
ISBN 978– 0– 19– 753138– 9
DOI: 10.1093/ oso/ 9780197531389.001.0001
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For Midnight. And the other feline companions who have kept
me such good company in my years in philosophy: Hegel,
Satan, Scruff, Little Scruff, Artemis, Moss Bros, Diva, Pretta
and Colette. Loved and missed.
Preface
Many books have a long prehistory, and this one is no exception.
I began thinking about human social evolution around the turn of
the century, largely in response to John Maynard Smith and Eors
Szathmary, and their Major Transitions in Evolution. At that time,
my core interest was in macroevolution and evolvability (the world
has been spared my great work on that), and Major Transitions
closes with the idea that the emergence of human social life was the
final major transition (so far) in evolution. So my initial idea was
to explore macroevolutionary issues and major transitions using
hominin evolution as a stalking horse. Alas, the example ate the
project, and for close to twenty years I have spent much of my time
digging skeletons out of the hominin closet and with the direction
of theoretical illumination going the other way. I used ideas about
the importance of niche construction in evolutionary change; the
importance of adaptive plasticity to evolutionary change, and ideas
about the nature and role of non- genetic inheritance to illumi-
nate the evolutionary trajectory through which we became such
aberrant great apes. An initial sketch of these ideas was roughed
out at the end of Thought in a Hostile World. That sketch, a view
in which the downstream niche construction of the parental gen-
eration shaped the developmental environment of the incoming
generation in ways that made further change possible, was fleshed
out in The Evolved Apprentice. In turn, at the end, that book briefly
engaged with the late Pleistocene transformation of hominin
life. The Pleistocene Social Contract takes up that challenge more
fully, while revisiting and (I hope) enriching the account of the
earlier Pleistocene prequel to the complexities of late Pleistocene
forager life.
x Preface
So it has been a long trip to the Neolithic, and like most travellers,
I have had a lot of help on the way. Early on, two of my postdocs,
Ben Jeffares and Brett Calcott, were influential. Ben infected me
with his scepticism about single case, big-b reakthrough accounts of
hominin evolution. Brett’s work on cooperation shaped how I see
the problem, with his clear separation between the explanation of
the profits of cooperation, and an explanation of its stability. Much
of the theoretical work, and virtually all of the work in experi-
mental economics, has assumed that the benefits of cooperation are
unproblematic. Rather, what needs explanation is why cooperation
is stable (when it is) given the threat of defection. Brett (and after
him, Jonathan Birch) showed that this is quite wrong: getting coop-
eration to work requires serious social and cognitive tools, whose
existence requires explanation.
Over this whole period, my thinking has owed a lot to my regular
interactions with Peter Godfrey- Smith, Russell Gray and Cecilia
Heyes. Peter’s specific influence has mostly come through his work
on Darwinian populations, and his distinction between paradigm
and marginal cases of such population. This has pushed me to be
more sceptical of cultural group selection, and back toward a more
individualist account of the hominin evolutionary trajectory. But
he has also been my most regular and acute pre-p ublication critic,
though more recently, Ron Planer has joined him in that role, with
the added advantage of a very deep immersion in the same pale-
oanthropological literature that I mine. This book owes much to
Ron. Russell has taught me always (I hope) to think phylogeneti-
cally and comparatively, and has perhaps slightly tempered my na-
tive adaptationism. He, like Celia Heyes, has also encouraged me to
think more consistently about scenario testing as well as scenario
construction. In addition to helping sensitize me to testability,
Celia’s own work is very challenging, in articulating a view in which
genetically- based cognitive adaptations play very little role in
hominin evolution. In more recent years, Peter Hiscock has come to
influence my thinking a lot, especially through his deep scepticism
Preface xi
about directional models of hominin evolutionary history. Despite
his sceptical erosion, the overall picture of The Pleistocene Social
Contract is directional. But it is I hope suitably sensitive to the il-
lusions of directionality that can be easily generated by temporal
biases in the material record. Finally, the last chapter of this book
owes a lot to Trevor Watkins, who single-h andedly hauled me out
of the Palaeolithic and into the Neolithic and its challenges.
In this last twenty years I have been very fortunate in both my in-
stitutional and personal circumstances. Initially, I divided my time
between the Victoria University of Wellington (New Zealand) and
the Australian National University (ANU) (Canberra, Australia).
Both were supportive, friendly, easy places at which to work,
and with a regular flow of able and engaged students. In the last
decade, I have been more or less exclusively at the ANU, a won-
derful base, with terrific colleagues, further enriched by a great co-
hort of graduate students and a regular influx of visitors. I am also
deeply indebted to the Australian Research Council for their reg-
ular and generous support of my research. This has enabled me to
surround myself with terrific postdocs: Brett Calcott, Ben Fraser,
Jess Isserow, Justin Bruner, Ron Planer, Anton Killin, Matt Spike.
My personal situation has been equally conducive to pushing this
project through to completion. As all my friends insist, I have been
for many reasons fortunate in my choice of partner, Melanie Nolan.
While most of those reasons are not for public consumption, one
is. Melanie is much more committed to her research than am I, so
there has never been a trace of disapproval as I disappeared off to
my office or to a workshop. Likewise, our daughter Kate is tolerant
of these eccentricities; indeed, she has dipped a toe into these aca-
demic waters herself.
Finally, I should specifically thank those who read and com-
mented on this manuscript or its ancestors: Jonathan Birch, Carl
Brusse, Chiara Ferrario, Peter Godfrey-S mith, Celia Heyes, Peter
Hiscock, Tim Lewens, Ross Pain, Ron Planer, Kim Shaw-W illiams
and Joeri Witteveen.
1
Building Cumulative Culture
1.1 Methodological Preliminaries
This book will present an account of the origins, elaboration and
interaction of two very distinctive features of our lineage: our de-
pendence on cooperation and our dependence on culture. In these
respects, as in many others, we are very different from other pri-
mates. In my view, those differences emerged by positive feedback
amongst a number of initially smaller divergences from the great
ape stock. These include bipedal locomotion, improved causal and
social reasoning, reproductive cooperation, increasing depend-
ence on tools, changes in diet and foraging style. Interaction be-
tween these initially small departures from great ape lifeways drove
an evolutionary trajectory that took us ever further from our great
ape relatives. In contrast to many others, I do not see the distinctive
features of human life as grounded in a key, difference-m aking in-
novation: not language, not understanding others; not a distinctive
kind of cognitive flexibility (Mithen 1996, Deacon 1997, Tomasello
2014). I will begin with some methodological remarks, and some
cautions about the empirical foundations of the analysis before
ending this section with a brief sketch of my general framework.
The account is largely in the form of a narrative, and it begins in
our deep past, shortly after the human lineage (collectively known
as the hominins1) diverged from its sister lineage, the lineage whose
living descendants are the two chimp species. The narrative is
1 A note on terminology: I will use “hominin” for any member of this lineage. I will use
“human” as an informal term for the late, large-b rained members of this lineage.
The Pleistocene Social Contract. Kim Sterelny, Oxford University Press (2021). © Oxford University Press.
DOI: 10.1093/ oso/ 9780197531389.003.0001
2 The Pleistocene Social Contract
developed as an explanation, not a mere chronicle: it is full of causal
claims about the factors that drove the human evolutionary trajec-
tory, and about their relative importance. However, as the narrative
begins in the deep past, 6+ mya (mya = millions of years ago), it is
reasonable to wonder whether any attempt to reconstruct the be-
haviours and ways of life of such long- extinct hominins is just base-
less speculation. Indeed, there is a standard sneer that evolutionary
narratives, especially human evolutionary narratives, are “just- so”
stories: easy to produce, sometimes sounding plausible, and impos-
sible to test (Gould and Lewontin 1978).
This suspicion is not entirely groundless. Traces of past lives dis-
appear; the more distant in time those lives, the more those traces
are lost. Those that remain must be interpreted through the lens
of theory, and these are themselves controversial. Even so, the ev-
olutionary narrative produced here is, I claim, detailed, coherent
and empirically grounded. It identifies multiple, causally inter-
connected strands, linking foraging strategies, social structure,
life history, reproductive strategies and intergenerational cultural
learning.2 What is said about each of these constrains what can
be said about the others. Coherence, the mutual fit between these
separate but causally interconnected elements, is a significant con-
straint on a complex evolutionary narrative, as any account of the
rise of the hominins must be. Moreover, the narrative is empirically
grounded at many points: if it is right, it predicts patterns in the
traces left by our ancestors. For example, one causal hypothesis links
a social change— increased social connection between residential
groups— to a more reliable preservation of culturally transmitted
information. If that hypothesis is right, signs of that social change
should covary with signs of more reliable preservation and expan-
sion of informational capital. In both cases, such traces will often
2 A second note on terminology: some authors use “cultural learning” as a term for
some advanced species of social learning. I use “cultural learning” and “social learning”
as equivalents.