Mammal Societies*
Tim Clutton-Brock
2016
Wiley-Blackwell (Oxford, UK)
744 pp
ISBN 97811119095323
“The key to the sociobiology of
mammals is milk.” E.O. Wilson (1975)
Knowledge about group-living mammals
may contribute to an understanding of vertebrate social evolution and
the evolution of gregariousness in animals with generalized
phenotypes. Compared to social insects and birds, the social biology
of mammals is poorly known with the exception of ungulates,
carnivores, and primates (3 of ~25 Orders). In 2011, Ladevèze
et al. reported fossil evidence documenting mammalian gregariousness
and its associated ecology from the basal Tertiary of Bolivia. These
findings suggested that extinct, marsupial-like Pucadelphys
andinus were group-living, probably exhibiting frequent
interactions, strong sexual dimorphism, and male-male competition, as
well as, polygyny. Based on the spatial and ecological settings of
their specimens, these authors speculated that the species may have
been cooperative breeders. In 2012, based on a phylogenetic analysis,
Briga et al. showed that relatedness and allomaternal¹
care are positively correlated in Class Mammalia. These papers
indicate that, though the population dispersion of most extant
mammals is sexually segregated (“solitary”), group-living has a
long history in these animals.
Tim Clutton-Brock (henceforth, “TC-B”)
is a highly-regarded empiricist at the University of Cambridge (UK),
recognized, particularly, for his field studies on primates, red
deer, and meerkats. He is a prolific scientist with a knack for
asking good questions and choosing animal models that have yielded
flagship research. The author will be familiar to most animal
behaviorists and behavioral ecologists as a specialist of cooperative
breeding and evolutionary aspects of reproduction (e.g., female
mating strategies, sexual selection). In the book under review, TC-B
notes that his undergraduate training was in Anthropology and that he
completed his doctorate under Robert Hinde, an animal behaviorist
that Psychology typically claims as one of its own. I have been
familiar with TC-B's work since the 1970s, and my personal favorites
among his copious publications are his 1995 paper with Geoff Parker
and the 2003 volume edited with R.M. Sibley & J. Hone. I am
pleased to have the opportunity to review Mammal Societies,
and, as a point of information, admit to having no “bones to pick”
with its author. I have interacted with TC-B on several occasions,
once face-to-face, and, more than once, via e-mail. He has
always been generous and courteous to me. In this review, I do not
intend to deconstruct, to question the book's authority, or to impose
my biases. Instead, I hope to provide a context for its readers,
particularly, mammalian social biologists, to decide on their own its
scope and utility.
Previous books by JH Crook, “Griff”
Ewer, J Eisenberg, EO Wilson, R Estes, D MacDonald, CB Jones, and
others, have treated mammalian social biology to one degree or
another. Mammal Societies, however, is the first attempt to
provide a comprehensive literature review of the topic. The
publisher's description of the volume states that it is intended for
“behavioral ecologists, ecologists, and anthropologists,” and
TC-B self-identifies as a “behavioral ecologist.” The book is, to
all purposes, a literature review of selected Natural History reports
emphasizing publications by his own laboratory, by primatologists,
and from the Old World. Of an estimated 5,300 references cited in the
book under review, only 64 [THIS NUMBER IS INCORRECT--corrected in next issue of ISBE Newsletter] derive from mainstream journals in Ecology
and Evolutionary Biology (N= 15 journals, including, Trends In
Ecology and Evolution, American Naturalist, Journal of
Theoretical Biology, Journal of Evolutionary Biology). While the
Table of Contents presents a detailed outline of topics of interest
to social biologists, there is little integration of technical
reports with ecology and evolution. Furthermore, the sheer number of
topics covered is so large that little space is devoted to most of
them. To provide context, professors using Mammal Societies as
a course textbook or reference work are strongly advised to acquaint
their students early on with Wilson's (1975) treatment of the same
topic (pp 456-574) presenting an explicitly articulated conceptual
framework for mammalian social biology, including, trends, general
and comparative features, an extensive glossary, as well as, case
studies and summary tables, figures, and diagrams.
Chapter 1, “Social evolution,”
omits definitions of terms (e.g., “aggregation,” “social”,
“cooperation”), leading to obfuscation throughout the book,
particularly, since there is no discussion of how to measure social
traits (cooperation, altruism) and to discuss their pertinence to
reproductive success. In this chapter, the author might have defined
“Mammal” and should tell the reader why mammalian social biology
is of import. The reader will want to understand possible
trajectories to cooperation and altruism from aggregations and groups
and how the (spatial and temporal) distribution of limiting resources
favor or disfavor the evolution of mammalian sociality. Chapter 1 is,
in great part, a selective account of the history of Animal Behavior
combined with some mention of theoretical issues (e.g., Darwinism,
competition, reciprocity, game theory). However, for rigorous
discussions of verbal and quantitative theory in Behavioral Ecology,
as well as, overviews of Methods and G x E interactions, readers are
referred to Davies et al. (2012) and Westneat & Fox (2010).
Chapters 2-9 address topics related to
features of female behavior, particularly, as they pertain to mating,
maternal tendencies, and gregariousness. Focusing on females, their
strategies, and their energetic requirements as the primary driver of
group-living and patterns of male behavior and dispersion is
fundamental to an understanding of mammal societies because
fertilizeable females are usually a limiting resource for males and,
subsequently, an ultimate determinant of male “fitness optima.”
Though these and other important concepts are implicit in some of
TC-B's discussions, explicit use of many principles inherent to
Behavioral Ecology are unclear or lacking (e.g., integration of
Hamilton's rule throughout chapters, acknowledgment of the many
competing hypotheses in Ecology pertaining to dispersal or
multiple-mating by females, use of optimality formulations). As an
example from Chapter 5 (“Maternal care”), TC-B's treatment
asserts, accurately, that mammalian females invest heavily in current
offspring, but theory holds that, after parturition, female
resources, above some critical minimum, are channeled into future
reproduction and lifetime “fitness.”
Chapters 10-16 pertain to males,
especially, mating strategies, relations with females, and paternal
care. Characteristic of Mammal Societies as a whole, these
chapters are literature reviews of mostly familiar Natural History
papers and book chapters from the Animal Behavior literature, and few
of the reports classifiable as Behavioral Ecology meet the standards
of, say, Bradbury 1981. Life history evolution is addressed in this
chapter without mentioning the importance of tradeoffs, the
distinction between semelparity and iteroparity (“fast” and
“slow” life history trajectories, respectively), and the role of
mortality as a driver of life-history evolution (Stearns 2000).
Chapter 17 reviews “Cooperative breeding,” one of TC-B's
specializations, and Chapter 18 presents a discussion of “Sex
differences” (without discussing classic theory). Throughout the
book, the author impresses the reader with the centrality of sex,
sexual competition, and mating—topics of import in TC-B's career,
though one is surprised that more attention is not given to Sexual
Selection. Chapters 19 and 20 address hominoids and hominids,
including, modern humans, topics often missing or skimmed in other
Animal Behavior texts.
TC-B presents at least one
controversial formulation in Mammal Societies by
asserting, with no supporting evidence or logical arguments, that no
mammals are “eusocial”²—that
the highest grade of sociality in mammals is “cooperative
breeding.” This view is orthogonal to standard practice in
Mammalian Social Biology whereby the social mole rats are typically
classified as “primitively” eusocial. Technically, according to
common usage, “cooperative breeders” might, as well, be
classified “primitively” eusocial because of the presence of
reproductive division of labor in the form of totipotent “helpers”
(see Jones 2014). Mammal Societies highlights the need for
practitioners of Natural History, Animal Behavior, and Behavioral
Ecology to revisit topics such as standardization of terminology,
advancement of the Hamiltonian Project, the roles of quantitative
theory and modeling (in particular, agent-based modeling), field
experiments, as well as, hypothesis-testing based on 1st
principles. The text will
appeal to professors wanting a Natural History, mostly,
non-quantitative, review allowing supplementary reading to be
incorporated into a syllabus. Future syntheses of Mammalian Social
Biology will rely more heavily on mainstream reports from Population
Ecology (e.g., Oikos, Functional Ecology, Journal of
Animal Ecology), of which Behavioral Ecology is a sub-field.
¹Care
of offspring by conspecifics other than the mother
²”The
evolution of eusociality, here defined as the emergence of societies
with reproductive division of labour and cooperative brood care, has
occurred under specific ecological, genetic, and life history
conditions. Although sophisticated levels of cooperation have evolved
in the largest and more complex societies, conflicts among
individuals are still common because, in contrast to cells of an
organism, they are not genetically identical.” (Keller &
Chapuisat, 2010)
References
Bradbury
JW (1981) The evolution of leks. In Natural
selection and social behavior.
(RD Alexander, DW Tinkle, eds). Chiron Press, New York, pp 138-169.
Briga
M, Pen I, Wright J (2012) Care for kin: within-group relatedness and
allomaternal care are positively correlated and conserved throughout
the mammalian phylogeny. Biology
Letters:
p.rsbl20120159
Clutton-Brock
TH, Parker GA (1995) Punishment in animal societies. Nature
373:
209-216.
Davies
NB, Krebs JR, West SA (2012) Introduction
to behavioral ecology.
Wiley-Blackwell, 4th
edition. Oxford, UK.
Jones
CB (2014) Evolution
of mammalian sociality in an ecological perspective.
Springer, New York.
Keller
L, Chapuisat M (2010) Eusociality and cooperation. In Encyclopedia
of life sciences.
Macmillan, published online: DOI: 10.1002/9780470015902.a0003670.pub
Ladevèze
S, de Muizon C, Beck RMD, Germain D, Cespedes-Paz R (2011) Earliest
evidence of mammalian social behaviour in the basal Tertiary of
Bolivia. Nature
474:
83-86.
Sibley
RM, Hone J, Clutton-Brock TH (eds) (2003) Wildlife
population growth rates.
The Royal Society: Cambridge University Press, Cambridge University
Press, UK.
Stearns
SC (2000) Life history evolution: successes, limitations, and
prospects. Naturwissenschaften
87: 476-486.
Westneat
D, Fox C (eds) (2010) Evolutionary
behavioral ecology.
Oxford University Press, Oxford University Press, UK.
Wilson
EO (1975) Sociobiology:
the new synthesis.
Belknap (Harvard), Cambridge, MA.
*Originally published in International Society for Behavioral Ecology Newsletter, 2016
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