BOOK REVIEW

Us and them: The science of animal minds

Thomas Suddendorf: The gap: The science of what separates usfrom other animals. New York: Basic Books, 2013, 368pp,$29.99 HB

Richard Moore

� Springer Science+Business Media Dordrecht 2014

Thomas Suddendorf’s The Gap: The Science of What Separates Us from Other

Animals takes as its subject the question of what separates human cognition from the

cognition of animals. In addition to providing a lengthy synthesis of the current state

of knowledge of the differences between human and animal minds, it also contains

an introduction to the history of thinking about ‘‘the gap’’ between us and them,

and—more implicitly—an introduction to the methods of experimental science. It

does not defend—at least, not at length—any new claim about the nature of what it

is that makes humans cognitively unique. In this respect, readers looking for bold

new hypotheses to challenge recent academic claims about human uniqueness (e.g.,

Tomasello 2014) may be disappointed. Nonetheless, the book is a highly impressive

work of popular science—and a very interesting, accessible, balanced, elegant, and

enjoyable introduction to the field.

Suddendorf’s book divides, roughly, into three parts. The first—spanning the

opening three chapters—describes our history of thinking about the gap and gives a

brief introduction to some of the methods for studying it. The second and longest

part consists of six chapters detailing, via surveys of recent work in comparative

psychology, points of continuity and discontinuity between human and animal

minds. The final chapters of the book contain an overview of what we know about

our early hominin ancestors and a discussion of their possible cognitive abilities, as

these are revealed by the archeological and fossil records, along with some well-

informed speculation about when (and why) in phylogeny our uniquely human

forms of cognition might have emerged. The book finishes with a discussion of the

future of the gap—and of the need to conserve the habitats of our nearest kin, whose

precarious existence makes the research discussed in the book possible.

R. Moore (&)

Berlin School of Mind and Brain, Humboldt-Universitat zu Berlin, Unter den Linden 6,

10099 Berlin, Germany

e-mail: r.t.moore@gmail.com

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DOI 10.1007/s11016-014-9918-3

The central question of the book is set up in the opening pages. In the Descent of

Man, Darwin had proposed that humans are, like other animals, the product of

evolution and that our closest relatives were the African great apes. This account

emphasized continuity and gradual change. However, writes Suddendorf, whereas

the physical continuity between man and animal is undeniable—we can substitute

the valves from a pig’s heart for our own—the relationship of human and animal

minds seems to be characterized by very substantial discontinuity.

Our minds have spawned civilizations and technologies that have changed the

face of the Earth, while our closest living animal relatives sit unobtrusively in

their remaining forests. (2–3)

The nature and origin of this cognitive ‘‘gap’’ is the central topic of Suddendorf’s

book.

In a very valuable third chapter, Suddendorf gives an introduction to the varieties

of evidence that are used to illustrate points of continuity and discontinuity. In what

becomes a fairly common strategy, he recalls his own experiences of working with

apes to show why it is sometimes tempting to give rich interpretations of animal

behavior. He then reflects critically upon these recollections to show why such

attributions may have been misplaced and appeals to the methods of experimental

psychology to indicate what would need to be shown for the richer interpretations to

be justified. Describing a case in which he introduced a rubber crocodile to two

chimpanzees, he writes:

They were intrigued, and when I pretended the crocodile was trying to bite my

co-investigator … they quickly jumped to her side and appeared to play along

– even to the extent of ‘‘reassuring’’ her when the danger had passed. At least,

that is how I remember the events, although frankly I cannot be sure whether

any pretense took place from the chimpanzee’s perspective. (47)

Such evenhanded appraisals are characteristic of Suddendorf’s writing and are

supported by lengthy discussions of the empirical evidence that would lend

credence to, or undermine, such anecdotal reports.

In six subsequent chapters, Suddendorf evaluates a series of claims about human

uniqueness, through comparative discussions of the cognitive abilities of human

children, non-human great apes, monkeys, and a variety of other species. Each

chapter takes the form of a survey of one major claim about what makes humans

unique: The topics discussed are language, mental time travel (including memory

and future planning), mind reading, intelligence (including tool use and causal

cognition), social learning, and morality. As the following recap will make clear, the

central theses of these chapters will not be new to anyone familiar with recent work

in animal cognition.

On the subject of language, Suddendorf writes that while apes (and some other

species) use symbols to communicate, they do not combine these symbols

recursively and do not communicate to enquire about one another’s minds. On

mental time travel, he argues that while animals possess semantic memory and some

can plan for an immediate future, only humans possess episodic memory, and the

related ability to project themselves into alternative possible worlds. This is what

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makes us so good at planning for the future. Additionally, while humans are mind

readers par excellence, Suddendorf shows that apes possess comparatively basic

abilities and demonstrate little motivation to engage with the minds of others, or to

join with them in cooperative activity. On the subject of intelligence, we learn that

while humans are boundlessly creative and other species of ape possess limited

skills for problem solving and tool use, no other species engages in abstract

thinking, theory building, or creative innovation. Additionally, while apes (and

other species) demonstrate some limited capacities for social learning and so

possess rudimentary culture, in the absence of teaching and high fidelity imitation,

they lack a capacity for cumulative culture. Finally, while great apes exhibit signs of

sympathy and a willingness to help others in distress, they do not live by moral

norms or engage in moral reasoning.

While none of these surveys is ground breaking, the research is up-to-date,

comprehensive and presented in consistently entertaining way.1 Perhaps unsurpris-

ingly, Suddendorf’s own research remains center stage. For example, he argues that

the limited intelligence of animals is likely to be a consequence of their lack of

recursive thinking and mental time travel—conclusions for which he has argued at

length elsewhere.

These review chapters finish with a short chapter in which Suddendorf attempts

to synthesize current findings into an account of some key differences and to spell

out the beginnings of a story about how these differences came to be. I found this

chapter—at around fifteen pages, one of the shortest in the book—somewhat

disappointing. Suddendorf posits two features as key to explaining the rest:

In all six domains we repeatedly find two major features that set us apart: our

open ended ability to imagine and reflect on different situations, and our deep

seated drive to link our scenario-building minds together. It seems to be

primarily these two attributes that carried our ancestors across the gap, turning

animal communication into open-ended human language, memory into mental

time travel, social cognition into theory of mind, problem solving into abstract

reasoning, social traditions into cumulative culture, and empathy into

morality. (216)

While this hypothesis is intriguing and somewhat intuitive, the key concepts

(‘‘nested scenario building’’ and the ‘‘urge to connect’’) and the transitions they

make possible are only sketched, rather than given the exhaustive treatment that

they deserve. While it feels ungenerous to expect a work of popular science to be

used to defend such hypotheses in detail, the remainder of Suddendorf’s book sets a

high bar, and I would have loved to see these claims elaborated.

As a piece of work for a primarily non-academic audience, there is a great deal to

admire in this book. It is beautifully written and full of judicious quotes, fascinating

historical insights, and great anecdotes. More than that, the discussions of the

experimental data that lie at the heart of the book are rigorous, fair, and informative.

1 Of course, Suddendorf’s claims are open to challenge from new experimental evidence. For example,

Martin-Ordas et al. (2013) present compelling evidence of something like episodic memory in

chimpanzees and orangutans.

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Throughout the book, footnotes are used to make substantive points, while endnotes

are used for references. More substantial notes and references can be downloaded

from the book’s website. The result is a book that flows well and remains readable

even in discussing points of relative complexity. In these respects, it is difficult to

conceive of a better non-academic introduction to the science of animal minds. It is

a shame that the photographs of apes are reproduced only in small scale and black

and white, though. One can only hope that in future editions the publishers could be

persuaded to include some color panels.

Given the remit of the book, its use in academic contexts will inevitably be

somewhat limited. While its reviews of the literature are very good, in anything but

introductory classes they would need to be supplemented with relevant journal

articles. Nonetheless, I would be happy to recommend the book as background

reading on an MA course or to any non-specialist wanting a readable introduction to

a particularly vibrant area of research.

References

Martin-Ordas, G., D. Berntsen, and J. Call. 2013. Memory for distant past events in chimpanzees and

orangutans. Current Biology 23: 1438–1441.

Tomasello, M. 2014. A natural history of human thinking. Cambridge, MA: Harvard University Press.

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