This interesting book is all about humanity’s prehistory,
its origins as a primate species, some of humanity’s unique
behaviours, and what these behaviours might mean for our future.
The title stems from genetic analysis revealing that humans have
a more recent common ancestor with chimpanzees than chimpanzees
or humans do with gorillas. Given that humans share such a high
proportion of their DNA with chimpanzees (98.4%), they might
reasonably be seen as a third chimpanzee species, in addition to
the two other species (“normal” and pygmy
chimpanzees).
The first sections of the book are about human biology, and
how various aspects of our biology resemble and differ from that
of the other primates. Diamond is amusing on sexual behaviour,
and sexual characteristics, speculating on why it is that humans
are principally monogamous while still living in groups (unlike
the other chimpanzees and unlike gorillas), why they have sex in
private, why their genitals are different from the other
species, and how mate selection happens.
These early sections of the book also explain why evolution might
have produced effects that might not seem to make evolutionary sense
when first looked at, including aging and menopause. Diamond also
discusses some unique (and mainly positive) human traits (language, farming,
art) that arguably have animal precursors, or at least explanations based
on animal behaviours. This material is fascinating.
Diamond then moves on to three ‘unique’ behaviours
in humans that are clearly bad: destruction of the environment,
destruction of each other (genocide), and drug (ab)use. He
discusses each of these three in turn. I found the section on
drug use easily the least convincing. Diamond claims that it
might be some sort of mating display akin to look,
I’m so tough I can handle this awful drug, and still stand
up straight; come and have sex with me this very
instant!
(by analogy with peacock tails, which are a
ridiculous handicap, but which still serve to attract mates). I
wouldn’t deny that this might explain some aspects of
alcohol use in the modern world, but it is not very convincing.
Diamond doesn’t back up his claim that this is uniquely
human. (What of catnip and cats? Have there not been experiments
trying to feed chimpanzees alcohol, or other drugs?) Diamond
also doesn’t give any time to the obvious argument that
drugs get used simply because brain chemistry happens to produce
pleasant effects when certain substances are ingested. I do
remember reading about an experiment that demonstrated that some
species of animal would repeatedly press the button that
stimulated their brains’ pleasure reaction (they’d
been wired up somehow) rather than the food button. The animals
starved to death. This seems to me to be pretty analogous to
drug use, suggesting that addictive behaviours are not really
unique to humans at all, and that it has nothing to do with sexual selection
displays.
Talking about destruction of the environment, Diamond discusses
the New Zealand Maori (extinction of the moa and a variety of other
bird species, including an awesome-sounding eagle species), the North
American Indians, the Easter Islanders, a central American
civilisation that turned its environment into a desert, the Middle
East in general, and all of the modern world, with its rapacious, and
probably unsustainable, appetite for resources, regardless of the
long-term cost. There’s a certain overlap here with the
material in Flannery’s
The eternal frontier, and also with material I
believe Diamond is about to turn into another book (about
human-induced environmental catastrophes), but it’s all
good.
On genocide, Diamond covers things in a rather bitty way. He
discusses how it is that the farmer humans did so much better than the
hunter-gather humans, which stuff he later expanded on in Guns,
germs and steel (which I highly recommend). He talks about the
humanity’s usual xenophobia, and also mentions that chimpanzee
troupes fight wars too (they’re just much less efficient at it,
not having weapons). He also has a cute chapter about the likelihood
of being contacted by aliens: one, intelligence is not necessarily as
inevitable as you might think (cue cool example about, yes,
woodpeckers); two, if humanity’s anything to go by, maybe
intelligent species all end up wiping themselves out in short order;
so, three, don’t hold your breath waiting for the aliens to
arrive. He talks about various genocides in recent history
(depressing reading, and the book isn’t even recent enough to
include Rwanda’s most recent genocide, nor what happened in
Yugoslavia).
Diamond concludes that at least some of us realise that much of
what we’re doing is horribly unsustainable, so that maybe this is
grounds for some optimism. A very good read.