It seems to be one of the most popular memes
of recent times. "Human being are just naked apes,"
you say, nodding sagely and looking wise. "There's
only 1.5% difference between human DNA and chimpanzee
DNA, you know." If your audience looks sufficiently
impressed and you've read the appropriate pop-science
magazine article, you can go on to talk
knowledgeably about "alpha males" and "beta males."
If you're male and talking to a female, you can even
try to imply that you, of course, are the alpha male
of the group...
though there are few documented examples of this
But how much truth is there to
The first time you hear it, it seems pretty
impressive that there's only 1.5% genetic
difference between humans and chimps: it sounds
like we're practically identical twins. In
practice though, things aren't quite that simple.
Genes code for proteins, all animals share
much the same proteins, and so all animals share
an awful lot of DNA. Instead of chimps, try
comparing us to
for instance. Mouse DNA is only 2.5% different
to human. Humans are actually not much closer
to chimpanzees than we are to mice.
Instead of describing humans as Naked Apes,
we could almost as accurately describe humans
as Very Big Mice.
The DNA comparison is flawed.
Evolution is not a gradual, steady
process: it proceeds in
what is sometimes known as "punctuated
equilibrium." Species that are in a stable
niche tend to remain the same. When a species changes
its environment, or a group becomes isolated from the
rest of its species, then it evolves rapidly until
the situation stabilizes. This is not necessarily
reflected in the DNA of the species. Most DNA does
not code for proteins, so a species that is stable
in this way
will still be accumulating substantial DNA changes,
even though these changes have little effect on
the organism itself.
Conversely, while a species is evolving rapidly,
its DNA may not be changing very much: a few tiny
mutations can have a huge effect.
While it's a nice way to deflate human egos,
the percentage comparison is scientifically
almost meaningless, except as a pointer
to some shared evolutionary history.
It's an occasional misconception that human
beings evolved from currently-existing apes. Actually
humans and apes have a common ancestor who
lived some time between
and 14 million years ago.
It's important to remember that we've been
evolving separately for this time. Our
common ancestor may even have been more human-like
and less ape-like than
currently surviving apes: we know very little
about it. Because we've been evolving separately,
this difference is comparable to a single species
evolving for twice that time.
Even in evolutionary terms, this is a long time.
chimpanzees are our closest surviving
relatives, they are still not actually very close to
It would potentially be very enlightening to
study the behaviour of animals that are
close relatives to humans, and it's a shame that
no such creatures exist. Up until fairly recently
they did. Neanderthals died out only 30,000 years
ago. Before that, various species of "plains apes"
seem to have existed simultaneously, such as
the different types of australopithecine.
Unfortunately, our relatives were also our
competitors, and they seem to have been competed
The remaining apes are those that were highly
adapted to rainforest environments. This is not
a coincidence: humans are adapted to life on
the savannah, and until recently were content
to leave the less-desirable rainforest alone.
This radical difference in habitat makes it
even less likely that chimpanzee behaviour is
similar to that of human ancestors:
the life of a hunter-gatherer on the plains
is very different to that of a mainly fruit-eating
life in the rainforest.
This also means that even traits which apply to
all out of the chimps, orangutans and
gorillas do not necessarily apply to humans. All of these
apes are forest-dwellers, quadrupedal, polygynous,
and primarily fruit-eaters. Similarities between their
behaviour may well be due to common elements of their
lifestyle; not innate qualities of our family group.
Society and Culture
In the last few decades some researchers,
most notably the legendary
have made an impressive series of studies into the
social structures of apes, and chimpanzees in particular.
Working for years in conditions of extreme hardship
and some danger, they have revolutionized our knowledge
of these animals.
structure of chimpanzee groups has been
studied in some detail. Male chimpanzees establish a
rigid dominance hierarchy based largely on fighting and
threat displays. Females have a more flexible hierarchy,
but are always subordinate to males. When a female is in
the fertile phase of her menstrual cycle, her perineum
becomes swollen and highly coloured, whereupon the dominant
"alpha male" attempts to isolate her from the rest of the
troop and mate with her.
Other apes have even more dominant alpha males. Gorilla
alpha males control exclusive sexual access to the females.
While the terms alpha and beta male are widely used for
other species, most notably wolves, it appears to be from
the ape studies that they have entered popular culture.
Businessmen, politicians and all are told that they
must become "alpha males". Geek culture, always at the
ready to completely misunderstand some oversimplified
science, has seized eagerly on the concept of the
alpha geek. Look: computer nerds can be alpha males, too!
But it's questionable how much all this applies to human beings.
As is well known, in polygynous species, where the male has
exclusive access to several females, there tends to be a
size difference between the males and the females.
It benefits the male to be larger, since it's a huge
advantage to be able fight off or intimidate rivals.
Polygyny is not the only reason for a size
difference, since there is almost always some competition
between males, but it is the most significant. In
strongly polygynous species, such as gorillas and
elephant seals, there is a greater size difference,
with the males twice the size of the females.
Chimpanzees are less polygynous than gorillas, and
the size difference between males and females is much
In human beings, the size difference is even less
than in chimps.
The problem with applying all this to humans is that
our sexual biology is very different. It's notoriously
difficult to tell when a human female is at the fertile
stage of her menstrual cycle. There is no helpful
swollen perineum, and human females will mate at any
stage of their cycle. What is even more interesting
is the curious tendency of female menstrual cycles
to synchronize with each other. If they live in close
proximity, female humans will all reach peak fertility
at the same time.
What this means is that human biology prevents
the existence of chimpanzee-style alpha males. A
alpha male chimp can isolate a fertile female
from the rest of the troop, but in a human troop
all the females will be fertile at the same time.
Furthermore, a human male can't tell from any
physical signs when the female is most fertile.
It appears that human sexuality has evolved specifically
to exclude the possibility of alpha
males dominating mating.
I Have Massive Testicles and an
Well. Maybe not compared to other humans,
but compared to the other apes, my genitals
are gigantic. A male chimpanzee has an erect
penis approximately 8cm (3 inches) long,
and testicles weighing 120g.
Gorillas are even worse off, with erect
penises only 3cm, and testicles of 35g
The reason gorillas are so apparently inadequate
is simple: gorilla societies really do have alpha
males. The chance that a non-alpha male will mate
with a fertile female is small, so there's
no need for a male to get a competitive advantage
this way. Human societies are more egalitarian
regarding access to females, and our relatively
huge genitals reflect this.
Bonobos, or pygmy chimpanzees, are very similar
to chimps, and were only identified as a separate
species in the 1920's. Although their lifestyle
and appearance is almost identical to chimps,
their social structure is very different.
They have a matriarchal society, where the alpha
female dominates, and the alpha male is usually
her son. Bonobos are noted for being less violent
and more sexually promiscuous than chimpanzees.
Some have attempted to argue that human society
reflect bonobo society rather than chimpanzee
society. This misses a rather fundamental point.
Since chimps and bonobos have such radically
different social structures, despite being so
similar, there is really no reason to expect
human society to reflect either. As we have
seen, our habitat, our sexual biology and
our genes are radically different to either species;
any similarities are likely to be pure coincidence.
Plato famously defined a human being as a
"featherless biped". Equally famously, Diogenes
presented him with a plucked chicken.
The phrase "naked ape" is a fine for the purpose
of deflating the human ego, and pointing out
that humans are just another animal; but as
a serious analogy is really no better than