How a single molecule may have created the pack instinct
Originally published on
April 22, 2009 at PsychologyToday.com.
Wolves Are an Anomaly
Wolves are an anomaly in the
natural world. They’re one of only two species of land mammals who have a history of hunting animals that are larger and more dangerous than
themselves, and who do so by working together in a socially sophisticated
manner. The other species is homo sapiens. (Members of the dolphin family, especially
orcas, also hunt large
prey as a team.)
So how did the wolf become
the wolf? Where did the pack instinct—the behavioral template for this unique
style of hunting—originate?
The common, broad-stroke
evolutionary explanation is that certain species form groups as part of an
adaptive strategy that changes the selection pressures felt by the individuals
so that those who align themselves socially rather than decide go it alone”
have better odds of passing on their genes to the next generation, and to the
next, etc, etc.
The thing is, individual
animals don’t have strategies, they don’t feel selection pressures, and they
certainly don’t have any awareness of what it means to pass on their genes to
the next generation, let alone the next and the next. On a certain level we all
But according to some theorists, evolution does take place in real time, it just does so
on a molecular level, which then transmigrates upwards into changes in
morphology, which influence changes in behavior, etc. And if this is true then
adaptation has nothing to do with an animal’s behavioral choices in response to
environmental changes, it’s part of a simple energy exchange, taking place
on a molecular level, one that doesn’t put selection pressures on the organism
but does put some kind of energetic pressure (probably thermodynamic) on the
nuclei of certain cells.
Of course I’m a dog trainer,
not an evolutionary biologist. So what do I know? I’m probably oversimplifying
this. But hear me out...
In most mammalian predators,
the offspring are kicked out of the “nest” once they reach adolescence. The
parents don’t continue nurturing them, and with good reason: nature doesn’t
want a group of “bloodthirsty” types living in close proximity; if food is
scarce you run the risk that they’ll vent some of their aggression on one
another. But unlike what we see with the big cats (with the exception of female
lions), wolf offspring aren’t kicked out of their nests (or don’t decide on
their own to leave) until they’re at least 2 years old. That’s a substantial
divergence from the norm.
Why the difference? Oxytocin.
It might sound improbable
that a simple neuropeptide,
even though it has some pretty fancy tricks up its sleeve (for one thing it
acts as both a hormone and a pheromone) could be responsible for such complex
changes in behavior. But recent research by Insel &
Young, 2002, shows that in monogamous prairie voles, when the
effects of both oxytocin
and vasopressin (which are
closely related), were disrupted—by derailing their connections to the “reward
pathways”1 in the nucleus
accumbens—the formerly monogamous voles quickly became promiscuous.
This was a huge reversal, and
it took place immediately.
In contrast, Lim et al,
2004, did a study with promiscuous meadow voles, and found that the
addition of oxytocin
and vasopressin (again, in
direct connection with the “reward circuits” in the brain), produced long term
pair bonding where no such behavior had previously existed. And again, the
results took place immediately, in real time.2,
“A change in the expression
of a single gene in the larger context of pre-existing genetic and neural
circuits can profoundly alter social behavior, providing a potential molecular
mechanism for the rapid evolution of complex social behavior.” (Lim et al,
See that? “A molecular
mechanism for the rapid evolution of complex social behavior.” So I think it’s
quite probable that at some point in the wolf’s evolutionary history, certain
wolf pups, or certain wolf parents, or possibly both, kept producing these
long past the time frame that their feline “rivals” did.
Over countless generations
the cats became more and more fearsome (yet still solitary) predators. Wolves,
meanwhile, took a different path. They didn’t become more fearsome; they
became more social. And they became more successful at
hunting. This could’ve happened fairly quickly, possibly within the span of a
few generations. Add to this the way intricate social behaviors—particularly
when used for hunting large prey—require enormous intelligence and emotional
flexibility, and it starts to become clear that the wolf’s social metamorphosis
may also be part of what enabled wolves to become much more adaptable to living
and thriving in various habitats, environments, and eco-systems, far more so
than any feline species has ever been capable of.
Why does hunting large
prey require more intelligence?
Intelligence is perhaps the
wrong word. Think of it as the number of computations necessary to successfully
hunt large, dangerous prey as part of a group, as opposed to the number
required to either hunt small prey by yourself or, if you’re a big cat, to hunt
the type of animal, large or small, that you can take down fairly easily on
If you’re a cheetah chasing a
gazelle your focus is fairly simple compared to that a wolf chasing an elk as
part of a group dynamic. The cheetah is focused primarily on 3 things: 1) the
changing movement, energy, and emotions of the prey, 2) changes in the terrain,
and 3) the changes in his own movements, levels of energy, intensity, drive,
But for a wolf, he’s doing
all that while focusing on the changing positions, energies,
intensities, emotions, and movements of each of his pack mates as well. If he’s hunted
with them before he’s also got a backlog of data about their preferences and
behavioral tendencies in similar situations. The larger the pack, the larger
the database, and the larger the number of computations necessary.
So as soon as wolves started
hunting in concert, they automatically became more “intelligent” and more
Then, when wolves began their
long relationship with human beings and eventually became domesticated by us
(or vice versa), and began their new incarnation as dogs, they expanded on the
wolf’s adaptability, so much so that the modern dog’s natural habitat now
includes every corner of the globe, including Antarctica. (Since a dog’s
natural habitat is anywhere that involves living and working alongside human
beings, Antarctica should clearly be on the list.)
To sum up: wolves probably
didn’t invent the “strategy” of hunting large prey as a way of adapting to
their environment. Their innovative pack hunting dynamic may have just been an
outgrowth of a simple molecular change in their brain chemistry. And it’s why
they were subsequently able to evolve so quickly into the most social, the most
adaptable, and most diverse species on earth: our best friend, the dog.
Anyway, that’s what this
dog trainer thinks might’ve happened.
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1) “Reward circuits” refers
to dopaminergic (and other neurotransmitter) circuits in the brain, even though
more and more research shows that these are not reward pathways, per se,
(dopamine is released when negative things happen, or when an animal senses a
change in the pattern of reward). They should probably be called attentional,
or mnemonic pathways, since dopamine’s purpose seems to be to make us pay
attention to and remember salient environmental patterns, both positive and
2) Oxytocin has more of an
effect on females while vasopressin
influences male behavior more directly. An interesting side note is that when
men and women kiss, the levels of oxytocin go down in the
female but go way up in their partners. Another interesting point is that vasopressin also controls
kidney and urinary function, primarily through regulating how much sodium is in
the blood. It’s also tied, in inverse proportion, to production of the stress
hormone cortisol; the
more stressed an animal is, the more sodium there is in its bloodstream, hence
the more the animal needs to urinate. I find this interesting because for years
I’ve noticed that most male dogs who are overly focused on “marking” also tend
to exhibit symptoms of emotional stress and anxiety, and marking seems to be a
way for them to reduce those feelings. But when you give these dogs an outlet
for their internal stress, they generally stop marking quite so much.
et al 2008 then did a study on human beings which showed that the
reason oxytocin creates feelings
of love, nurturing, trust, generosity, and perhaps even altruism, is that it
selectively deactivates neural activity in the amygdalla and midbrain regions,
switching off some of the brain’s fear circuitry. Oxytocin doesn’t prevent
people from responding to imminent danger, but it does influence people to have
feelings of deep trust toward members of their families and social groups
4) In terms of adaptability, wolves were once
the most widely-distributed land mammal on earth except for human beings, and
we were primarily responsible for reducing their range by killing them whenever
and wherever we could. (At the same time we were doing this we were inviting
the wolf’s brother, the dog, into our homes.) By the way: the most
widely-distributed marine mammal is the orca. It can’t be an accident that these
three species are all group predators.