In a battle for survival, you'd probably bet on the strong silent type.
But maybe you should put your money where the mouths are.
In the long run, sensitive talkers have an advantage over active
aggressors. That's because more talking can mean fewer offspring. And
contrary to common understanding, reproductive restraint might be a
better way to evolve.
It's one of those odd nuances of evolution – seemingly straightforward
logic turns out not to be so logical. Life is complicated, and in the
real world of dog-eat-dog – or predator-eat-prey – the "be fruitful and
multiply" approach is not always a sound strategy.
On the one hand, reproducing is the key to passing your genes down to
future generations, which is what evolution is supposed to be all about.
But the so-called "selfish gene" idea doesn't tell the whole story. If
predators proliferate uncontrollably, there won't be enough prey around
to eat. So the predators will go extinct.
There must be some other trick to being the species that survives. And a
new computer simulation suggests that the trick is learning how to talk.
Talking – in the general sense of communicating, or sensing signals – is
the secret to evolutionary success, say Justin Werfel of MIT and Yaneer
Bar-Yam of Harvard University. Communication permits cooperation, and by
cooperating individuals can avoid the pitfalls of unbridled greed.
Bacteria, for example, emit chemical signals allowing members of a
colony to adopt strategies that benefit the group. More elaborate
intercellular signaling was essential for many-celled organisms to
evolve. And more sophisticated communication drives social cooperation
in advanced animals, including humans.
Among communication's many benefits is enforcing restraint on
reproduction when resources are in short supply, Dr. Bar-Yam and Mr.
Werfel assert in a new paper, published online last week in the
Proceedings of the National Academy of Sciences. Using a fairly
simple computer simulation (analyzed with some fairly complicated math),
the scientists show how sensitive talkers succeed in the cyberspace
equivalent of life in the jungle.
In the simulation, predators and prey occupy squares on a grid. As the
simulation runs, the grid is repeatedly updated. Prey reproduce at a
constant rate to occupy more squares; predators reproduce and spread to
new squares as well, eating any prey that they encounter.
At each update step, some of the predators undergo "mutations" that
alter their reproduction rate. These mutations create new genetic
strains of predators with more or less propensity to multiply. At first,
the strain of predators that reproduce more rapidly appears to be
winning the battle to conquer the grid. But in the long run, those
strains eat too much of the prey. "Eventually, resources are exhausted
and the strain goes extinct," the scientists point out.
Strains that reproduce more slowly survive longer, since the prey
reproduce fast enough to keep those predators supplied with food.
Now, if a predator's rate of reproducing and spreading depends only on
its genes, it takes a long time for the species to respond to changes in
the prey population. But when a predator has communication skills – say,
the ability to sense the presence of neighbors – it can respond to
changing circumstances more rapidly. In the grid game, predators
sensitive to such "crowding" signals reduce their reproduction rate when
surrounded by other predators on adjacent squares. Simulations show that
those sensitive predators win the game in the end. And if sensitive
predators invade an established community of noncommunicators, sooner or
later those with sensing skill will prevail. Communication ability
therefore seems to offer an evolutionary advantage.
This result might explain an old evolutionary mystery: Why do animals
ever cooperate? In day-to-day life, the battle for survival is among
individual organisms. It really does seem like the stronger and selfish
ones should be the winners. If you're looking out for the welfare of
others instead of yourself, you're likely to be a loser. And your
selfish genes will go nowhere.
However, as the late Stephen Jay Gould emphasized, evolution really
works on multiple levels. The battle for survival is not restricted to
organisms or their genes, but to groups and species as well. So
cooperation can sometimes be a useful ability for the greater good of
the community.
Under certain circumstances, strains of predators who respond to signals
can cooperate, and therefore outcompete the strains that can't. And in
the early history of life, mutations must have on occasion conferred the
ability to respond to signals. "If a single, rare mutation can toggle
the presence or absence of that ability," say the scientists, "then a
simpler, noncommunication population will tend to give way over time to
a responsive one, bringing about full-fledged social communication in
the population."
Any strain of cheaters showing up later – refusing to go along with the
group and reproducing at will – soon goes extinct, further simulations
show.
So for those who think that evolution teaches the supremacy of
selfishness, it would be good to remember that natural selection is not
as simplistic as it sounds. And that it's wrong to think that only the
strong survive.
E-mail
tsiegfried@dallasnews.com
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