On Population Chaos
This essay discusses four models of
population dynamics. The models are: exponential growth, population spike,
demographic transition, and population chaos. They are, respectively, naïve,
pessimistic, optimistic, and realistic. This essay then delivers good news and
bad news about the far future.
In exponential growth, in each generation the
population grows by an amount proportional to the population:
P(n+1)
= P(n) + r * P(n)
P(n) is the population in
generation N, and r is the growth factor.
If r<0 then this is an
exponential decay, which soon reaches zero. If r>0 then this is an
exponential explosion, which soon reaches unrealistic levels. For instance, at
a 1% growth factor, the population expands by a factor of more than a googol in
less than 24000 generations. Absurd! This model is naïve.
In a population spike, the population explodes
exponentially until a certain point, then it decays exponentially:
P(n) = P0 * (1+r)n , for
n<0 and with r>0;
P(0) = P0 ;
P(n)
= P0 * (1+R)n , for
n>0 and with R<0 .
This is a pessimistic vision of
over-reach and extinction.
In the demographic transition, population growth is limited.
The recursion equation is:
P(n+1) = P(n) + K * P(n) * ( L – P(n) )
If K is negative then the population
goes extinct. For moderate positive K, then the population grows up to the
limit L, stops there, and remains there. This model is conservative and
optimistic.
Population chaos occurs when the factor K
is too big for stability. The population doesn’t stabilize at its niche-size;
instead it overshoots on the way up and on the way down. The system has
sensitive dependence on initial conditions; small causes can have big effects;
so its vacillations are unpredictable. The species must adapt to the dangers
and opportunities of both overpopulation and underpopulation.
I was taught the exponential model, but I rejected
it as unrealistic. I feared the population-spike, and I hoped for the
demographic transition; but the population spike is for a worse world than
ours, and the demographic transition is for a better world than ours. The most
realistic prediction for our world is Nature’s way: population chaos.
The 20th century was an expansion phase
of population chaos. The explosion will peak soon, due to the global baby bust,
caused by urbanization, economic pressure, and ecological limits. I predict
that the mid-21st through late 22nd century will witness population
implosion. Then there will be rebound, overshoot, re-collapse, and so on. The
chaos will last for centuries, and maybe millennia.
Population chaos implies cultural chaos. Sexual
customs will vacillate in phase with economic and ecological pressures. The
resulting reversals in law and custom will be attributed to human rights or divine
intervention; in reality they will depend on if raising children is worth the
price. To breed or not to breed? That is the question.
Those who wish to control the chaos by policy must
note that outdated policy is part of the chaos. What was conservative is now
radical, and vice versa. I could name names, but that would just add to the
chaos. The best response to chaos is to adapt.
Population explosions increase variation. Population
collapses increase natural selection. Variation and selection, in quick succession,
hasten evolution. Therefore the coming millennia of population chaos will be an
evolutionary punctuation event. We will evolve, rapidly.
So will the natural world, for it will collapse
when we explode, and explode when we collapse. So if you think that raccoons have
clever hands, now, and that kudzu is invasive, now, then just you wait!
I predict that far future humankind
will be superior to us in intelligence, empathy, resilience, endurance, courage,
wisdom and cunning. They will be athletes, acrobats, singers, artists, poets, and
lightning calculators, from an early age. Their immune systems will easily defeat
all parasites, bacteria, viruses, prions, and toxins. They will have superhuman
compassion, superhuman bullshit detection, and a superhuman sense of humor. And
they will have many other gifts. That’s the good news.
The bad news is that they will need all of those superhuman gifts to survive long
enough to reproduce.
