Overpopulation post to KurzweilAI.net Mind Exchange- 16th April, 2001
Reading Max More's article on "Life Extension and Overpopulation" (see The Big Thinkers in this <<KurzweilAI.net>> site) has prompted me to write the following response.
Basically, Max More is correct in saying that birth rates are more relevant to the issue of overpopulation than lifespan. However, this is not the whole story.
The growth rate for a human population is calculated by taking the difference between the birth-rate-per-1000 and the death-rate-per-1000, and then expressing that as a percentage figure. Only then is it possible to project future populations, and this is usually done in terms of population doubling times. The rule of thumb, for growth rates of 5% per annum or less, is to divide the percentage increase into 70. This gives the population doubling time in years.
So, a sustained average population increase of 1% would result in a population doubling time of 70 years whereas a 2% rate would mean a doubling time of 35 years.
People often assume that we don't experience "real" exponential growth because our global rate of growth varies. Yet, strangely, our global population has doubled from 1 billion in 1800 to 2 billion in 1930 and 4 billion in 1974. We should hit 8 billion well before 2050AD. In fact, it is a simple matter to prove that, so long as the growth rate remains positive (however variable it may be) you will definitely get exponential growth (and so can talk of population doubling times). Currently, our population growth rate is slowing, and so it will take longer for a our population to double.
I disagree with the assertion that we can safely assume population stability (Zero Population Growth), and I've said so in a series of articles on my web site. See The Cassandra Prediction, the first draft of which was posted to Nanodot.org:
If you just read that, I'd regard Ray Kurzweil as an exponentialist who deserves our respect.
An extension to our life-span will result in a temporary bulge in our human population graph, as death rates fall for the years in which people would normally have died. However, as they still die eventually (200 years?) so their deaths form part of the death rate statistic in some future year.
Immortality is another thing. Effectively, you end up with the difference between the standard exponential doubling series (1 2 4 8 etc) and the Fibonacci series (0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987 ...). This is because you can add the previous generations to any new generations. See my New Malthusian Scale
Anyway, my main issue is not with life extension (which only has a temporary effect on population growth). My main concern is with the effect of technologies such as nanotechnology, genetic engineering, biotechnology, cloning, and artificial intelligence.
As Drexler argued in his "Engines Of Creation", the limits to growth will always apply. However, the question is how fast will we hit the first limit (Earth) and then hit the second (our own solar system)? In short, each of these technologies encourages population growth. I'd accept any argument which states that those populations may not be human, and may in fact compete with our own human population. Nonetheless, the faster we push back the limits to growth with a technology like nanotechnology, the faster we may rush towards the limits to growth.
For the record, I embrace this future and I hope that the predictions are right so that I can get to see some of it. Please don't take that to mean that I embrace population growth, as I do NOT. I embrace the use of technology to push back the limits to growth, whilst at the same time pointing out that such technology can encourage population growth. So, we need to remain vigilant and slow population growth (and thus prolong the coming age of abundance). Furthermore, we must recognise the natural limits to growth in our own neighbourhood (the Earth, then the whole solar system) and do our best to exploit the latter before the former becomes too much of an issue.
However, I'm still keen to see a future for today's humanity in tomorrow's world.
For a list of articles by me, see the Articles page.
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