The Essentials - Pop Science

"The mathematics of uncontrolled growth are frightening. A single cell of the bacterium E. coli would, under ideal circumstances, divide every twenty minutes. That is not particularly disturbing until you think about it, but the fact is that bacteria multiply geometrically: one becomes two, two become four, four become eight, and so on. In this way it can be shown that in a single day, one cell of E. coli could produce a super-colony equal in size and weight to the entire planet Earth."

Michael Crichton (1969) The Andromeda Strain, Dell, N.Y. p247

I knew this postulation existed, just not exactly where, so a quick Google search provided an example.  This surely isn’t the only example but the website that provided the quote also does a nice job of laying out the mathematical reasons for why the claims are valid. The site also points out some of the critical questions beyond the validity of the mathematics especially the possibility of ideal circumstances.

In the late 1700s Thomas Malthus famously wrote, “That the increase of population is necessarily limited by the means of subsistence,” and in expounding on this notion influenced Charles Darwin and others as the theory of evolution by natural selection was being formulated.  Malthus counters the idea of ideal circumstances with the realities of the economies of life and ecosystems.  If Malthus would have read Crichton I suspect he might have written a polite yet firm letter, sent by post, informing him that, while mathematically sound his example was all but impossible. 

This isn’t to take anything away from the awesome growth potential of populations (and I should say that  Crichton’s point was really about the risks of rapidly spreading disease and I suspect he is well aware of Malthus) but it is to say that populations have natural limits. This realization is one of the bits of inspiration that drew Darwin closer to his evolution conclusions.  His thinking was that if populations are limited then there will be competition for those limited resources and in competition the strongest survive. 

Remember that being strong, or fit, for survival doesn’t necessarily have anything to do with big muscles or being the best fighter. Evolutionary fitness simply refers to the ability to pass on genes by having offspring.  This could mean that as a population approaches its limits the most fit individuals will be those that go dormant for a period while others in the population die of starvation.  Or perhaps the most fit individuals will exhibit a behavior that opens up another food source to them. (I wrote previously about the skittish vs. trusting wolves as an example of a new food source opening with a change in behavior.)

There are a few things that I like about this whole population business.  To begin with I like how math can be used to describe the natural world very accurately.  I also like how three academic areas come together to create a better understanding of the world around us.  Math shows us how it could play out, demography describes how it really happens then science comes in to tie the two together with an explanation that is descriptive, predictive and can even be tested.  

As an additional like I’ll add that in this example we see a science fiction author in Crichton, an Anglican clergyman in Malthus and a naturalist in Darwin all engaged in a conversation that has spanned the centuries.  Science and society share an unbreakable bond and our degree of investment in science literacy, both personally and as a society, determines if that bond is restrictive or empowering.