[FoRK] Carrying Capacity Tangent

Jeff Bone jbone at place.org
Sat Nov 7 16:09:52 PST 2009


Michael notes:

> I saw this Economist.com link on InstaPundit today, it was  
> tangentially related to the current discussion on carrying capacity,  
> so I thought I'd throw it in here:http://www.economist.com/opinion/displaystory.cfm?story_id=14744915&fsrc=rss 
>  "As industrialisation swept through what is now the developed  
> world, fertility fell sharply, first in France, then in Britain,  
> then throughout Europe and America. When people got richer, families  
> got smaller; and as families got smaller, people got richer. Now,  
> something similar is happening in developing countries. Fertility is  
> falling and families are shrinking in places- such as Brazil,  
> Indonesia, and even parts of India-that people think of as teeming  
> with children. As our briefing shows, the fertility rate of half the  
> world is now 2.1 or less-the magic number that is consistent with a  
> stable population and is usually called "the replacement rate of  
> fertility". Sometime between 2020 and 2050 the world's fertility  
> rate will fall below the global replacement rate."

Cf.  population ecology and "self-thinning," etc.

Point being, different species adjust to greater or lesser overall  
and / or per-capita resource availability, and changes to such  
availability, differently.

Similar (not identical) things happen even among trees.  (Actually  
it's *very* well studied in trees in particular...)  The problem is  
that humanity, perhaps unique among the planet's species, is super- 
linear in population over the last couple of centuries and isn't  
linear in its mean resource utilization per capita over time.  So even  
though we do indeed see a falling reproductive rate with increasing  
access to and exploitation of resources in various subpopulations,  
it's not at all clear that this effect is enough to counter the  
overall effects of population explosion and / or resource  
utilization / depletion.

jb





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