Friday, January 25, 2013

The Mathematics of the Lifespan of Species

the summary says that the result is valid for species, not individuals. even that is wrong; it's not exactly valid for every species; the result is actually that there is a significant power-law trend across species which is that the mortality rate and birth rate both scale approximately as -0.25*(dry mass) on a log-log scale. however there is also significant variation from the log-log line-of-best-fit; the r^2 is around 0.8, though i don't care enough to read exactly how they designed the study. http://www.pnas.org/content/104/40/15777.full [pnas.org]

humans have, of course, cheated death to some extent, so we're outliers, though it is worth noting that prehistoric humans had a max. lifespan of around 40 years...

this is an old result for animal species; the `result' here is that they checked the extrapolated fit for ~700 plant species and validated it in that domain. scientists generally make small extensions or validate previous conjectures; since the public doesn't understand what they're building from, the media has to present the history as the novelty. it's kind of funny, really.

i remember reading a paper (from sante fe institute, of course) ~20 years ago or so which tried to define a `generalized heartbeat' for cities and nation-states to see if the scaling law would extrapolate. of course, the problem is you can define such a thing however you want.

Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/vscarFQ_wZc/story01.htm

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