Dense interconnectedness is critical to the evolution and growth of
both brains and cities, according to a new research by scientists at
Rensselaer Polytechnic Institute.
The study, described on the Rensselaer website
and in a story at World-Science.net,
found surprising similarities in the way big cities and big brains maintain sufficient interconnectedness. Mark Changizi,
a neurobiologist at Rensselaer who led the study, explains: "Natural
selection has passively guided the evolution of mammalian brains through
out time, just as politicians and entrepreneurs, have indirectly shaped
the organization of cities large and small. It seems both of these
'invisible hands' have arrived at a similar conclusion: brains and
cities, as they grow larger, have to be similarly densely
interconnected to function properly."
Changizi and coauthor Marc Destefano,
a clinical assistant professor in cognitive science at Rensselaer,
report their findings in "Common Scaling Laws for City Highway Systems
and the Mammalian Neocortex", publishedin the journal Complexity.
authors explain one could not simply combine two dog brains and
expectto have something that functions as a human brain, because the
human brain doesn't just have more cells, it has more connections among
the cells. In the same way, three Seattles combined wouldn'tfunction
like a Chicago, even though the area would be the same. There would be
too many highways with too few exits and lanes that were too narrow.
researchers say when scaling up in size and function, brains and
cities seem to follow similar empirical laws. As cities and the neocortex
thinking region of the brain-grow in surface area, the number of
connections scale to the 3/4 power. For cities, that means highways
and in brains it's a type of closely interconnected cells called pyramidal neurons.
In brains and cities, the number of highway exits and synapses, which
have similar function as terminal points along highways and neurons,
increase with an exponent of 9/8. The 3/4 power law is famous among math
mavens. Click here
an explanation by physicist Brad Roth. Melanie Mitchell also
discusses the phenomenon clearly in "The Mystery of Scaling", which is
Chapter 17 of her book Complexity, a Guided Tour.
Visit Changizi's website
for more information about his research and his new book, The Vision Revolution: How the Latest Research Overturns Everything We Thought We Knew About Human Vision.