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Re: Pick one - massive or agile

Bah, nonsense! The travel time increase for nervous signals is utterly
irrelevant compared to the increase in inertia. That's what's slowing
huge animals down!


On Tue, Jul 6, 2010 at 4:54 AM, Richard W. Travsky <rtravsky@uwyo.edu> wrote:
> http://www.nytimes.com/2010/07/06/science/06obelephan.html
> It takes an elephant much longer to notice a fly and flick it away than it
> takes a shrew, and the reason is not that the elephants great brain is too
> busy with philosophy, or that it simply does not concern itself with flies.
> Its a matter of round-trip travel time - in the nervous system. The trip
> from the elephants skin to the brain and back again to the muscles to flick
> the tail is 100 times as long as the same trip in a shrew, according to a
> new study published in the Proceedings of the Royal Society B.
> The nervous system acts like an information superhighway, sending messages
> back and forth from the brain throughout the body. The bigger the animal,
> the greater the distance traveled.
> Nerves have a maximum speed limit of about 180 feet per second, said Maxwell
> Donelan, the studys lead author.
> It makes sense that in a large animal, like an elephant, messages have a
> longer way to travel, he said.
> ...
> http://rspb.royalsocietypublishing.org/content/early/2010/06/24/rspb.2010.0898.full
> ...
> As a consequence, larger animals are burdened with relatively long
> physiological delays, which may have broad implications for their behaviour,
> ecology and evolution, including constraining agility and requiring
> prediction to help control movements. ...
> Large animals may cope with these relatively long delays by simply moving
> slowly, explaining at least in part the low maximum speeds of large mammals
> (Garland 1983; Hutchinson et al. 2006) and providing further evidence for
> the idea that dinosaurs could not be both massive and agile (Hutchinson &
> Garcia 2002).
> ...