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Re: Impacts and ETs




On Sat, 12 Feb 2005 Mesosuchus@aol.com wrote:

> Why would one need to be a primate to be sentient? Given the right selective
> pressures wouldnt a saurian group be able to achieve that level of
> intelligence?

A relationship exists between the number of neurons possessed and the
cognitive ability of an organism.  Yes, the relationship is fuzzy,
difficult to quantify, and, between species, difficult to compare.  And
birds make extraordinary decisions with a relatively small amount of
neurons.  Still, while demonstrations of parrot and crow intelligence are
wildly impressive, they don't compare with human cognition...as far as we
can test it, anyway.
Our massive supply of neuron is due in large part to the amount of time
available to develop them--both before and after birth.  Neurons are
the most expensive (energetically) tissue to create.  Other organisms
must make harder choices...e.g., marsupials must devote embryonic energy
to developing jaw and musculature for climbing and sucking at an early
age.  Like some chromosomal conditions in humans, there are some very
smart marsupials...but, by an large, they are limited by this ontological
demand!  For an egg layer, the longer one tends a nest in one location,
the longer that nest is at risk.  This provides a pressure to vacate.
And, after hatching, a long period of precociality adds even more
of the same pressure.  Hatchlings that fly or run immediately must be
under the same
developmental pressure as marsupials, i.e., physiological choices favoring
locomotion/coordination must be made.
I think this leaves archosaurs with only one option: develop safety and
ontological leisure time _in utero_.
I know we've talked about this before...but I can't remember why--or if
there are good hypotheses--why this was not done as far as we know in
archosaurs.  The one I do remember goes like this: lizards and other
_small_ reptiles have evolved similar structures independently and
repeatedly.  But archosaurs were too big (i.e., small populations/slow
evoltionary rates) to create such a revolutionary structure (meaning, a
structure which would have to have so many physiological factors
changing).