Re: Do dolphins or elephants have as many brain cells as humans do?

There ARE other animals that I'm sure have as many, if not more brain cells
in their heads as we humans do.  It is pretty much impossible to accurately
count the number of neurons (cells) in our brains, although it is estimated
that the human brain has more than 180 billion cells (more than 80 billion
of these are directly involved in `thinking`, or 'information processing').
Furthermore, each cell receives up to 15,000 connections from other
cells....which makes for a VERY complicated network of 'communication
wires' whatever the size of the brain!

The number of neurons does seem to relate directly to the size of brain, so
it would be natural to assume that the elephants brain would have more
cells than us...the dolphin on the other hand (from what I remember,
rightly or wrongly) has a similarly sized brain to us.  As your second
question rightly assumes, the size of animal brains does give us food for
thought as to whether the size relates directly to function, and more
importantly to intelligence or even consciousness itself.  A useful
observation that has helped make this correlation is a calculation known as
the 'encephalisation quotient' or EQ.  This is a ration of actual brain
size to expected brain size...the expected size being some sort of average
that takes body size into account. Hence the cat is considered having an
averaged sized brain for its body size, so its EQ is 1.  A rat has a
relatively small brain for its body, so its EQ is 0.4.  A Rhesus monkey has
a relatively larger brain for its body, with an EQ of 2.09, a chimpanzee
has an EQ of 2.48 and Humans have an EQ of 6.3, us having very large brains
for our body size.  As a matter of fact, elephants have an EQ of 1.3 (with
a brain only a little bigger than expected for an animal of its size), and
dolphins have 6, comparable to ours.

The measurement of EQ seems to superficially relate an increase in brain
size to the development of new abilities in species, but it is likely that
the development of new areas is much more important....particularly areas
of the cortex (the major thought-processing region of the brain).  For
example, very simple animals have a minimum number of cortical areas - one
for each of the senses, and one for movement - whereas more sophisticated
animals have many areas.  e.g. the squirrel has 4 visual areas, the cat
appears to have at least 12, and the owl monkey has 14...humans are thought
to have at least 20.  In terms of evolution the increased size of brain in
primates (apes and humans) seemed to relate to the increased number of
functions in the cortex...or greater variety of 'areas`.  These functions
are directly related to our behaviours, hence dolphins have similarly large
brains primarily because of their extremely evolved navigational and
communicational abilities.  Humans have more complicated external and
internal awareness as demonstrated by sociological acheivements through
evolution, so it would not be surprising to find that the human cortex has
many more areas associated with emotional behaviour and possibly memory
that dolphins.

Hope this mix of information has helped to answer your query!