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MAN, CHIMP AND RAT
Leaving our huge-brained assistants
to once again roam the seas in peace,
we return our inquiry to dry land.
We now restrict our investigation to
the
relative
positions among the
braim
of man, chimp, and rat as compared
to the
relative positions
among the
men!td aclil"itin
of man, chimp, rat.
l.
The traditional (and generally
valid) method of determining the
relative
state of brain sophistication is
by comparing percentages of intrinsic
cortex to total cortex. Thjs percentage
is roughly
90%
in humans, 80% in
chimp, and
1
O% in rat. This means
that the rat-to-chimp incrcase is 56
times greater than the correspondíng
chimp-to-man increase.
2.
Qualitatively, thc same relative
positions among man, chimp, and rat
also hold wíth respect to the structural
neuroanatomy of cerebro-cortical den–
drites and the waveform neuro–
physíology of cerebro-cortical electrícal
activity. (See accompanyíng íllustra–
tions.) These are two of the most
significant measuríng stícks for braín
capacity - and man and chimp are
similar in comparison with the obvíous
disparity betwcen chimp and rat.
3. Comparative brain studies show:
a. Brain weight is 3 pounds for
man,
L
pound for chimp, and 0.004
pounds for rat. Therefore, while chimp
brain is 250 times larger than rat
brain, human brain is only 3 times
larger than chimp brain.
b. The brainfbrain-stem wcight
ratio is extremely similar in man and
chimp - much higher than in rat.
c.
The relative weight percentage
of the
frontal /obes
to total brain
weight is perhaps the best weight–
ratio-indicator of higber mental func–
tioning. For man and chimp, this
ratio is almost identical - whcn com–
pared with the miniscule frontal lobe
ratio in rat.
d. From all appearances, it would
take a trained individual to distinguish
the cerebro-cortical convolutions of
chimp from those of man, while in
rat convolutions are unknown.
e. Jt would take a skilled neuro–
anatomist to differentiate laminar dis–
tribution in human cerebral cortex
from the laminar distribution in chimp
cerebral cortex - but a
laym,m
could
appreciate the laminar differences
between cerebral cortices of chimp
and rat. (See previous pages.)
f. All these empi rica! observations
lead to one conclusion:
Chimp brain
is enormomly more co1nplex /han ral
brai11, 11'het"eas ill compariso11, httman
brai11
i.r
01zly fai1ltly more complex
than chimp brain.
4.
Conseqttently,
011.
the basis of
al/
physical data, if physical bt·ai1l is the
s11bstrate of mental aclivity, chimp
sho~tld
be menta/ly s11perior lo ral lo
a far greater degree 1ha11 man is men–
tally superior to chimp.
We should
logically expect that the
mental
output
of braín function in man, chimp, and
rat - the psychological accomplish–
ments of the individuals and the
sociological attainments of thc species
- would dosely follow the rclative
positions of their respective brains,
and be rather similar for man and
chimp, while much different for chimp
and rat. As a result, based on their
physical brains alone, humans should
think only a
bit
better than cbimp,
whereas chimp should think
substan–
tially
better than rat.
). Precisely the
opposite
is true.
Chimps and rats think very similar/y.
Both can learn extraordinarily complex
problems involving long sequences of
signals and moves. Both have similar
drives, motivatioos, emotions, etc.