April 06, 2018 Friday
Bedtime Story
Human Brain Follows Evolutionary Trend
The microscopic chamber of the
hemocytometer is engraved with laser-etched grid of perpendicular lines so
cunningly crafted that the area and the depth bounded by the lines are known
very accurately.
By observing a defined area of the grid and
counting the number of cells lying within it, once can calculate the
concentration of cells overall and from it, the numbers for the entire volume
of tissue sample can be extrapolated.
The only assumption that is made here is
that every brain neuron has one and only nucleus, which translates the counting
of nuclei into counting the number of neurons.
So this is the technique that the
neuroscientist Suzana Herculano-Houzel brings into service to count the number
of neurons in various brains and which eventually she uses to form her
hypothesis about the evolution of brains.
Some at the Vanderbilt University, Nashville
in the state of Tennessee (where she
currently holds the position of Associate Professor in the Department of
Psychology and Biological Sciences) call this technique Suzana’s innovative
‘brain soup’ method of neuronal counting.
The amazing conclusion that her data
analysis forced her to come to was that human brain though seems to be such an
evolutionarily marvel in terms of its almost divine cognitive powers, is
nothing special, at least in terms of the number of neurons it has compared to
other primates.
Even the size of the human brains is NOT
remarkable, as long as the great apes are left out of the comparison, who, by
the way, have just as many neurons as a generic primate of their brain size
would have.
The only surprising question or the fact
that she came across during her research was this:
Human brain, among the group of great apes,
is much larger in size for its body size.
Or in other words, from the point of view
of other great apes, the question they ought to be asking is this:
Relative to the hairless human apes, why are
our brain sizes smaller with respect to our large body sizes?
The only answer that Suzana
Herculano-Houzel find sensible is cooking.
It was cooking the meat on fire that
allowed the brains of bunch of hairy apes living in the savannas of Eastern
Africa that allowed the brains the balloon up, for the fact is that the brain
is a colossal energy sinkhole that our cousin great apes simply cannot afford.
Their uncooked diet simply cannot pay
adequately in caloric currency for the metabolic cost that such a ballooned-up
brain would demand.
Yet leaving aside the great apes, larger
bodies do tend to have larger brains though brain size increases at a slower
rate than the body size.
Mathematically the correlation between the
body size and the brain size can be stated in terms of function; brain size
when expressed as power function of exponents between 0.6 and 1.0 across species.
All this is very interestingly summarized in
the concluding remarks of the paper that I started with and we shall be reading
that in the nights to come.
Stay tuned to the voice of an average story storytelling
chimpanzee or login at http://panarrans.blogspot.com
Good night mon ami and my fellow cousin ape.
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Another great educator and a teacher that I am aware of is
Professor Subhashish Chattopadhyay in Bangalore, India.
While I narrate stories, Professor Subhashish an electronic
engineer and a former professor at BARC, does and teaches real mathematics and
physics.
He started the participation of Indian students at the
International Physics Olympiad.
Do visit him here:
All his books can be downloaded for free through this link:
For edutainment and English education of your children, I
recommend this large collection of Halloween Songs for Kids:
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