Measuring the volume of a healthy, living brain, while possible to
some degree, will not provide much useful data related to
intelligence. Albert Einstein, one of the greatest geniuses of our
time, had a rather small brain:
Einstein's brain weighed only 1,230 grams, which is less than the
average adult male brain (about 1,400 grams). The authors also
reported that the thickness of Einstein's cerebral cortex (area 9) was
thinner than that of five control brains. However, the DENSITY of
neurons in Einstein's brain was greater. In other words, Einstein was
able to pack more neurons in a given area of cortex.
University of Washington
Professor [Susan] Greenfield said that the size of the brain was not a
good indicator of mental ability.
"Einstein had a marginally below average size of brain. It is more the
connections between the brain cells that is really important, and that
gives you the unique ability to adapt and evolve as a person."
The mass of a newborn human brain is about 350-400g. The mass of an
adult human brain is about 1,300 to 1,400 g. The brain makes up about
two percent of the human"s mass. Its average width is about 140 mm,
average length is about 167 mm, and average height about 93 mm.
According to the Grolier Multimedia Encyclopedia, "A theory has been
proposed which states that behavioral capacity, a broad term
indicating intelligence, is related not to the size of the brain but
to the index of cephalization -- the amount of brain in excess of that
required for transmitting to and from the brain." Another source (High
North Alliance) states "neither absolute brain weight nor the
relationship between brain weight and body size provide us with
sensible criteria for comparing the intelligence of different
species". Therefore meaning, the size of the brain doesn't necessarily
determine the intelligence of that species. The table below shows
this; because we know that humans are more intelligent than the other
species on the chart, yet our brains are considerably smaller than
Species Brain weight Body weight Brain weight
(gram) (tonn) as % of
Man 1500 0,07 2,1
Bottlenose dolphin 1600 0,17 0,94
Dolphin 840 0,11 0,74
Asian elephant 7500 5,0 0,15
Killer whale 5620 6,0 0,094
Cow 500 0,5 0,1
Pilot whale 2670 3,5 0,076
Sperm whale 7820 37,0 0,021
Fin whale 6930 90,0 0,008
Mouse 0,4 0,000,012 3,2
HyperTextbook: Mass of a Human Brain
How do you measure intelligence? That is a problem which has plagued
psychologists for decades, and really you can define intelligence in
any way you want to get the answers you want. Brains are complicated
collections of nerve cells which co-ordinate all sorts of functions,
and can be specialised for many tasks in different groups of animals.
Humans have a very large areas of the brain devoted to language, for
Modern humans brains vary very little in size, and so comparisons
between them are probably meaningless. Size is also not the only
important factor in brain development - the way it is structured and
the way the nerve cells interact is also vital in producing a
A team of researchers from the University of Pennsylvania has come up
with an explanation for the brain-size mystery. It's not just the
size, but what's inside.
The researchers subjected 80 volunteers (40 men and 40 women, ages 18
to 45) to 3-D magnetic resonance imaging. The high-tech brain scan
revealed notable differences in the proportions of some key components
inside the female and the male brain...
Of special interest was the amount of "gray matter," the part of the
brain that allows us to think. The researchers wanted to know if women
have as much gray matter as men.
"You find no difference in the amount of gray matter," says Ruben Gur,
professor of psychology at the University of Pennsylvania... To make
up for the smaller brains, women have 55.4 percent gray matter vs.
50.8 in men. The average brain weight of an adult male is 49.5 ounces
- just over 3 pounds - while women typically have a 44-ounce brain, a
Regarding the use of machines in measuring various aspects of the
brain, as mentioned in the ABC article, Magnetic Resonance Imaging
(MRI) is one of the tools that can be used to determine the size of a
person's brain. The device you refer to, where "plugs" are placed on
the scalp, is the Electroencephalograph (EEG), which creates a
printout that represents various electrical activities in the brain.
Computerized Axial Tomography (CAT scan) is somewhat like an MRI, in
that it produces a viewable image. The image of the brain produced by
a CAT scan typically is less detailed than that of an MRI. None of
these will produce a measurement of the brain's volume which would be
accurate to the cubic centimeter, however. We have to wait until
autopsy for that degree of accuracy.
Here's a good explanation of MRI and CAT scans:
And here is info about the EEG:
New York Online Access to Health
Here you'll find interesting details on many statistics relating to
University of Washington
Google search strategy:
Google Web Search: "size of the brain"
I hope this information is useful. If anything is unclear, or if a
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offer further assistance before you rate my answer.