Genetics versus Environment 75cortex involved in vision. The visual processing network of primates includes
at least 30 distinguishable brain areas, with a complex web of interconnections.
It has been estimated that visual processing areas occupy more than half of the
total surface of the primate neocortex. The prefrontal cortex carries out func-
tions that include planning, working memory, motivation, attention, and
executive control. It takes up a much larger proportion of the brain in primates
than in other species, and an especially large fraction of the human brain.
Genetics versus Environment
We are still stuck in the genetic dogma of autism and most researchers still
believe that autism is a genetic disorder albeit an unusual one. It is not a single
gene illness, but is caused by a cluster of genetic errors that occurs in an autistic
child’s brain. ASD results in a distinctive constellation of behavior that mani-
fests in the form of a varied number of disorders that are lumped together as a
spectrum.
To understand how exposure to extremely small amounts of chemicals may
interfere in the normal development of a human fetus, we have to look at not
Table 2.2 Encephalization quotient. This is a measure of relative brain size given
as the ratio between actual brain mass and predicted brain mass for an animal
of a given weight. EQ estimates the intelligence of an animal.
Species Encephalization quotient (EQ)Human 7.44
Bottlenose dolphin 5.31
Orca 2.57
Chimpanzee 2.48
Rhesus monkey 2.09
Elephant 1.87
Whale 1.76
Dog 1.17
Cat 1.00
Horse 0.86
Sheep 0.81
Mouse 0.50
Rat 0.40
Rabbit 0.40Source: Adapted from https://forum.bodybuilding.com/showthread.php?t=139128283.