Autism and Environmental Factors, First Edition. Omar Bagasra and Cherilyn Heggen.
© 2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.
83
3
It is also an era dominated by industry, in which the right to make a dollar
at whatever cost is seldom challenged.
Rachel Carson, 1962, Silent Spring
As with human beings, genes are classified by common characteristics, and
grouped into units called families. In mammals, the largest of all gene families
are the odorant receptors (ORs). Every olfactory sensory neuron selects only
one such OR from over ~450 choices that are encoded in the genetic material
available to it in the human genome. Many other mammals have up to 1,200
different ORs. However, these 450 ORs are akin to 450 different colors, combi-
nations of which can be essentially unlimited [1–3]. Neurons are crucial to this
process. Their shaft‐like and finger‐like extensions, axons and dendrites, facili-
tate the movement of electrical impulses and the attendant communication
that helps the body function. Disruptions to the process can cause loss of a
particular faculty, such as the ability to sense odors when ORs cannot carry out
their customary functions, including the effective coordination of communica-
tive nerve impulses. A complex circuit passes information from the nose to the
brain [2,3].
Compared with other senses, such as sight or touch or hearing, olfaction (the
capacity to smell) has commonly been regarded as less important. As more
research links olfactory ability to various diseases, the importance of olfaction,
including its relationship with the capacity to taste (gustation), may well
deserve higher priority, if not equality, on research agendas. Individuals may
survive better without the ability to smell than without the capacity to see, but
the implications for having an impaired olfactory system, including the onset
of disease in the elderly or prenatal or early childhood exposure to dangerous
toxins, could be extremely serious in terms of quality of life for these individu-
als and others with whom they interact [4–19].
3 Olfaction and Autism
