Biology Reference
In-Depth Information
mothers themselves. The effects of maternal behavior are mediated in part
through epigenetic mechanisms.
Brain Genetics More Complex Than Other Traits
For centuries, intensive selection in dogs has narrowed the gene pool for
traits such as body shape and type of coat. Researchers have discovered that
only a few genomic regions control many dog appearance traits ( Boyko
et al., 2010 ). This is not true for behavior. Genetics that control brain devel-
opment are much more complex. Selective breeding experiments in foxes
and other experiments involving selection for appearance traits show that
those traits are sometimes linked to behavior traits. Why does selecting for
a calm temperament produce a black and white fox? When the first edition
of this topic was written, these unusually linked traits were unexplained.
The long-running ENCODE project (2012) which is mapping the non-coding
regions of DNA may help provide answers. Regions of non-coding DNA are
not always located adjacent to the piece of code it regulates. There are
long-range interactions. Sanyal et al. (2012) states that regulatory elements
and coding DNA are in complex three-dimensional networks. Maybe when
long strands of DNA are folded up, the temperament and coat color regions
are folded up beside each other.
A BRIEF HISTORICAL REVIEW OF ANIMAL BEHAVIOR STUDY
This historical review is not intended to be completely comprehensive.
Our objective is to discuss some of the early discoveries important for our
current understanding of animal behavior, with particular emphasis on genetic
influences on behavior in domestic animals.
Early in the 17th century, Descartes came to the conclusion “that the bod-
ies of animals and men act wholly like machines and move in accordance
with purely mechanical laws” (in Huxley, 1874 ). After Descartes, others
undertook the task of explaining behavior as reactions to purely physical,
chemical, or mechanical events. For the next three centuries, scientific
thought on behavior oscillated between a mechanistic view that animals are
“automatons” moving through life without consciousness or self-awareness
and an opposing view that animals had thoughts and feelings similar to those
of humans.
In “On the Origin of the Species” ( 1859 ), Darwin's ideas about evolution
began to raise serious doubts about the mechanistic view of animal behavior.
He noticed animals share many physical characteristics and was one of the
first to discuss variation within a species, both in behavior and in physical
appearance. Darwin believed that artificial selection and natural selection
were intimately associated. Darwin (1868) cleverly outlined the theory of
evolution without any knowledge of genetics. In “The Descent of Man” ( 1871 )
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