Biology Reference
In-Depth Information
local directional selection for or against any particular behavioral traits, human
influence would act as a selection pressure for that population of macaques.
Over time, the traits better fitted for not being removed and thus better fitted for
the human-inhabited environment would propagate, and the macaques would
begin to biologically adapt to the anthropogenic ecology by which they are
affected. The traits most likely to be affected would be those related to direct
interactions with people, such as their temperamental tendencies to show fear,
submission, aggression, and interest towards humans.
A model for comparison is the domestication of the dog, which has been
the result of an increasing proximity and interaction between humans and
wolves over at least the last 14,000 years (Clutton-Brock,
1995
; Coppinger
and Shneider,
1995
; Coppinger and Coppinger,
2001
). According to some sci-
entists studying canine evolution, the basic transition occurred with wolves
(
Canis lupus
) beginning to live near humans, as they scavenge litter in gar-
bage dumps and hunted livestock. They suggest that humans attempted to repel
wolves, which would have selected against the most aggressive and danger-
ous individuals. Overall, this created a directional selection pressure that left a
higher proportion of submissive and tame individuals living on the fringes of
human settlement to reproduce. Over time, through these processes and also
the direct capture and breeding of pets, wolves were eventually selected to
resemble village dogs (
Canis familiaris
). They evolved a higher frequency of
tame traits adapted for living in a human environment and directly interacting
with people (Coppinger and Schneider,
1995
).
Studies on silvered foxes (
Vulpes vulpes
) have shown that with intense arti-
ficial selection against aggressive individuals, tamer populations can evolve
within several generations (Belyaev,
1979
; Trut,
1999
). These changes in
temperament also correlated with changes in morphology, such as floppy ears
and patchy fur coloration (Trut,
1999
), indicating there can be marked phys-
ical changes that co-evolve with behavioral traits. Further research on silver
foxes has shown these behavioral adaptations are associated with changes
in brain gene expression (Linberg
et al
.,
2005
). Other research investigat-
ing tameness in rats (
Rattus norvegicus
) has shown clear genetic differences
in rats which are more tolerant and comfortable around humans, which is
related to changes in the genetic expression affecting hypo-pituitary-adre-
nal (HPA) axis and serotonin system activity (Albert
et al
.,
2008
,
2009
).
Overall, this line of work suggests that human influence can potentially alter
the behavioral and morphological evolution of local populations when there
is sustained directional selection across only several generations. This work
has all been artificially done in captivity, and thus it remains to be studied
how much influence human activity could actually have on animal behavior
in natural environments. The overlap of humans and macaques provides a
