Guinea Pigs and Domestication
Domestication changes animals in many ways. We still don’t
fully understand how – or when, or where – the dog was domesticated. But it
turns out the guinea pig is the guinea pig of domestication research as scientists compare
guinea pigs to their wild cousins, cavies.
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A new paper by Benjamin Zipser et al (University of Münster,
Germany) compares adolescent guinea pigs and wild cavies. Previous research has
found differences between adult guinea pigs and cavies in things like
sociability, aggression, and exploratory behaviour. But no one had found out whether these
differences were already present in adolescent guinea pigs, until now.
The word cavy is sometimes used to refer to different
members of the guinea pig family, including the domestic guinea pig. The wild
cavies in this study were Cavia aperea,
also known as the Brazilian guinea pig. It is found in the grasslands of several South American countries
including Brazil, Argentina and Peru. They mainly eat grass but will also eat
leaves, seeds and roots.
They have many predators especially when they are juveniles. Humans also eat
them as food.
Ten guinea pigs and eight cavies took part in the study.
Only male animals were used, and all the animals were lab-raised. The cavies
were bred from a lineage that began with wild animals and now, over 50 generations
later, the cavies are still apparently like their wild relatives and not
domesticated.
It’s interesting to note that, just as dogs come in many
different colours, domestication has led to many different coat markings in
guinea pigs. However cavies are all the
same colour. The researchers dyed markings into their
fur for identification purposes.
Guinea pigs and cavies were tested in a variety of
situations, including a stress test, an exploration test, and sociability tests
with an infant and an adult female (the female was in the early stages of
pregnancy to ensure no mating behaviour). Each testing period took place over a
number of days. Animals were tested in early adolescence (age 51-62 days) and
again in late adolescence (age 120-132 days) when they are sexually mature.
The results showed that wild cavies are more exploratory and
take more risks than domestic guinea pigs. When put in an open field, the
cavies explored further, and when put in a dark box they came out of the box
and spent more time in the light. Some of the guinea pigs did not explore at
all.
There were differences in hormonal stress response as
measured by cortisol reactivity. The researchers say this reflects the
difficult environment in which wild cavies live; their body’s response to
stress is an adaptation which enables them to survive.
The researchers say, “In man-made housing systems, guinea
pigs are usually provided with all relevant resources and hence the selection
pressure for high levels of exploration and risk-taking was removed. The humans
who kept cavies at their homes probably chose (or were only able to catch and
keep) animals that were less prone to flee the artificial housing in their
homes – that is, they selected animals with less exploratory and risk-taking
tendencies.”
The domestic guinea pigs were more sociable. Although both
cavies and guinea pigs were interested in the unfamiliar infant and female, the
guinea pigs engaged in more social interaction with the infant and more
courtship behaviours towards the female. Sociability is a useful feature of
domestication because it means people can keep many guinea pigs in a relatively
small space, whereas in the wild cavies have much larger territories.
The researchers say the wish to keep many
animals “certainly forced the first breeders of wild cavies to choose and
select for the most agreeable and least aggressive individuals since otherwise
it would not have been possible to keep a reasonably large stock of animals in
captivity.”
The study shows that the kind of differences previously
found between adult guinea pigs and wild cavies are also present in adolescent
guinea pigs. Thus, even though sexual maturity brings behavioural and hormonal
changes, guinea pigs already have a bio-behavioural profile suited to
domestication at a young age.
What do you like about guinea pigs as pets?
Reference
Zipser, B., Schleking, A., Kaiser, S., & Sachser, N. (2014). Effects of domestication on biobehavioural profiles: a comparison of domestic guinea pigs and wild cavies from early to late adolescence Frontiers in Zoology, 11 (1) You might also like:
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