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, as seen in this short video clip. 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?
ReferenceZipser, 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) DOI: 10.1186/1742-9994-11-30
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