Zen recently wrote mentioned this study on his blog, therefore I thought it was time come dredge it the end of the archives. Also, I’ve just returned indigenous APS (see my everyday recaps here here and here), and I am TIRED.

You are watching: How big is a guinea pig brain

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Zen newly wrote discussed this study on his blog, so I assumed it was time to dredge it the end of the archives. Also, I"ve just returned indigenous APS (see my day-to-day recaps right here here and also here), and also I to be TIRED.

ResearchBlogging.orgDomestic animals and their wild counterparts deserve to be different in large ways; there have the right to be distinctions in morphology (physical characteristics), physiology, and behavior. These alters may depend on voluntary adaptations to bondage or to artificial selection pressures arising from the an inspiration for domesticating the animal in the an initial place.

One readjust that is often observed as a result of domestication is a basic reduction in relative mind size. This reduction has actually been observed in all varieties that have been investigated with only one exception: the house mouse (mus musculus). Importantly, this palliation is not just a result of increased body size. Regardless of the fact that it has not been scientifically explored, many assume that the reductions in brain size room reflected in a comparable reduction in mind function. In other words: smaller sized brains (relative to body size) and dumber animals.

Behold the trained guinea pig (Cavia aperea f. Porcellus):


A Brief history of the trained Guinea Pig (isn"t this what you always wanted come know?)

Guinea pigs were very first domesticated about 4500 years back in southern America, offering the aboriginal South Americans with meat and critters for routine sacrifice. Apparently, guinea pigs room still vital source that meat in Peru. (They taste like rabbit, supposedly. Monitor the link. I challenge you. However don"t if you have actually a pet guinea pig. You"ll it is in sorry, and also I will have actually told friend so.) In the 16th century, tamed guinea pigs were lugged to Europe whereby they to be subjected to additional selective breeding, resulting in the common type we know and love today as pets and also laboratory animals.

Their wild ancestors, the wild cavy (cavia aperea) remains one of the most common rodents in south America. Their natural habitat consists of open areas used for quick feeding periods, as well as areas of thick vegetation whereby they spend many of your time.

Not much is known around the cognitive or memory skills of wild cavies, despite they different in countless ways from domestic guinea pigs. Guinea pigs are much less aggressive, more "friendly," display much more male courtship behavior, and also have lessened stress reactivity. In various other words, lock don"t gain stressed the end as easily as your wild cousins. Does this sound familiar? Also, the mind of the domesticated guinea pig is about 13% smaller sized than the of the wild cavy.

Dumb Guinea Pigs; intelligent Cavies?

A team of behavioral biologists and also neuroscientists indigenous the university of Munster (Germany) wondered about the spatial navigating abilities of domestic guinea pigs and also wild cavies. Despite their reduced mind size, would the guinea pigs outperform the wild cavies in ~ the Morris water maze?

The Morris water maze is one apparatus generally used to study spatial and navigational abilities in mice and also rats. The pet is put right into the ring tank and made to swim. In one spot, there is a submerged communication which will permit the animal to comfortably was standing without needing come swim or tread water to save afloat. This would be pretty basic in clean water, for this reason the tank is filled through an opaque milky liquid. The walls of the tank have actually various geometric markings on lock in different places. The question is: after being introduced to the maze and finding the place of the platform throughout training, will certainly the animal be may be to usage the navigational cues provided by the different geometric markers to swim directly towards the platform during testing? Importantly, the tank is circular, therefore corners and edges deserve to not be supplied to help in navigating - the only cues easily accessible are the geometric markings.

During the trial and error phase, you put the animal in that bath, and it swims approximately until it find the platform. If, after a offered amount the time (45 secs in this experiment), it had not found the platform, the experimenter would certainly manually relocate the guinea pig to the platform. This was recurring up to three times, until, after gift moved, the guinea pig continued to be on the platform because that at least fifteen seconds. If s/he found the communication by him- or herself, s/he was left there because that fifteen seconds. After ~ the training period ended, there were five days in i m sorry the guinea pigs were not placed into the water maze.

Video 1: clock this wild-type mouse find out the place of the communication on day 1, and also immediately discover the communication by day 10.

Then, they to be placed ago into the maze for 60 seconds, yet the platform to be removed. Would they spend more time in the previously-correct quadrant that the pool? If so, climate they had actually accurately supplied spatial cues to discover the task. If they spent equal quantities of time in all 4 quadrants, climate they walk not discover the task.

Was the generalized problem solving, or simply a conditioned response? Finally, they were put into a pool in which the submerged platform was located in a various quadrant. Can they re-learn the location of the platform? If so, this suggested that they can generalize the task. (This is a similar to the experiment in which Rio (the sea lion) generalized her categorization of arbitrary stimuli.)


Figure 4: There to be a far-reaching effect the domestication because that both genders in discovering performance. How straight was the course to the platform? (D = domesticated; W = wild. M = male; F = female.)
Figure 5: No far-ranging effects for sex or because that domestication for the amount of time that took because that the pet to find the platform.
Figure 6: The attempt in i m sorry the platform was removed. How much time walk they spend in the ideal quadrant? Dotted heat represents chance.

So domesticated guinea pigs go somewhat better than the wild cavies at finding out the job (figure 4), though the cavies did eventually learn the task and also perform over chance (figure 6).

What can account for the relatively poorer performance of the wild cavies in regards to finding the most straight path (figure 4), while likewise considering your equal performance on the amount of time it take it to uncover the platform (figure 5), and the reality that all teams were actually over chance on learning the task overall (figure 6)?

It can have miscellaneous to carry out with swim speed. Male residential guinea pigs swam in ~ a rate of 1.12 km/h top top average and also females in ~ an average speed of 1.19 km/h. In the team of wild cavies, average swimming speeds were 1.18 km/h for males and also 1.35 km/h for females. Females were substantially faster 보다 males, and also wild cavies were substantially faster than tamed guinea pigs. Regardless of taking more circuitous courses to the communication (demonstrating the they weren"t taking benefit of the spatial cues), their much faster swimming rate meant the they discovered the platform in roughly the very same amount the time. The is as such likely the the wild cavies were making use of some various other sort of problem-solving strategy, and also the data suggest that it was sufficiently successful. That is unclear, however, what your strategy was.

Figure 7: In case you haven"t gained your sheep of cute for the day. All together now: "awwwwwwwwwww."

And why to be the wild cavies faster swimmers than the domesticated guinea pigs? Remember just how domesticated pets tend come respond much better to stressful situations? In addition to gift able to use the spatial cues, that is possible that the tamed guinea pigs were less stressed out by gift in the water maze (maybe they were less stressed out since they can use the spatial cues). The is possible that greater levels the physiological stress and anxiety in the wild cavies resulted in the faster, an ext panicked, swimming.

Why is this important?

The writer say the pretty well, for this reason I"ll let their words carry out the speaking:

Thus, guinea pigs" domestication as an artificial selection for human-desired traits walk not resulted in a degeneration of cognitive capabilities however rather come an adaptation come a artificial environment that enables solving the task even more efficiently.

As with various other studies of pet cognition, this gives us essential knowledge about the evolution and architecture that spatial navigation and generalized problem-solving. It reminds united state that bigger brains execute not always equal much better problem-solving. It additionally gives united state some clues regarding the evolution adaptations that might have allowed humans to build increasing spatial and navigational skills.

See more: " Warriors Come Out And Play Song, Warriors (Come Out To Play)

Lewejohann L, Pickel T, Sachser N, & Kaiser S (2010). Wild genius - domestic fool? Spatial finding out abilities that wild and domestic guinea pigs. Frontiers in Zoology, 7 (1). PMID: 20334697

The see expressed are those of the author(s) and also are no necessarily those of scientific American.


Jason G. Goldman is a scientific research journalist based in Los Angeles. He has written about animal behavior, wildlife biology, conservation, and ecology for scientific American, Los Angeles magazine, the Washington Post, the Guardian, the BBC, Conservation magazine, and also elsewhere. The contributes come Scientific American"s "60-Second Science" podcast, and also is co-editor of Science Blogging: The essential Guide (Yale university Press). He enjoys share his wildlife expertise on television and also on the radio, and often speak to the public about wildlife and also science communication.