Thinking Livestock | Thinking Animals United

There is more to farm animals than meets the eye 

Photo: Tim Green / Flickr, source.

By Maria Ter-Mikaelian, Ph.D.

My two-year-old son is fascinated by cows. He loves to look at all the cow pictures on his milk carton, and a really special treat is watching a 5-minute YouTube video of cows grazing in a field. I bet that most of us started out with the same fascination with farm animals. What toddler didn’t love learning that a cow says “moo” and a pig says “oink” (or, if your first language was Mandarin, “hroo”)?

Somewhere along the way, though, we lose that sense of awe about farm animals. As adults, we rarely spare a thought for cows, or if we do, our opinion of them is not too flattering. Expressions like “they stared at him like cows at a passing train” show what we think of cows’ intelligence and engagement with the outside world. Other livestock don’t fare much better: a “sheep” thoughtlessly follows the crowd, and a “pig” eats too much and makes a mess. But is that really all there is to farm animals: just mindlessly eating away?

In fact, when cows stare at someone, there is more going on in their heads than we give them credit for. A recent study showed that they can recognize individual cows in head shots from different angles and tell them apart from other individuals. [1] Sound easy? Try it!


Can you pick out which of the two bottom cows is the same animal shown in the top photo? Cows can. (Answer: it’s the one on the right.) Adapted from images shown to cows in an experiment by Marjorie Coulon and colleagues [1]; source.

This is particularly surprising because we expect animals to use smell over other senses to recognize each other. Of course, cows have had a lot of practice identifying other cows, while you probably haven’t. However, they can also recognize humans, at least in person [2] (unfortunately, the equivalent test with photos has never been done). Interestingly, sheep are also pretty good at recognizing other sheep from head shots – especially if the photos are of adult sheep of the same breed. [3] In fact, the brain of the sheep has a special area that responds to faces of sheep (especially familiar ones) as well as faces of dogs and humans. [4] (Humans and monkeys also have this kind of specialized brain tissue, found in the temporal lobe of the brain, i.e. near your temples. [5]) Perhaps sheep evolved to be especially good at recognizing the faces of animals who might matter in their life – their companions in the herd as well as the powerful shepherd and sheepdog.

Also like humans, farm animals use sound to identify individuals and to communicate with them. We all know that cows moo, but not all “moos” are created equal: by varying subtle features of their calls, like length and repetition frequency, cows can communicate information about their age, sex, dominance, and possibly even readiness to mate to others in the herd. [6] There is some evidence that calves as young as just 1 day old who have been separated from their mother can recognize her calls and differentiate them from those of other dairy cows [7], and they can certainly do this by three weeks old [8]. Sows, too, communicate with their piglets using sound, and pig calls contain information allowing others in the drove to identify them. [9]

So farm animals can recognize and communicate with others of their own species – perhaps you’re not impressed. Do we have any evidence of more complex cognitive abilities in livestock?

Image: Maria Ter-Mikaelian. Cartoons from here, here, and here.

Although this topic has only recently begun receiving much scientific attention, the answer is yes. One favorite test of higher intelligence used by psychologists and zoologists is the mirror test: finding out whether an animal is self-aware enough to recognize itself in the mirror. Only a small number of species, including great apes, bottlenose dolphins, Asian elephants, and magpies, can do this. [9, 10] While pigs fall short of this feat, they do show an understanding of mirrors equaling that of some monkeys and African Grey parrots. [9, 11]   Have you ever watched a puppy or kitten attacking its reflection in the mirror? By contrast, when a pig is first introduced to a mirror, it will spend some time making movements and observing the effect on the reflection from different angles. [12] After apparently learning something about how a mirror works, the pig is able to use the mirror to find hidden food which is only seen in the reflection, but is otherwise invisible. [12] A pig who has never had any experience with mirrors can’t do this – it will simply look behind the mirror for the food – so this is evidence of some complex learning on the animal’s part.

Another interesting experiment shows that goats can form an abstract concept and apply it to new circumstances. Researchers in Germany trained goats to look at four symbols on a computer screen and press a button next to one of the images to earn a reward. [13] Initially, the goat learned which specific images were associated with a reward (such as the arrow in the left-side square in the picture below), but then the experimenters gave the goat completely new symbols (right-side square). The only similarity was that, like in the first test, all the symbols were shaded except one – the correct one to choose. The goats were able to quickly solve this new problem, demonstrating that they had created a rule or category in their minds. [13]

 Goats learned to press a button next to an unshaded symbol to earn a reward. Although they were trained with one set of symbols (left), they were able to apply the same principle to completely new symbols (right). [11] Image: Maria Ter-Mikaelian, based on experiment by Meyer and colleagues.

Much has been made of how dogs can understand and follow human pointing, whereas our close relatives, the chimpanzees, cannot. [14] Interestingly, pigs are also able to use human pointing to find a hidden reward [15], as are goats [16] and horses [17]. Furthermore, a pig can be trained to recognize 6 different gestures – three for different objects and three for different actions – then combine them to execute a complex command, like “fetch the Frisbee” or “sit in front of the ball”. [18] Goats can learn to solve a puzzle that they previously couldn’t crack by watching a human do it just once [19] – demonstrating so-called “social learning” from another species, something which is relatively rare in the animal kingdom. This raises interesting questions about whether it’s a long history of coexisting with humans, or being raised by humans from a young age, that has shaped the brains of domesticated animals to respond to our cues. [20,21]

Sadly, much of our understanding of how farm animals think and behave comes from observing them in adverse conditions (like hearing the sounds they make when in pain or separated from their mothers) or from studies aimed at improving farming practices, so our perspective is limited. It’s no coincidence that we know the most about the cognitive abilities of pigs – a farm animal that some people also keep as pets. There is still so much for us to learn – knowledge that will help us not only to recapture our childhood love of these fascinating animals, but to improve their lives as well.

Maria Ter-Mikaelian teaches Animal Behavior and also writes at https://medium.com/@maria.ter
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Sources

[1] Coulon, M. et al. (2009). Individual recognition in domestic cattle (Bos taurus): Evidence from 2D-images of heads from different breeds. PLoS One 4(2):e4441. doi: 10.1371/journal.pone.0004441

[2] Taylor, A.A. and H. Davis. (1998). Individual humans as discriminative stimuli for cattle (Bos taurus). Applied Animal Behaviour Science 58(1-2): 13–21

[3] Kendrick, K.M. et al. (1996). Are faces special for sheep? Evidence from facial and object discrimination learning tests showing effects of inversion and social familiarity. Behavioural Processes
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[4] Kendrick, K.M. (1991). How the sheep’s brain controls the visual recognition of animals and humans. Journal of Animal Science 69(12): 5008-5016

[5] Op de Beeck, H.P. et al. (2008). Fine-scale spatial organization of face and object selectivity

in the temporal lobe: Do functional magnetic resonance imaging, optical imaging, and electrophysiology agree? The Journal of Neuroscience 28(46):11796 –11801

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[7] Marchant-Forde, J.N. et al. (2002). Responses of dairy cows and calves to each other’s vocalisations after early separation. Applied Animal Behaviour Science 78(1): 19–28

[8] Barfield, C.H. et al. (1994). Domestic calves (Bos taurus) recognize their own mothers by auditory cues. Ethology 97: 257–264

[9] Marino, L. and C.M. Colvin. (2015). Thinking pigs: a comparative review of cognition, emotion, and personality in Sus domesticus. International Journal of Comparative Psychology 28: 1- 23

[10] Prior, H. et al. (2008). Mirror-induced behavior in the magpie (Pica pica): Evidence of self-recognition. PLoS Biology 6(8): e202. doi:10.1371/journal.pbio.0060202

[11] Pepperberg., I.M. et al. (1995). Mirror use by African Grey parrots (Psittacus erithacus). Journal of Comparative Psychology 109(2): 182-195

[12] Broom, D. et al. (2009). Pigs learn what a mirror image represents and use it to obtain information. Animal Behaviour 78(5): 1037-1041

[13] Meyer, S. et al. (2012). The cognitive capabilities of farm animals: categorisation learning in dwarf goats (Capra hircus). Animal Cognition 15:567–576

[14] Kirchhofer, K.C. et al. (2012). Dogs (Canis familiaris), but not chimpanzees (Pan troglodytes), understand imperative pointing. PLoS One 7(2):e30913. doi: 10.1371/journal.pone.0030913

[15] Nawroth, C. et al. (2016). Are domestic pigs (Sus scrofa domestica) able to use complex human-given cues to find a hidden reward? Animal welfare 25(2):185-190

[16] Kaminski, J. et al. (2005). Domestic goats, Capra hircus, follow gaze direction and use social cues in an object choice task. Animal Behaviour 69(1): 11–18

[17] Maros, K. et al. (2008). Comprehension of human pointing gestures in horses (Equus caballus). Animal Cognition 11(3): 457–466

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[19] Nawroth, C. et al. (2016). Goats learn socially from humans in a spatial problem-solving task. Animal Behaviour 121: 123-129

[20] Udell, M.A.R. et al. (2008). Wolves outperform dogs in following human social cues. Animal Behaviour 76(6): 1767–1773

[21] Hare, B. et al. (2010). The domestication hypothesis for dogs’ skills with human communication: a response to Udell et al. (2008) and Wynne et al. (2008). Animal Behaviour 79(2):e1-e6