Hammocks, hamsters and happiness

Extra hammocks are the key to keeping hamsters happy, but how do you ever know how an animal is feeling?
03 August 2015

Interview with 

Dr Emily Bethell, Liverpool John Moore’s University


Hamsters are popular pets, and research this week has revealed that more Hamsterhammocks and fluffy bedding make for happier hamsters. While this itself may not sound too surprising, finding a way to measure an animal's happiness has always posed a major challenge - how do you know what's going on inside their heads?  Georgia Mills caught up with Dr Emily Bethell, a senior lecturer in primate behaviour at liverpool John Moore's University...

Emily - People often think that researching emotions means that you're looking at subjective feeling states. It doesn't, emotions are basic survival mechanisms which animals have evolved over time to direct them to seek rewards and to avoid threats. So, we would expect that all animals have emotions because this is what allows individuals to survive to move around their environment, to gain food, mate, shelter, and to avoid predators, poisonous foods and so on.

Georgia - How did you test this in hamsters?

Emily - We trained the hamsters to approach drinkers that were placed at one of five locations in a test arena. The arena was one metre by one metre and had five holes along one side. The hamsters learned that when a drinker was placed at one of the locations, for example, at the far right, it would always contain sugar water. However, when the same drinker was placed at the far left location, it would always contain quinine in the water. Quinine is bitter and hamsters really don't like it.

Georgia - But they like sugar water?

Emily - They love the sugar water. So over time, the hamsters learned to approach the sugar drinker which they did so quickly and regularly. They pretty much stopped responding altogether to the quinine drinker.

Georgia - At this point, half the hamsters got a fancy home upgrade. They get extra bedding, extra hammocks and chews. What Emily would call 'enrichment'. The other less-lucky hamsters are stuck with the status quo. They all have a weekend to enjoy their quarters before the drinkers are back. But this time, there's a twist. There are five of them. There's one back in the sweet sugar location, one still in the bitter quinine location, and then three intermediates in between. Get inside the mind of the hamster. Do you expect the middle ones to be nice or nasty?

Emily - We predicted that the hamsters housed with the enrichments would be in a more positive emotional state and would therefore make more optimistic judgements about what might be in the drinker, at the intermediate locations. So, we'd expect those hamsters to approach these three middle locations more often and more quickly than hamsters when they didn't have the enrichments and therefore were in a more negative emotional state.

Georgia - And you're thinking there is that an optimistic hamster is a happy hamster.

Emily - Possibly. By definition in humans, we talk about happiness and welfare in terms of our expectation of future positive events, and our positive interpretations of otherwise ambiguous stimuli.

Georgia - Did you find that the hamsters who had the nice bedding and the hammocks, they were more optimistic?

Emily - This is exactly what we found. The hamsters who had received the enrichment approached the ambiguous queues more often than the hamsters who weren't enriched.

Georgia - I wish I'd known that when I had my pet hamsters. They just seem to die in about two weeks. I obviously hadn't used enough hammocks... or food potentially.

Emily - Hamsters are short-lived and that's what makes them good pets in a way. You don't have to clean their cages out for too long.

Georgia - Now, we think we know that this test works on hamsters and we can test them for happiness, do we think we could take this forward and use it across the board in animals?

Emily - Yes. Well, I have a paper coming out soon, talking about the possibility of using these kinds of tests for examining emotions in species or groups of animals which are more problematic when it comes to talking about emotion states, and that's the fishes, the reptiles, and amphibians. I'm proposing that these kinds of tests are absolutely perfect for the use with these species as well.


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