Tickling rats for science…

…by Tayla / from the United Kingdom / PhD Developmental Biology / 2nd Year

When asked what I am doing for my PhD (a question often asked more out of politeness than actual interest), I’m sure many people expect a complicated and ‘sciencey’ title. Instead, my reply of ‘I tickle rats’, typically inspires a deadpan expression followed by genuine interest.

Can animals feel?

Anyone with an experience of animals can tell you that they can feel emotions: your dog subdued and depressed when you put on your shoes for work and pure happiness of an uncontrollable tail when you arrive home.

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Throughout history there has be a certain reluctance to attribute emotions to non-human animals. Despite this, over the past 20 years or so of animal welfare science, we accumulated a wealth of evidence that animals can feel pain, anxiety and fear. However, for animals to have a good life and a ‘life worth living’ they must also experience pleasure or happiness. For us to tell if animals are experiencing positive emotions, we have to develop tell-tale indicators of animal happiness.

So why am I tickling rats?

We’ve all seen videos of animals playing and there’s no doubt they are having a good time. Play also disappears when animals are experiencing poor life conditions, such as a lack of food or predation threats. As such, play has long been thought of as a way of telling us if animals are happy. The trouble with play, from a science point of view, is that it bursts spontaneously out of nowhere and we therefore cannot control when it happens.

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This is where tickling comes in – the purpose of tickling is to generate a positive, happy mental state in rats. Much like when you tickle a child, when you tickle a rat, they produce sounds which are also produced during other experiences we think are positive for rats, such as during play and receiving a tasty food reward. Two scientists, Jaak Panksepp and Jeffrey Burgdorf, discovered that rats were ticklish back in 2000. They had been studying social play in rats for quite some time and wanted to see if they could mimic this play themselves. Since then, rat tickling has been used in over 56 different experiments and is gaining popularity within animal behaviour science (see the video at the bottom for a video of rat tickling in action!).

What have I found so far? A VERY short synthesis

Because tickling is thought to mimic social play in rats, I wanted to see whether tickling and play have a relationship with each other. First, I wanted to see whether tickling made rats happier and if this positive mood was expressed by an increase in play. We found that before a daily handling experience, rats which were tickled would leap and jump more than those who were not regularly tickled, a type of play known as solitary play. In solitary play, as the name suggests, animals play by themselves (think of leaps and jumps by lambs in the field). The rats were excited to be tickled!

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I’m sure you’ve had the experience of seeing someone yawn and supressing the urge to yawn yourself. This is a form of contagion, where someone else’s behaviour has an instant impact on your own behaviour. This also happens with emotional states and we wanted to see whether the positive, happy, excited mood of a tickled rat would change the behaviour of his cage mate would was not tickled.  The cage mates of tickled rats chased my hand around the arena more than those whose cage-mates had not previously been tickled. The pleasurable emotional experience of tickling could pass to a rat which had not been tickled!

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If you want to know more, my first EVER peer review paper on this research (available online 26th September 2019) can be found here; https://doi.org/10.1016/j.applanim.2019.104879

I’m also very contactable on Twitter! @Tayla_Hammond


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