Researchers have successfully trained rats to detect landmines, sniff out tuberculosis and even drive cars, but their next challenge – to find survivors in a collapsed building – could be their bravest yet. We spoke to Dr Donna Kean, behavioural researcher at APOPO, an organisation at the forefront of training rats to save lives.


Why rats?

They can contribute something that the other technologies can't, at least for the areas we train them in. Their sense of smell and their trainability is on a par with dogs'. But it’s the rats’ small size that really makes a difference.

At APOPO, we work with the African giant pouched rat [Cricetomys ansorgei]. We taught the rats to detect landmines, because they're too small, too light, to set off a landmine. We’re teaching them to detect the scent of illegally smuggled wildlife in shipping ports, because they can reach the containers stacked up high on top one another.

For my research training rats for search and rescue, the main reason is that they can get into the small, tight areas of a debris site. Search and rescue dogs typically just go around debris sites, whereas we're hoping the rats can actually go inside, through all the rubble, because they're so small.

Any application has to be in response to a humanitarian challenge, and it has to need the unique capabilities of our rats to help. If there's already [other] technology available, and it's affordable, we're not going to train our rats just for the fun of it.

How do you train a rat to do these things?

We use positive reinforcement to train them on a basic sequence of behaviour. So, here it’s to search for a human, indicate to us that they’ve found them, and then return to where they were released from.

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[Training] starts off in a really basic environment: a small, empty room. Then we gradually expand and increase the complexity so it because more like real life. We can start adding in debris and making the training area look more like an actual collapsed building site.

A person with long brown hair and wearing a blue jumpsuit, looking at a rat on their shoulder
Dr Donna Kean with Jo, one of the rats being trained for search and rescue © APOPO

What happens when they find someone?

They need to trigger a switch, which makes a noise. Currently, we put them in a vest that has a little ball on its collar, containing a microswitch. The rats are trained to pull the ball when they find someone, which triggers the microswitch and lets out a beep.

Pulling the ball isn’t a natural behaviour for them, but they can be trained in a process we call shaping. We start by putting the vest with the ball on them. The rats are naturally quite curious, so when they have the ball hanging there, you can see they’re kind of like, ‘What is this?’

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In the beginning, we’re just reinforcing them for touching the ball at all. Then, as is standard for shaping, you would stop reinforcing for just touching so they realise, ‘Oh, I’m not getting reinforced any more’. Then they’ll try harder [to get the reward]. That typically leads them to pull on the ball, and we have to really quickly reward them, so they know that is the target behaviour. Then, in a similar way, we can shape up until they’re pulling it for two to three seconds, so it’s a really strong signal to us.

Of course, in the field we won't be able to see the rats, or hear them. So, we’re working with a group of engineers to develop a multi-function backpack that will be linked up to our computer, so we can be notified when the rats pull the ball. We’ll be able to know exactly where they are, because the backpacks should have a location transmitter, as well.

How can they tell the difference between those who are alive and those who aren’t?

We’ve talked about this a lot, because we will only do the training with live people and don't know how they'll react to dead bodies until they're in a real scenario. However, dog trainers have told us that the odour profile of a person that's alive, compared to a person that's dead, is very different. Dogs can tell the difference between a living and deceased person from around three to four hours after death.

We thought that maybe we’d have to train the rats using some sort of smell that we might be able to get our hands on – it’s hard to know what to call it, but would we need the smell of death, basically.

But the dog trainers have told us we don't have to do that, because the odour change between living and dead people is so different, it's not a problem.

A rat wearing a cream vest, navigating a terrain where there are tyres, pipes and other debris
During their training, the rats wear a vest that has a microswitch inside a ball that they have been taught to pull when they find a victim © APOPO

When will these rats be out in the field?

We just started training in August 2021, and we still have to run training trials outside the research environment. We’re working with a search and rescue group called GEA, who are based in Turkey, a country prone to earthquakes. We’re hoping that by next year we’ll be able to take the rats to Turkey for trials there, but in terms of going to real disaster sites, real collapsed buildings... it’s very, very difficult to tell.

APOPO’s landmine research started in 1998, and its first operational trials ran in 2003 and 2004. Our tuberculosis detection research began in 2003, and the rats began operating in 2007. For these projects it costs, on average, around €6,000 [roughly £5,175] to fully train one rat so they’re ready for operations.

We’re currently training seven for search and rescue, although they’ll have to take turns using the one backpack!

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Amy ArthurEditorial Assistant, BBC Science Focus

Amy is the Editorial Assistant at BBC Science Focus. Her BA degree specialised in science publishing and she has been working as a journalist since graduating in 2018. In 2020, Amy was named Editorial Assistant of the Year by the British Society of Magazine Editors. She looks after all things books, culture and media. Her interests range from natural history and wildlife, to women in STEM and accessibility tech.