The Truth about Tortoises

Read on for the story of Dr Tamar Gutnick, an incredible biologist. All words in bold can be found in the glossary at the end of the story. Questions and resources can also be found after the glossary. Happy reading!

A woman is sitting on the ground. She has dark hair and is dressed in khakis ready to work outdoors.

Meet Tamar. She’s a research scientist from Israel.

Tamar loves tortoises. They might not be as big or colourful as other animals, but to her, they are fascinating.

A text box. It reads: 
What is a tortoise? 
Tortoises are part of a group of animals called reptiles. Reptiles have skin covered in scales, and lay eggs. Humans like Tamar (and you!) aren't reptiles, they're mammals. Mammals have hair and give birth to live young - other examples are dogs, bears, and even seals! Scientists don't know as much about reptiles as they do about mammals, because their bodies work in a way that is very different to human bodies. 
There is a picture of a happy-looking green and brown tortoise to the right of the text box.

Tamar likes to watch the tortoises at her local reptile centre.

All the tortoises that Tamar has met look slightly different – some are bigger, some smaller. Some have unusual patterns on their shells, or a unique mark on their skin. These traits allow Tamar to see who is who.

Two tortoises. One is small and has a red face, while the other is taller and has a large, domed shell with a yellow pattern on it.

The more she watched the tortoises, the more Tamar noticed that each one behaved differently, too. Some were always first to the food bowl, even if it meant pushing others out of the way, while some hung back. Some liked to explore all the corners of their enclosure, but others didn’t seem interested in leaving the comfort of their hutch.

Scientists like Tamar call these differences personalities. Just like you and me have our own personalities, so do tortoises and other animals! They can be bold, shy, active, or lazy – just like humans can!

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Types of Tortoise
In the wild, tortoises live in many countries around the world, from Spain, to India, to Australia. They all live in relatively warm areas, as they rely on the sun’s heat to keep them healthy, but different tortoises prefer different places. Some types of tortoises live in swamps, some in tropical forests, and others live in deserts where there is hardly any water. 
Why do you think that there aren’t any tortoises in the far north or south? 
These types of tortoises each have different names – such as the Brown Tortoise, or Red-footed Tortoise. Scientists have a special name for a type of animal: a species. The particular place in which a species lives is its habitat. Sometimes the species is even named after the habitat – one species of tortoise that lives in deserts, for example, is called the Desert Tortoise!

Because tortoises are slow-moving, scientists had always assumed that they were slow-thinking, too. They thought the animals were stupid, and even described them as being like living rocks! Tamar thought differently. She was sure that tortoises were cleverer than scientists believed.

To be able to prove that tortoises are clever, Tamar needed the help of some real-life ones which she could train and observe. Sadly, she could not reach any of the habitats of tortoises in the wild. The tortoises there would be difficult to find, and getting to them would take a lot of time and money. So, to help her with her research, Tamar turned to tortoises in zoos.

Tamar travelled to Austria to visit Timmy the tortoise and his friends, at Vienna Zoo. Timmy is a Galapagos Tortoise – the largest species of tortoise on the planet. As well as getting very large, Galapagos tortoises can be incredibly old, with some living for over 100 years in the wild. Imagine how much they must see in that 100 years!

Tamar is knelt down beside a large tortoise - Timmy. She is stroking his head with one hand, and he looks content.

Tamar wanted to test whether Timmy had a good memory. Tortoises of his species were able to live for so long – she wanted to know whether they might be able to remember any useful information that could help them to survive for all that time.

Other scientists had found that reptiles, including tortoises, were able to solve mazes and remember the location of food.

Can you help this tortoise find their way to some tasty treats?

A labyrinth-style maze, with Timmy waiting outside it and a handful of tasty beetroots waiting in the centre.

Tamar wanted to see if Timmy could remember how to complete tasks, in the same way that a mammal like a dog can learn and remember how to sit when they’re told to. So, armed with Timmy’s favourite snacks (dandelion and beetroot!) to use as rewards, Tamar set to work with his training.

The first task was simple: Tamar wanted to teach Timmy to bite a green ball on the end of a stick. She began by touching Timmy’s nose with the ball, to draw his attention to it. After the ball touched his nose, she gave him a treat.

After a while, Timmy began to bite the ball without Tamar having to touch it to his nose. From then on, she only gave treats when he bit the ball by himself, without her prompting him. Soon, he learned to bite the ball when Tamar simply held the stick out in front of him. He had mastered the first task!

A drawing of Timmy facing a blue ball on the end of a stick. He is reaching for it with his mouth.

Next, Tamar moved onto something a bit more difficult – teaching Timmy to move towards the ball when it was held up to 2 metres away. To us humans, 2 metres might not sound like a long way to travel, but for tortoises it’s quite a distance! Tortoises aren’t built for speed – their hard shells protect them from predators, so they don’t need to run away, and they mostly eat plants, which they never need to chase down.

Tamar is holding the blue ball on a stick, down to her side and away from her.

Though it took Timmy a while to learn to move towards the target (mostly because tortoises only move about 8cm every 10 minutes), he eventually mastered this task too.

Now for the hardest test of all!

Remember when Tamar taught Timmy to bite a green ball, back in the first task? She wanted to test whether Timmy had learned the colour of the ball that he should bite. So, she offered him both the green ball and a ‘distractor’ ball at the same time. The ‘distractor’ ball was exactly the same as the green one, except that it was red rather than green.

Timmy’s task was to remember which ball was the right one to bite. If Timmy bit the green ball, Tamar would know that he had remembered what colour he should bite. If not, then she would know that he had learned just to bite any ball, not his particular one.

During the task, Timmy had to walk towards the balls and then pick the right one – it combined learning to bite, learning to go to, and the new element of remembering the right colour. Tamar was careful to look away from both of the balls while Timmy was doing the task, to make sure she didn’t give him any clues about which one to bite.

Timmy remembered the correct ball! The training was a success! Tamar treated Timmy to a feast of his favourite snacks, to reward him for his hard work.

Timmy is stood in front of a clump of beetroots and some dandelions.

Over the next few weeks, Tamar repeated the task several times, often switching which side the green ball was on, and every time she did, Timmy made the right choice.

Tamar then did the training and test with 14 more tortoises – Timmy’s friends!

It was important that she repeated the training with lots of other tortoises, to make sure that her results were similar for them all. She wanted to show that they all had good memories, not just Timmy!

Two other tortoises approach two different balls on sticks. One has a red ball; the other, a yellow ball.

She did the training in the same way every time (though the colour of the ball changed for each tortoise). This made sure that the experiment was a fair test.

A text box. It reads: 
What is a fair test?
In a fair test, every part of the experiment is kept the same, except the part that is being studied. Tamar had to change the colour of the balls for each tortoise, to make sure that they were each learning their colour. 
If she had used a green ball for all of them, she wouldn’t be able to tell whether they had all remembered the colour that they were trained with, or whether they all just preferred green balls to the distractor balls! 
There is also an image of a tortoise, which is choosing between a red ball, and a yellow ball.

The other tortoises managed to memorise the tasks correctly too. This meant that Tamar knew that her results weren’t just due to chance, or to Timmy having an unusually excellent memory. She was right – tortoises have good memories!

Even more interestingly, Tamar found that tortoises learnt better when they were in a group. This might be because the tortoises can learn faster if they’ve watched another tortoise complete the task, compared with if they’ve never seen it happen. Scientists didn’t know that tortoises were able to learn from each other in this way!

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Learning in the wild.
In their wild habitats, tortoises don’t usually live in groups: they are solitary. However, they do have to share resources. 
In places like deserts, water is scarce, and so one important pool of water is often shared by many animals. Being able to learn about a source of water from another tortoise, and remember its location, could be the difference between life and death for a wild tortoise! 
A tortoise in the wild could learn the location of a water pool in a similar way to how Tamar taught Timmy. Like when a tortoise in the zoo saw Tamar teaching Timmy to travel towards the ball, a wild tortoise would see another tortoise interacting with a ‘target’ (the water), and by watching them, learn to go to it themselves. 
As well as water sources, this could help tortoises learn to identify certain foods, and remember their location. This could make a big difference to how long they are able to survive!

To test whether Timmy’s memory of the tasks lasted for a long time, Tamar came back to visit him three months later.

Timmy remembered that when the ball was presented to him, he should bite it, and that, when the ball was held out some distance away, he should travel towards it. Though he didn’t remember that he had been trained to bite a green ball specifically, he relearned which colour ball to bite quickly – much faster than he had the first time Tamar had taught him.

Tamar was so proud of Timmy – his memory was remarkable!

Even more impressively, when Tamar returned again a whole nine years later, Timmy still remembered that biting or going towards a target would get him a tasty reward. That means that Timmy’s memory had lasted for longer than some of you have been alive!

Through teaching her tasks, Tamar discovered that tortoises could remember things for a long time, and that they learnt better in groups than alone. These are signs that tortoises are clever. Learning from watching others also shows that tortoises can do a special kind of learning, called social learning.

A drawing of Timmy from face on. There is some greenery around his mouth and he is smiling.

These were two important discoveries, which she could not have found out without Timmy and the other zoo tortoises’ help. Together, Timmy and Tamar proved that tortoises were far from stupid. The truth is, that though they may be slow-moving, tortoises are likely to be a lot cleverer than anyone knew.

Learning from tortoises like Timmy may have important consequences for his relatives in the wild. Knowing how tortoises’ brains work, through experiments like Tamar’s, will help scientists look after them in the future.

There’s still lots to learn – Tamar will be requiring Timmy’s help again soon, as she continues to find out about how reptiles think.

Maybe, in the future, you could help her too!

Thank you for reading!

This story was written as part of a Masters in Science Communication project, investigating whether storytelling is an effective way to teach children about science and scientists. As a result, I would really appreciate some feedback, which you can give by answering a short survey. The survey takes less than 5 minutes to complete, and I will use the results to develop even better science stories in the future. To help, just click on the button below.

A text box. It reads:
Fair test – a test where only one thing (also known as a factor, or variable) is changed at a time. By only changing one thing at a time, the researcher can be certain that the thing changing is what has caused the results of the experiment. 
Habitat – a place where an animal lives e.g. desert
Mammal – an animal that gives birth to live young, feeds their babies milk, and has hair (sometimes called fur) on its body.
Personality – the combination of characteristics or qualities that form an individual’s distinctive character.
Reptile – an animal that lays eggs and has skin that is scaly.
Resource (in nature) – a supply of something essential for life, like food or water. 
Social learning – learning by observing the behaviour of others.
Solitary – not living in a group; preferring to be alone.
Species – a group of animals, plants, or other living things that all share common characteristics and are similar enough to exist together and form families.
Trait – a characteristic or quality that makes something different from others.
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Hungry for more? 
If you’ve loved hearing about Timmy, and what Tamar learned from teaching him to do particular tasks, have a think about these questions…
1.	Tamar was able to train two species of tortoise: Galapagos tortoises and Aldabra tortoises. But, in the wild, there are over 300 species of tortoise. Should Tamar try to repeat the training on some more species of tortoise? Why? Why might it be difficult for her to do this? 

2.	To keep the third task a fair test, Tamar changed the colour of the ball for each tortoise she taught, and kept all the other factors the same. These other factors could have affected the results of the experiment if they had been changed - can you think of any? What would changing these factors have resulted in?

3.	Why was Tamar able to train tortoises that lived in a zoo, but not those in the wild? What would be the problem with her trying to train some in her small university laboratory?

4.	Of the 300 tortoise species that exist, about half are endangered. Thinking about what you have learned about tortoises, what threats do you think they may face in the wild? 

5.	Before research like Tamar’s was done, scientists used to think that reptiles had simple brains and only acted on instinct, rather than with thought. Other than memory, can you think of any other mental skills reptiles might have, that we don’t yet know about?


Tamar’s research paper: Gutnick, T., Weissenbacher, A., Kuba, M. (2020). The underestimated giants: operant conditioning, visual discrimination and long-term memory in giant tortoises. Animal Cognition. 23: 159-167.

More information about Tamar and Timmy:

Article: Tortoises remember what you did last summer

Article: Reptiles known as ‘living rocks’ show surprising cognitive powers

Article: A tortoise never forgets.

More information about Fair Tests:

BBC Bitesize: How do you make sure a test is fair?

More information about Galapagos Tortoises (Timmy’s species!):

Galapagos Conservation Trust


The research was produced not just by Tamar Gutnick, but also by the other members of her research team: Anton Weissenbacher and Michael Kuba. They too deserve credit for this discovery – good science is often best done as a team.  

This story would not be nearly so good without its illustrations by the wonderful Daisy Harrison, and the advice and support of Dr. Nicola Hemmings. Thank you!

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