And I'm Georgie.

Animal testing is when living animals are used in scientific research to find out how effective a new medicine is, or how safe a product is for humans.

Scientists in favour of it argue that animal testing shows whether medicines are safe or dangerous for humans and has saved many lives. But animal rights campaigners say it's cruel and also ineffective because animals and humans are so different.

Under British law, medicines must be tested on two different types of animals, usually starting with rats, mice or guinea pigs. And in everyday English, the term human guinea pig can be used to mean the first people to have something tested on them. But now groups both for and against animal testing are thinking again, thanks to a recent development in the debate – AI.

In this programme, we'll be hearing how artificial intelligence could help reduce the need for scientific testing on animals.

But first, I have a question for you, Georgie. Does one commonly used medicine in particular which is harmful for animals but safe for humans? But what?

Is it… a. Antibiotics b. Aspirin or c. Paracetamol?

I guess it's aspirin.

OK Georgie, I'll reveal the answer at the end of the programme.

Christine Rowe is a science journalist who's interested in the animal testing debate.

Here she explains to BBC World Service programme TechLife some of the limitations of testing medicines on animals.

Of course, you can't necessarily predict from a mouse or a dog what's going to happen in a human. And there have been a number of cases where substances that have proven to be toxic in animals have been proven to be safe in humans and vice versa. There are also of course animal welfare limitations to animal testing. Most people, I think, if they had the choice, would want their substances to be used on as few animals or no animals as possible while still ensuring safety. Now that's been a really difficult needle to thread, but AI might help to make that more possible.

Christine says that medicines which are safe for animals might not be safe for humans.

But the opposite is also true. What's safe for humans might not be safe for animals.

Christine uses the phrase vice versa to show that the opposite of what she says is also true.

Christine also uses the idiom to thread the needle, to describe a task which requires a lot of skill and precision, especially one involving a conflict. Yes, medical animal testing may save human lives, but many people see it as cruel and distressing for the animal.

It's a difficult needle to thread.

But now the challenge of threading that needle has got a little easier because of artificial intelligence. Predicting how likely a new medicine is to harm humans involves analysing the results of thousands of experiments. And one thing AI is really good at is analysing mountains and mountains of data. Here's Christine Rowe again speaking with BBC World

Services TechLife.

So AI isn't the whole picture, of course, but it's an increasingly important part of the picture. And one reason for that is that there is a huge amount of toxicology data to wade through when it comes to determining a chemical's safety. And on top of that, there's this staggering number of chemicals being invented all of the time.

AI helps scientists wade through huge amounts of data. If you wade through something, you spend a lot of time and effort doing something boring or difficult, especially reading a lot of information.

AI can process huge amounts of data. And what's more, that amount keeps growing as new chemicals are invented. Christine uses the phrase, on top of that, meaning in addition to something.

Often this extra thing is negative. She means there's already so much data to understand and additionally there's even more to be understood about these new chemicals.

Of course, the good news is that with AI, testing on animals could one day stop. Although

Christine warns that AI is not the whole picture, it's not a complete description of something which includes all the relevant information. Nevertheless, the news is a step forward for both animal welfare and for modern medicine.

Speaking of which, what was the answer to your question, Phil? What is a commonly used medicine which is safe for humans but harmful to animals? I guessed it was aspirin.

Which was the correct answer! Right, let's recap the vocabulary we've discussed, starting with human guinea pigs, meaning the first people to have something new tested on them.

The phrase vice versa is used to indicate that the opposite of what you have just said is also true. To thread the needle describes a task which requires extreme skill and precision to do successfully. The whole picture means a complete description of something which includes all the relevant information and opinions about it. If you wade through something, you spend a lot of time and effort doing something boring or difficult, especially reading a lot of information.

And finally, the phrase on top of something means in addition to something, and that extra thing is often negative. That's all for this week. Goodbye for now!

Bye!