Instant Genius - How we define intelligent life

Episode Date: August 6, 2026

What does it mean to be a living organism? What are the driving forces that motivate our thoughts and actions? Are we all simply acting the way we do thanks to the instructions built into our genes and our automatic responses to the environments we live in? In this episode we’re joined by researcher, broadcaster and author Melanie Challenger to talk about her latest book, Alive: The Hidden Intelligence of the Living World. She talks us through her ideas about how intelligence emerges from living organisms, explores the connection between the bodies and mind, and investigates the possibility of AI developing genuine intelligence. Take your curiosity further with a subscription to BBC Science Focus magazine. Every issue is packed with fascinating insights into the science behind everyday life, the latest breakthroughs and expert analysis, delivered straight to your door. Plus, save an extra £5 when you subscribe using the code SF5OFF, (minimum spend £20, see full terms and conditions on our website). https://www.ourmediashop.com/bbc-science-focus-magazine-pod30 Learn more about your ad choices. Visit podcastchoices.com/adchoices

This episode is brought to you by Accenture. When your advertising operations fall out of sync, everything else follows. Spotify and Accenture are working together to reinvent the rhythm of ad sales, using automation, analytics, and smarter workflows to simplify campaign delivery and access better data across the business. The result? Less time spent on operations, more time connecting brands with the moments and fandoms that matter most. Learn more at Accenture.com slash Spotify.

Hello and welcome to Instant Genius, a bite-sized masterclass in podcast form. Every Monday and Friday, you'll hear world-leading scientists and experts talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor at BBC Science Focus. What does it mean to be a living organism? What are the driving forces that motivate our thoughts and actions? And are we simply acting the way we do thanks to the instructions built into our genes and our automatic responses to the environment? we live in. In this episode, we're joined by researcher, broadcaster and author Melanie Challenger to talk about her latest book, Alive, the Hidden Intelligence of the Living World. She talks

us through her ideas about how intelligence emerges from living organisms, explores the connection between the body and mind, and investigates the possibility of AI developing genuine intelligence. Welcome to the podcast. Thanks so much for joining us. Oh, it's a pleasure to be here. Oh, it's great to have you. So today we're talking about your latest book, Alive, the Hidden Intelligence of the Living World. So we're taking on some pretty huge fundamental questions here. So like what does it mean to be alive? What do we mean by intelligent action, etc? So I think the best place to start then is by asking you, how did you begin approaching this question? Yes, what kind of madness overtook me? So I'm an amateur naturalist. I spend a lot of time in the living world and observing other animals, other species. And I was always curious about, you know, really, really what it is that makes an organism, like a life form different to everything else that's around us. And that was really the starting place. It was just a kind of curiosity. And then it became a sort of stubborn curiosity. And then it became a full inquiry.

And the book is really the results of that. So some of the approaches that you look at are from various philosophers and scientists who have tackled this question over the years. And the book kicks off with a quote from Aristotle. So I thought that's interesting. What was it about his ideas that you were particularly drawn to? Yeah, so Aristotle, I've been reading on and off for maybe 20 years. You know, Aristotle was in many ways our first systematic biologist. And he had a wide range of extraordinary different kinds of ideas, some that have not sort of held through time and others that have proven absolutely right. And his insight into biology, he had this idea of psyche, or in the Greek, it would be Pseuke. And this is the idea that life is particular for the fact

that it's directed towards ends. So there seems to be a purpose at work in life. And he thought his insight was that it had to come from some kind of marriage, something particular about living form, that was a marriage of the matter from which it was made, and a kind of direction, a sort of drive, like a purposeful drive that had to exist, which today we might describe as the matter and energy flow or metabolism, for example. He didn't have those insights then, but I was very curious about this two and a half thousand year old insight that he had and the kinds of modern science that we have today that might map onto that. Yeah, so obviously we're talking about life.

So when we talk about a living thing, you know, what do we mean? Can we say sort of at base, it's a system of organised, animated matter? Yeah, so if we take us just a quick step back from that, we've had so many different ideas about life through the thousands of years that people have been thinking about it. And I suppose the one thing that is very particular about life is that living beings seem to be doing things for reasons. So the plant grows towards the light,

or their roots are going towards water, or animals are seeking food, and things can be better or worse for them. And this kind of particular, as you said, action seems to be really particular to life. And so through history, we've always been trying to understand how does that happen and what's particular about life that enables that kind of action. And I guess what I was very curious about is that actually,

sort of science and philosophy have kind of spent centuries looking for that kind of purposeful intelligence, I think, in the wrong kinds of places. So they've either restricted it to sort of conscious human minds and brain chemistry or something or to the idea that it's our genes, that it's something within us that's causing this. And so really my idea, it's not just my idea, but the idea that I think is important for us to understand now is that there's something about the way, a living being actively works to preserve their body, actively works to preserve themselves. That effortful work is very particular about what it is to be alive. So is that sort of due to an innate drive for survival, essentially?

When I started really thinking about this, that's where we automatically go. And that's quite an evolutionary idea. But I think the most exciting idea for me, and the one that's actually the hardest to grasp. So there's quite a difficult chapter in the book, which is on the origins of life. And you have to kind of sit with it a bit. It isn't easy and the science isn't easy. And also it's contested. So it's important to know that we don't know for sure how life emerged.

And we have two sort of really dominant ideas. The first idea is that life must have evolved. So that would be more of the kind of survival narrative, if you like. And that would be a gene first theory. So the idea that something like gene, must have come first and set life off on its pathway. And the other idea is that it's something to do with persistence. So it's to do with being the kind of organisation, as you said earlier,

being organised in a particular kind of way, those materials and the energy flow, and this is the sort of metabolism first idea, that means that you can persist through time. And the system, if you like, can generate that persistence. And those two ideas are slightly incompetitive. competition with one another, it may be that there are a mixture of both that really got us to life. But I think that it's less necessarily a drive to survive. I think that comes a little bit later. What I think it is, is that it's an inherent organisation that leads to persistence.

That's one of the important parts of life. I don't think it's all that it is, but I think we could think about that as being the sort of first goal, if you like, without having to think about a goal. So this is not a conscious goal. This is just inherent in the organisation. of matter. So obviously nothing exists just entirely by itself. So the environment is very important in which living things are shaped. So this driving force, is it a reaction to external stimuli? Or are there other more sort of subtle processes going on alongside that? Well, again, I think if we think about this sort of minimal model of life, and that's a cell, really. So all life obviously comes from single cells, and we all have to start as single cells as well. And a single cell,

not a cell in our body, so not a cell in a multicellular organism, but a single-celled organism has certain things that are really important for life. So we've talked about that organisation, and that organisation is a way in which the kind of chemical pathways can rebuild themselves. So that leads us on to kind of having the capacity to repair your body, for example. So when we think about the difference between a living being and a machine, a machine gets broken and the parts are bent, they're going to stay bent, right? But if you get hurt, unless it's really critical, your body has the capacity to repair itself. You also have an inner and an outer state. So a life form is bounded. And that boundary, and this is really crucial,

that sort of boundary that you have that we can see in a cell is a dynamic feature. It's doing work. it's literally generating energy, it's got an electrical charge, and it's capable of controlling what comes in and what goes out again. So it can allow good things to come inside, and this is getting to a point about, you know, we're not sealed, we're not a closed system as a life when we're open, but we're able to control what's coming in and what's going out again. And that means that things can be better or worse for us, for example, and it's a very dynamic process. So I think that dynamism, that flexibility and that effort and boundedness of very particular living beings and help us to start to see why life is so unique and intelligent.

Okay, so let's take a little bit of a leap. So you mentioned they're intelligent. So intelligence, absolutely fascinating question, which you investigate in some depth. So often people would say, well, our intelligence and ability to think is ultimately due to the chemical processes that are going on. in our brains, you know, and that leads to this idea of the separation, sort of almost sort of Cartesian idea of the separation between body and mind. But this isn't something that you're on board with. I'm not, no, which isn't to say that I don't think minds are incredibly important. In fact, I think if we think about life as having that kind of intrinsic purposiveness or that

intrinsic goal-directedness, whatever you want to call it, you know, some people are more or less comfortable with the different sorts of language, but the fact that life is trying to do something that is better or worse for it, that sort of behaviour about life, that action. We can think about brains as extensions of that aspect of life that's intrinsic to life itself, rather than something different. But what has actually happened through quite a lot of history is that we've thought about what, you know, really purposeful behaviour has to be or intentional behaviour or intelligent behaviour. And we've assumed a sort of top-down model.

We've assumed that there has to be a thought first. So we're thinking about causation now. What causes it? A thought causes it. And then the action follows. And if you can't, therefore, think in that kind of way, you can't be acting in a truly intelligent way, which basically eliminates all life forms that aren't brained,

for example, as being intelligent. And actually, most living beings aren't sort of intentionally thinking in the kind of way that we are. They aren't introspecting. and so it probably gets rid of most other animals as agents as well. What happened, which was very interesting, as we started to understand the mind better and we were getting neuroscientific insights, is we started to realise that sometimes we're thinking about something

after the body has already started acting. So the sort of feeling of intentionally acting often is separated from the body doing the thing that it is useful for us to do, like picking up our cup of tea and drinking it if we're thirsty, for example. And that caused a problem for people who wanted this really strong idea that the agency and intelligence had to be caused by thought, you know, this sort of idea that this conscious intention. And the body doesn't really work like that.

It doesn't work like that for us. And what had got lost here was the whole of the rest of the body is involved in anything that we do. You know, our whole bodies are sensing. and signaling. And yes, the brain is critical, of course, with a lot of action, but there isn't some sort of mind-body dualism at play, that idea that we've held onto for so long.

There's something much more like a wholism happening. Yeah, so having said that, how about a kind of sort of sense of self, you know, the fact that we can recognize that we are sort of autonomous beings and we're separate from other beings. How does that fit into this picture? Yeah, and I thought about this an awful lot,

because you have to be very careful when you're dismantling an idea that you don't dismantle it to absurdity, you know, that you don't lose sight of the fact that human intelligence, there's obviously something remarkable at play, and our sense of self is very particular. And in fact, that strong sense of attention to self

that we have, So the ways in which we are really able to have an interior life and be very introspective can give us the sensation that we are actually a body and a mind, that we're somehow being sort of carried around by our bodies. That's not, of course, what's really happening. But we can have the sensation of that, and that's coming from the fact that human beings are highly, highly social. And our superpower is our particular kind of consciousness. That's our kind of dinosaur clause, if you like. And so that's what we've specialised in. And it does generate a kind of selfhood, an introspective, subjective selfhood that is

particular to human beings. And perhaps not exclusively humans, there will be other social mammals that will have this and perhaps some birds as well. But I think is very, very heightened in human beings. And from which different kinds of ethics might flow, you know, different duties that we might have and different experiences might flow. But does it mean that only human beings have subjectivity? That I don't think is right. So I think to be a minimal self of some kind, you have to be a body. And I also don't think our selfhood is a mental selfhood

only. It is also an embodied selfhood. So I think it's about being careful to both recognize how important our sense of self is and not to fall into the illusion. that it's purely a mental self or that it's no other living beings have some kind of minimal selfhood. This episode is brought to you by Accenture. When your advertising operations fall out of sync, everything else follows.

Spotify and Accenture are working together to reinvent the rhythm of ad sales, using automation, analytics and smarter workflows to simplify campaign delivery and access better data across the business. The result? Less time spent on operations, more time connecting brands with the moments and fandums that matter most. Learn more at Accenture.com slash Spotify. Yeah, so with this topic, people often talk about something called the theory of mind.

Yes. So first off, what is that? And, you know, what's your take on that? How does it apply under these circumstances? So theory of mind is the ability to know that you have a mind and know that others have a mind, I mean, in very, very simple terms. And there's a little bit more to it than that as well. So as is often the case, we have these sorts of scientific experiments and we get an insight into something that we're trying to make sense of in biology. And actually, there's usually two or three

or four different sorts of things that are quite closely related that are at work with the body. So another area that people look at is agent detection. So agent detection is the ability to determine or identify another agent. And what do we mean by that? Well, we mean not just whether or not someone has a mind, but whether or not they're behaving with agency, which is doing things for reasons, doing acting in this kind of quite life-like way. And those are related, but slightly different theories and their research slightly differently within the science, even though they heavily overlap. What's very interesting about human beings is that our agency detection is really sort of scattergun.

Like, we see agency all over the place. I always say that one of the funny ones is fire hydrants. You know, fire hydrants seem to have a sort of face on them. And so, you know, we think that, or a cloud that seems to move in an animal-like way, to us, we might detect an agent there. We're not the only animals that do that. So other mammals do this, particularly animals that hunt other animals. So they have to be able to detect their preference.

or animals that are in sort of competitive environments and they have to be able to determine a living being from a non-living being. Theory of mind's a little bit different because we're really trying to detect another human-like person. And so that can make us quite biased in what we're looking for. And it is quite flexible. So we tend to see more mind among those who we relate to more, for example,

all those who are in our in group, than we see in those who are in our outgroup. And it's quite a fluid thing. So it's not a perfect mind, an agency detection system. But what it shows us is how important detecting other living beings is for humans in particular, but animals more widely. Yeah. So when we're thinking about topics like this, intelligent actions, maybe reactions based on responses to external stimuli, motivations, different internal thoughts that we might be having, in essence, due to various biological processes. The question of free will always sort of raises its head here. So what are your thoughts about this? Yes, it's really interesting. When I've been talking about the book to people, I found that audiences have tended to split. So when I talk to

academic audiences, quite often people are asking me about AI, for example, and you know, how I might apply these sorts of ideas to AI and artificial intelligence. But when I talk to most general public, they're really interested in free will. What does this mean? So this is a huge topic and it's difficult to reduce it down to something simple. But I think that what I would say is what is a free action? So if we just take Will out for a minute and think about who is in? agent and how are they able to act in this kind of unique and remarkable way? Now, we've focused on

the extent to which we can really determine our action for ourselves. And through history, we've had this idea that basically the rest of the living world is kind of like a machine. So it's being pushed about by its environment and or it's running on a bit of a program that evolution has kind of written through time. And there's quite limited action. And so to a certain extent, everything is being determined by the environment or by their genes. But human beings, because we are able to have these sorts of intentional thoughts, are the only outlier here who are able to act more freely.

And yet, you know, we've spent the last kind of 20, 30 years trying to destroy that idea as well and prove that free will is an illusion. And I find those sorts of, the free will illusion idea problematic only if you think that it does have to be this mental form of agency. Actually, if you think that most agency comes from the body itself, so having the living body as a whole, Aristotle's idea of this psyche,

this special kind of purposeful living form, if you don't think it has to be, coming from thought alone, but nonetheless there's different levels of sophistication. So some organisms are capable of really kind of quite a large field of actions available to them and a lot of flexibility and dynamism. And some are quite limited, you know, like an ecoli bacteria, for example, there's not a huge amount that it can do, but still an awful lot more than a rock, for example, like dramatically more than a rock or a river. And yet much, much, much. less than a human being, but that they're still actually all coming from the same underlying

capacity to be able to act flexibly in response to kind of stimuli. I think if we re-centre the body, then we don't get into the trap of thinking free will is some kind of illusion because we haven't created that kind of separation in the first place. And nor do we expect that there's no influence from the outside world. That's not how the living form works. If you pay attention to the living form, then it's an open form. There's influence coming from inside and there's influence coming from outside. But what matters is, are you the kind of thing that can respond to events that are better or worse for you, for yourself? Are you the one that is the agent? I think that's what really is at the heart of all of this. So let's sort of sum up then with talking about

AI. You mentioned that earlier. So yeah, I wanted to talk to you about this. So obviously for the last or few decades, really, there have been huge advances in AI technology. And it's in the news every day. It's in public discourse now. So what do you think, like either currently or perhaps in the future? Can we say AI shows any signs of intelligence? Well, everything turns on definitions. And I did as much as I could within the book here, but even I, you know, found as I was writing it that I need to always keep saying, this is what I mean by intelligence, this is what I mean by purpose or, you know, and so on. So let's look a bit more concretely about what we might take intelligence to mean. And, you know, similar thing happens with life. But if we take intelligence

to mean doing something that is reasonable, that is an action that is kind of goal directed, the kind of standard ways that we think about intelligence. If we just think about that without any concern for where the goals come from, then AI is intelligent. It's got an algorithmic intelligence, of course, which is remarkable. If, however, you think to truly be intelligent, you have to also generate your own goals intrinsically, then AI isn't intelligent in that kind of way.

So there's a nice idea that was developed in terms of how the difference between a living being and a machine. So if you think about a steam engine, for example, it's behaving a little bit like a living being. Energy's going in, energy's going out, that's powering work, the work has some kind of purpose. That looks quite like what a living being looks like. But there are actually a number of different things that are quite different. But the most important one is that the goals don't belong to or derive from the machine itself. There's another agent which is us that has designed it. And that isn't the same for life forms.

The goals are intrinsic to the living being. And that has enormous consequences because in order to have that kind of intrinsic goal or that kind of, you know, if we were being more technical, that kind of imminent teleology that Aristotle was, was talking about to be that kind of living being, it looks like, as best as we can see, you need a living body. You need to have the kinds of vulnerable, complex, dynamic bodies that are doing that kind of effortful work that is very particular to life forms. And without that, I don't think you get towards the kind of intelligence that living beings have. And I don't think without that AI would ever get there either. It'll show a remarkable kind of algorithmic intelligence if we narrow what we take intelligence to mean, but it's not going to be sentient

or conscious in the way a living being is. Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus. That was Melanie Challenger. To discover more about the topics we've just discussed, check out her book, Alive, the Hidden Intelligence of the Living World. If you liked what you just heard, then please do consider subscribing to Instant Genius on your preferred podcast platform.

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