Forensics

Danilo Russo first noticed something rather odd about bats when out in the field, catching them for his PhD thesis. Picking them out of the net, he noticed that many would vibrate and hum. In fact, the sound was uncannily like a wasp or hornet. Could they, he wondered, be doing it to fool a predator into thinking they’re a stinging insect and to steer clear? Now, 20 years later, he’s followed up on his hunch and provoked quite a buzz by showing these bats do indeed do just that, as Harry Lewis has been hearing…

Danilo - Among animals we have a lot of situations where unarmed animals imitate dangerous or unpalatable species mimicking their colours or morphology or whatever, so that they can actually deter predators for the time needed to escape. In this particular case, these bats actually use sound rather than colour, which is very unusual. And you know, it's the very first time that this kind of strategy is found in mammals. We have no other situations where mammals mimic insects.

Harry - We've got a clip. So let's, um, let's take a listen. How did you figure out that this sound could be used to scare away predators?

Danilo - What we did first was to record bats, then we recorded insects which might be potentially mimicked. And we recorded four species: buff-tailed bumblebees, European Hornets, domestic bees and European paper Wass. All these guys actually may be encountered by owls for example, when owls explore cavities, where they roost in caves or whatever, because the main predators of these guys are birds of prey, especially owls. So the idea is that owls can sometimes experience the stinging defense of these insects and the outcome was that especially if you take out of your data set the variables that cannot be heard by the owls. These kind of buzzes are especially convincing, for owls because they don't detect the higher frequency. They just sound like insects to them.

Harry - Right. So it doesn't need to be a precise mimicry. It just needs to fool the owl. It just needs to sit within the owls hearing threshold.

Danilo - That's exactly the point. Yeah. You know, I was just surprised to see that owls actually have a sensitivity to higher frequencies, which is quite similar to that of the human ear. And this is why when these bats buzz, they really sound like wasps or hornets to us as well. I mean it's quite convincing.

Harry - Okay. So here is a comparison. This is the sound a domestic bee makes. And this is that bat mimicry again. I mean, it still strikes me as strange though that this sound alone is capable of scaring your birds of prey.

Danilo - Owls that have not been raised in captivity, that have been out there for say at least one year or more, they are especially reactive. So the idea is that they may have encountered buzzing insects and know that they're dangerous. While if you use naive owls, they're sort of less reactive.

Harry - Why is it then that this mimicry is so hard to find in other mammals? Why is it that the bat is the only specialist?

Danilo - I don't think that bats are the only specialists. We know that there are some rodents, for example, that buzz when disturbed, and that's gonna be our next step, because I'm pretty convinced that this kind of mechanism may actually be more widespread than thought.

Harry - This is like opening the scientific curiosity door. There's a lot of research that could be built upon your findings, that stem all the way back to your PhD.

Danilo - Yeah, I really think so. I really think so. It's quite exciting. And you know what a nice part of the story is that I actually thought about that first time over 20 years ago. And it stayed there in corner of my mind, waiting for the right people to start doing the experiments.

Cambridge University has a famous Museum of Zoology. And like all museums, it’s got a lot of artefacts that have never been properly catalogued, or were packed away years ago and forgotten. And recently, going through some of these “lost finds”, assistant director Jack Ashby came across an amazing piece of history: the collection of platypuses, echidnas and possums - dating back to the 1880s - that convinced the world that these animals were real. Previously people couldn’t believe they weren’t some sort of hoax: “how can a mammal lay eggs?” they protested! The specimens were assembled by William Caldwell who was paid to travel to Australia, from Cambridge, just to answer this question. Those were the days weren’t they! Robert Spencer went to the Museum of Zoology to see these decisive specimens, and find out exactly what Cambridge University, Australian aboriginal people, and the French revolution had to do with it…

Jack - So the smallest ones we've got here are two little tiny echidnas. They're like eight millimeters long and they're they're pink. These are from within an egg. There's a tiny bit of yolk sac there, I think. And so these are the youngest ones in front of us. And at the other end of the scale, we've got a puggle here, which is a baby echidna - that's about 12 centimeters long. It's got no spines. Echnidnas, for those who don't know, are termite-eating, ant-eating egg-laying mammals that are covered in really thick porcupine-like spines. But once they start growing those spines, then they don't stay in the pouch very often. And so this is a pouch young, got a long little snout and really big digging claws for smashing into termite nests.

Robert - I mean, they really do look rather strange don't they?

Jack - Well, that is how they're typically described. So, people describe these animals as strange, as inferior and bizarre and kind of lower life forms.

Robert - Do you think we still have that outlook on them or have they moved from lower life forms to merely curiosities in the modern public eye?

Jack - I think there's probably both. It is quite common surprisingly to see these animals described as primitive, which doesn't make any evolutionary sense - no living species can be considered primitive. Everything is equally evolved.

Robert - What was the European, at least, reaction when these animals were first described?

Jack - So platapus' and echidnas were first described by Europeans in the 1790s and straight away, there was some suggestion that maybe they lay eggs, but that's not something that mamals were supposed to do. So people were very suspicious of it and it took them those 85 years until their actual specimens that they would accept were uncovered.

Robert - Why did it take so long?

Jack - That's a good question. I think a big part of it was that people weren't really willing to accept that mammals could lay eggs, but another defining feature of mammals is that they produce milk. And there was a big question about whether platapus' and echidnas could do that, because they don't have any nipples. This created a big problem because it meant that the rules of how the tree of life had been arranged, didn't work. One scientist on the very much "they do not lay eggs" side of the argument was Richard Owen. He was the first superintendent of the Natural History Museum in London, described countless fossil species, he coined the term dinosaur. But he was also kind of on the wrong side of the Darwinian evolution debate, he was fighting against evolution. But he was the one that proved that they do produce milk. And what he did was get a load of specimens sent over. He looked under the skin and found these glands and squeezed them and tasted the milk that came out, the oily substance that came out

Robert - Do we know what his reaction was?

Jack - He said he couldn't perceive anything other than the taste of the preserving spirits. It just tasted of alcohol.

Robert - So he had specimens, he was examining them, he'd shown that this furred animal was producing milk and still said that no, it couldn't have been laying eggs.

Jack - Yeah, it's bizarre. The problem was basically if you've got an animal that has some mammal-like features and some reptile-like features, then the suggestion is that one group can turn into another one, which isn't quite how we see it today. But basically means that yes, evolution is real. And there's a political side to it too. Owen was a staunch, conservative high-end society and he wanted things to stay that way, I think. The concept that if animals can change over time, should I say, then humans can change over time too. And especially in the decades after the French revolution.

Robert - And science did draw those kinds of parallels at that time?

Jack - Yes. Well, there's a very, very close alignment between who was fighting on the liberal side of political arguments and who was fighting those "animals change" arguments.

Robert - What happened? We're now certain that echidnas and platapus' do lay eggs.

Jack - What happened is, as soon as those species were encountered by Europeans, people were sent to Australia to try and solve the mystery. And indeed settlers in Australia or Aboriginal Australians, were asked whether they could tell them whether they laid eggs. And what you might consider evidence was gathered at the time, like people were saying, "I found this platapus with eggs" or indigenous people were saying, yes, they lay eggs. But that information was ignored or dismissed. So the University of Cambridge and the Royal Society and the UK government sent this recent Cambridge graduate called William Caldwell to Australia with this specific question in mind. They gave quite a lot of money and he employed a massive army of Aboriginal Australians to collect platapus' and echidnas for him. He was trying to find the smoking gun of specimens with an egg in the pouch or an egg in the nest, and that's exactly what he did in August, 1884. He sent a telegram across the oceans to the British society of the advancement of science and shared the news. And given, I think, in that kind of Caldwell was one of their own, they were willing to accept that.

Under the site of the new Croft Gardens accomodation in Cambridge lay one of the best archaeological finds in the UK for a long time. Katie Haworth, from the University of Cambridge, explained how she is studying these remains to Julia Ravey...

News Reel - Addressing the United Nations today, president Zelensky accused Moscow of war crimes. Some breaking news, the UN human rights office has issued a damning statement describing the war in Ukraine as a horror story of violations against civilians. They have reported finding hundreds of bodies and mass graves in the town of Bucha. Russia denies doing this, but there's skepticism from a watching world.

Julia - War crimes. Violations of international law, such as the targeted killing of civilians, which could lead to the prosecution of those responsible. Proving a crime has been committed in these circumstances is a long process and can be incredibly tough. But science can provide vital evidence, specifically archaeology and anthropology. These are fields often associated with historical findings or learning about ancient life. But when applied within forensics, they can help solve crime. Through the use of context, evidence and examination, both disciplines can tell us about who individuals are and potentially help us understand what happened to them. Even if they lived a very long time ago. I'm standing right now in front of, well, pretty much a building site, to be honest. This is Croft Gardens and these are new college accommodation for Kings College in Cambridge. To look at, you wouldn't think this was a really interesting archaeological site, but last year, when this site was being cleared for these buildings, there was a cemetery found under this plot. This was a cemetery with 62 plots containing 69 bodies. And these people were thought to have lived between the fifth and sixth century. Katie Haworth from King's college, Cambridge is now studying who these people were.

Katie - I think it's really important to say that cemeteries are quite different from other kinds of archaeology because often archaeology is the remains of things that aren't intentional deposits. Whereas a cemetery is a very carefully structured space. There's a lot of decision making about how to deal with the death of a, presumably, valued community member. And I think behind all these decisions, we can start to understand something about the community as a whole and how social relationships might have played into those decisions that are made.

Julia - I think it's so interesting how you can take this static scene of a cemetery and then try and piece together what it might have been like to be alive during that time within this community.

Katie - It's so fascinating. And it's drawing together so many strands of evidence -  analysing the bones, analysing the spatial layout of the cemetery, the objects that are there, unpicking the DNA - which should tell us more about their health on one side, but also the relatedness of our population.

Julia - Can this finding of the cemetery - of the bodies themselves - tell us anything about how these individuals may have died?

Katie - We don't have a huge amount of evidence to say how people died. Often we're working with just bones, but we can pull out a good amount of information from that. One of the studies that's being looked at is an examination of evidence for plague. But I think for most people, it would've been quite a difficult life. People would've suffered a great deal with periods of stress in life. In many cases that is probably what's resulted in death, but we're just not seeing it represented in the bones.

Once evidence at the scene has been documented, the body undergoes examination to try to understand who this person was and what happened to them. This involves the work of forensic anthropologists, who use bones and other human remains to tell us more about the individual. Corinne Duhig, an osteoarcheologist at the University of Cambridge, explains to Julia Ravey what processes are undertaken to answer these questions...

Corinne - We start small scale and we are looking to build up a profile of that person, looking at their ethnicity, family relatedness sex, age, stature, and body form. And when we've done that, we've created in a sense, a little description of that person

Julia - And how does this play into forensics? So for example, how can we identify potentially how someone died from the remains that we find?

Corinne - As you can probably guess, it's very uncommon to find a clear cut answer just from the remains themselves. The smoking gun or the smoking bullet; the weapon embedded in the body or the cutoff head or whatever it is; is pretty rare. But what we can do is we can say things like -  I'm looking at this man's spine and he has one crushed vertebra that has not healed, so it's been done relatively recently. Now this looks a bit odd. What can you tell me about this man's story until the time when he disappears for us to work out; was this just an accident he had in the country where he'd moved to or was it something connected with his actual moment of death? So we start binding our information in with what the police have, the coroners have - absolutely combined work.

Tube Tannoy - The next station is South Kensignton. Exit for the museums and Royal Albert Hall...

Julia - Bones are a key component in informing identity. To see this evidence firsthand, I went to the Natural History Museum in London, which holds a selection of human bone replicas. Principle curator in anthropology, Heather Bonney, talked me through some of the characteristics bones can reveal.

Heather - This is a cast of a neonatal skeleton. And you can see that the bones are all really, really tiny. And then as the child ages, these bones begin to fuse and they obviously grow in size. And we can use either measurements of some of these long bones or the stages of the fusion to determine how old that individual was. And we can continue using development changes up until around the age of 30. Some of the very last bones fuse, fuse in your late twenties, but then we start looking at degenerative changes.

Julia - Well, I'm 29 now, I'm 30 in a few months. You're looking for degenerative changes.

Heather - Degenerative changes. And the issue with these are that they're far more impacted by your day-to-day life. This is a cast of a pelvic bone from a 65 year old male, who you can see the changes related to arthritis in the hip here. So what happens is that the cartilage within the joint erodes away and you essentially have bone rubbing on bone, which causes stress on that joint, and you can see the extra bone growth within there. It's not all nice and smooth, it's quite rough and nobbly.

Julia - Can we identify from remains potentially how they died?

Heather - Sure. So I've got some examples here.

Julia - Wow. That skull doesn't look too healthy.

Heather - No, this is the cast of a skull of someone who'd sustained quite a massive head injury during life that had completely penetrated the skull. But you can see how healed it is, it's all completely smooth and rounded at the edges. And the bone has grown over the hole that went through and they survived that. And they've lived for some time afterwards enough so that there's no reaction going on anymore. There's no bone gross happening. That's completely healed up. And then we have an example of a cast of a shotgun injury that did kill this individual. And you can see the very sharp edges and you've even got the outline of some of the shotgun pellets, where you've got these round circular depressions at the edges.

Julia - Whilst leaving the museum, one particular image of a human jaw bone caught my eye. And Heather explained the gruesome story it told.

Heather - This is a prehistoric individual who we suspect was decapitated. And you can see these cut marks here on the back of the mandible. If you're decapitating somebody from the back, you can't see where they're chin is and so it often leaves these cut marks.

Julia - It is a really blunt clear cut.

Heather - This took a few attempts here.

Julia - Oh my goodness. I feel like when you see something like that, you are almost transported back in time. I can like feel that in my jaw, when you said that took a few times and you can see the impact there on that individual.

Heather - Yeah, very much so it's pretty violent.

A key tool in forensic anthropology is analyzing DNA, our genetic fingerprint, to get a closer match on identifying an individual. This tool has also been useful in solving more ancient mysteries as Corinne Duhig from Cambridge university explains to Julia Ravey...

Corinne - In Egypt, we have had the question of the royal mummies. Particularly ones that were found in caches, where they had been robbed and then taken by priests and rewrapped and reburied and put in what were thought to be secure places. Now, it was always thought that we knew who they were because the priests doing the re-wrapping had written the names on the wrappings. In about 1990, lots of the royal mummies, though not all, were x-rayed again and had DNA samples taken. And from this, various family trees were produced. And it was quite helpful because there was one mummy of a Pharaoh and we all looked at him and said, "that can't be a Pharaoh because he's not buried in the right body position." And this was useful because the DNA actually showed yes, he's part of the Royal family, but he's not deep within the Royal family. He is actually somebody else misnamed.

Identifying individuals is also crucial in events like natural disasters or instances of war. And as Nick mentioned, this could also be important for implicating crime. Sue Black, forensic anthropologist at Lancaster University, has worked on some of these tragic cases and explained to Julia Ravey how forensics is used in these circumstances...

Sue - So if we take the tsunami, for example, so the boxing day tsunami that happened in 2004. We knew that in Thailand, there were at least five and a half thousand, if not more, bodies that were recovered and taken to the centre where we were going to do the examinations. All the countries around the world would say, we've had a missing person report. You will take all of the antimortem information. So you'll have a DNA sample from parents or children. You might have fingerprints of the individual. If you think about where your fingerprints are in your house; they're all over your screen, they're all over your phone. Your DNA we'll find in your bedroom, we'll find it in your laundry. Is there any information in your medical records that might be important? You might have broken your arm six weeks ago or six months ago or 10 years ago. And so we create this huge picture of the missing person, the antimortem missing person. And then we go to the postmortem and we collect as much information as we can. DNA samples, fingerprints, how tall were they? How heavy were they? Did they have tatoos? And then we bring them together in a matching centre and you'll get a match that says it's most likely.

Julia - And science is obviously at the heart of this process, but it seems to be really quite an emotional job. So have there been any particular moments during your career which have been emotionally very challenging?

Sue - We try not to be involved in the emotion because as a scientist, your job is to be unbiased. But we're not cold, but we know that we have to have that level of detachment. Sometimes it's almost impossible to have that. And I think back to one case in Kosovo in particular, which was a gentleman whose entire family was caught in a rocket propel grenade. And he said to us, "I'm concerned that they're all buried in this one hole together," and that his God could not find them unless they all had their own grave with their own name. And so we laid out the number of sheets of individuals that we believed were present in the mortuary and a spare one, because we knew we wouldn't separate all of the bits. And as we went through each part, we were able to say, that's a baby, that's a child of about four, that's an adult, but it's an elderly adult. And so we were able to then put a little bit on each sheet. We have that moral pressure on us. And it is that tension sometimes that is really challenging, but we still try not to get involved in the emotion.

Julia - A really tragic instance of a loss of a lot of life is war. Have these findings been used in implicating war crimes in the past?

Sue - Oh, absolutely. So, I mean, you just need to go back to Kosovo. So Miloservic, Mladic, Karadzic, forensic anthropology was at the core of a lot of the evidence against them. Because what you have in a war crime situation is you have somebody who says they saw something, you bring the forensic teams into that scene, but you don't tell them all the information because they need to recover what they find, they need their independent opinion. And if the evidence and the opinion of the experts matches with what the witnesses are saying happened, and there's no prior knowledge crossed between the two teams, then you have a really strong set of evidence to take into the courtroom.

Julia - And we're seeing a really tough situation at the minute in Ukraine with this information. And I've seen that teams of anthropologists and archeologists are going over. Is that the aim of this? Is it for identification purposes and then down the line to try and corroborate others' stories about what's actually been going on on the ground?

Sue - So the identification and the evidence of crime go hand in hand. It's much more appropriate when you can say, this is Joe Blogs, who was 33 when he died. Because then you can look into the history of that individual. Did they have any paramilitary connections or not? Because it'll be the definition of was this a legitimate combat death, or was this death of a civilian? If the individual is a five year old child, then that answer is very obvious. The evidence is saying, who was killed here? Are they all men of a fighting age? No there's wome, and there's elderly, and there's children. This is a war crime is the conclusion that you may come to based on the evidence, but the identity of the people is inextricably linked to the charge that you're going to place on that particular site.

Julia - Identity is at the heart of understanding who a person was. And when placed within the context of the scene in which they were found, what happened to them. This is important in reuniting loved ones with those they have lost, but also in the wider implications of understanding the circumstances of their death and trying to ensure these events are never repeated. The claims of war crimes in Ukraine are ever growing as the conflict continues on and through using archeology and anthropology, hopefully one day, those claims can be brought to justice