Fabulous Fabrics and Nifty Knitting

From 27000-year-old thread to weaving with human cells, we're unpicking the science of textiles
18 January 2021
Presented by Chris Smith, Eva Higginbotham
Production by Eva Higginbotham.


Yarn on shelf


This week, looking for a new hobby? We’re exploring the science of handicrafts, including why knitting boosts wellbeing, the first textiles from 27,000 years ago, and the project that’s knitting human tissue to make replacement blood vessels. Plus, in the news, novel insights into who gets severe COVID and what might cause Long COVID, the WHO arrive in China to probe for the origins of the pandemic, and the snakes that tie themselves in knots to climb trees...

In this episode

An artist's interpretation of a coronavirus particle.

01:05 - Immune changes reflect severity of COVID infection

New research aims to predict who will get severe COVID from how their immune system responds from the start

Immune changes reflect severity of COVID infection
Ken Smith, University of Cambridge

The coronavirus pandemic continues to paralyse countries across the world. The UK has nearly double the number of patients in hospital now compared with last March when the outbreak began, and last week saw over 1500 people die on a single day. The bizarre thing about COVID-19 is that some people get off scot free, while others have a very rough time and symptoms that persist for months after the virus has been cleared from the body. But could clues to why this happens - and to whom - be present in the way the immune system responds to the virus right at the start of the infection? Cambridge University immunologist Ken Smith thinks so. He and his colleagues have collected multiple samples from hundreds of COVID patients over the days to weeks as their individual disease syndromes progressed. And in those samples is a clear pattern that shows a very different immune response in people destined to get severe COVID compared with people who don’t. There are also hints in there of what “long covid” might be, as he told Chris Smith...

Ken - We recruited over 200 patients, ranging from people with very severe disease on intensive care, all the way through to healthcare workers who were screened positive for the virus while feeling perfectly well. And then we followed those patients up and kept taking samples at intervals out two to three months, to understand the evolution of the disease.

Chris - When you say samples, blood samples?

Ken - Yes. Patients who entered the studies all had to have a positive swab. So we had viral information at the beginning of the study, and then some patients we gathered that later on, but blood samples were the main thing that we studied.

Chris - What were you asking of those blood samples? What were you actually looking for and measuring?

Ken - The two key things we wanted to explore were how effective was the immune response, and the nature and the extent of inflammation that was coinciding with those immune changes.

Chris - Given that we've got this really broad spectrum of disease symptoms, the syndrome goes from people with no symptoms whatsoever to people who pass away from the infection. Do any of those symptom patterns map onto changes that you see in these blood samples in the patients you studied?

Ken - Yes. So we saw two key changes. The first thing was that in patients who had very mild disease or indeed no symptoms of disease at all, they had evidence of a more robust, very early immune response. In contrast, in people who ended up doing badly, even in the very first blood sample we took, which was often within a day or so of them first developing symptoms, there was already evidence of profound abnormalities in immune cell number, across a range of different cell types, and evidence of systemic inflammation. So they already had an abnormally inflammatory immune response, even at the very first blood test. So it could be [that] people are predisposed from the outset. And the implications of that is if we're going to act early to prevent this inflammation, we have to have very early. We can't wait and watch.

Chris - Are those changes present sufficiently early that if someone had their diagnosis in the community, they could be identified as at high risk or at low risk, right at the get-go? So that the intervention could be different. It could be tailored and therefore, potentially, the outcome for them could be changed.

Ken - That's what we have to aim for. What we don't know is when this inflammation starts. We know that it starts pretty well at the time symptoms develop. It may be that in fact, the abnormally inflammatory immune response is present even before symptoms develop. And how you detect such people is really of course difficult because they don't know they've got the infection yet.

Chris - And when people get better, do these changes all revert back to normal? Or are there persistent changes which could account for some of the longer term symptoms people complain of when they've had coronavirus?

Ken - I've only looked out to three months at this stage of our cohort. We are still following. So we will have six months data very soon. But at three months, the interesting thing is that there's still evidence of marked immune abnormalities in many patients. And those immune abnormalities can be seen even in patients who've got better and gone home. So those things could underpin some of the clinical features of long Covid. And so what's going to be important for us to do is to follow patients up at later time points to see if they in fact do resolve beyond three months, or if they represent an ongoing problem for patients.

Chris - And what shape do those abnormalities take in the wake of having had the infection previously?

Ken - So the immune cell abnormalities are largely a reduction in number of a lot of the different white cells in the blood, so-called lymphocytes, many different lymphocyte classes are profoundly reduced. And some of those cell numbers remain very low after three months, which could be consistent with, or could lead to an inability of good immune responsiveness to, for example, other infections or secondary infections. And that's why we have to see if those recover.

a scientist at a lab bench with samples

06:23 - Asymptomatic testing for COVID

Studying COVID transmission by testing asymptomatic students at Cambridge University

Asymptomatic testing for COVID
Ben Warne, University of Cambridge

Testing is critical for controlling the virus, but if someone doesn’t have any symptoms, which happens about half the time, they won’t get a test and their infection will be missed. This is a big problem, because even though they have no symptoms, these people can still spread the infection. One strategy is just to test everyone regularly, but we have only a limited number of tests we can reasonably carry out. One tactic, though, that might solve this, is to “pool” or mix together the swab samples from everyone in a household and do one test on all of them. A negative result means everyone in that batch is in the clear. And if you get a positive result, you then only need to test a much smaller group of samples to find out who the infected people really are. This is what they’ve been doing at the University of Cambridge over the last term and now they’ve released a report on how well it can work. Phil Sansom heard from one of the doctors behind it, Ben Warne....

Ben - Between 2 to 10 students, depending on the size of the pool, would each take a swab and they put it into the same test tube. And that test tube would then go to the laboratory. And we would be able to test all of those students in one go. And that way we were able to test up to 10,000 students with 2000 tests.

Phil - How long were you testing students for then? Was it the whole term?

Ben - So over nine weeks in total. 1-2 people in each household at the start of term. And then by the end, we were able to test everybody in that household on a weekly basis.

Phil - Did it pay off?

Ben - We think that it did. Testing capacity is one of the really key limiting things in terms of COVID-19, the way that it's managed in the UK and indeed internationally. And if you can test five people with one test, that's a really, really, really efficient use of your testing capacity that we were keen to try and optimise.

Phil - We also heard on the show that some students were so keen to share things, they actually shared a swab.

Ben - You hear stories where people took it to the next level, and they're actually sharing swabs. Err, not the best way of getting tested, possibly an okay way of sharing COVID.

Phil - How many asymptomatic cases did you end up finding?

Ben - Over the course of the programme, we found well over 200 cases of asymptomatic COVID-19 infection. And the reason that I sort of hesitate slightly when mentioning that is because they were asymptomatic at the time that they took their swab. We have gone back and interviewed those students again, to see if they went on to develop symptoms. And actually a significant proportion of them did. So they'd been pre-symptomatic when they had the swab, they went on to develop symptoms afterwards.

Phil - Do you have an idea of how many of the COVID cases you found were asymptomatic?

Ben - Yeah. And it's a question that we're all trying to answer. And if you look at the published studies, I remember reading the first published study from Wuhan and they equated levels of less than 1%. And then there are some more recent studies that equate levels above 90%. There are a number of studies that sort of publish a range in between. It's probably different depending on which population you're looking at. So it's going to be different if you're looking at university students versus school-aged children and - although I haven't got a number to quote to you today, we are working hard to try and find one. I think it is a really, really important question to answer.

Phil - So once you had this knowledge, did it help you tracking down the infections going on spreading through the university?

Ben - Absolutely. So in the first couple of weeks we identified a number of transmission events among people in the same household or the same block of accommodation. It spread between people who share the same course in some cases, or in some cases the same social activities. I'll give you one specific example though. In the second week of term, we saw quite a big outbreak in one of our blocks of college accommodation. And if you look at the genetic code, this virus is only found in weeks two and three of term. After that the accommodation block was locked down, it was closed. And we don't see that virus again later in the term. Although we don't necessarily understand all of the way that the virus is transmitted, we do know that some of the interventions we're putting in place do help to control it.

Phil - Ben, what about this programme really worked and has made you go, "Yes. I think schools, universities should be doing this when they reopen"?

Ben - The problem with testing is that there's no one size fits all solution to all scenarios. What we have here though is a programme which first of all, really utilises tests to the maximum capacity that we have available to us by using pooling. Secondly, we've, it's been a really successful programme in terms of students participating. So it was an entirely voluntary programme, but more than 80% percent of the students that were eligible were taking part. It's through this combination of using efficient testing and getting lots and lots of people engaged to participate in it that has the real public health benefit.

Phil - Should families be getting tests that are then pooled together to save time so that there can be more tests?

Ben - Yeah, it's a really, really good question. And I think that certainly there is an option of using pooled testing for households. There are two things that are really important. The first is that they all live together, which means that in the event of a positive test, that's the household of people that you isolate together. And secondly, it makes the logistics a bit easier. The practicalities of getting the test delivered to a household of people is straightforward. It's just their postal address.

The logo of the World Health Organisation.

12:25 - The WHO in China

The WHO arrive in China to investigate the origins of the coronavirus pandemic

The WHO in China
Maureen Miller, Columbia Public Heath

A team of World Health Organisation officials have this week arrived in Wuhan to begin their investigation into the origin of the coronavirus. More than a year after it was first reported, its source is still disputed; many accept that while Wuhan seemed to host the first major outbreak, it may not be the site where the virus first entered humans. China, having just reported its first COVID death in eight months, has suggested it may have originated outside the country; while others remain suspicious of China itself, especially after they appeared to be blocking or delaying the WHO entry into the country. But now they’re in, how will they approach this? Maureen Miller is an infectious disease epidemiologist who spoke with Chris Smith...

Maureen - Hi, thank you for having me. First of all, they arrived on Thursday and they're going to be in quarantine for two weeks. So during the time that they're in quarantine, the hope is that they will have the ability to communicate directly with the scientists who have done research because make no mistake, China has not been idle and the government has funded an incredible amount of research. The only thing that was shared from all of this research, however, was the genetic sequence of SARS-COV-2, the virus that causes COVID-19 and because of that, we have been able to develop a vaccine with record speed.

Chris - Well, yes, quite and many people argue that in fact, China must have known quite a lot about coronavirus and known it existed for quite some time to produce that genome code. Because they handed that to the world health organisation right at the beginning of January, but you know, I've worked on viruses like coronaviruses for a long time and I know that you don't just go from an outbreak to identifying the cause to having the genome of that virus in a matter of days or weeks, it takes a long time to pull all those strands together. So China maybe perhaps sat on this for longer than people realise.

Maureen - I think there are two issues. One is the spillover of the virus into a human population. When did that happen? I don't think China can be held responsible for that. It clearly happened in China. We don't know when, we don't know where - it's unlikely to have happened in Wuhan, because most scientists agree that it is a bat virus that then went through another animal and infected human beings.

Chris - So if you're saying that China did share the genome code, but they haven't been terribly helpful since in fact they have in fact delayed the arrival of the WHO into their country, what difference would it make having people on the ground in Wuhan now, compared to just asking the Chinese, can you share your learning so far with us?

Maureen - The team that is there of international scientists, most of them have previously worked with Chinese scientists. So they're well known, they have long standing relationships. The Chinese government has blocked Chinese scientists from communicating with the outside world. Once they're face-to-face even virtually through the internet while they’re there, when they have the ability to communicate that information gets shared. It's clearly monitored and China has a lot of explaining to do why they didn't allow this to happen earlier.

Chris - Yes, indeed but if you're concerned that people can't speak out from within China is that same fear not going to apply inside China? Because there will be, for want of a better phrase, heavies sitting in on these meetings, won’t there who are going to report straight back what's being said, who's saying it, and there will therefore be a fear among those scientists to perhaps not impart as much information as they could.

Maureen - Absolutely, that is a huge concern and I think this first visit is more political than scientific in terms of developing a collaboration. But China is suffering in public relations because of their inability and unwillingness to do this, there will be some information shared and some information is better than no information. But there are cracks. Professor Shi Zhengli, who is a director at the Wuhan Institute of Virology, has already broken ranks by speaking with the BBC about a month ago, saying she very much wanted the scientists to come to Wuhan and speak with her directly. And three or four weeks ago the Chinese government was not going to let a science team go to Wuhan, which is where the virus was discovered.

A ray of light with a bright spot.

17:26 - Photon avalanches: a one pot method

Scientists have found a novel method for creating photon avalanches with wide-ranging potential applications

Photon avalanches: a one pot method
P James Schuck, Columbia University

Adam Murphy’s been looking into avalanches, but not ones made of snow…

Adam - When you think of an avalanche, you probably think of snow. One bit of snow moves, causing a cascade of snow beneath it. But lots of things can avalanche - nuclear reactions, the bubbles in champagne bottles, even particles of light, photons.

P. James - A photon avalanche is a process by which you have a material and that material is in a certain state, such that when it absorbs a single photon, it sets off this chain reaction that ultimately leads to a whole slew of photons coming out the other side.

Adam - That's P. James Schuck from Columbia University. Now photon avalanches aren't new. We've seen them for 40 years, but making this process happen has been difficult, only occurring in big bulk materials or at super low temperatures.

P. James - What we did here was create a material where we were able to realise this avalanching, that's not only it doesn't require being in a bulk piece of crystal, but actually happens in a little nano-scale packet of material and it can happen at room temperature. The particles themselves they're made of something called sodium yttrium fluoride, but it is a ceramic. So you think of them as basically a transparent ceramic. And then what we do is take lanthanide ions that have very interesting optical properties and we dope them into that material.

Adam - Sounds very complicated to put together. So is it really as hard as it looks?

P. James - No, it's actually a relatively straight-forward one pot synthesis as the chemists like to say. It really can be made at reasonable temperatures inside someone's lab. It's much simpler than what chemical companies go through I think to create gasoline, for example.

Adam - Another strange thing about these particles is that the photons that come out have a higher energy than the one that went in. Now, one of the biggest rules in physics is that you can't just make energy. It has to come from somewhere. So where is all this energy coming from? There's no such thing as a free lunch after all.

P. James - No free lunch. That's right. So the way that these actually work is the material works when bathed in infrared light. We're taking the material and we're surrounding it in infrared light. So these are sort of low energy photons but what happens is then when you're sitting in this bath of infrared, when your one photon does come into the material and gets absorbed, it puts the material up into this excited state that can then interact with this infrared bath very, very efficiently and that then leads to a chain reaction of events that leads to lots of photons coming out the other side.

Adam - And this isn't just nice physics to be put in a folder, labelled parlour trick. It's got some potentially huge applications. Like say you wanted to detect a molecule or a virus that only gives off single bits of photons or single bits of energy. Well, something like this might come in handy.

P. James - That means it can be a very energy efficient way to do things like make an ultra sensitive detector because what you want in a sensor is you want to detect a small change, and you want that small change then to lead to something big that's easily detectable. That's exactly what these do.

Adam - And there are some weirder applications. The cameras in night vision goggles detect infrared photons or heat, but the Silicon in the detector isn't usually very good at detecting infrared. Well?

P. James - If you were to then, for example, take our material, which happens to respond very nicely in the near infrared in fact, that has this very large response. Then you could imagine a scenario where you can simply take Silicon detectors, you coat it with avalanching nanoparticles, and now you've just made your camera an infrared camera, as well as a visible camera. Now that we know how these work, they give us a good clue as to how to make new materials and then these would even further expand the potential applications of it.

Brown tree snake climbing

21:28 - Slippery snakes sneaking up trees

Scientists have discovered an entirely new and unique method for snakes to climb smooth trees

Slippery snakes sneaking up trees
Julie Savidge, Colorado State University

Guam is a small island in the Western Pacific ocean whose native bird population has been decimated by invasive brown tree snakes accidentally introduced in the 1940s and 50s. The snakes readily climb the island’s trees to feast from birds’ nests. One particularly hard-hit victim is the Micronesian starling. Scientists have been trying to protect the birds by putting nesting boxes high up on poles which are surrounded by smooth baffles, like metal covers, to stop the snakes climbing up. But, as it turns out, these snakes are slippery customers, as Eva Higginbotham heard this week from Colorado State University’s Julie Savidge…

Julie - We had an outdoor arena where we would put maybe two to four snakes in during the night, this is a nocturnal snake and then we had cameras that would record their activity. Snakes couldn't defeat the baffle, but then all of a sudden, one of the snakes wrapped its body around the metal cylinder. This is an eight inch metal cylinder and formed a loop and then wiggled its way upwards.

Eva - You've actually sent me some videos of this. Honestly, it looks sort of like a cartoon. It doesn't look like a snake should be able to do this. Were you surprised when you saw this?

Julie - Oh, we were absolutely amazed. Tom, my colleague on the paper said that he watched the video probably a dozen times. He then sent it to me. I wasn't able to be on island at the time and I had never seen a snake doing anything like this. So yes, it appeared we are seeing a very unique form of movement. The snake first forms a loop around the cylinder with its body, and it creates a knot or some sort of interlocking region with the tail part of its body, and the anterior part of the body towards the head. And this loop - lasso, which we're calling it - squeezes the cylinder to generate friction and prevent the snake from slipping down this smooth surface. The snake has little bends of its body within the loop of the lasso, which it can then move upward, and it kind of looks like a wave moving along the body; and it gradually shifts these bends upward.

Eva - How many snakes did you see climb up the pole this way? Was this just a one hit wonder super snake, or do you think this is something this species can do in general?

Julie - We think this species can do it in general. For our studies we had a total of 15 snakes - that we had tested - that actually showed this type of locomotion, but undoubtedly more can do this as well. Brown tree snakes evolved in tropical regions where there are smooth barked trees, and it's possible that this form of locomotion helped them scale these sorts of trees and get to resources in those trees.

Eva - So now you've seen that these snakes can climb up to get to the birds this way - what's next?

Julie - Understanding this lasso locomotion, we can predict circular structures that brown tree snakes couldn't readily climb. So we know now that placing nest boxes for Micronesian starlings on relatively narrow utility poles is not such a smart idea. Placing them on larger diameter poles would probably be safe. We can also develop other baffles that we think brown tree snakes would have a much more difficult time using lasso locomotion on; for instance, my colleague and I developed an ice cream shaped cone where it's narrower at the bottom and wider at the top, and that makes the snakes have to adjust that loop that lasts as they climb, and that's pretty difficult for them.

Yarn for knitting

28:23 - Knitting to improve wellbeing

Looking to feel calmer during lockdown? A knitting habit could help

Knitting to improve wellbeing
Betsan Corkhill, Stitchlinks

Many people are turning to knitting at the moment, but is there evidence that a knitting habit and mental well-being go hand in hand? Betsan Corkhill is the director of Stitchlinks, an organisation that advocates for the use of knitting to improve our wellbeing, and she spoke to Chris Smith...

Chris - Betsan, are you a knitter?

Betsan - I am, I do knit. I learned when I was seven, but I picked it up again when I started this project, because I believe in practicing what I preach. I've just finished a lockdown blanket, actually, that's for a virtual hug for our daughter who's alone in lockdown.

Chris - It sounds wonderful. Someone when I was making a programme about a year ago when the coronavirus first began to come in, she promised to knit me a toilet roll holder that had a naked scientist on it. I'm still waiting, so I can only presume she's a slow knitter. But how many people are there out there like you, Betsan? How many fellow knitters have you got?

Betsan - There are millions of people across the globe from all age groups, from different backgrounds and cultures. Our Stitchlinks newsletter now goes out to about 92 different countries. And it's certainly become more acceptable and recognised as a tool for improving wellbeing since I started this work in 2005. When I first started, I had to call knitting something different -  I had to call it a 'bilateral rhythmic psychosocial intervention' to get my foot in the door with clinicians and scientists.

Chris - Was this to get grant money or funding - is that why you had to use fancy scientific language?

Betsan - Yes, yes. I don't have to do that anymore though, which is good.

Chris - Well, that's very encouraging to hear! But what actually is the evidence, then, that if I indulge in a bit of knitting, that it's going to actually benefit my mental health?

Betsan - The thing that first drew me to it was getting access to hundreds of thousands of letters and stories from knitters, and the large numbers of people from all over the world saying very similar things. So Stitchlinks and Cardiff University did a survey, and we had over three and a half thousand valid responses from 31 countries in two weeks, which was a huge response; and our most significant finding was the more frequently people knit, the happier and calmer they feel. 81% of respondents reported feeling happier, 54% said they felt happy or very happy, and fewer than 1% remained sad; and very excitingly that translated across to people with clinical depression. We also found the texture was twice as significant as colour for affecting mood, and that touching something good makes you feel good. And over the last year, the Centre for Integrative Neuroscience and Neurodynamics at Reading University have been carrying out a range of studies; they carried out a range of validated questionnaires on stress, anxiety, mood, and depression. We were then going to go on to do some EEG studies, but of course COVID intervened there, so we haven't been able to do that...

Chris - That's looking at brainwaves, isn't it, to find out how people's brain patterns change. But one question I would ask then is -  is this cause or effect? Because if I was feeling jittery and unable to settle, I perhaps wouldn't settle to my hobby if it's knitting. Whereas if I was feeling calmer, I was feeling in a better place, I might. And therefore - are you just measuring people's mood with the knitting, or is the knitting causing people's mood to improve?

Betsan - From the work I've done, knitting is causing people's moods to improve, because we've actually managed to cure anxiety and panic attacks, for example, with knitting -  giving people a portable project to carry around with them, and whenever they feel anxiety rising, they take out their knitting and it helps them to calm down. And I think that has to do with the rhythmic movement, the rhythmic nature of the movement. As you know, brains are constantly predicting, so our brain likes rhythm because it's predictable, it makes the brain feel safe. So yes, the work I'm doing is certainly pointing to the fact that knitting is helping people to lower stress and to remain calm.

Chris - Do you think it's just knitting? Because I put it to you -  I might not knit, but I might have another kind of hobby that involves doing something where I immerse myself, I focus on the thing I'm doing, I concentrate, and if I'm concentrating on doing something that I find pleasurable - it might be, say car mechanics or something - it's removing me from ruminating on the thing that I was stressing about, or worried about, or obsessing about, and that might help me to distance myself from the cause of anxiety, and therefore I would feel better! And it wouldn't have to be knitting; it could be any kind of hobby.

Betsan - I would say, anything you enjoy doing would have that kind of effect, but I think the things that set knitting apart from other activities are the patterns of movement - the rhythmic movement seems to be really important in that - and the fact that it's portable as well. And we've struggled to find anything else that's portable, because then that gives you a tool that you can use anytime, anywhere. You can use it in bed, for example; you can use it on public transport. A lot of people use it as a self-soothing tool on public transport, and otherwise wouldn't be able to use public transport.

Chris - Sometimes wasting very long times for public transport to arrive, which can be a cause of anxiety in and of itself, can't it. Who would you recommend then? Who would be a good candidate to take up knitting, if they don't knit already, to get this sort of relief?

Betsan - Anybody who wants to deal with the challenges of everyday life, to decrease stress, improve mood, help with loneliness, pain, addiction, social anxiety; anybody who does screen-based work, for example, 3D tactile activity is really good. So really it helps you to deal with the challenges of life, because it's really important to switch off every day if you want to stay well, particularly at this current moment in time where it can be very stressful.

Egyptian pyramid

34:15 - Textile archaeology

Unravelling the story of how our ancestors made fabric

Textile archaeology
Margarita Gleba, University College London

So when did our ancestors first begin to master the art of making things from material? Let’s follow the thread back to the origins of fabric-making with textile history expert Margarita Gleba from University College London, who spoke with Eva Higginbotham...

Margarita - The oldest textile that we know of comes from the Czech Republic site of Pavlov, and consists of tiny imprints of twined fabric. These are not true loom woven textiles, but handmade, twined textiles that existed at the time. And they date to about 27,000 years ago; so quite a long time ago.

Eva - Do we know what those were made of?

Margarita - We do not know exactly what they were made of, because these are imprints; so obviously none of the actual material survives. But, we do know that most of the textiles in these early periods were made from plant fibres. And at this point there were no domesticated plants, such as flax or hemp. And so more than likely these were made from some sort of wild plant material, a lot of tree bast fibers such as lime bast, or oak bast, were used at the time. So more than likely it was one of these materials that was used to make these early textiles.

Eva - How do you make a fibre out of a tree?

Margarita - You have to subject the tree to certain processing techniques. With lime, usually what happens is you cut off a tree of a certain age, depending on whether it's younger or older, it will produce finer, or coarser fibres. And then you soak it in water for a long time. And the layers that produce fibre, which effectively, is part of the plant that gives it stability. It supports it in its standing, they separate from each other and then one can peel them off in layers, and then separate them into finer strips and use them to produce a thread. Of course, there are also lots of plants, even some grasses, sedges, and materials that often were used to make basketry, that could be used effectively in their raw state. So they can be just softened in the hand and used as they are. So they don't require too much processing.

Eva - If the oldest textiles were mostly made of plant fibres, how long do they last? Because you think they would degrade?

Margarita - Yes, indeed we do. And it all depends on the conditions of preservation. So for example, everybody's probably familiar with large amounts of textiles that are found in Egypt. Those are made out of linen, and some of them are 5,000 years old. Some of them are even older. The dry climate of Egypt allows preservation of textiles, that keeps them in almost perfect condition for very long periods of time.

Eva - What were the first textiles used for, as far as we know?

Margarita - So some of these earliest ones probably were not used for any kind of practical purpose. The reason we think that is because, one of the early indications of the use of fibrous materials, are the so-called Venus figurines that come from the Palaeolithic period. This is the old Stone Age, and they date between 27,000 to 20,000 years ago. Many of them have decorations that clearly indicate the use of string. And often these are not garments. They are decorations on the heads, such as head dresses of some sort, or string skirts. Clearly these are not practical. They more likely had to do with expression of identity, and possibly status as well.

Eva - People have been dressing up forever!

Margarita - Exactly.

Eva - So say you found a piece of old textile. How do you figure out what it's made of, if it's made of sheep or goat or bits of tree?

Margarita - These days, we have a lot of scientific techniques at our disposal to identify the raw material. The most common one is microscopy. A common technique these days is scanning electron microscopy, which allows very high magnifications, and very high resolution of the surface topography, or surface characteristics of the fibre. And each fibre has very particular elements that allow us to identify them. So for example, animal fibres have scales on their surface, whereas plant fibres such as flax, nettle, or hemp, have dislocations, or nodes along the surface, cotton fibres look like ribbons. Silk fibers are very, very smooth and long and again, have a very particular look when we look at them under the microscope.

Eva - So seeing as it's been literally tens of thousands of years, since we first developed textiles, we've come a long way.

Margarita - Indeed we have, I think textiles were absolutely fundamental in human development, and development of many civilizations as well. When you think about it, textiles have been the primary material for clothing and a lot of other utilitarian textiles, for the last 10,000 years of human existence. It's the technology that predates ceramic or metal technologies. The only technology that's older than that is the stone technology that goes back millions of years. So in this respect, textiles were among the earliest materials, artificial materials, if you will, that were produced by human beings. When we think of the industrial revolution, it was largely driven by desire to improve textile production, to make it faster, to make it more efficient, to increase the quality of particular types of textiles. Even until a hundred years ago, people were still producing textiles at home. And that took up an incredible amount of time, and skill, and also materials. Even today, a large amount of world GDP consists of textile production. So I think we still can think of textiles as something that is absolutely fundamental to our human existence.

Laundry drying on a washing line

40:20 - The cost of fast fashion

Some clothing might be cheap, but the environment is paying the price

The cost of fast fashion
Kirsi Niinimäki, Aalto University

We've come along way from laborious hand-crafting of textiles to the mass manufacturing of today. In recent years there’s been a big shift from things being built well and intended to last a lifetime to fast and loose fashions intended, in some cases, to be worn once and thrown away. But what price is the planet paying for this? Kirsi Niinimäki is a professor at Aalto University’s Department of Design, and she spoke to Eva Higginbotham...

Kirsi - Yes, the global fashion business is a huge industrial sector, and fast fashion has really increased the manufacturing figures. So the last 20 years actually, the fibre production has doubled. And of course that also has led to a huge amount of new fashion items, as well as speeding up the consumption side. So there's a lot of this, kind of like, environmental impacts throughout the whole supply chain, and it's also a complex supply chain. So that means that industries are located in different countries, and each step in the process might happen in different countries. That means that actually, might be that some garments have travelled, two times around the globe before they reached the end consumer. So that of course causes a lot of environmental impacts.

Eva - Are there specific points in the supply chain, from growing a fibre, or collecting a fibre from a sheep, wherever it is that you've got it from, down to making a piece of clothing that someone's going to go buy in a shop, are there points in that process that are particularly harmful for the environment, and how does that work?

Kirsi - All those kinds of processes which use a lot of water, or chemicals are quite harmful. For example, starting from cotton cultivation. So actually cotton uses a lot of water as well as a lot of chemicals used in that process. But also there are a lot of steps when the fibres are made, when the yarns are produced. And especially those ones where the chemicals are used to dye textiles, or printing textiles, or do some kind of finishing processes. All these kinds of chemicals, and waters, and the use of energy are quite harmful. And of course in those processes, also a lot of waste is produced to soil water or air.

Eva - And so there are some different materials, or different fibres that are grown in different ways, aren't there, between cotton or hemp, or a polymer, something that's an artificial material. Are there some materials that are better for the environment, and some which are worse?

Kirsi - Yes. That's actually a quite interesting question because each garment has some kind of environmental impact, but they might be different in different fibres. So for example, with the cotton. Cotton, so it uses a lot of water and chemicals in the cultivation phase, but also throughout the industrial processes. Polyester on the other hand uses a lot of energy. So it has a huge carbon footprint, but nowadays we also know these kinds of problems from the polyester use, that actually this kind of microplastics in ocean waters, are actually quite big part of it is caused by washing polyester garments. But then these kinds of good ones are those like plant-based materials, renewable materials, for example, linen and hemp, which actually has quite a small environmental impact. And even this carbon footprint is quite small. So it doesn't use so much water when it's cultivated and not so much chemicals. So those kinds of fibres are quite good from the environmental point of view. But of course, when we talk about fibres, also, they use phase is quite critical in that sense, that of course we should always select a fibre, which is most suitable for that use context. So that is the garments should be durable. So this kind of like a balance is you always have to think when you are selecting different fibres.

Eva - When we think about all of the different parts of modern life that are contributing to climate change and the destruction of different environments, how big of a problem is the fashion industry within that context?

Kirsi - Actually, this is quite an interesting point of view because in recent years there has been a new discussion in the sustainable fashion field, linked to this climate change. A recent study shows that even 8 to 10% of global climate change is actually caused by the textile and fashion industry. So there's a huge impact from this industrial sector.

Eva - And what about homemade clothing? I have recently started knitting and although my skills aren't quite there yet, I have grand plans for the jumpers and the scarves and the hats and things that I want to make. What could be said about the environmental impact of making yourself a jumper versus going to any high street shop and buying one?

Kirsi - Yes. I think that these kind of Do-It-Yourself practices are really good ones. Of course it might be that those textiles or yarns that you are still using are produced on the other side of the globe, but there are some processes that you could actually avoid by making your clothes yourself, and what is also important is that you learn skills. That means that you actually understand how the garments are constructed, so that it's possible even to repair the garment or even redesign or modify the garment with this kind of new skill set that you are learning by making things by yourself.

Eva - You've shown that the fashion industry is playing this big role in environmental harm and in climate change, what do you think we need to do to try and fix this problem?

Kirsi - Well, we should try to create a new balance in the fashion sector. The main thing is that we try to slow down the material throughput in the system. That means that we should actually manufacture a little bit less, we should consume a little bit less. We should extend the use time of the garments. So actually those are quite effective ways of trying to build a new balance in the system. And of course, all the models - coming from this fast fashion might be that those also need to change, creating a little bit of a new kind of business understanding in the fashion sector is really important.

Eva - And what about for the average person who's trying to reduce their environmental impact?

Kirsi - Well, yeah, of course we have other ways of consuming fashion so we can buy second hand, for example. We can swap clothing items or we can rent or lease. The main thing is that we try to extend the use time of the garment. So that's really important. So in that way also we can decrease buying new stuff and still try to appreciate what we already own.

A masked scientist uses a pipette to draw up blue liquid from a petri dish.

46:29 - Knitting with human yarn

Scientists have created thread out of human cells to make replacement blood vessels

Knitting with human yarn
Nicolas L'heureux, INSERM

We’ve heard about tree fibres, wool, cotton, linen, and other materials you can use to make fabrics, and we’ve gone back over 27,000 years in the process. But, looking ahead now, we’ve not yet considered making things out of our own bodies. And Nicolas L’Heureux is a Bioengineer at INSERM, in France, where he’s developed a technique to produce a “yarn” made from human tissue that can be woven, knitted or braided into new structures, like replacement repair blood vessels, as he told Chris Smith...

Nicolas - We take a small skin biopsy, and from that we can get cells. And some of these cells are specialized in building the architecture of the body, building the scaffolding of body. And we take these cells, we put them in the lab. We give them a nice little environment where they're happy and they multiply. And they work really hard at building this scaffolding that makes us strong and sturdy.

Chris - And that's actually referred to as extracellular matrix, isn't it, it's basically the cells secreting around themselves material that they then sit down in and it gives the tissue strength.

Nicolas - Exactly. It's their little house I like to call it. That's where they live. That's where they're comfortable. And this extracellular matrix, as the name says, it's outside the cells. You may have heard of the most common protein that makes up this extracellular matrix, which is collagen. It's in beauty creams and in shampoos, but it's much more useful in your body as a strength device. It's like wood on your house. And these sheets of collagen-rich extracellular matrix is what we start with. And we take these sheets that the cells nicely laid down at the bottom of the flask, where we grow them, and we get these typically 10 by 18 centimeter sheets. And from these nice sheets, we can cut ribbons. And then with the ribbons, we can use them as a yarn.

Chris - What do they look like - when you get the sheet of tissue that you then cut into these strips to use as your starting material, what does it actually look like?

Nicolas - Well, it looks a lot like a piece of paper, a little yellowish and wet. It's about the same thickness and it's probably a little stronger than a piece of paper and it is much more flexible though.

Chris - And what do you then do with it? So you've got the sheet of material. You can cut that into strips. I get that. And that would give you almost individual strands, but how do you use them?

Nicolas - So once you have a ribbon or a thread you can use the three typical textile assembly approaches, which are weaving, knitting and braiding. So we use a lot of weaving because it makes very tight constructs. As you know, you can weave a basket with vegetable fibres and be able to put water into it. So that's our favourite for making blood vessels because of course being leak-proof is quite important for blood.

Chris - We've got lots of materials that are artificial that we can knock out pretty rapidly and they work very well to do replacement parts for blood vessels. For instance, you can replace sections of someone's main body blood vessel the aorta this way, can't you? So why do we need to make things your way?

Nicolas - What really works best when you have a blocked artery is your own artery to replace it. That's what surgeons do today. They take an artery from a place where it's not critical and they transfer it somewhere else in your body where it is critical. If you run out of vessels, for example, which happens quite often because we don't have a big reserve of vessels that we don't know what to do with, the surgeons will put in plastics that are very inert chemically, but the body recognises them as foreign. And eventually the vessel will fail. It will be obstructed by the reaction of the body. What we want to do is we want to put in the same basic architecture that you find in your own vessels, and we expect the body not to see this as foreign. And in fact, we have had many studies that have shown that it is the fact it is well accepted by the host.

Chris - So are you in a stage where you've actually now made blood vessels of the sort of calibre that could be plumbed into someone's heart to bridge a blocked coronary artery, for example, and do they work at the sorts of pressures that you see in the human arterial circuit?

Nicolas - Yes, actually we have made blood vessels by weaving from 2 to about 5 millimetres in diameter, and that's exactly the right range for small vascular surgery in different places, including on the heart. And these are actually extremely strong. We probably overdid it from the engineering point of view because they are twice to three times as strong as a native artery.

Chris - And have you actually tried implanting them to see how a real living body receives them and whether it does indeed accept them?

Nicolas - So we are in the process of doing that. The problem here is that we're specializing in making human tissue. Of course, if you put human tissue into an animal for testing, it will be rejected very aggressively. So what we have been doing for a few years now is trying to make an animal tissue to be able to take this animal tissue and put it into an animal to see what's going to happen.

Chris - Of course, there's a problem with size though isn't there because the size of a mouse blood vessel is quite different to the size of a human blood vessel, and therefore what works in one might not work so well in the other.

Nicolas - Yes. And in fact, we are not attempting to do a mouse or a rat because it is very, very small. We're using sheep as our model, which have vessels that are about the size of human’s and are widely used to study vascular devices.

CGI images of DNA double helix

53:27 - QotW: Can you get DNA out of crematorium ashes?

Can you learn information about the deceased by examining their ashes?

QotW: Can you get DNA out of crematorium ashes?

Katie Haylor got in touch with Charmaine Bale to find out the answer...

Katie - Well Paul, during cremation, the soft tissue of the deceased burns away due to the extremely high heat of the oven and the solid skeleton is desiccated, leaving only fragile bones. These are taken from the cremator and crunched up by a machine. It is this process of breaking the delicate bones up that creates ‘ashes’.

I spoke to Charmaine Bale, who has worked as a crime scene investigator, worked at a crematorium, and is currently lecturer in crime and investigative studies at Anglia Ruskin university.

Charmaine - DNA is damaged by high heats as this breaks the connecting strands of the molecule. If you’re trying to get DNA from a cremated skeleton, there’s a very slim chance of collecting enough remaining DNA. The bone would mainly be brittle calcium and have few places left to protect any tissue suitable for sampling.

As for height and weight - when the skeleton is still laying in the oven, then yes you can see the height of the person. People have different size bones so maybe mass could be estimated, but getting an accurate physical size would be tricky as all the muscle and fat will have burnt away.

Katie - Charmaine explained that an anatomist may be able to determine where the muscles had joined the bones and could possibly comment on someone’s build. However, once ground down, you could only really tell if the person was big or small by the amount of ashes left.

Charmaine - This is why it is very important for a crematorium to follow labelling procedures and ensure the name tag is followed from the coffin, through to the oven, to the ash collection area and then adhered to the ashes container.

Katie - Thank you Charmaine for uncovering the answer for us. Next week, we’re tackling Stephen’s stellar space question:

Stephen - Is it true, that if the mass of the Earth were greater it would render our chemical rockets incapable of reaching orbit and therefore make us a non space faring species with the same level of knowledge as our pre Sputnik society?


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