Animal research: varying standards are leading to bad science

How an animal is treated can actually affect research results. Understanding Animal Research/Flickr , CC BY-SA

Scientific research sometimes requires the use of animals. It’s a fact. And as long as that is the case, we need to do everything in our power to minimise the distress for laboratory animals. This is not just for the sake of the animals, but also for the sake of science itself. We know that the quality of life of an animal can actually affect its physiology and, thereby, the research data.

But unfortunately, the standards of animal care vary greatly across countries and even across research institutes. The time has come to overhaul this system and replace it with globally enforced rules.

Necessary evil

There are a lot of misconceptions about animal research, for instance what it is used for. Across the EU and in a number of other countries (including India, Israel, Norway and New Zealand), it is actually illegal to use animals to test cosmetics or household products. It is, however, allowed in medical research.

Animals are vital to medical research – they help us understand how drugs and genes function in our wonderfully complex bodies. By law, new compounds must be tested on animals before they can reach human trials. This is partly because humans are so genetically diverse and come from such a wide range of environments that we are not of much use in the initial phases of drug testing.

A lot of real breakthroughs in medical research would have been impossible without animals. Take the dogs in Emile Roux and Louis Pasteur’s research for example – they helped develop the human and canine rabies vaccines. Likewise, Frederick Banting and Charles Best’s work on diabetic dogs led to the discovery of insulin, arguably one of the most significant discoveries of the 20th century.

In reality, larger animals such as dogs play an increasingly minor role in animal research; more than 84% of studies are now conducted using mice, rats, and flies.

An small proportion of animal experiments today use dogs or other larger animals. Understanding Animal Research/Flickr

Thankfully animal research is highly policed in countries such as Australia, the USA, and the UK. Some institutes follow the rules and maintain the highest possible standards. For example, animal research in Australia is legally bound to follow the so-called “three R’s” – Reduction (of animal numbers), Refinement (to minimise distress) and Replacement (with non-animal models). They are also required to conduct ethical and humane research as described in The Australian Code for the Care and Use of Animals for Scientific Purposes.

Unfortunately, there are some instances, even in highly policed countries, where research doesn’t follow the guidelines, with some institutes and labs slipping through the cracks. Bad practices are much less likely to happen in countries where governing bodies review research proposals and conduct regular inspections. But they still happen.

Guidelines and policing are completely up to individual governments, which can be uninformed or lacking in funding. So what about countries with less stringent rules, such as Italy? Animal-based scientific research is common in Italy. But researchers feel that the occasional threats of institute inspections will almost never result in a real inspection.

In an ideal world, researchers should undergo extensive training to develop a keen eye for any kind of distress and to guarantee a high quality of life of the animals in their charge. In many countries this training, if it exists, doesn’t actually occur when new researchers join an institute. Animal facilities vary wildly in quality, and as such, both the quality of life of the animals, as well as the data itself, is compromised.

Bad animal practices, bad science?

Research has shown that data at the behavioural, cellular, and biochemical levels can be completely different depending on whether rats had access to enrichments (such as toys to play with, tunnels to run through, and things to climb). This can affect things like gene expression, hormones and are cell-signalling molecules called cytokines.

One study showed that mice born in an enriched environment developed more neurons in part of the brain. Another suggested that the progression of neurological disorders changed with environmental variation.

Monitoring environmental enrichments would both markedly improve the lives of research animals and also preserve data quality. Without such procedures, conflicting animal data is wasting both time and research funds. International collaborations often experience this, and research can drag on for years trying to sift through the muddy waters to find solid data.

Animal research in industry is actually easier to regulate because parent companies can set rules for all subdivisions to follow, regardless of the host country. Plus the number of labs is typically small enough to enable strict monitoring.

But what about academia – why haven’t we already done something about this? In some cases researchers are simply not trained properly. In others, overworked and often underpaid scientists are just trying to survive in an increasingly competitive research environment. Time wasted trying to change the established setup could mean loss of data, loss of papers, and thus compromised job security.

But we need to do something, and the shock tactics of animal rights activists are certainly not the best way of tackling this. Instead, changes need to be made at the level of government and science policy. There needs to be better training, and better monitoring of every single facility with international guidelines that are actually enforced. In an ideal world, researchers would come together with regulatory bodies and government representatives, agree on global standards, and stick to them.

With time and a lot of determination, it may be possible to achieve worldwide collaboration on such a project, and both the animals and the data will be better for it.

Our lip-reading technology promises to make hearing aids more human

It's written on your face. Shutterstock

Hearing aids can be lifelines for people with hearing loss. But their limitations can mean that, in particularly noisy environments, users cannot exploit the best of the existing technology. Most new hearing aid designs just make small improvements to microphones, power efficiency and noise filtering. We propose an entirely new approach.

My colleagues and I are working as part of a multi-disciplinary team led by Stirling University, which includes a psychologist and a clinical scientist and is supported by a hearing aid manufacturer. Our aim is to develop an audio-visual hearing aid for the 21st century, taking inspiration from the way that the human body naturally deals with noisy situations, something often known as the cocktail party effect.

Imagine a scenario such as a very busy party with lots of noise, music and people talking. Despite this overwhelming environment, a person with full hearing is often able to pick out and listen to the voice of someone next to them. This is something that people with hearing aids often find extremely challenging. In fact, in really busy environments many deaf people may prefer to remove their hearing aids altogether.

Dealing with noisy environments

The answer to why it is so difficult for hearing aids to deal with these situations is complicated. It’s partly down to the limitations of directional microphones, of inadequate noise cancelling, and of the loss of information about where sound is coming from. But the reason why deaf people can often “hear” better in overwhelming environments like this can be partly explained by lip-reading.

Lip-reading is known to enable individuals with hearing-loss to better understand speech. We all lip-read to a greater or lesser extent, but in people with hearing loss it can become a vital skill. Yet it’s a component of communication that existing hearing aids simply ignore.

No more smiling and nodding. Shutterstock

Our vision is for an ear or body-worn hearing aid linked to a small wearable camera, which could be mounted in a pair of ordinary glasses, jewellery or perhaps even worn as a discreet badge. The device would process the camera’s video stream to isolate relevant information about lip movement.

This data can be used by the hearing aid in several ways. On a simple level, if it knows someone is speaking it could apply some general background noise-reduction filtering. It could identify the direction the voice is coming from and focus a directional microphone accordingly.

Significantly, it could also use the lip movement information to apply an appropriate filter for further noise reduction, just as our brains do naturally. Specifically, if the device can estimate what the speech is likely to be, then it can remove sound elements that don’t match this. For example, if loud music is playing, “reading” the lips of the target speaker would indicate to the device that it should remove this music because it does not match the expected sound.

What are the challenges?

There are multiple challenges to ensuring a hearing aid like this can work practically in the real world, involving the same problems that human lip-readers face. It has to be able to deal with multiple speakers at once and sound that isn’t in front of it. And, generally, people do not simply stand motionless in front of the listener, but instead tend to move, turn their heads, cover their faces or show their emotions visually. They may also be interrupted or have someone else walk in front of them.

To overcome this, our solution will be to again consider how humans function. How much lip-reading we do depends on the circumstances. The more noisy it is, the more we tend to look at people’s lips. So a system that exclusively lip-reads would not be very useful when it comes to real conversations in real environments. We plan to integrate our approach with other non-camera approaches that hearing aids presently use, including noise cancelling and directional microphones.

Our aim is to produce an aesthetically designed system that improves users' ability to understand what someone is saying in a range of environments, potentially with less listening effort. This would help solve the real problems faced by those with hearing loss, including their low uptake of available technology, by delivering a freely available, next-generation hearing device prototype, inspired by the way we naturally think, hear and see.

Are robot surgeons in the operating theatre as safe as they could be?

Today's Da Vinci sticks to surgery rather than the wide interests of its namesake. Intuitive Surgical

A study has revealed that robotic surgery was involved in 144 deaths and 1,391 injuries in the US during a 14-year period. While this may seem a cause for concern, considering there were 1.7m operations carried out during the same period, this is very few indeed.

Of course there is always the possibility of complications occurring in surgery, with or without robot involvement. But as robotic procedures become more common, health service users have a reason to wonder what these machines do and how complications can occur, so that we can try to prevent them in the future.

First, are robots really conducting surgical procedures? A more accurate term is robot-assisted surgery. This is a form of keyhole surgery, where the surgeon performs operations using small incisions, through which a fibre-optic camera and instruments pass. Keyhole surgery is better for patients as it is less invasive, but can be difficult for surgeons as the long instruments can be awkward to handle.

In robot-assisted surgery, the robot holds the instruments while the surgeon sits at a console, remotely controlling the robot’s arms. In these cases, the surgeon has more precise control than without the robot, because with extra robotic arms to assist the surgeon can control the camera and an additional instrument at the same time, whereas otherwise an assistant surgeon would be needed.

The business end of the Da Vinci robotic device. Intuitive Surgical

While there are robotic devices that cater to specific needs such as assisting surgeons with catheter or vascular control, inserting spinal implants or joint replacement procedures, there are few multi-purpose devices. The market leading device is the Da Vinci, manufactured by Intuitive Surgical, sales of which have rapidly risen despite the latest model’s £1.7m price tag and annual maintenance costs of £150,000. Between 2007 and 2011, the number of Da Vinci robots in use in the US increased from 800 to 1,400, while the number worldwide reached 2,300 in 2011. There are around 50 in the UK.

Robot-assisted surgery is primarily used in urology, but is expanding into gynaecology, ear, nose and throat, colorectal, cardiology, and paediatric surgery. NHS England is currently reviewing the evidence for robot-assisted surgery in order to develop rules for where and for what operations robot-assisted surgery can be used.

Two well-designed and conducted studies comparing keyhole and robot-assisted surgery for treatment of prostate cancer found that robot-assisted surgery offered quality-of-life benefits for patients, in terms of higher rates of continence and sexual function. However there is a lack of high-quality studies for other types of surgery.

Robots not always best team players

While studies of robot-assisted surgery tend to focus on the role of the surgeon, the surgeon does not work alone – safe and effective surgery depends on a team. What is known as the surgeon’s first assistant is often a trainee surgeon, or a nurse or operating practitioner who has undertaken specialist training. There is a scrub practitioner, responsible for passing instruments as needed, who is in turn supported by one or more circulator nurses, who gather additional instruments and supplies. There is also the anaesthetist, who will often be supported by a trainee or an operating department practitioner.

Even with robot assistants this team is still essential – what has changed is how they are arranged around the operating theatre. The surgeon is normally sat a couple of metres away from the patient and the rest of the team at the console. This is really important because the collaboration on which safe and effective surgery depends is affected by this arrangement.

When we have interviewed surgical teams about their experience of robot-assisted surgery, they described difficulties in hearing the surgeon’s instructions. It’s sometimes unclear who the surgeon is speaking to, because when the surgeon’s head is in the console, there’s no opportunity to use non-verbal communication such as gestures and eye contact. This results in repetition of instructions and reduced coordination, potentially leading to a longer operation. It becomes harder for the surgeon to guide the first assistant, so having an experienced first assistant is more important in robot-assisted surgery. The surgeon’s position at the console also affects their awareness of what is happening in the operating theatre. Theatre teams told us of having to quickly tell the surgeon to stop because the robot arms were going to hit the patient.

The theatre teams we spoke to had also developed strategies to overcome the problems they were experiencing. So alongside gathering more evidence on the just how effective robot-assisted surgery is, we need to develop a better understanding of what changes it introduces to the teamwork of surgery, and to assess how best surgeons and their teams can make changes that will improve the safety of robot-assisted surgery.

Scientists at work: what's your poison? Tackling India's snakebite problem

Gerry meets Kaulback's pit viper, which could be one of the most lethal snakes in India. Inset picture: Wolfgang Wüster Author provided

Gerry climbs up to the veranda of our tribal longhouse with a snake bag held out in front of him. “Now don’t get too excited, but I’ve just caught a Kaulbacki,” he says, looking pleased but exhausted from a long hike and a six-metre climb up a tree. We gape, hardly able to believe that we have finally found this rare snake alive after four years of intensive searching.

Kaulback’s pit viper, first discovered in 1938 by British explorer and botanist Ronald Kaulback in northern Burma, is one of the largest pit vipers in Asia. On top of that, according to local reports, its bite is lethal. Despite being a co-author on the most recent paper on the species, I had never before seen a living specimen – few scientists have.

I can’t believe my luck at being present for this moment on my first trip to Arunachal Pradesh, a heavily forested state on the north-east frontier of India. This trip is, for me, the culmination of a long personal journey. During my teenage years in India, a family holiday to neighbouring Assam had triggered my curiosity about the natural world, until then only nurtured by tales of exploration and discovery.

Deadly denizens

While now considerably less remote, life on the edge of the jungle is still hazardous. The Nyishi tribals now cultivate rice in the valleys, but on steep hillsides still resort to traditional shifting cultivation – using an area for a while and then abandoning it. As they clear forest, they encounter snakes. And while not all are venomous, monocled cobras, king cobras, banded kraits and others are quite capable of killing people. Yet, of all these, it is the barta (a local name for Kaulback’s pit viper) that the locals fear the most.

Watch your step! Wolfgang Wüster, Author provided

Despite its reputation, our snake is actually not aggressive and rarely attempts to strike – and when it does, it is slow. Curiously, the locals identify the snake that Gerry has just caught as something they call taiji rather than barta, and are adamant that this is a different, less deadly, snake. We count scales and confirm that is a male Kaulback’s pit viper.

As in many pit vipers, female Kaulback’s are bigger and may be more dangerous than males as they guard their eggs near the ground. When we release the male, it heads up a large tree at a leisurely pace; we lose sight of it at around eight metres, still climbing. It is hard to view this beautiful snake as a terrible threat to people. But for the time being we don’t actually know just how dangerous it is – analysis of its venom is needed to confirm that.

Regional anti-venom?

This expedition is part of a larger collaborative study to document the identity and distribution of dangerously venomous snakes and to study their venom in order to reduce the India’s death toll by snakebite which is a massive 45,000 people each year.

Each species of snake has unique venom containing a cocktail of toxins, requiring specific antibodies to neutralise. Even a single species can cause paralysis, blood disorders and tissue damage in varying proportions in different parts of its range.

Snake spotting across the distant, jungle-cloaked hills in Arunachal Pradesh. Anita Malhotra, Author provided

The most effective treatment for snakebite, anti-venom, is still made in the same way as it was when invented in the 19th century, by extracting blood plasma containing antibodies from animals injected with diluted snake venom. It can therefore only effectively neutralise toxins present in the venom mixture used in the immunisation process. Yet all anti-venom in India is currently manufactured predominantly using venom obtained from a single licensed producer.

While several proposed snake farms in different parts of India may soon allow venom from all over India to be used to raise antibodies against a wider range of toxins, more work needs to be done to reduce the dosage, cost of treatment and occurrence of serious side-effects.

Furthermore, none of the “Big Four” (Russell’s viper, spectacled cobra, common krait and saw-scaled viper) against which the Indian anti-venom is manufactured, are found Arunachal Pradesh. Exactly which species are the most deadly there and how many snakebite deaths they cause is unknown.

The spectacled cobra - one of the Big Four Kamalnv/wikimedia, CC BY-SA

Official records of snakebite are virtually non-existent and the tribes in the region are unlikely to go to hospital, even after a life-threatening bite. Emerging evidence from the southern states of India also suggests that the hump-nosed pit viper may be at least as medically significant as the saw-scaled vipers in the few states in which it occurs. This implies that producing regionally specific anti-venom, rather than a single one for all India, might be a better approach.

Permits and policies

Venom research is one of many activities needed to reduce the burden of snakebite – but this is currently hindered by lack of funding and the need for permits to catch snakes, which are strictly protected in India. What’s more, you need to contact each state individually for permits, magnifying the problem considerably.

It is also important to raise awareness of the problem in rural areas – and provide training for primary health care staff, as well as equipping them with vital equipment (such as ventilators) and providing them with direct links to snakebite experts.

A few grass-roots organisations around the country are working on this, but they are largely dependent on volunteers and charitable donations. In some areas of India, doctors specialising in treating snakebite have achieved success rates of 100%, but in a country as large and densely populated as India, it is difficult to see how the burden of snakebite can be reduced substantially without being government-sponsored and properly funded.

In some states, the families of snakebite victims are able to claim up to 1 lakh rupees (about £1,000) as compensation. Ironically, just one year’s potential compensation bill would go a long way to acchieving a long-term reduction in the financial cost of snakebite – let alone the cost in human misery and suffering.

Why we won't be moving to the new 'Earth-like' exoplanet any time soon

Pretty picture (artist's impression) but unlikely scenario. SETI institute

NASA’s announcement of the discovery of a new extrasolar planet that is the closest yet to an Earth 2.0 has been met with a lot of excitement. But the truth is that it is impossible to judge whether it is similar to Earth with the few parameters we have – it might just as well resemble Neptune, Venus or something entirely different.

The planet, Kepler-452b, was detected by the Kepler telescope, which looks for small dips in a star’s brightness as planets pass across its surface. It is a method that measures the planet’s size, but not its mass. Conditions on Kepler-452b are therefore entirely estimated from just two data points: the planet’s size and the radiation it receives from its star.

The habitable-zone myth

Kepler-452b was found to be 60% larger than the Earth. It orbits a sun-like star once every 384.84 days. As a result, the planet receives a similar amount of radiation as we do from the sun; just 10% higher. This puts the Kepler-452b in the so-called “habitable zone”; a term that sounds excitingly promising for life, but is actually misleading.

Looks familiar? Artist’s impression of the new exo-planet and its star NASA

The habitable zone is the region around a star where liquid water could exist on a suitable planet’s surface. The key word is “suitable”. A gas-planet like Neptune in the habitable zone would clearly not host oceans since it has no surface. The habitable zone is best considered as a way of narrowing down candidates for investigation in future missions.

Kepler-452b’s radius puts it on the brink of the divide between a rocky planet and a small Neptune. In the research paper that announced the discovery, the authors put the probability of the planet having a rocky surface about 50%-60%, so it is by no means sure.

Unpredictable geology

Rocky planets like the Earth are made from iron, silicon, magnesium and carbon. While these ingredients are expected to be similar in other planetary systems, their relative quantities may be quite different. Variations would produce alternative planet interiors with a completely different geology.

For example, a planet made mostly out of carbon could have mantles made of diamond, meaning they would not move easily. This would bring plate tectonics to a screeching halt. Similarly, magnesium-rich planets may have thick crusts that are resilient to fractures. Both results would limit volcano activity that is thought to be essential for sustaining a long lasting atmosphere.

Venus and Earth. Similar but oh so different. wikimedia

If Kepler-452b nevertheless has a similar composition to Earth, we run into another problem: gravity. Based on an Earth-like density, Kepler-452b would be five times more massive than our planet.

This would correspond to a stronger gravitational pull, capable of drawing in a thick atmosphere to create a potential runaway greenhouse effect, which means that the planet’s temperature continues to climb. This could be especially problematic as the increasing energy from its ageing sun is likely to be heating up the surface. Any water present on the planet’s surface would then boil away, leaving a super-Venus, rather than a super-Earth.

No neighbours

Another problem is that Kepler-452b is alone. As far as we know, there are no other planets in the same system. This is an issue because it was most likely our giant gas planets that helped direct water to Earth.

At our position from the sun, the dust grains that came together to form the Earth were too warm to contain ice. Instead, they produced a dry planet that later had its water most likely delivered by icy meteorites. These frozen seas formed in the colder outer solar system and were kicked towards Earth by Jupiter’s huge gravitational tug. No Jupiter analogue for Kepler-452b might mean no water and therefore, no recognisable life.

All these possibilities mean that even a planet exactly the same size as Earth, orbiting a star identical to our sun on an orbit that takes exactly one year might still be an utterly alien world. Conditions on a planet’s surface are dictated by a myriad of factors – including atmosphere, magnetic fields and planet interactions, which we currently have no way of measuring.

That does not mean that Kepler-452b is not a fantastic find. It has the longest year of any transiting planet of its size, holding the door open to finding more diverse planetary system. However, whether these discoveries are truly like Earth is a problem we cannot yet tackle.

UK satellite Twinkle will boost search for Earth-like exoplanets

Exoplanets: we know a little, but not a lot. Goddard Space Flight Centre

NASA’s recent discovery of 12 more exoplanets, including the most Earth-like yet, brings the number of exoplanets – those outside our solar system – discovered to nearly 2,000. It’s now thought that almost every star has a planetary system, with Earth just one of several billion planets in our galaxy alone.

Many of the exoplanets we’ve found are quite different to those in our solar system: “hot-Jupiters” are giant planets orbiting very close to their star, while “super-Earths” are rocky planets up to ten times the mass of Earth. The newly discovered Kepler-452b is the first exoplanet that is relatively similar to Earth in size and within the habitable zone around its star – not too hot and not too cold – that might be able to support life.

The Twinkle satellite, observing exoplanets twinkling far away. Twinkle/SSTL/UCL, Author provided

But really we know very little about these alien worlds beyond their mass, density and distance from their star. What are they made of? How did they form? What’s the weather like there? Our small and fast-track satellite observatory dedicated to studying exoplanets, Twinkle, aims to answer these questions.

It’s a huge challenge, since exoplanets are so far away. Most have been detected only indirectly – by a star’s dip in brightness as a planet passes in front of it, or by looking for a wobble in a star’s position caused by an orbiting planet’s gravitational tug. A very few have been imaged directly but, due to their enormous distance from Earth, they are no more than pinpricks of light.

However, even a tiny amount of light can reveal a huge amount of information. In recent years, we have pioneered techniques to extract information about exoplanets from starlight filtered through their atmospheres as they pass in front of their star.

NASA Solar Dynamics Observatory records transit of Venus across the sun, in the same way that exoplanets are detected.

It’s all in the waves

Spectroscopy allows us to split light – in this sense, the entire electromagnetic spectrum, not just that visible to the human eye – into a “rainbow” of its constituent parts so it can be examined in detail. Molecules formed from the periodic table’s elements absorb specific wavelengths from the electromagnetic spectrum, leaving a unique pattern of lines, a bit like a barcode. By detecting and separating out these barcodes we can identify the tell-tale footprints of the elements present, and therefore which gases the exoplanets’ atmospheres contain.

The composition of an exoplanet’s atmosphere can reveal whether a planet formed in its current orbit, or whether it migrated from a different part of its planetary system. The evolution, chemistry and physical processes driving an exoplanet’s atmosphere are strongly affected by the distance from its parent star. The loss of lighter molecules, impacts with other bodies such as comets or asteroids, volcanic activity, or even life can significantly alter the composition of primordial atmospheres. So a planet’s atmospheric composition traces its history, and gives an indication as to whether it might be habitable – or even host life.

Eyes in the sky

However, aside from the Hubble and Spitzer space telescopes, both nearing the end of their lives, there is currently a gap in facilities suitable for studying, rather than finding, exoplanets. Space missions such as ARIEL, a European candidate mission competing for launch in 2026, won’t be available for a decade or more. Upcoming general observatories, like the James Webb space telescope or E-ELT may have some of the capabilities needed, but time available on these for exoplanet research will be limited.

This is what led us to develop Twinkle: a small, relatively low-cost at £50m commercial mission dedicated to studying exoplanets. The Twinkle satellite will be built in the UK using a platform designed by Surrey Satellite Technology Ltd and instrumentation led by UCL.

How Twinkle’s instruments capture data from exoplanets. Twinkle/SSTL/UCL, Author provided

Putting a low cost approach to work for science in space

From a vantage point in orbit 700km above the Earth, Twinkle will observe more than 100 planets orbiting distant stars, its instruments analysing light in the visible and near-infrared wavelengths (from 0.5 to 5 micrometers). It will be able to detect a range of molecules including water vapour, carbon dioxide and exotic metallic compounds, and organic molecules such as methane, acetylene and ethane. It will also be sensitive to precursors to amino acids – the building blocks of life – such as ammonia and hydrogen cyanide.

By measuring the visible light reflected by an exoplanet and the infrared heat that it emits, Twinkle will work out the planet’s energy balance, its temperature and whether clouds are present or absent in the atmosphere. For very large planets orbiting very bright stars, Twinkle will even be able to obtain 2-D maps of temperature and clouds. With repeated observations over the five-year lifetime of the mission, this will tell us about climate and weather on those planets.

As an independent endeavour funded through a mixture of private and public sources, Twinkle is pioneering a new model for astronomy missions. The spacecraft’s structure will be a platform developed for high-resolution Earth imaging, while the instruments will use off-the-shelf components and reuse existing software to bring down costs and increase reliability. With studies already underway, the instruments should be completed by the end of this year, the aim being to launch in 2019.

The consortium includes more than 15 UK research institutions and companies so far and continues to grow – hopefully kickstarting a new era of exoplanet science, but also demonstrating the feasibility of small, nimble and cost-effective science projects.

Fossil from Brazil sheds light on how snakes lost their legs

Snake ancestor was crawly as well as creepy. Dave Martill, University of Portsmouth

How did the snake get its slither? Ever since the crafty serpent in Genesis tempted Eve into eating the forbidden fruit, we’ve been fascinated by snakes. And, despite our interest in this animal, we have a poor understanding of how it actually evolved. But scientists have now released a new study on the fossil of a snake that appears to have lived between 100m and 146m years ago. And what’s more it had legs.

The reasons we know so little about snake evolution is because there are so few fossils. Molecular data suggests that snakes appeared within the squamate family tree – including lizards and amphibians without limbs – sometime in the Jurassic (more than 150m years ago). However, the oldest known undisputed fossil snakes are much younger, from the Cretaceous (about 110m years ago).

The worm-like slender glass lizard. Dawson/wikimedia, CC BY-SA

While snakes are thought to be a single evolutionary group, sharing a common ancestor, the evolution of limblessness is actually quite a common feature of squamate evolution. The loss of limbs, correlated with body elongation, has occurred during the evolution of more than 20 members of this group of vertebrates. An example are the flap-footed lizards called Pygopodidae, which look very similar to snakes.

Perhaps there is a biomechanical reason for this kind of evolution? If the body evolves to get longer and longer, it may be physically harder to effectively use legs and arms. In the case of snakes, some fossils are known that document one part of this transition, showing that, earlier in their evolution, some snakes had hindlimbs. This has also led to suggestions that these squamates evolved from animals in the oceans.

A body for burrowing

But the new fossil, Tetrapodophis, from Brazil, has four intact limbs and a super-elongate body – similar to modern snakes. Interestingly it also has many more vertebrae than is normal for any snake known so far, living or fossil.

Well preserved specimen. Dave Martill, University of Portsmouth.

This fossil suggests that this body structure would work for burrowing rather than swimming. That’s one reason why it is so important – it implies that snakes evolved on land rather than in the sea.

Aside from being critical to new understanding of the early evolution of snakes, this fossil is also interesting in a wider palaeontological context.

As I have argued previously argued, fossil collecting is a field in which anyone can, and should, be encouraged to participate. Fossils housed in all kinds of collections should form the basis of our scientific work.

Artist’s impresion of the four-legged snake. Julius T Cstonyi

Many people, including some professional societies, argue that only fossils curated and reposited in recognised public institutions (such as museums and universities) should be worked on and appear in scientific journals.

According to this paper, the snake fossil specimen is part of a private collection, where it was housed for many decades before its importance was realised. The owner has now placed it in the long-term care of the Bürgermeister-Müller-Museum in Germany. However, many of us working in the field are hoping that it will be returned to Brazil in the near future.