Rising anxiety about air pollution, physical, and mental health, exacerbated by Covid-19 and concerns about public transport, has seen an increase in the popularity of cycling around Europe, leading many cities to transform their infrastructure correspondingly.
These days, Amsterdam is synonymous with cycling culture. Images of thousands of bikes piled up in tailor-made parking facilities continue to amaze and it is routinely held up as an example of greener, cleaner, healthier cities. Because The Netherlands is so flat, people often believe it has always been this way. But, in the 1970s, Amsterdam was a gridlocked city dominated by cars. The shift to cycling primacy took work and great public pressure.
For some cities, however, the pandemic has provided an unexpected opportunity on the roads. Milan's Deputy Mayor for Urban Planning, Green Areas and Agriculture, Pierfrancesco Maran, has explained that, "We tried to build bike lanes before, but car drivers protested". Now, however, numbers have increased from 1,000 to 7,000 on the main shopping street. "Most people who are cycling used public transport before”, he said. “But now they need an alternative”.
Creating joined up cycling networks is a major challenge for urban planners.
In Paris, the Deputy Mayor David Belliard does not seem concerned that the city’s investment since the start of the pandemic will go to waste. “It's like a revolution," he said. “Some sections of this road are now completely car-free. The more you give space for bicycles, the more they will use it.” They are committed to creating a cycle culture, providing free cycling lessons and subsidising the cost of bike repairs. The city intends to create more than 650km of cycle lanes in the near future.
The success in these two cities has been supported by local government but it has also been fuelled by an understandable (and encouraged) avoidance of public transport and fewer cars on the road generally. Going forward, however, it seems likely that those last two factors won’t be present. So how do you create a cycling culture in your city in the long run?
The answer is both simple and difficult: cyclists (and pedestrians) need to have priority over cars. In Brussels, where 40km of cycle track have been put down in the last year, specific zones have been implemented where this is the case, and speed limits have been reintroduced across the city.
In Copenhagen, in the late 1970s, the Danish Cyclists’ Federation arranged demonstrations demanding more cycle tracks and a return to the first half of the century, when cyclists had dominated the roads. Eventually, public pressure paid off — although there is still high demand for more cycle lanes. A range of measures, including changes made to intersections, make cyclists feel safer and local studies show that, as cyclist numbers increase, safety also increases. In many parts of the city, it is noticeable how little of the wide roads are actually available to cars: bikes, joggers, and pedestrians are all accommodated.
Segregated cycleways, like this one in Cascais, Portugal, make people more likely to cycle.
But, if you were starting from scratch, you might not simply add cycle lanes to existing roads and encourage behavioural changes on the road. Segregated, protected bike lanes like those introduced in Paris are the next level up and the results suggest they work — separated from the roads, more people are inclined to try cycling.
Dutch experts suggest, where possible, going even further. Frans Jan van Rossem, a civil servant specialising in cycling policy in Utrecht, believes the best option is to create solitary paths, separated from the road by grass, trees, or elevated concrete. Consistency is also important. Cities need networks of cycle tracks, not just a few highways. Again, prioritising cyclists is key to the Dutch approach. Many cities have roads where cars are treated as guests, restricted by a speed limit of 30km/hour and not permitted to pass. Signage is also key.
In London, Mayor Sadiq Khan’s target is for 80% of journeys to be made by walking, cycling, and/or public transport by 2041. Since 2018, the city has been using artificial intelligence to better understand road use in the city and plan new cycle routes in the capital. However, the experience of other European capitals suggests that, "if you build it, they will come" might be a better approach than working off current usage.
A completely clean, renewable energy system that can be produced locally and that can easily power heat, energy storage and transportation, and travel — that's the future that promoters of a hydrogen economy envisage.
If it sounds a bit like rocket science, that's because it is. Hydrogen is what's used to fuel rockets — that’s how powerful it is. In fact, it’s three times more powerful as a fuel than gas or other fossil-based sources. And, after use, it’s frequently converted to drinking water for astronauts.
US President Joe Biden has highlighted the potential of hydrogen in his ambitious plans for economic and climate recovery and a number of recent reports have been encouraging about hydrogen’s breakthrough moment, including McKinsey and Company (Road Map to a US Hydrogen Economy, 2020) and the International Energy Agency.
Hydrogen fuel cells provide a tantalising glimpse into our low-carbon future
The McKinsey report claims that, by 2030, the hydrogen sector could generate 700,000 jobs and $140bn in revenue, growing to 3.4 million jobs and $750bn by 2050. It also believes it could account for a 16% reduction in CO2 emissions, a 36% reduction in NOx emissions, and supply 14% of US energy demand.
So how does it work?
Simply put, hydrogen fuel cells combine hydrogen and oxygen atoms to produce electricity. The hydrogen reacts with oxygen across an electrochemical cell and produces electricity, water, and heat.
This is what gets supporters so excited. In theory, hydrogen is a limitless, incredibly powerful fuel source with no direct emissions of pollutants or greenhouse gases.
So what's the problem?
Right now, there are actually a few problems. The process relies on electrolysis and steam reforming, which are extremely expensive. The IEA estimates that to produce all of today’s dedicated hydrogen output from electricity would require 3,600TWh, more than the total annual electricity generation of the European Union.
Moreover, almost 95% of hydrogen currently is produced using fossil fuels such as methane, natural gas, or coal (this is called "grey hydrogen"). Its production is responsible for annual CO2 emissions equivalent to those of Indonesia and the United Kingdom combined. In addition, its low density makes it difficult to store and transport — it must be under high pressure at all times. It’s also well-known for being highly flammable — its use as a fuel has come a long way since the Hindenburg Disaster but the association still makes many people nervous.
A Hydrogen refuelling station Hafencity in Hamburg, Germany. Infrastructure issues must be addressed if we are to see more hydrogen-fuelled vehicles on our roads. | Image credit: fritschk / Shutterstock.com
So there are quite a few problems. What’s the good news?
In the last few years, we've seen how rapidly investment, innovation, and infrastructure policy can completely transform individual renewable energy industries. For example, the IEA analysis believes the declining costs of renewables and the scaling up of hydrogen production could reduce the cost of producing hydrogen from renewable electricity 30% by 2030.
Some of the issues around expense could be resolved by mass manufacture of fuel cells, refuelling equipment, and electrolysers (which produce hydrogen from electricity and water), made more likely by the increased interest and urgency. Those same driving forces could improve infrastructural issues such as refuelling stations for private and commercial vehicles, although this is likely to require coordination between various stakeholders, including national and local governments, industry, and investors.
The significant gains in renewable energy mean that “green” hydrogen, where renewable electricity powers the electrolysis process, is within sight.
The IEA report makes clear that international co-operation is “vital” to progress quickly and successfully with hydrogen energy. R&D requires support, as do first movers in mitigating risks. Standards need to be harmonised, good practice shared, and existing international infrastructure built on (especially existing gas infrastructure).
If hydrogen can be as efficient and powerful a contributor to a green global energy mix as its proponents believe, then it's better to invest sooner rather than later. If that investment can help power a post-Covid economic recovery, even better.
Thinking of popping to your nearest specialist store for some sesame oil, turmeric, or soy? Some things haven't changed in 3,700 years, it turns out...
At least, that's what a growing new field of research, palaeoproteomics, suggests. Human mouths are full of bacteria, which continually petrify and form dental calculus — which can entrap and preserve tiny food particles. These remnants can be accessed and analysed thousands of years later, providing remarkable insight into the dietary habits of our ancestors.
Philip Stockhammer, an archaeologist at the Ludwig Maximilian University of Munich (LMU), has worked with Christina Warinner, a molecular archaeologist at Harvard University and the Max Planck Institute for the Science of Human History, and a team of researchers to apply this new method to the eastern Mediterranean, including the Bronze Age site of Megiddo and the Early Iron Age site of Tel Erani.
“Our high-resolution study of ancient proteins and plant residues from human dental calculus is the first of its kind to study the cuisines of the ancient Near East,” said Warinner, explaining its significance. “Our research demonstrates the great potential of these methods to detect foods that otherwise leave few archaeological traces. Dental calculus is such a valuable source of information about the lives of ancient peoples.”
High-resolution analyses of ancient dental calculus have given us a whole new perspective on the diets of Bronze Age people.
The research team took samples from a range of individuals and analysed which food proteins and plant residues were preserved in their teeth. “This enables us to find traces of what a person ate,” said Stockhammer. “Anyone who does not practice good dental hygiene will still be telling us archaeologists what they have been eating thousands of years from now!”
Of course, it's not quite as simple as looking at the teeth of those who didn't thoroughly clean them nearly four millennia ago and hoping the proteins survived. “Interestingly, we find that allergy-associated proteins appear to be the most stable in human calculus”, remarked Ashley Scott, LMU biochemist and lead author. That might be because of the known thermostability of many allergens. For instance, the researchers were able to detect wheat via wheat gluten proteins, which they independently confirmed with a different method using a type of plant microfossil known as phytoliths.
This substance has previously been used to identify millet and date palm in the same area during the Bronze and Iron Ages but phytoliths are not plentiful or even present in many foods, which is why this research is so exciting — palaeoproteomics means foods that have left few other traces, such as sesame, can now be identified.
Research suggests that the humble banana was eaten throughout the Mediterranean far earlier than first thought.
The method has allowed the team to identify that people at these sites ate, among other things, sesame, turmeric, soy, and bananas far earlier than anyone had realised. “Exotic spices, fruits and oils from Asia had thus reached the Mediterranean several centuries, in some cases even millennia, earlier than had been previously thought,” explained Stockhammer.
The finds mean that we have direct evidence for a flourishing long-distance trade in fruits, spices, and oils, from East and South Asia to the Levant via Mesopotamia or Egypt as early as the second millennium BCE.
More than that, the analyses "provide crucial information on the spread of the banana around the world. No archaeological or written evidence had previously suggested such an early spread into the Mediterranean region,” according to Stockhammer (although the sudden appearance of bananas in West Africa a few centuries later has previously led archaeologists to believe that such a trade might have existed, this is the first evidence).
The team acknowledged that other explanations are possible, including that the individuals concerned had travelled to East or South Asia at some point but there is evidence for other trade in food and spices in the Eastern Mediterranean — for instance, we know Pharaoh Ramses II was buried with peppercorns from India in 1213 BCE.
But it certainly seems like some foods might have been popular in the Mediterranean for much longer than we realised, which might be an interesting thought to accompany you next time you add some spices or bananas to your shopping basket.
Where once a country might have wanted to strike gold, now hitting upon a hydrocarbon find feels like a prize. But finding a hydrocarbon is only the beginning of the process and might not be worth it — as Lebanon is discovering.
First, a little background: for some time, Lebanon has been experiencing an energy crisis. Without resources of their own, the industry (which is government-owned) is reliant on foreign imports, which are expensive. Electricity in early 2020 was responsible for almost 50% of Lebanon's national debt. Major blackouts were common.
This contributed to a spiralling financial crisis, prompting public protests and riots as the middle class disappeared and even wealthier citizens struggled. Before Covid-19 and the devastating August 2020 blast in Beirut, Lebanon was in crisis.
The idea that the country might be able to switch from foreign oil to local gas was understandably appealing, especially when a major find was literally right there on the Lebanese shore. In 2019, a consortium of Israeli and US firms discovered more than 8tcm of natural gas in several offshore fields in the Eastern Mediterranean, much of it in Lebanese waters.
A hydrocarbon find off the Beirut coast has failed to live up to its early promise.
But a find is only the beginning. With trust in Lebanese politicians low (the country ranks highly in most government corruption indexes) and a system that has repeatedly struggled to deliver a stable government, there are additional difficulties, not least a delay in the licensing rounds and a lack of trust — both internally, from citizens, and externally, from potential bidders. Meanwhile, Lebanon's neighbours race ahead to exploit their own finds, which ratchets up tensions.
Amid all that, a drilling exploration managed to go ahead last summer. But the joint venture between Total, ENI, and Novatek, which operated a well 30km offshore Beirut and drilled to approximately 1,500 metres, did not bring back the hoped-for results. The results confirmed the presence of a hydrocarbon system generally but did not encounter any reservoirs of the Tamar formation, which was the target.
Offshore exploration is a long process, with a lot of challenges and uncertainties and Ricardo Darré, Managing Director of Total E&P Liban, said afterwards, "Despite the negative result, this well has provided valuable data and learnings that will be integrated into our evaluation of the area". But the faith national politicians have long put in the hydrocarbon find, selling it as an answer to all Lebanon's problems, seems to have only worsened the domestic situation since.
And domestic politics is just the start of the problems…
Unlike other countries in the Middle East, Lebanon has no pipeline infrastructure of its own.
Israel, Egypt, and Jordan already have pipelines, which go to Italy. Turkey is working with Libya on a pipeline. Lebanon has no pipeline infrastructure of its own yet, although Russia has storage facilities and pipelines in the country and an eye on possible competition in the gas market.
None of that is an issue if the supply is intended for domestic use but that might not be profitable enough for investors and the Lebanese government would struggle to underwrite production on its own. Cyprus has encountered similar issues exploiting its share of the find.
Lebanon has also set an ambitious goal of having 30% of domestic energy mix sourced from renewable energy by 2030. The hoped-for gas was intended to support the renewable energy mix but, with the clock ticking, it might be that priorities shift to focusing on renewables. The Covid-19 pandemic will significantly impact the budgets of drilling companies and the push for renewable energy, both from governments and investors, seems to be growing as a way to boost economic recovery.
It may be that, after all the excitement around the hydrocarbon find, Lebanon starts to look elsewhere for its energy provision.
The world’s biggest ever survey of public opinion on climate change was published on 27th January, covering 50 countries with over half of the world’s population, by the United Nations Development Programme (UNDP) and the University of Oxford. Of the respondents, 64% believe climate change is a global emergency, despite the ongoing Covid-19 pandemic, and sought broader action to combat it. Earlier in the month, US President Joe Biden reaffirmed the country's commitment to the Paris Agreement on Climate Change.
It is possible that the momentum, combined with the difficulties many countries currently face, may make many look again to geoengineering as an approach. Is it likely that large scale engineering techniques could mitigate the damage of carbon emissions? And is it safe to do so or could we be exacerbating the problem?
The term has long been controversial, as have many of the suggested techniques. But it would seem that some approaches are gaining more mainstream interest, particularly Carbon Dioxide Removal (CDR) and Solar Radiation Modification (SRM), which the 2018 Intergovernmental Panel on Climate Change (IPCC) report for the UN suggested were worth further investigation (significantly, it did not use the term "geoengineering" and distinguished these two methods from others).
One of the most covered CDR techniques is Carbon Capture and Storage (CCS) or Carbon Capture, Utilisation, and Storage (CCUS), the process of capturing waste carbon dioxide, usually from carbon intensive industries, and storing (or first re-using) it so it will not enter the atmosphere. Since 2017, after a period of declining investment, more than 30 new integrated CCUS facilities have been announced. However, there is concern among many that it will encourage further carbon emissions when the goal should be to reduce and use CCS to buy time to do so.
CDR techniques that utilise existing natural processes of natural repair, such as reforestation, agricultural practices that absorb carbon in soils, and ocean fertilisation are areas that many feel could and should be pursued on a large scale and would come with ecological and biodiversity benefits, as well as fostering a different, more beneficial relationship with local environments.
A controversial iron compound deposition approach has been trialled to boost salmon numbers and biodiversity in the Pacific Ocean.
The ocean is a mostly untapped area with huge potential and iron fertilisation is one very promising area. The controversial Haida Salmon Corporation trial in 2012 is perhaps the most well-known example and brings together a lot of the pros and cons frequently discussed in geoengineering — in many ways, we can see it as a microcosm of the bigger issue.
The trial deposited 120 tonnes of iron compound in the migration routes of pink and sockeye salmon in the Pacific Ocean 300k west of Haida Gwaii over a period of 30 days, which resulted in a 35,000km2, several month long phytoplankton bloom that was confirmed by NASA satellite imagery. That phytoplankton bloom fed the local salmon population, revitalising it — the following year, the number of salmon caught in the northeast Pacific went from 50 million to 226 million. The local economy benefited, as did the biodiversity of the area, and the increased iron in the sea captured carbon (as did the biomass of fish, for their lifetimes).
Small but mighty, phytoplankton are the laborers of the ocean. They serve as the base of the food web.
But Environment Canada believes the corporation violated national environmental laws by depositing iron without a permit. Much of the fear around geoengineering is how much might be possible by rogue states or even rogue individuals, taking large scale action with global consequences without global consent.
The conversation around SRM has many similarities — who decides that the pros are worth the cons, when the people most likely to suffer the negative effects, with or without action, are already the most vulnerable? This is a concern of some of the leading experts in the field. Professor David Keith, an expert in the field, has publicly spoken about his concern around climate change and inequality, adding after the latest study that, "the poorest people tend to suffer most from climate change because they’re the most vulnerable. Reducing extreme weather benefits the most vulnerable the most. The only reason I’m interested in this is because of that."
But he doesn't believe anywhere near sufficient research has been done into the viability of the approach or the possible consequences and cautions that there is a need for "an adequate governance system in place".
There is no doubt that the research in this field is exciting but there are serious ethical and governance problems to be dealt with before it can be considered a serious component of an emissions reduction strategy.
We are increasingly conscious of the need to recycle waste products, but it is never quite so easy as rinsing and sorting your waste into the appropriate bins, especially when it comes to plastic.
Despite our best intentions, only around 16% of plastic is recycled into new products — and, worse, plastics tend to be recycled into low quality materials because transformation into high-value chemicals requires substantial amounts of energy, meaning the choices are either downcycling or prohibitively difficult. The majority of single-use plastics end up in landfills or abandoned in the environment.
This is a particular problem when it comes to polyolefins such as polyethylene (PE) and polypropylene (PP), which use cheap and readily available raw materials. Approximately 380 million tonnes of plastics are generated annually around the world and it is estimated that, by 2050, that figure will be 1.1 billion tonnes. Currently, 57% of this total are polyolefins.
Why are polyolefins an issue? The strong sp3 carbon–carbon bonds (essentially long, straight chains of carbon and hydrogen atoms) that make them useful as a material also make them particularly difficult to degrade and reuse without intensive, high energy procedures or strong chemicals. More than most plastics, downcycling or landfill disposal tend to be the main end-of-life options for polyolefins.
Polyethylene is used to make plastic bags and packaging.
Now, however, a team of scientists from MIT, led by Yuriy Román-Leshkov, believe they may have made a significant step towards solving this problem.
Previous research has demonstrated that noble metals, such as zirconium, platinum, and ruthenium can help split apart short, simple hydrocarbon chains as well as more complicated, but plant-based lignin molecules, in processes with much lower temperatures and energy.
So the team looked at using the same approach for the long hydrocarbon chains in polyolefins, aiming to disintegrate the plastics into usable chemicals and natural gas. It worked.
First, they used ruthenium-carbon nanoparticles to convert more than 90% of the hydrocarbons into shorter compounds at 200 Celsius (previously, temperatures of 430–760 Celsius were required).
Next, they tested their new method on commercially available, more complex polyolefins without pre-treatment (an energy intensive requirement). Not only were the samples completely broken down into gaseous and liquid products, the end product could be selected by tuning the reaction, yielding either natural gas or a combination of natural gas and liquid alkanes (both highly desirable) as preferred.
Polypropylene is used in bottle caps, houseware, and other packaging and consumer products.
The researchers believe that an industrial scale use of their method could eventually help reduce the volume of post-consumer waste in landfills by recycling plastics to desirable, highly valuable alkanes — but, of course, it's not that simple. The team says that more research into the effects of moisture and contaminants in the process is required, as well as product removal strategies to decrease the formation of light alkanes which will be critical for the industrialisation of this reaction.
However, they believe the path they're on could lead to affordable upcycling technology that would better integrate polyolefins into the global economy and incentivise the removal of waste plastics from landfill and the environment.
More about the study can be read here:
The theme of the 2021 World Economic Forum’s Davos Agenda was ‘The Great Reset’ and how the world might recover from the effects of Covid-19. Because of the current circumstances, the forum was split into two parts, with a virtual meeting held January 25-29 and an in-person gathering planned for May 13-16, in Singapore.
Each day of the January summit was dedicated to discussing a key area for recovery. On Monday, January 25, the focus was on designing cohesive, sustainable and resilient economic systems. On Tuesday, delegates discussed how to drive responsible industry transformation and growth, while on Wednesday they spoke about enhancing the stewardship of our global commons. Thursday's talks centred on harnessing the technologies of the Fourth Industrial Revolution, and on Friday attendees discussed ways to advance global and regional cooperation.
With the International Labor Organization jobs report, published at the start of the week, stating that at least 225 million jobs vanished worldwide over the past year (four times more than the 2008 global financial crisis) and concerns that vaccine nationalism will see the pandemic continue to ravage many less wealthy nations, much of the talk was around equality and unity.
Christine Lagarde, President of the European Central Bank, spoke in Monday's meeting. ‘Once we’re through to the "second phase" of the 2021 Covid-19 recovery,’ Lagarde said, ‘it is most likely going to be a new economy, which will be associated with positive developments and also with challenges.’ Many advanced economies, she noted, particularly in Europe, have jumped forward in terms of digitalisation, some by up to seven years.
Christine Lagarde, President of the European Central Bank, has called for continued support for the digital-centred, post-pandemic economy. | Credit: Alexandros Michailidis / Shutterstock.com
She added that it is likely that there will be a 20% increase in the amount of people working from home post-pandemic, which will have an impact on many economies, and claimed that technological changes are already having positive effects. She said that it is critical to continue ‘favouring and supporting investment into this new economy’ and that on the fiscal and monetary policy front, authorities will have to stay the course and continue to support. At the same time, investment will have to be focused on laying the ground for a new economy.
Ursula von der Leyen, President of the European Commission (EC), agreed about the increase in digitalisation, and reported that the EU hopes ‘the 2020s can finally be Europe’s Digital Decade’, highlighting a number of investments to boost this process, including the startup scenes in cities such as Sofia and Lisbon.
However, she warned that there is a ‘darker side of the digital world,’ noting the assault on Capitol Hill in the US and making clear that ‘The immense power of the big digital companies must be contained. She spoke of the EC's plans ‘to make internet companies take responsibility for content, from dissemination to promotion and removal, and highlighted the Commission’s new rulebooks, the Digital Services Act and the Digital Markets Act.
Ursula von der Leyen, President of the European Commission, believes the 2020s can be Europe’s ‘Digital Decade’. | Credit: John Smith Williams / Shutterstock.com
She invited the US to work together to: ‘Create a digital economy rulebook that is valid worldwide: it goes from data protection and privacy to the security of critical infrastructure. A body of rules based on our values: Human rights and pluralism, inclusion and the protection of privacy.’
Marc Benioff, Salesforce CEO, made a noteworthy intervention in his panel discussion, claiming, ‘There has been a mantra for too long that the business of business is business, but today the business of business is improving the state of the world.’ He added that, while there were many CEOs who had been ‘bad actors,’ others had used their considerable resources to help fight the pandemic.
Many speakers noted a shift towards sustainability in investments, with others demanding more change and faster. Of the latter, Mark Carney, Special Envoy for Climate Action and Finance to the UN, said bluntly, ‘if you are part of the private financial sector and you are not part of the solution […] you will have made the conscious decision not to be aligned to net zero […] if you’re not in, you’re out because you chose to be out.’
It could be concluded that there was a great deal to feel positive about, but the circumstances are difficult. Now we will see whether the attendees of the World Economic Forum can deliver on their inspiring rhetoric.
Galen (129-216 CE) is one of the most famous and influential medical practitioners in history but he was also a scientist, an author, a philosopher, and a celebrity. He wrote hundreds of treatises, travelled and studied widely, was the physician to three emperors, and left a legacy of scientific thought that lasted for fifteen hundred years — even today, his work has an influence.
Header image Editorial credit: Eray Adiguzel / Shutterstock.com
He grew up in Pergamum, an intellectual centre of the Mediterranean world, in a wealthy family that encouraged him to pursue academia and funded his travels to learn in the best environments available, acquiring the latest techniques in medicine and healing.
He understood that diet, exercise, and hygiene were essential for good health and put that into practice in the four years he spent working for the High Priest of Pergamum's Gladiator School. This was a high profile and high pressure role and we know he reduced the death rate dramatically in his four years there. The recommendation he got helped secure him a position in Rome, capital of the empire.
He was not popular in the city — at one point, he seems to have been chased out by the local physicians, who strenuously disagreed with his methods — but he was eventually summoned by the emperor Marcus Aurelius to be his personal physician. He was described by the emperor as, “First among doctors and unique among philosophers".
Galen; Line engraving | Credit: Wellcome Images, Wikimedia Commons
Galen continued to navigate the difficult political environment of the imperial capital and was personal physician to two more emperors, while publishing prolifically and becoming one of the most well-known figures in the Roman Empire. Much of his work is lost to us but we still know a great deal about him, including that he had a flair for showmanship and controversy.
In the Greek world where he grew up, dissections had been common — of animals and humans. In Rome, this was not the case. In fact, human dissections were banned across the empire shortly before Galen arrived in the city. Undaunted, he gave a number of public anatomical demonstrations using pigs, monkeys, sheep, and goats to show his new city what they were missing (this was one of many incidents that contributed to local dislike of his methods as well as his increasing fame).
His legacy was huge, both because he recorded and critiqued the work of others in his field and because of the huge volumes of his own observations and theories. His texts were the foundation for much of medical education in the Islamic, Byzantine, and European worlds until the 17th Century.
The ban on human dissection likely limited his progress in some areas and many of his theories have (eventually) been disproved, such as the theory of the four humours — blood, black bile, yellow bile, and phlegm — based on Hippocrates' system and elaborated, as well as the efficacy of bloodletting.
Galen observed that cataracts could be removed.
In other areas, however, he was remarkably successful. He observed that the heart has four valves that allow blood to flow in only one direction, that a patient's pulse or urine held clues to their disease, that urine forms in kidneys (previously thought to be the bladder), that arteries carry liquid blood (previously thought to be air), that cataracts could be removed from patients' eyes, among others. He also identified seven of the 12 cranial nerves, including the optic and acoustic nerves.
His focus on practical methods such as direct observation, dissection, and vivisection is obviously still relevant to modern medical research. Indeed, scientists who disproved his theories, such as Andreas Vesalius and Michael Servetus in the 16th century, did so using Galen's own methods.
The study of his work remains hugely important to the history and understanding of medicine and science, as well as the ancient world. The Galenic formulation, which deals with the principles of preparing and compounding medicines in order to optimise their absorption, is named after him.