Extinction of nature's giants tracks human expansion across the globe
When did humanity's destructive
relationship with nature
begin? Was it the unleashing of neoliberal market reforms in the 1980s? Was it the dawn of the Industrial Revolution in the late 1700s? Or even the beginning of the era of capitalist colonialism in the late 1490s?
Or does it go back further, to the rise in agriculture, or organised religion that granted on to men dominion over all the beasts of the earth? While these are all important points of inflection in our troubled relationship with nature, none point neatly to a juncture where peaceful harmony gave way to something darker in the human spirit.
Last year,
a fascinating paper
published by a team from Aarhus University in Denmark, tells the remarkable tale of early modern humans and their relationship with the giants that had, up to then, ruled the land for millions of years. Large animals, referred to as 'megafauna', dominated terrestrial ecosystems in a way that is hard to imagine today.
For instance, there are only three species of elephant in Africa and parts of southern Asia, but until quite recently, 12 other elephants roamed throughout Europe, the Americas and across Asia as far as the high Arctic. There were
distinct species
of dwarf elephants living on islands, including off the coast of California and in the Mediterranean, including Cyprus and Sicily (later, the unearthing of their skulls would inspire myths of the Cyclops).
READ MORE
Many of these mammoths and mastodons were huge, well over 1,000kg, but they were not alone. There were 16 types of ground sloths (one nearly as tall as a modern African elephant), giant marsupials in Australia, an armadillo the size of a small car in South America and an American beaver twice the size of those that exist today.
Then there were the carnivores: sabre-toothed cats, dire wolves and cave bears (both substantially bigger than their surviving relatives). There were lions and rhinos across Europe and America. The world was also inhabited by monster birds, including the flightless moas in New Zealand, some up to 3m in height, and Haast's eagle, the largest eagle ever to have existed, up to twice the size of the largest eagle in existence today.
Due to their large size and abundance, the megafauna shaped the ecosystems in which they lived, but today they are nearly all gone. From 50,000 years ago, their signature in the fossil record starts to flicker out. Today, only 11 out of 57 species weighing in at more than one tonne survive, while nearly half of the animals in the 100-1,000kg size range also disappeared. The researchers from Aarhus refer to this 'simplification' of the fauna as 'unique on a 30 million-year timescale.'
When the bones of the megafauna started to be unearthed by European scientists in the 1700s, they caused bafflement. Extinction was not an accepted concept at the time, indeed, it was heretical to believe that God, after creating a perfect world, would allow any of his creations to disappear.
Thomas Jefferson, third president of the United States, fervently hoped that America's elephant, the mastodon, still roamed the western parts of the Continent which were then unknown to white people. As evidence grew from around the world, and it became clear that extinction was a real phenomenon, investigation into the vanishing of the megafauna narrowed to two prime suspects: changing climate or 'overkill', the idea that early hunter-gatherers hunted the great beasts off the face of the earth.
However, that debate now seems to be settled, with the Danish researchers finding that 'there is little support' for the climate-driven theory'. There are two principal reasons which point the finger at humans: first, the extinction was heavily biased towards the largest animals on land, smaller animals were much less affected while plants, and animals in the ocean, not at all.
Second, the time frame over which extinctions occurred tracks closely the expansion of humans across the world's land bodies. Africa, where the human story begins, is not so much affected (though it doesn't escape completely). But as people spread to Asia, Europe and Australia, the giants fell. In the Americas, dates for extinction match the arrival of people 15,000 years ago, while the moas and Hast's eagle survived in New Zealand up to human colonisation in the 1400s.
Jens-Christian Svenning is the lead author of the paper and believes that rather than looking at the megafauna extinctions as an 'event', it is instead 'the start of humanity's transformation of the biosphere', something that continues to this day.
Populations of surviving megafauna are in a 'dire state' says his paper and nearly half of all mammals today weighing more than 10kg are threatened with extinction. He notes that 'it's a process that likely has very deep roots, the start of it is probably a million years ago but became really apparent from about 50,000 years ago'.
That humans are the cause can still stoke debate, but at this stage, Svenning seems confident to brush this off. 'To be completely honest, the relation to humans, and the lack of a consistent relationship to climate, is a very clear pattern. From that perspective, it's weird that it's still controversial ... People undervalue how resourceful and impactful hunter-gatherer people have been.
'In Europe, there is a strong tendency to interpret the ecosystems before agriculture as natural, implying that people hardly had any influence on their environment before that. But people 50,000 years ago were just as capable as we are ... there's no reason why they wouldn't try to manipulate their environment for their own benefit ... the ideal of the 'noble savage' is still quite prevalent.'
Svenning notes that at the scale of a human lifetime, extinctions happened over a very prolonged period (woolly mammoths survived in Siberia right up to 4,300 years ago) so people were likely unaware of the impact of their actions, something that can't be said for us today.
Humans and our ancestors have been hunting large animals for a long time, and possibly precipitated extinctions even before the arrival of modern humans. 'It's well established that Neanderthals killed straight-tusked elephants in Europe,' he points out, however their impact was limited due to their small population sizes (it is also notable that Neanderthals also went extinct with the rise of Homo sapiens). Human impact was not related, therefore, only to their capabilities, but to their expansion in numbers.
The consequences of the absence of large herbivores, which play key roles in seed dispersal, spreading of nutrients and the structure of vegetation, have been profound. Less grazing has meant more growth of woody plants, which, depending on the climate, leads to more fires, a pattern that is perpetuated to this day with the absence of large grazers that were common even a few centuries ago. As for the impact on climate, the picture is complicated as multiple effects are likely to have had warming and cooling effects.
Today, wild animals only make up a mere 4 per cent of the total mass of mammals in the world. Today's megafauna is mostly made up of cattle and other domestic animals and there have been suggestions from some in the livestock industry that the overall effect on the planet is neutral.
However, today's 1.5 billion cattle, many of which are confined for some or all of their lives, eating processed foodstuffs and prevented from displaying their natural behaviours, are no substitute for healthy natural ecosystems.
Whole processes, driven by a fantastic diversity of animals, such as migration, predation, seed dispersal, decomposition and scavenging, are now absent from swathes of Earth's land surface.
'I'm pretty sure we have a lot more livestock now, and a lot more [methane-emitting] ruminants than there were wild animals in the past,' says Svenning. 'The way we keep the livestock is completely non-analogue to naturally living megafauna, there's no doubt it's not comparable.
'If one wanted to have more sustainable livestock production from a climate and biodiversity perspective, the way to go is low intensity, low stocking rates, such as in European semi-natural landscapes, that's very possible. Of course, the consequence of this is that the production is much, much lower. So, it means there won't be so much meat available for everybody to consume. That's simply impossible.'
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Irish Times
4 hours ago
- Irish Times
Extinction of nature's giants tracks human expansion across the globe
When did humanity's destructive relationship with nature begin? Was it the unleashing of neoliberal market reforms in the 1980s? Was it the dawn of the Industrial Revolution in the late 1700s? Or even the beginning of the era of capitalist colonialism in the late 1490s? Or does it go back further, to the rise in agriculture, or organised religion that granted on to men dominion over all the beasts of the earth? While these are all important points of inflection in our troubled relationship with nature, none point neatly to a juncture where peaceful harmony gave way to something darker in the human spirit. Last year, a fascinating paper published by a team from Aarhus University in Denmark, tells the remarkable tale of early modern humans and their relationship with the giants that had, up to then, ruled the land for millions of years. Large animals, referred to as 'megafauna', dominated terrestrial ecosystems in a way that is hard to imagine today. For instance, there are only three species of elephant in Africa and parts of southern Asia, but until quite recently, 12 other elephants roamed throughout Europe, the Americas and across Asia as far as the high Arctic. There were distinct species of dwarf elephants living on islands, including off the coast of California and in the Mediterranean, including Cyprus and Sicily (later, the unearthing of their skulls would inspire myths of the Cyclops). READ MORE Many of these mammoths and mastodons were huge, well over 1,000kg, but they were not alone. There were 16 types of ground sloths (one nearly as tall as a modern African elephant), giant marsupials in Australia, an armadillo the size of a small car in South America and an American beaver twice the size of those that exist today. Then there were the carnivores: sabre-toothed cats, dire wolves and cave bears (both substantially bigger than their surviving relatives). There were lions and rhinos across Europe and America. The world was also inhabited by monster birds, including the flightless moas in New Zealand, some up to 3m in height, and Haast's eagle, the largest eagle ever to have existed, up to twice the size of the largest eagle in existence today. Due to their large size and abundance, the megafauna shaped the ecosystems in which they lived, but today they are nearly all gone. From 50,000 years ago, their signature in the fossil record starts to flicker out. Today, only 11 out of 57 species weighing in at more than one tonne survive, while nearly half of the animals in the 100-1,000kg size range also disappeared. The researchers from Aarhus refer to this 'simplification' of the fauna as 'unique on a 30 million-year timescale.' When the bones of the megafauna started to be unearthed by European scientists in the 1700s, they caused bafflement. Extinction was not an accepted concept at the time, indeed, it was heretical to believe that God, after creating a perfect world, would allow any of his creations to disappear. Thomas Jefferson, third president of the United States, fervently hoped that America's elephant, the mastodon, still roamed the western parts of the Continent which were then unknown to white people. As evidence grew from around the world, and it became clear that extinction was a real phenomenon, investigation into the vanishing of the megafauna narrowed to two prime suspects: changing climate or 'overkill', the idea that early hunter-gatherers hunted the great beasts off the face of the earth. However, that debate now seems to be settled, with the Danish researchers finding that 'there is little support' for the climate-driven theory'. There are two principal reasons which point the finger at humans: first, the extinction was heavily biased towards the largest animals on land, smaller animals were much less affected while plants, and animals in the ocean, not at all. Second, the time frame over which extinctions occurred tracks closely the expansion of humans across the world's land bodies. Africa, where the human story begins, is not so much affected (though it doesn't escape completely). But as people spread to Asia, Europe and Australia, the giants fell. In the Americas, dates for extinction match the arrival of people 15,000 years ago, while the moas and Hast's eagle survived in New Zealand up to human colonisation in the 1400s. Jens-Christian Svenning is the lead author of the paper and believes that rather than looking at the megafauna extinctions as an 'event', it is instead 'the start of humanity's transformation of the biosphere', something that continues to this day. Populations of surviving megafauna are in a 'dire state' says his paper and nearly half of all mammals today weighing more than 10kg are threatened with extinction. He notes that 'it's a process that likely has very deep roots, the start of it is probably a million years ago but became really apparent from about 50,000 years ago'. That humans are the cause can still stoke debate, but at this stage, Svenning seems confident to brush this off. 'To be completely honest, the relation to humans, and the lack of a consistent relationship to climate, is a very clear pattern. From that perspective, it's weird that it's still controversial ... People undervalue how resourceful and impactful hunter-gatherer people have been. 'In Europe, there is a strong tendency to interpret the ecosystems before agriculture as natural, implying that people hardly had any influence on their environment before that. But people 50,000 years ago were just as capable as we are ... there's no reason why they wouldn't try to manipulate their environment for their own benefit ... the ideal of the 'noble savage' is still quite prevalent.' Svenning notes that at the scale of a human lifetime, extinctions happened over a very prolonged period (woolly mammoths survived in Siberia right up to 4,300 years ago) so people were likely unaware of the impact of their actions, something that can't be said for us today. Humans and our ancestors have been hunting large animals for a long time, and possibly precipitated extinctions even before the arrival of modern humans. 'It's well established that Neanderthals killed straight-tusked elephants in Europe,' he points out, however their impact was limited due to their small population sizes (it is also notable that Neanderthals also went extinct with the rise of Homo sapiens). Human impact was not related, therefore, only to their capabilities, but to their expansion in numbers. The consequences of the absence of large herbivores, which play key roles in seed dispersal, spreading of nutrients and the structure of vegetation, have been profound. Less grazing has meant more growth of woody plants, which, depending on the climate, leads to more fires, a pattern that is perpetuated to this day with the absence of large grazers that were common even a few centuries ago. As for the impact on climate, the picture is complicated as multiple effects are likely to have had warming and cooling effects. Today, wild animals only make up a mere 4 per cent of the total mass of mammals in the world. Today's megafauna is mostly made up of cattle and other domestic animals and there have been suggestions from some in the livestock industry that the overall effect on the planet is neutral. However, today's 1.5 billion cattle, many of which are confined for some or all of their lives, eating processed foodstuffs and prevented from displaying their natural behaviours, are no substitute for healthy natural ecosystems. Whole processes, driven by a fantastic diversity of animals, such as migration, predation, seed dispersal, decomposition and scavenging, are now absent from swathes of Earth's land surface. 'I'm pretty sure we have a lot more livestock now, and a lot more [methane-emitting] ruminants than there were wild animals in the past,' says Svenning. 'The way we keep the livestock is completely non-analogue to naturally living megafauna, there's no doubt it's not comparable. 'If one wanted to have more sustainable livestock production from a climate and biodiversity perspective, the way to go is low intensity, low stocking rates, such as in European semi-natural landscapes, that's very possible. Of course, the consequence of this is that the production is much, much lower. So, it means there won't be so much meat available for everybody to consume. That's simply impossible.'
Irish Times
9 hours ago
- Irish Times
Long-term study links coffee to healthier ageing
Most people who drink coffee appreciate the quick jolt of energy it provides. But in a new study, presented recently at the annual meeting of the American Society for Nutrition, scientists have found that coffee may offer a much longer-term health benefit. The study has not been peer-reviewed or published, but it was rigorous and included a large number of women who were followed for many years. It also adds to a large body of evidence linking coffee to longer lives and various health advantages, including lower risks of certain chronic diseases – though all of these studies had limitations, including that they were observational and could not prove cause and effect. Still, the results linking coffee to healthier ageing were not surprising, said Fang Fang Zhang, a professor of nutritional epidemiology who was not involved with the study. 'The data is quite consistent that coffee consumption is actually beneficial,' she said. In the study, researchers followed more than 47,000 female nurses for several decades beginning in the 1970s. Every few years, the women answered detailed questions about their diets, including how much coffee, tea and cola (such as Coca-Cola or Pepsi ) they typically drank. Then the scientists looked at how many of the women were still alive and met their definition of 'healthy ageing' in 2016. READ MORE Just over 3,700 women met that definition: They were 70 or older, reported good physical and mental health, with no cognitive impairment or memory problems. Additionally, they were free of 11 chronic diseases including cancer, Type 2 diabetes, heart disease, kidney failure, Parkinson's disease and multiple sclerosis. The researchers found a correlation between how much caffeine the women typically drank (which was mostly from coffee) when they were between 45 and 60 years old and their likelihood of healthy ageing. After adjusting for other factors that could affect ageing, such as their overall diet, how much they exercised and whether they smoked, those who consumed the most caffeine (equivalent to nearly seven 237ml cups of coffee per day) had odds of healthy ageing that were 13 per cent higher than those who consumed the least caffeine (equivalent to less than one cup per day). Studies have found links between regular (not decaffeinated) coffee and a reduced risk of Parkinson's disease Drinking tea or decaffeinated coffee was not associated with healthy ageing, the researchers found. That may be because the study participants generally consumed less tea and decaffeinated coffee overall, so perhaps there were fewer chances for the researchers to find benefits linked to them, said Sara Mahdavi, an adjunct professor of nutritional sciences at the University of Toronto who led the study. Tea and decaf coffee also have less caffeine, and tea has different plant compounds from regular coffee, so that may explain the results, too, she added. Drinking cola, another potential source of caffeine, was associated with significantly decreased odds of healthy ageing. Dr Mahdavi cautioned that while drinking up to seven small cups of coffee per day was associated with healthy ageing in her study, that doesn't necessarily mean that drinking that much will benefit everyone, or that it is healthy to do so. Research in other groups of people suggests that the health benefits of coffee may plateau or even dip when they drink more than three to four cups per day. Many other studies have linked drinking coffee regularly to a lower risk of early death. In a study of more than 46,000 adults published in May, Dr Zhang and her colleagues found that those who consumed one to three cups of coffee per day were about 15 per cent less likely to die within the next nine to 11 years than those who didn't drink coffee. That benefit disappeared, though, for people who said they typically added more than about a half-teaspoon of sugar to their coffee and for people who added more than 1 gram of saturated fat (equivalent to about one tablespoon of half-and-half or 3.5 tablespoons of whole milk) per cup of coffee. Research has also suggested that people who drink coffee regularly have lower risks of heart disease, Type 2 diabetes, Parkinson's disease, liver disease, osteoporosis and some types of cancer. These kinds of studies can't prove cause and effect, said Aladdin Shadyab, an associate professor of public health and medicine. But because the benefits associated with coffee have been so consistent, it's unlikely that they are entirely explained by other aspects of a person's life, Dr Zhang said. If anything, drinking coffee is often associated with unhealthy habits, such as smoking and less exercise. The fact that you see benefits after accounting for these differences means that coffee is probably helping, Dr Zhang said. Researchers aren't entirely sure why coffee may be beneficial. 'It's a bit of a mystery,' said Marilyn Cornelis, an associate professor of preventive medicine. Studies of mice have found that caffeine may improve memory and protect brain cells from damage. And human studies have found links between regular (not decaffeinated) coffee and a reduced risk of Parkinson's disease. Both regular and decaf coffee contain hundreds of chemical compounds, including many that may lower inflammation and prevent cell damage, Dr Mahdavi said. [ How to make barista grade coffee at home - according to the experts Opens in new window ] [ In a Word... Coffee Opens in new window ] While the new study didn't find a benefit associated with decaf coffee, other research has linked it, along with regular coffee, to lower rates of Type 2 diabetes and other conditions, Dr Cornelis said. Tea also contains many beneficial compounds and drinking it has been associated with better heart health and a longer life. If you drink coffee regularly, consider the new findings and others like it as good news that it may benefit your health – as long as you don't add too much cream or sugar, Dr Zhang said. But if you don't enjoy coffee, Dr Mahdavi added, there's no need to start drinking it. It can interfere with sleep and make some people feel anxious or jittery. There are plenty of other, more evidence-backed ways to boost your health and longevity, Dr Shadyab added, such as following a balanced diet, exercising regularly, getting enough sleep and having an active social life. – This article originally appeared in the New York Times
Irish Times
2 days ago
- Irish Times
Scientists develop new way to detect deepfake videos
Scientists at the Netherlands Forensic Institute have developed a groundbreaking new method to identify deepfake videos by looking for subtle changes in facial colour caused by the human heartbeat. 'In video of a real person, one can detect blood flow around the eyes, forehead and jaw – and that's exactly what's missing in deepfakes', according to lead investigator Zeno Geradts, professor of forensic data science at Amsterdam University. Deepfake videos – artificial intelligence -generated content in which real people appear to do or say things they never did or said – are seen as posing risks to society because victims can be inserted into sexually explicit content, for example, or misrepresented in fake news. The new technique, called blood flow detection, uses advanced image analysis to identify tiny variations in skin tone created by a human subject's pulse – variations that are absent in manufactured or manipulated footage. READ MORE When the Dutch team first investigated the issue 13 years ago, poor video quality made such sophisticated analysis impossible. Since then, video technology has evolved, and a combination of improved picture resolution – measured in terms of the number of pixels in a video frame – and rapidly developing artificial intelligence (AI) tools has allowed the experts to successfully revisit the problem. 'When we looked at this first in 2012, we were being asked by police to analyse so-called snuff videos showing extreme violence, including torture and murder, circulated via dark web platforms and on encrypted messaging apps. 'We were trying to find a way to establish scientifically that the victims being shown in those videos were real people.' The fundamental crux was the inadequacy of video compression technology, said Prof Geradts. 'Large video files had to be reduced in size and during that compression process the colour differences per heartbeat were lost. 'But now, more than a decade later, compression methods have improved and we can detect even the slightest discolouration caused by pulsing blood flow.' How to manage your pension in these volatile times Listen | 37:00 In the most recent tests, volunteers were filmed wearing heart monitors and their heart rates were then matched against colour changes at 79 points on the face, under a range of lighting conditions and varieties of movement. The project confirmed a strong correlation between visible colour changes and the heart rate measurements in all the different settings. The results, say the Dutch team, were 'very promising'. 'AI can do a lot but it still cannot generate a convincing pulse', said Prof Geradts. Although it is used in individual investigations, blood flow detection is not yet in routine forensic use, mainly because it hasn't been fully validated for use in court cases – but that may be just a matter of time. 'In the world we live in, forensic research into deepfakes is more urgent than ever,' said Prof Geradts. 'I sometimes worry that soon everything will be regarded as potentially fake. Then how will we know what's real?' According to a Dutch national helpline for victims of online abuse, reports of deepfake pornography and manipulated nude images increased in the Netherlands by 31 per cent in 2024.
