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Living with aliens
OPINION
Living with aliens Non-native species get nothing but bad press, but this often has more to do with prejudice than science, says biologist Mark Davis HUMANS have been transporting species around the world, intentionally and unintentionally, for centuries. Many of the species we think of as a natural part of our landscape are, in fact, non-native. For example, the honeybee, which nearly a third of US states have named as their state insect, was introduced into North America from Europe in the 1600s. Naturalists have long been aware of this bio-globalisation, but widespread research on introduced species did not begin until the early 1980s. In those days, the message from invasion biologists was clear and simple: introduced species were bad news. They were referred to as invaders, aliens, exotics or even “biological pollution”. A common refrain was that invasive species were one of the greatest extinction threats for native species, second only to habitat destruction. Make no mistake, some introduced species have caused great harm. For example, the brown tree snake, introduced into Guam in the mid-20th century, caused the extinction of most of the island’s native birds. Many other island and lake species have been driven extinct by introduced predators. The global cost of damage by non-native species to farming, timber, fisheries and waterways is estimated at well over $100 billion annually. Many of the human diseases of greatest concern are viruses that have been transported to new regions, such as SARS, West Nile virus, Ebola, H1N1 flu and HIV. However, you may be surprised to learn that only a few per cent of 26 | NewScientist | 26 September 2009
introduced species are harmful. Most are relatively benign; some, such as the honeybee, can even have beneficial effects. Despite this, many people cling to the idea that non-native species are uniformly undesirable. In my discussions with people involved in conservation and restoration programmes, for example, I find that many view native species as inherently more desirable than non-native ones. Many land managers and ecologists also hold this view. If most non-native species are not harmful, why have so many people adopted this “nativism paradigm”? I believe
there are two explanations. The first is the message sent by invasion biologists to the public over the past three decades. The second involves some general predispositions that we seem to share as humans. Some anthropologists argue that the desire to classify is inherent in humans, as we crave a sense of order. Similarly, recent evolutionary research suggests that humans are predisposed to impose group boundaries and to see outsiders as a threat. We seek
“It is crucial we distinguish harm from mere change so that we can spend scarce resources wisely”
every opportunity to identify with a home land, a home tribe, a home religion, a home team, and to declare everybody else the enemy. This declaration of identity extends to the natural world. Most countries, states and provinces have designated a species of animal or plant as “theirs”, declaring it the national bird or the state flower. Given this powerful predisposition, it is not surprising that people, including ecologists, show favouritism toward native organisms. We need to move on. Scientific disciplines are often guided at their outset by a few simple ideas. However, as the field matures, participants typically recognise the complexity of their subject and the need for a more nuanced approach. This is what is happening in invasion biology. Philosophers, social scientists and some invasion biologists have challenged the choice of language used to describe nonnative species and have argued that conclusions about them sometimes rest more on prejudice than science. Others have criticised the preference for native species as scientifically unsound, arguing that invasive species do not represent a separate category, evolutionarily, biogeographically or ecologically. Others have pointed out flaws in the claim that non-native species are the second-greatest extinction threat after habitiat destruction. In fact, with the exception of insular environments such as islands and lakes, there are very few examples of extinctions being caused by non-native species.
Comment on these stories at www.NewScientist.com/opinion
Mark Davis is DeWitt Wallace Professor of Biology at Macalester College in St Paul, Minnesota. His new book is Invasion Biology (OUP)
One minute with…
Alec Jeffreys It is 25 years since the “father of DNA evidence” made an accidental discovery that transformed forensics – and his life The first DNA “fingerprint” was a murky pattern on X-ray film. Did you realise the potential of what you had stumbled upon? On that Monday morning 25 years ago I remember putting the light on, looking at the patterns and thinking “what a horrible mess”. Then the penny dropped. We realised the potential for DNA identification within about a minute and then the possible applications came flooding in. By evening we had a pretty good shopping list of the stuff that DNA could, theoretically, be applied to. DNA fingerprinting has enabled so much, from solving crimes and paternity disputes to freeing innocent prisoners from death row. Is there one story that stands out for you? The first case we ever did. It was an immigration dispute involving a young lad threatened with deportation from the UK. We did a DNA test, showed he was a full member of his family, and the immigration tribunal dropped the case. I was there when his mother was told. That was the magic moment for me, when I saw the science move into a very different realm. DNA databases attract controversy, especially in the UK where DNA profiles gathered by police are retained regardless of guilt. How should we deal with that? Databases should be governed through proper legislation that prohibits the taking and retention of entirely innocent people’s DNA. That’s a major violation of the Human Rights Act. Is it really such a problem to be on a database? Having your DNA on a database – to be branded the same as a criminal – is painful for a considerable number of people. And I’ve not heard those people have a voice in this debate. What are the biggest issues for DNA technology in the future? Not so far down the track, you’ll be able to send a mouth swab off and get a complete genome sequence back – all 3000 million bases. Then
PROFILE Alec Jeffreys is a geneticist at the University of Leicester, UK. In 1984 he invented genetic fingerprinting, which identifies individuals based on their DNA. He was knighted in 1994
there will be a million-and-one issues. Who stores the data? Who owns it? The idea that I can plough around my genome willy-nilly finding out fun things about me – that could have a very big impact on family members too. Because my genome is mine, but really it’s not – I share it. What mind-boggling future applications of DNA sequencing do you foresee? The idea of finding out someone’s surname from their DNA might sound completely bonkers, but it’s not. Also miniaturisation: getting a lab-on-a-chip you can take out to a crime scene. But the Holy Grail for the field is to get instant DNA typing, to get it in 1 second flat. Then you have DNA entering the world of real-time security. What does that mean in practice? Imagine going to the supermarket 20 years from now. To use your credit card, you don’t have a PIN that everyone can see. Instead, you spit on something, and there’s a little DNA detector that says “yeah, that’s right”. And away you go. Interview by Catherine de Lange
26 September 2009 | NewScientist | 27
MARTIN POPE/CAMERA PRESS
Despite this more nuanced approach, many of my invasion biologist colleagues are reluctant to discard the nativism paradigm. Some have told me that “message enhancement” is a necessary strategy when dealing with the public and policy-makers, in order to get their attention. I believe this strategy carries serious risks. If messages are enhanced to the point of exaggeration, they can end up eliciting well-intentioned but misguided responses, such as spending scarce resources on projects that should not be a priority. The harm being caused by introduced species is well documented. We do not need to enhance the message. Whether we like it or not, the world’s biodiversity is becoming globalised. We can call them aliens, exotics or biological pollution, but the fact is that introduced species are our new residents. It is common for humans to resist change, particularly when change is rapid and profound, as is the case with globalisation of cultures and biota. In some cases, real economic, social or ecological harm is caused. When the harm is great, society needs to mobilise its human and financial resources and respond quickly and effectively. But resources are finite. It is crucial that we distinguish harm from mere change so that we can spend scarce human and economic capital wisely. We scientists can best assist by making sure that our messages are accessible, interesting and meaningful without compromising the science. As long as the harm is real, it should not be necessary for us to overgeneralise, exaggerate, use incendiary language or misrepresent data in order to attract attention. ■
Living with aliens Non-native species get nothing but bad press, but this often has more to do with prejudice than science, says biologist Mark Davis HUMANS have been transporting species around the world, intentionally and unintentionally, for centuries. Many of the species we think of as a natural part of our landscape are, in fact, non-native. For example, the honeybee, which nearly a third of US states have named as their state insect, was introduced into North America from Europe in the 1600s. Naturalists have long been aware of this bio-globalisation, but widespread research on introduced species did not begin until the early 1980s. In those days, the message from invasion biologists was clear and simple: introduced species were bad news. They were referred to as invaders, aliens, exotics or even “biological pollution”. A common refrain was that invasive species were one of the greatest extinction threats for native species, second only to habitat destruction. Make no mistake, some introduced species have caused great harm. For example, the brown tree snake, introduced into Guam in the mid-20th century, caused the extinction of most of the island’s native birds. Many other island and lake species have been driven extinct by introduced predators. The global cost of damage by non-native species to farming, timber, fisheries and waterways is estimated at well over $100 billion annually. Many of the human diseases of greatest concern are viruses that have been transported to new regions, such as SARS, West Nile virus, Ebola, H1N1 flu and HIV. However, you may be surprised to learn that only a few per cent of 26 | NewScientist | 26 September 2009
introduced species are harmful. Most are relatively benign; some, such as the honeybee, can even have beneficial effects. Despite this, many people cling to the idea that non-native species are uniformly undesirable. In my discussions with people involved in conservation and restoration programmes, for example, I find that many view native species as inherently more desirable than non-native ones. Many land managers and ecologists also hold this view. If most non-native species are not harmful, why have so many people adopted this “nativism paradigm”? I believe
there are two explanations. The first is the message sent by invasion biologists to the public over the past three decades. The second involves some general predispositions that we seem to share as humans. Some anthropologists argue that the desire to classify is inherent in humans, as we crave a sense of order. Similarly, recent evolutionary research suggests that humans are predisposed to impose group boundaries and to see outsiders as a threat. We seek
“It is crucial we distinguish harm from mere change so that we can spend scarce resources wisely”
every opportunity to identify with a home land, a home tribe, a home religion, a home team, and to declare everybody else the enemy. This declaration of identity extends to the natural world. Most countries, states and provinces have designated a species of animal or plant as “theirs”, declaring it the national bird or the state flower. Given this powerful predisposition, it is not surprising that people, including ecologists, show favouritism toward native organisms. We need to move on. Scientific disciplines are often guided at their outset by a few simple ideas. However, as the field matures, participants typically recognise the complexity of their subject and the need for a more nuanced approach. This is what is happening in invasion biology. Philosophers, social scientists and some invasion biologists have challenged the choice of language used to describe nonnative species and have argued that conclusions about them sometimes rest more on prejudice than science. Others have criticised the preference for native species as scientifically unsound, arguing that invasive species do not represent a separate category, evolutionarily, biogeographically or ecologically. Others have pointed out flaws in the claim that non-native species are the second-greatest extinction threat after habitiat destruction. In fact, with the exception of insular environments such as islands and lakes, there are very few examples of extinctions being caused by non-native species.
Comment on these stories at www.NewScientist.com/opinion
Mark Davis is DeWitt Wallace Professor of Biology at Macalester College in St Paul, Minnesota. His new book is Invasion Biology (OUP)
One minute with…
Alec Jeffreys It is 25 years since the “father of DNA evidence” made an accidental discovery that transformed forensics – and his life The first DNA “fingerprint” was a murky pattern on X-ray film. Did you realise the potential of what you had stumbled upon? On that Monday morning 25 years ago I remember putting the light on, looking at the patterns and thinking “what a horrible mess”. Then the penny dropped. We realised the potential for DNA identification within about a minute and then the possible applications came flooding in. By evening we had a pretty good shopping list of the stuff that DNA could, theoretically, be applied to. DNA fingerprinting has enabled so much, from solving crimes and paternity disputes to freeing innocent prisoners from death row. Is there one story that stands out for you? The first case we ever did. It was an immigration dispute involving a young lad threatened with deportation from the UK. We did a DNA test, showed he was a full member of his family, and the immigration tribunal dropped the case. I was there when his mother was told. That was the magic moment for me, when I saw the science move into a very different realm. DNA databases attract controversy, especially in the UK where DNA profiles gathered by police are retained regardless of guilt. How should we deal with that? Databases should be governed through proper legislation that prohibits the taking and retention of entirely innocent people’s DNA. That’s a major violation of the Human Rights Act. Is it really such a problem to be on a database? Having your DNA on a database – to be branded the same as a criminal – is painful for a considerable number of people. And I’ve not heard those people have a voice in this debate. What are the biggest issues for DNA technology in the future? Not so far down the track, you’ll be able to send a mouth swab off and get a complete genome sequence back – all 3000 million bases. Then
PROFILE Alec Jeffreys is a geneticist at the University of Leicester, UK. In 1984 he invented genetic fingerprinting, which identifies individuals based on their DNA. He was knighted in 1994
there will be a million-and-one issues. Who stores the data? Who owns it? The idea that I can plough around my genome willy-nilly finding out fun things about me – that could have a very big impact on family members too. Because my genome is mine, but really it’s not – I share it. What mind-boggling future applications of DNA sequencing do you foresee? The idea of finding out someone’s surname from their DNA might sound completely bonkers, but it’s not. Also miniaturisation: getting a lab-on-a-chip you can take out to a crime scene. But the Holy Grail for the field is to get instant DNA typing, to get it in 1 second flat. Then you have DNA entering the world of real-time security. What does that mean in practice? Imagine going to the supermarket 20 years from now. To use your credit card, you don’t have a PIN that everyone can see. Instead, you spit on something, and there’s a little DNA detector that says “yeah, that’s right”. And away you go. Interview by Catherine de Lange
26 September 2009 | NewScientist | 27
MARTIN POPE/CAMERA PRESS
Despite this more nuanced approach, many of my invasion biologist colleagues are reluctant to discard the nativism paradigm. Some have told me that “message enhancement” is a necessary strategy when dealing with the public and policy-makers, in order to get their attention. I believe this strategy carries serious risks. If messages are enhanced to the point of exaggeration, they can end up eliciting well-intentioned but misguided responses, such as spending scarce resources on projects that should not be a priority. The harm being caused by introduced species is well documented. We do not need to enhance the message. Whether we like it or not, the world’s biodiversity is becoming globalised. We can call them aliens, exotics or biological pollution, but the fact is that introduced species are our new residents. It is common for humans to resist change, particularly when change is rapid and profound, as is the case with globalisation of cultures and biota. In some cases, real economic, social or ecological harm is caused. When the harm is great, society needs to mobilise its human and financial resources and respond quickly and effectively. But resources are finite. It is crucial that we distinguish harm from mere change so that we can spend scarce human and economic capital wisely. We scientists can best assist by making sure that our messages are accessible, interesting and meaningful without compromising the science. As long as the harm is real, it should not be necessary for us to overgeneralise, exaggerate, use incendiary language or misrepresent data in order to attract attention. ■