Biologists such as Elton and others who’d dismissed migrants as suicidal zombies and mindless invaders never really examined migrants’ behaviour itself nor considered in any depth how it might have evolved. What drives creatures to move into new territories, away from where they were born? Leaving behind the known comforts of a home habitat, migrants strike out into the unknown. They forsake the help of kin who stay behind. In return, they may not find anywhere suitable to live at all.
And yet they do it anyway.
Baleen whales migrate thousands of miles from their rich feeding grounds in the far north to the warm waters of the tropics. Zooplankton migrate vertically between the depths and the surface the migrant formula in sync with the fluctuating light. Forests move over thousands of years with the advance and retreat of glaciers. In jungle-dripped Hawaii, tiny goby fish migrate from the open Pacific Ocean back to their birthplaces at the tops of waterfalls. The journey requires swimming against ocean currents into fresh waters and climbing up cliffs. They use suckers on the undersides of their bodies to do it.
In humans, the origin and ecological role of migration continue to be shrouded in controversy and contention. But biologists have forwarded a clear idea about its provenance in animals.
Migration experts such as Hugh Dingle say that migration most likely evolved as an adaptive response to environmental change. Migratory behaviour is more common among species that depend on resources exposed to environmental variations than in those whose livelihoods are more buffered from environmental change. Arthropods that live in temporary habitats such as shallow pools and seasonal ponds, for example, are more likely to migrate than those that live in relatively stable environments such as forests and salt marshes. Species that live in places with erratic rainfall or that feed on patchily distributed resources such as fruit and flowers are more likely to migrate than those that live in relatively stable places such as alpine tundra or deep lakes, where a disproportionate number of insect species don’t even have wings. Species that live on the edges of forests or in their canopies are more likely to migrate than those that live in their interiors. Bird species that feed on fruit, which is available only seasonally, tend to migrate more than bird species that feed on insects in the interior of forests, which are not. Bats that roost in trees, where they’re more exposed to the cold and the rain, migrate more than bats that roost in caves, which protect them from the elements.
Even within species, individuals that live in habitats exposed to change migrate more than those less exposed. The migratory behaviour of white-tailed deer, for example, correlates with the size the next great migration of their forest patches: deer that live in small patches more exposed to changing conditions migrate more frequently than deer that live in large patches.
For creatures that live in habitats subject to environmental change, survival rests on one of two strategies: either go dormant and wait for the altered conditions to recede or migrate. Again and again, those creatures capable of movement have opted for migration, despite the costs. Dingle distilled a formula that predicts the emergence of migratory behaviour. It lies in the ratio between the time it takes to reproduce a new generation and the stability of the environment. If that ratio is less than one—if, say, it takes a couple of years to reproduce the next generation but the habitat, say a vernal pond, lasts only for a season—migration is likely to emerge. And so as the northern hemisphere tilts away from the sun, lengthening shadows and shortening days, creatures of all kinds prepare to move. Physiological changes transpire inside their bodies, hormones spiking and nervous systems mobilizing. Sap-sucking rosy apple aphids birth special forms with wings. Salmon on the verge of migration experience spikes of hormones such as prolactin and cortisol. Baby eels metamorphose into transparent forms that prefer fresh water to salt water. In preparation for their travels, migratory birds and insects build up fat stores that can comprise more than 50 per cent of their body mass, and plants produce tough coats on their seeds. The proportion of fat they deposit in their seeds correlates to the distance the seeds are likely to travel.
As the time to leave approaches, a restlessness sets in. Migratory birds trapped in cages will flutter repeatedly to one side of a cage, jumping off their perches and crashing to the side. Which side depends on the direction it faces: whichever matches that of their migratory path. Scientists named their agitation Zugunruhe, German for “migratory restlessness.”
It’s hormonal. Remove the gonads of sparrows in the spring, and they’ll be less restless; castrate the migrant formula a migratory bird, and it will still migrate, but in a different direction.
Migratory journeys are not simple extensions of everyday movements, like flying from one tree to another or moving from one cave to the next. In birds, you can tell as soon as they leave, from their rate of climb and the altitude they achieve, that their migratory flights are something different. While en route, their behaviour and bodily functions are fundamentally altered. Unlike during ordinary movements, during migrations their bodies halt their own growth and development. They ignore stimuli they’d ordinarily respond to, passing by appealing foods and breeding spots.
But while migration is driven by physiological changes, it is not necessarily the result of some fixed itinerary instilled into the bones or some blueprint encoded in genes, propelling creatures in fixed directions at standardized times. The physiological states required for migration can be flexible and dynamic, too. The muscles that power the wings of migratory aphids, for example, start to break down after migration, the proteins diverted to reproduction instead. Animals’ sensitivity to the quivers and trembles of our pulsating planet—not predetermined internal programs— drives their behaviour and movement.
Wild animals’ sensitivity to environmental perturbances is the stuff of legend. Anecdotal stories of animals apparently sensing impending environmental disruptions hours or days before they’re detectable to humans stretch back to ancient times. Pliny the Elder described birds’ restlessness before earthquakes. Geese detected the arrival of an invading army of Celts in 387 BCE. Rome before the sleeping residents did, their quacking alerting them to the impending onslaught. In 1975 snakes outside the city of Haicheng in China emerged from their hidden shelters and froze to death in the winter’s cold, in advance of a 7.3 magnitude quake.
How the urge to migrate is coded in our genes. By Soniah Shah. Daily O, July 24, 2020.
Excerpt from The Next Great Migration: The Story of
Movement on a Changing Planet by Sonia Shah.
When
people start moving, we call it a “migrant crisis”. It’s reflexive. And it
happens regardless of whether host societies have the capacity to absorb
migrants or whether migrants themselves and the societies they enter and leave
would be better or worse off because of their movements.
In part, that’s because we’ve long misunderstood the scale and meaning of movement on our shared planet.
In the 18th century, the founder of modern taxonomy, Carl Linnaeus, characterised the natural world as essentially still. Each animal belonged where it was found and hadn’t moved from one place to another; each human population was similarly fixed in place on the planet. Thanks to Linnaean taxonomy, we name things based on their fixed places and where they “belong”: the Canadian goose, the Japanese maple. We use animals to stand in for places, as if they are one and the same: the camel stands in for the Middle East; the kangaroo for Australia – as if they have been there from time immemorial and could never shift.
Linnaeus decided that people who lived in different continents had been so biologically isolated from each other that they were separate subspecies, creating a human taxonomy which separated people by colour, continent, and his sense of their morals. He relied heavily on folklore and myth about tailed men and African women with bizarre genital growths (his taxonomy was famously based on sexual characteristics, which is why it was controversial and called “loathsome harlotry”). Elevating the degree of differentiation between us obscured our common origin and our shared migratory history. Nevertheless, his ideas formed the foundation for modern ideas about racial difference, which are used to justify anti-migrant policies to this day.
We’ve minimised the role and scope of migration ever since. For example, Europeans refused to believe Polynesian people’s story of prehistoric migrations to the Pacific Islands by canoe from Asia. They thought that purposeful long-distance movements were only possible with modern Western technology. In the 1940s, the Norwegian explorer Thor Heyerdahl theorised that the only way people could have gotten to the remote Pacific islands was by floating there on a raft from Peru. He was so convinced of his theory that he tried it himself on the Kon Tiki raft, which became a popular movie and book. Up until the 1960s, top geographers said that migration has played such a minor role in human history that the people who lived on different continents had actually evolved there.
Today’s policymakers similarly underestimated the pace of human movements when they claimed they could arrest the spread of novel coronavirus by closing the borders, seemingly unaware that seven million people had already left the city of Wuhan before it was locked down. It was only after the borders slammed shut that it became clear that our movement patterns made even our most stringent efforts to stop the microbe’s dispersal futile.
Our underestimation of the scope of migration has been coupled with an outsized focus on migration’s disruptive effects. We call the movement of wild species into novel habitats “invasions” of unwanted “aliens,” even though according to a general rule in invasion biology, only 10 per cent of alien species establish themselves in new habitats and only 10 per cent of those are likely to cause unwanted harm to economies, ecosystems or human health.
Human migrants are blamed for all manner of social ills, from the spread of crime and terror to disease. One result is that today, more borders are fortified with walls and fences than at any time in history.
But new findings made possible by advancements in genetics and navigation are upending conventional notions of migration as rare and disruptive, revealing migratory capacities more extensive and more deeply embedded in history and nature than ever before imagined.
Ancient DNA shows that we’ve continuously migrated. We didn’t just disperse out of Africa into an empty planet and then stop moving until modern times. We migrated out of Africa into Eurasia and then back again; we moved from Eurasia into South Asia; we migrated into the Americas and then back to Europe. Some of the most forbidding migrations, such as into the Tibetan plateau and the remote Pacific had been accomplished not just once but multiple times.
A revolution in animal tracking thanks to GPS and solar technology has revealed that animal movements are much more expansive in scale and more complex and responsive than ever before imagined, too. The movements of mountain goats is shaped by the timing of volcanic eruptions, which they detect six hours before seismologists can. The flight paths of swans curve according to cold snaps, and could forecast outbreaks of avian influenza days before traditional methods of influenza surveillance. The creep of thousands of species toward the poles and into the heights tracks the shifting climate.
We live in a world on the move. And nature depends on our journeys. Ecosystems depend on the biological connections provided by wild species on the move. Over 90 per cent of the trees in rainforests, for example, rely on the movements of birds and other animals to disperse their seeds. Human mobility is fundamental to our biological resilience. Our capacity to co-operate across geographic barriers relies on the cultural connections forged by people on the move, injecting genetic and cultural diversity into otherwise insular societies.
Migration is the planet’s connective tissue. It’s not the crisis we reflexively imagine it to be. In a rapidly changing world, migration may be just the opposite: the solution.
“Migration is the planet’s connective tissue” By Sonia Shah. The Big Issue , June 26, 2020.
How should countries protect citizens from deadly diseases? The most promising solution is often not the most popular, explains author Sonia Shah.
In her forthcoming book, The Next Great Migration: The Beauty and Terror of Life on the Move, Shah explores whether, in a world of disruptive and deadly biota on the move, there is any lasting solace in closed borders and isolated societies—or whether our survival depends on just the opposite.
On April 23, 2020, Shah joined the Pulitzer Center for a discussion of her past and present reporting as part of the Talks @ Pulitzer Science and Health Series. Her latest book grew out of a Pulitzer Center-supported investigation into contagions facing Syrian and Afghan refugees trapped in Greece.
The following is an edited transcript of the Question & Answer segment of Shah's Talks @ Pulitzer, moderated by Ann Peters, the Center's university and community outreach director. Also included are several audience questions that were not presented during the 45-minute webinar due to time constraints, but were answered by Shah after the session via email communication.
The post-session answers are indicated by an asterisk*. Portions of this text have been revised for clarity and/or length.
Question: You said that flight paths affect the spread of pathogens. If nations across the world would have shut down traveling faster, do you think the coronavirus would not have become such a large pandemic?
Answer: I don’t think that there’s been any respiratory pathogen that we’ve been able to contain as such in the history of pandemics. Look at the seasonal flu virus, for example: We have that every year, and even though we have some degree of herd immunity that we’ve acquired at a great cost to our health, even though we have a scientific establishment that creates a cool new flu vaccine every year, we still lose billions and billions of dollars to sickness and we lose half a million people every year to flu. Given that example, I think the idea of containing a respiratory pathogen that spreads just from people moving around and talking to each other, the social contacts that happen, is really difficult. We’ve never been able to do it even though we’ve had lots of opportunity to try and lots of incentive to try.
Q: What has your research shown in terms of migration harming a country’s health care system?
A: It’s exactly the opposite. A lot of political leaders think migrants are coming into their societies because they’re attracted by some special benefits that they’ll get from getting there. ‘They’re coming to steal our jobs, they’re coming to get our healthcare,’ there’s all these attractives that pull them in, and so when they don’t want them to come policies of deprivation get put into place. And we see that across countries—the ordinary health care that’s available to citizens is not available to newly arrived people and migrants, whether they’re documented or not documented. Even things that would protect all of us better like vaccination programs [are not available]. Undocumented children across Europe don’t get the routine vaccinations in a lot of countries that residents do. I think it comes out of this idea about migration as being this negative phenomenon that we have to deter. Also, that if we don’t give them any ‘goodies’ and deprive them then they’re going to stop coming, which is not what I’ve found at all. It’s exactly the opposite.
Q: Is there a solution to create equity across the world so that migration can be reduced and made less risky? Does not access to natural resources often drive migration?*
A: Migration is shaped by many factors, not just the availability of resources or even jobs, which is why poor countries situated next to wealthier ones with porous borders are not depopulated. In fact most international migration in the world occurs between poor countries. Still, migration can be made a lot more orderly, safe, and humane. The UN's Global Compact on Safe, Orderly and Regular Migration provides a roadmap.
Q: Did you come across any interesting research about vaccines for animals? If so, do they make a difference (positive or negative) in preventing disease outbreaks?
A: One point to clarify is that these microbes that become pathogens in humans are not pathogenic in animal reservoirs—they’re harmless to the animals. So there wouldn’t be any role of vaccination because the animal already has the immunity. The bats are not falling sick with Ebola, they’re the reservoir of Ebola. In terms of antibiotic consumption in agriculture, it’s a huge driver of antibiotic-resistant pathogens. Here in the United States, about 80 percent of the antibiotics that we consume as a country are used in commercial applications in agriculture. And we know that in countries where that practice is not allowed, that they don’t have problems with antibiotic-resistant bacteria the way we do here in the United States. It’s really something that scientists realized in the very beginning—if you use them in ways that are not medically necessary, you will provoke the evolution of antibiotic-resistant bacteria. That’s basically what we have been doing here in the United States over the past decades. I think it’s a ticking bomb, really.
Q: Are
CAFOs (concentrated animal feeding operations) in the U.S. part of this current
contagion?*
A: Industrial livestock farming is a known driver of pathogens with pandemic potential. The use of antibiotics for growth promotion in livestock contributes to the spread of antibiotic-resistant bacterial pathogens, for example; poultry farms where thousands of captive chickens are crammed together allow avian influenza viruses to replicate, amplify, and become more virulent. Here in the U.S., about half of all cattle on feedlots are infected with Shiga-toxin producing E. Coli (STEC). Because cattle waste so often contaminates our food and water, hundreds of thousands of American fall ill with STEC every year.
Q: Can you explain the positive migration benefits in the context of invasive species? Especially in vulnerable areas?*
A: There's no doubt that migration is disruptive and in some cases, such as for invasive species, the costs might outweigh the benefits. But these are a tiny fraction of introduced species. There's no reason to make the problem of invasives the centerpiece of our policies toward species on the move. They should be managed as outliers, and dealt with on a case-by-case basis.
Q: Could you describe your research and reporting processes?
A: In a nutshell, my process is to do a ton of background research before I go into any of these places. I do all of the background reading and to talk to all the experts I can on the phone in the places that I’m going to before so I have established my background level of understanding of the communities and what their own priorities are. I’ve also established social contact with the leaders in those communities so that when I go there I can concentrate once I’m on the ground. The other part is just making enough time to really listen. It’s not the most efficient thing to do, but if you go to, say, a hurricane shelter where you have traumatized people who have lost everything and you just need information about one part of their experience, you can’t just extract that. You have to sit down and establish trust and really listen to what people want to say because people want to be listened to but they dont wanna just give you the one piece of information you want. So, you have to have the patience to sit there and really listen to all of it and absorb it and respond in a humane way. That’s how you get a more complete picture of what’s going on, even if you’re just looking at one angle of the experience.
Q: Can you share some policies or advocacy that offer some hope for tackling these issues?
A: I do see hopeful signs everywhere and the one thing I keep in mind is that history doesn’t progress in a linear fashion. There’s always unexpected outcomes and little things that can have outside effects in ways you can’t imagine. We’ve seen backlash against science around the world with right-wing populist leaders coming into power saying ‘we don’t need to do vaccines, we don’t need to listen to the science, we don’t need experts, we don’t need all these environmental regulations,’ or whatever it is, and I think it grows in part out of the elitism that is inherent in the scientific establishment. The establishment itself is complicit, to some extent, in trying to elevate its authority and saying ‘we’re going to speak in lingo that none of you people can understand and you have to study for years and years to even know what we’re talking about,’ and I think that dynamic is not helpful for us as a society. I’m very hopeful about the fact that that’s starting to change. I think scientists themselves are starting to get involved in the political process—we’ve seen scientists running for office and they’re speaking out more. On the other side, we’re seeing the democratization of science. This is coming out of the climate movement, I think, where people are learning about atmospheric chemistry, and how energy works, and thermodynamics—now that’s all stuff we have to know about. We’re seeing that now with public health: We’re all getting a crash course in epidemiology right now which I think just a few years ago would have been considered a very obscure part of the scientific establishment that we didn’t have to think about. And I think what my work has always been about is that civil society has to be part of the scientific process—it shouldn’t be two separate things. So the fact that these things are colliding and starting to meld a little more, I think that’s a hopeful movement that’s happening right now.
Anne Peters talks with Sonia Shah.
Talks @ Pulitzer: Author Sonia Shah on Migration Patterns and Fighting Diseases. By Holly Piepenburg. Pulitzer Centre , April 24, 2020.
Carl Linnaeus
Climate change has put organisms on the move. In her new book, The Next Great Migration, Science writer Sonia Shah writes about migration — and the ways in which outmoded notions of "belonging" have been used throughout history to curb what she sees as a biological imperative.
There is a tendency to view plants, animals and people who cross into a new territory as a threat to the current habitat. But Shah says there's another way to think about these "invaders."
Humans "thrive in such widely variable places — from the Tibetan plateau to the middle of rainforests," she says. "You have to think about the whole picture of, why did we evolve this way? It's because its benefits outweighed its risks over the long term."
Shah's 2016 book, Pandemic, explored the increasing threat of viral outbreaks.
Interview Highlights
On the origins of the idea that human migration was problematic
I traced most of these ideas back to Carl Linnaeus, who's considered the father of modern taxonomy. He's this 18th-century Swedish naturalist, and he kind of decided for all of us: Where does everything belong? He named everything. He came from a very Christian household, and like most naturalists of the time, he was very religious. He thought of nature as an expression of God's perfection. So everything was in its rightful place for him. ...
Wherever he found things, that's where they "belonged," and that extended to his human taxonomy. So he decided that the people in Africa belong in Africa, that people in America, they belong in America, etc., to such an extent that he decided that all of these different peoples on different continents didn't have a shared ancestry, a shared migration history, but were actually separate subspecies of humans. And, in fact, he called Africans even less than human, that they were sort of a hybrid between real humans and this other archaic, mythical human that he called "troglodytes."
But those ideas were incredibly influential because we see them today in our ideas about race and about where people belong and where wild species belong. When a wild creature crosses from a different place into a new territory, we think of it as an invasive; we call it an alien. We see hints of all of that in the way we make policy around immigration and newcomers in places around the world.
On how Linnaeus' ideas opened the door for junk "race science" within the scientific community
[The "race" scientists] really felt like immigration would cause a biological catastrophe, because they thought that people from Africa or Polynesia or elsewhere in the world were biologically distinct. And so if they came into our country and started to partner with "native" people, with local people, that they would have these hybrid children that would be like deformed, essentially degenerated and deformed. They did all this science to try to prove that, which, by modern standards is not scientific, as we understand it at all. But they were scientists. So they had that kind of authority of being people who are looking into this really deeply.
But even leading people in the American Public Health Association and President Calvin Coolidge actually wrote about what he called "biological laws," according to which divergent people could not mix or blend. And the Public Health Association said that if we allowed immigrants in, and these are people who are of different subspecies to mix with native people, that would lead to hybrid generations that would lead to, I think the quote, was "absolute ruin" for American society.
On what we've learned from tracking the migrations of animals
With solar technology and GPS, we can track animals 24/7 over the course of their lifetimes, sort of continuously. So you can see the full picture of the way they move. And what they're finding is that these creatures are moving farther and faster and in more complex and responsive ways, dynamic ways than anyone ever thought before. What's funny is we've created all these parks and reservations to kind of protect animals, and when we've actually now studied well, where do they actually go? It turns out the giraffes, they're supposed to stay in the park in Ethiopia that we set aside for them, in fact, they're crossing borders and going much farther than that. The turtles are swimming well beyond the boundaries of the marine protected-zones we've made up for them. We see animals are moving sort of en masse now because of the climate crisis.
On rethinking invasive species like "murder hornets" and lanternflies
I don't deny that those disruptions are occurring, but I dispute what the reason is behind it. There's so many species that are moving around, and to think that every newcomer who comes into your territory is sort of alien to it as opposed to the natives who belong there, I think that's where we go wrong. I mean, it's interesting with the hornets. This is very typical of how we respond to new novel creatures that we think are out of place. I mean, we were calling these hornets, "murder hornets," which is a very pejorative way to talk about anything, really. Lions also are predators, we don't call them "murder cats." ...
What they're really threatening is honeybees and stuff, which are also not native either. They're from Europe. So, I'm not saying the disruption doesn't exist — but it's the way we think about it. What we know is that only 10 percent of species that move into new places are able to establish themselves. And then only 10 percent of those become sort of pests, cause disruptions, unwanted effects on either human health or our economies or on already resident species. So we're talking about one percent of all the species that are moving around actually causing these problems of what we call invasiveness. And yet we have this approach that's embedded in our conservation policies, like the Convention on Biological Diversity, which recommends that we detect species that are new in our environments early, that we repel them and that we eradicate them before they are able to establish themselves. And the idea there is that you get rid of them because you're presuming that they're going to cause problems. And so that presumption, I think, is what is problematic, because especially right now, because the climate is changing, and we need species to move into new places and we don't want to repel them as invaders or aliens just because they're moving into new places, which is what's going to allow them to survive.
On going to borders to report on human migration
Right now, we have more borders around the world ... fortified with walls and other barriers than ever before. And ... it hasn't repelled movement. It hasn't made people stay home. It's just made migration a lot more deadly. So people are risking their lives now to find refuge from bombs and beheadings and poverty and the rest of it. So that was what was most striking to me. And the thing about reporting on migration is you basically can go anywhere because there's migration happening sort of behind-the-scenes everywhere you go. So what I wanted to do is look at, well, where are people getting stuck? Whether it's refugee camps or border checks or dying in the desert on the U.S.-Mexico border.
On the underlying biodiversity crisis behind the coronavirus and other pathogens
New Coronavirus 'Won't Be The Last' Outbreak To Move From Animal To Human
I think
we need to look more deeply at the way we're interacting with nature. We need
to look more deeply at the crisis of biodiversity, which is really the
fundamental driver of all of these spillover pathogens coming into human
populations. I mean, it's not just the novel coronavirus. It's also Ebola and
Zika and HIV in the 1980s and West Nile Virus and new kinds of Lyme disease, a
tick-borne disease. We have a whole host of these pathogens that are coming out
of animal populations into humans because we are destroying wildlife habitat at
such a huge rate. We're losing 150 species every day. So this biodiversity
crisis is the fundamental driver. So we need to, I think, look at that more
deeply and consider human health to be connected to the health of our
livestock, our wildlife and our ecosystems more generally.
New Book Argues Migration Isn't A Crisis — It's The Solution. Dave Davies talks with Sonia Shah.
NPR ,
June 2, 2020.
This
fascinating study debunks false narratives about immigration and finds that, in
common with other species, the urge to move is written in our genes
Sonia Shah’s last two books Pandemic, published in 2016, and The Fever, published in 2010, introduced her as a storyteller in a novel genre: travel books that went in search of the spread of disease - cholera in the former, malaria in the latter. That literature of track and trace, part detective story, part reportage, took Shah to remote corners of the world and to distant grid references of history. Her books were also prescient case studies of the way that human progress has been shaped by its love-hate relationship with microbes – how disease has caused empires to rise and fall and economies to stutter and implode.
This book – a wandering narrative about why people wander – is likely to prove equally prophetic in the coming months and years, since it asks two questions that are already shaping our geopolitics: what causes human beings to migrate? And is such mass movement beneficial to more settled communities and nations?
The “next great migration” has been predicted by many – and feared by some – ever since the end of the cold war. The national security expert Robert D Kaplan described it in a 1994 Atlantic magazine article as “the coming anarchy” – the binary superpowers had held borders mostly in check, now people would start to move. “There would likely be 50 million on the move by 2020, experts at the United Nations University projected. Two hundred million by 2050, the environmental security analyst Norman Myers announced. One billion! the NGO Christian Aid projected.” One result of those alarmist predictions had been the populist politics that has emerged with a single purpose in mind: how to make those people stay still. “End freedom of movement!”; “build the wall!”
Shah begins her history with a series of observations that become parables from the natural world. The first concerns the habits and behaviour of the checkerspot butterfly. The checkerspot, most abundant on the west coast of America, is not a powerful creature. It flies very low to the ground and only lives for 10 days. Because of its sensitivity to changes in habitat and environment, it also proved one of the first bellwethers of climate change. A celebrated paper in Nature in 1996 showed that in response to warming temperatures the edges of the population of checkerspots were moving northwards at a rate of 20km per decade. Shah joined the butterfly hunters marking that progress and along the way found evidence that myriad other species are also checking out of familiar territories: Atlantic cod, for example, are moving at a rate of 200km a decade toward the cooler poles.
Shah confesses to a certain kinship with those migrations. Her parents – alone among their siblings – moved from India 50 years ago to fulfil a need for doctors in New York City, in the first wave of legal migration from the subcontinent. That migration instilled in Shah “an acute feeling of being somehow out of place”; despite having been born American, “I didn’t consider myself as being ‘from’ that place, even though I’d borne both of my children there”. For a few years, she and her husband left to live in Australia and became doubly “alien”. These feelings prompted questions in Shah: where did that concept of home originate? And was that a learned or an innate understanding?
Her
compulsive investigation into these questions becomes a political history of the
human urge to move from one place to another. It begins with the “mitochondrial
Eve” identified as the African ancestor of all human societies – the prime
mover of a species hardwired to migrate – and ends in the determined and futile
efforts of contemporary politicians to deny that instinct in individual
refugees with nowhere to go except somewhere else.
Shah identifies the emergence of biological taxonomy, the naming of things, as the historical moment when we decided that nature, which had never stopped moving and evolving, was actually fixed. Carl Linnaeus, “the sex-crazed Swedish taxonomist”, becomes the founding father of a political principle of nativism that can be summed up simply: “We belong here. They belong there.” She shows how this enlightenment control freakery gave rise not only to eugenics and “race science” but also to the underpinnings of fascism. Heinrich Himmler, in addition to masterminding the genocide of millions, issued rules for landscape design: “The head of the Reich central office for ‘Vegetation Mapping’ called the delicate flowering herb Impatiens parviflora a ‘Mongolian invader’ and recommended its extermination.”
Having established this history, Shah unpicks its pernicious effects on contemporary false narratives about immigration and the re-emergence of supremacist racial rhetoric in the political mainstream. It is only two decades since Bill Clinton stood on the White House steps and announced the sequencing of the human genome, which offered incontrovertible proof that we not only have infinitely more in common than that which divides us – “The sequencers had found [that] a paltry 0.1% of the 3bn nucleotides strung together on our strands of DNA differed from any one person to the next” – but that encoded in our DNA was the age-old urge to mix and move about.
Towards the end of this fascinating study, Shah travels to some of the frontlines of the denial of that instinct. She meets the gravediggers of the Greek island of Lesbos, who bury the migrants who wash up on their shores, many of them children, in unmarked graves. She has no easy answers, except to argue that our biology and our history tell us a very different story to our politicians. Nigel Farage’s efforts to police the English Channel are about as likely to succeed as those of King Canute. “Life is on the move, today as in the past,” Shah insists. “For too long, we’ve suppressed the fact of the migration instinct, demonising it as a harbinger of terror. We’ve constructed a story about ourselves, our history, our bodies, and the natural world around us in which migration is the anomaly. It’s an illusion. And once it falls, the entire world shifts.”
The Next Great Migration by Sonia Shah review – why people wander. By Tim Adams. The Guardian, June 7, 2020.
“A wild
exodus has begun,” writes Sonia Shah early on in The Next Great Migration. “It
is happening on every continent and in every ocean.” In response to the climate
crisis, plants and animals that until recently scientists thought were fixed to
a particular habitat have been seeking out different surroundings. Butterflies
and birds have been edging their way towards the Earth’s poles; frogs and fungi
are slowly climbing mountain ranges – while in the oceans, even some coral
reefs are moving at the rate of a few kilometres per year. And where wild
species go, humans may follow, Shah suggests, noting that more people already
live outside their countries of birth than ever before, some of them pushed by
war, floods, rising seas and creeping deserts.
It sounds apocalyptic. But are we wrong to think so? Shah, a US science journalist, argues in a deeply researched and counterintuitive history that much received wisdom about migration – human or otherwise – rests on a series of misconceptions. We tend to see migration as unwelcome and rare, a flight from hardship or a burden for the place of arrival. But techniques including genetic history, navigational mapping and climatology have revealed that migration and mixing are far more central to life on Earth than previously thought. They may, in fact, “be our best shot at preserving biodiversity and resilient human societies”.
In making this argument, Shah takes on the dominant view of displacement as an overwhelming tide of human misery that will threaten global stability. Over the past few decades, this perspective has shaped national security policy in powerful countries such as the US, as well as the approach of international institutions such as the UN. Migration, crudely put, equals disorder.
If we are to escape this way of thinking, we will have to dispense with the deep-seated assumption that peoples and species are fixed to specific parts of the planet; a “stillness”, as Shah puts it, that sits “at the centre of our ideas about the past”. To make her point, she takes the reader through a history of modern biology, beginning with the 18th-century European naturalists whose effort to categorise the world went hand in hand with the exploration and colonisation of large parts of the globe. From the start, the idea that humans could be divided into a distinct set of biologically different types, each linked to one of the world’s continents, came with value judgments. White Europeans were generally seen as superior, and mixing as undesirable. Shah traces the development of 19th century race science, and how that in turn came to inform political arguments in favour of immigration control. (Arguments in America, at least: while Shah tells a global story in terms of biology, the political narrative is constructed mainly with a US readership in mind.)
Ideas about wild species also informed attitudes to humans. Chief among them, in Shah’s account, is the relationship between population and habitat. A mistaken belief among some 20th-century zoologists that nature was essentially “filled up” – each species occupying its own ecological niche, vulnerable to disruption from invasive outsiders, or to self-destruction through overbreeding – led some to imagine migration as “a vector of death”. In the 1960s, a number of ecologists and other scientists began to voice concerns about the supposed destructive effects of human overpopulation, an argument that gained mass appeal through the 1968 bestseller The Population Bomb, by Paul and Anne Ehrlich, which predicted widespread famine and social unrest unless drastic action was taken to limit the world’s population. Although the authors didn’t link this to an explicit call for immigration control, others who followed them did, giving weight to criticism that this was a form of Malthusianism, where “population control really meant controlling certain populations and not others”. Inferior foreigners and the poor, in other words.
Yet although Shah is firm in pointing out where scientists have got it wrong, she has faith in science. Animal populations fluctuate, move and adapt their bodies according to the availability of resources. When human population numbers rise, people often work together to find innovative solutions: Shah gives the example of Mexico, where a rising population prompted farmers to improve the efficiency of wheat production, and of cross-border cooperation over water shortages.
Perhaps the most groundbreaking discoveries of recent years have been in genetic history. It has already been several decades since the study of DNA revealed how little substance there was to claims of racial difference. Study of genetic material found in ancient bones also suggests that, rather than a single migration out of Africa, humans populated the globe in waves that intermingled, coming back as well as going forwards. “We weren’t migrants once in the distant past and then again in the most recent era,” Shah writes. “We’ve been migrants all along.”
That general truth might not be enough to defuse conflicts over migration by itself. But Shah’s tone is neither smug nor triumphalist. She is clear about the power and the danger of xenophobic politics, tracing the anti-refugee backlash that has been mobilised by the right, as well as the threat to our lives posed by the climate emergency. Hers is an optimistic book nonetheless, because it tells us that this is just the latest chapter in a long story of survival and adaptation. Climate change will cause people to move, she argues, but it won’t necessarily be in the way we think: extreme weather, for instance, generally prompts people to move short distances; longer migrations are the result of more gradual change. Migration is disruptive, “but the next great migration will not unfold as an unstoppable physical phenomenon, like a cold front sweeping in from the north”.
This is a vivid and engaging story that weaves in the accounts of refugees Shah has met to illustrate the harm done by today’s border controls. As a writer, she has an eye for the visual metaphor, likening anti-immigration arguments to puffball mushrooms, which grow huge, then burst to release their spores, leaving “an empty, crinkled shell”. Those arguments may indeed be hollow but they spread their spores nonetheless: we need books such as this to expose them.
The Next Great Migration by Sonia Shah review – movement is central to human history. By Daniel Trilling. The Guardian, June 26, 2020.
The
Edith’s checkerspot butterfly is a delicate insect, with a wingspan less than a
thumb’s length and a tendency to hide from the rain. For many years, these
butterflies were thought to be “the entomological equivalent of homebodies,”
science journalist Sonia Shah writes in her new book, The Next Great Migration.
Researchers hardly ever saw them stray far from the places where they were
born. As cities encroached on the species’ habitats and climate change made it
harder to survive, many believed they were destined for extinction.
But in the mid-1990s, a Texas biologist named Camille Parmesan made a startling discovery. After gathering data on their habitats, she found that these fragile little animals weren’t homebodies at all: they had been shifting their range in response to climate change, moving north and to higher altitudes in order to survive. Parmesan’s discovery brought about a revolution in climate science, and soon researchers found legions more species that were migrating in response to climate change, including corals, red foxes, and even fungi.
This is the anecdote that opens The Next Great Migration, an ambitious work of journalism that argues migration has played a vital role in our planet’s history. For centuries, Shah writes, scientists and political leaders have portrayed migration as something “unnatural” and “disruptive,” clinging to the idea that people, plants, and animals aren’t meant to move. But in reality, she argues, movement is completely natural, and we’ve been doing it for millennia. And while it’s sobering to know that our changing climate has disrupted so many species’ way of life, Shah sees reason for hope. “A wild exodus has begun,” she writes. “It is happening on every continent and every ocean.” In the coming years, as climate change threatens human and animal habitats, migration “may be our best shot at preserving biodiversity and resilient human societies.” In other words, it has the power to save all our lives.
Shah makes her case by moving nimbly between scientific history, scenes from her travels with ecologists, and occasional stories from refugees around the world. She takes a reportorial approach, mostly staying out of the picture, but she does briefly wrestle with her own experience as a daughter of Indian immigrants who spent many years feeling “somehow out of place” in the United States. “As a child, I was ashamed of even small things, like my preference for suspiciously fruity strawberry ice cream over the unimpeachably American chocolate for which the other children clamored,” she writes. It’s only after starting to research migration as an adult that she begins to feel like she truly belongs.
Scientists have been depicting migration as a destructive force since at least the 18th century, Shah writes, when the Swedish botanist Carl Linnaeus invented modern taxonomy. Linnaeus believed that all the world’s species had left the Garden of Eden long ago—and then stayed put for centuries. The notion of mass migration was unthinkable: like many of his contemporaries, Linnaeus assumed birds hibernated for the winter, diving to the bottom of lakes or hiding out in caves. Accordingly, Linnaeus developed a system for classifying plants, animals, and people based on their geographic location. Humans who lived on different continents, he believed, were separate subspecies. It was a false idea, but a politically expedient one: “From a colonial perspective, it was more convenient to cast foreigners as so strange as to be unrelated or perhaps not even human at all,” Shah notes. Using Linnaeus as a jumping-off point, Shah surveys the vast legacy of scientific xenophobia, showing how the idea that migration is unnatural went on to influence eugenicists and the Nazis, along with prominent biologists and even U.S. presidents.
Along the way, Shah offers an important reminder that the history of American conservation movements can’t be separated from that of anti-immigrant politics. Madison Grant, who played a key role in developing the national park system, was also a white supremacist who shaped U.S. immigration policy. John Tanton, a conservationist who started a chapter of the Audubon Society, was a racist thinker who launched a network of anti-immigration groups that continue to influence the Trump administration today. Even David Brower, the famous Sierra Club leader, tried to push his organization to adopt an anti-immigration platform as recently as the late 1990s. (Tanton also participated in that effort.) Brower was one of a group of environmentalists at the time who were obsessed with the false idea that migration would lead to overpopulation and destroy the planet.
In the latter half of the book, Shah presents a skillful rebuke to the long line of scientists, environmentalists, and elected officials who’ve advanced such xenophobic thinking. In recent years, scientists have begun to discover the full extent of ancient human migration: we now know that early humans traveled out of Africa in several waves and back again, moving continuously between continents throughout the course of history. “Migration is not an exception to the rule,” she writes. “We’ve been moving all along.”
She also wades into the debate about invasive species, arguing that migratory plants and animals have been unfairly maligned. It turns out many scientists think that only about one percent of nonnative species pose a threat to resident plants and animals—the rest tend to increase biodiversity, if they have any impact at all. Moreover, leading biologists say that migration “most likely evolved as an adaptive response to environmental change.” That’s why creatures like the checkerspots move as the earth gets warmer, and why migration will play a critical role in the planet’s future.
In this last part of the book, you get the sense that Shah is rushing a little—I wish she’d spent more time exploring the complicated contemporary science of wildlife migration. She also gives a brief overview of the ways we’re seeing climate change influence human movement today, but she doesn’t go into much depth on the topic. Despite the book’s title, The Next Great Migration focuses more on the past than on the future.
But maybe it’s inevitable that you can’t cover everything when you’re trying to wrangle hundreds of years of human and environmental history into a book that’s just over 300 pages. Shah has done a remarkable job, distilling complex ideas from a variety of disciplines into concise and elegant prose. She has a knack for summing up a big idea in a punchy sentence, but she also knows how to linger on a lovely scene, transporting the reader from the jungles of Hawaii to the Himalayan foothills.
Prior to The Next Great Migration, Shah wrote a book about pandemics, and she admits that her work in that field once contributed to her “sense of movement as aberrant, something anomalous that needed to be examined and explained.” In the past few months, politicians have been especially eager to exploit Americans’ heightened fear of movement. We’ve seen Trump use COVID-19 as an excuse to push through draconian measures—like indefinitely closing the border to asylum seekers—that have nothing to do with stopping the virus.
In this time of rampant xenophobia, Shah’s book offers a call to “reclaim our history of migration and our place in nature as migrants like the butterflies and the birds.” It’s a powerful invitation, and one that’s never been more urgent.
A Science Writer Makes the Case for Embracing Migration. By Sophie Murguia. Outside , July 30, 2020.
No comments:
Post a Comment