Ecology

Credit: The Aldo Leopold Foundation and University of Wisconsin-Madison Archives

Estella Bergere Leopold was a palaeobotanist whose studies of fossil pollen and spores helped to reconstruct past environments and link them to the present. Her investigations of the Cenozoic era (from 66 million years ago to the present) provided some of the first insights into the evolution of modern plant communities and the factors that governed their development, including the consequences of long-term climate change, mountain building and volcanism. Few researchers before her had traced the rise of present-day ecosystems through time, and her discoveries helped to connect the relatively well-studied ice-age influences on vegetation with deep-time geological processes.Leopold, who has died aged 97, was an ardent conservationist who argued that nature should be cherished and protected. She thought that science should be used in defence of the planet; this is evident in her writings, lectures and political activism.Leopold was born in Madison, Wisconsin, the youngest daughter of conservationist Aldo Leopold and his wife Estella Bergere Leopold. All five Leopold children became esteemed scientists and conservationists in their own right. Her childhood, particularly her time spent at the family cabin, called ‘the Shack’, in central Wisconsin spurred an early interest in ecology. Leopold graduated with a degree in botany from the University of Wisconsin–Madison in 1948 and a master’s degree from the University of California, Berkeley, in 1950. She moved to Yale University in New Haven, Connecticut, to join a new graduate programme in conservation headed by Paul Sears, a pioneer in palynology (pollen analysis), and also to study with mathematical ecologist G. Evelyn Hutchinson and his former student Edward Deevey Jr. Her dissertation focused on the history of New England forests through the analysis of pollen and spores extracted from peat deposits, and palynology became her main research tool.
Current conservation policies risk accelerating biodiversity loss
After graduating from Yale in 1955, Leopold was one of the few women who joined the US Geological Survey in Lakewood, Colorado, as a scientist. By meticulously comparing fossil pollen and spores with modern ones, she reconstructed past floras — innovative and insightful findings at the time. Her early study of the Eniwetok and Bikini atolls in the Pacific Ocean revealed the existence of a tropical rainforest in the south Pacific during the Miocene epoch (23 million to 5 million years ago). She examined Cenozoic plant-fossil sites for evidence of the origins of modern flora. Leopold described the transition from ancient species to newer variants in the Rocky Mountains of western North America, which showed an earlier modernization trend in the middle of the continent than in coastal areas, as a result of greater cooling, seasonality and mountain uplift.Her research in Colorado on the Florissant fossil beds — well-preserved sediments from a 34-million-year-old lake — spurred her to lead a conservation effort in the area. In 1969, the 2,428-hectare Florissant Fossil Beds National Monument was established. Other successful actions included opposing oil-shale development in western Colorado, protesting dam building in the US Grand Canyon and stopping the shipping of highly radioactive materials through waterways that connected the Pacific Northwest region to the Pacific Ocean. Leopold also served on several conservation boards and was president of the Aldo Leopold Foundation, which she founded with her siblings to promote ethical land stewardship.From 1976 to 1982, she directed the Quaternary Research Center at the University of Washington in Seattle and maintained an active research programme there, studying the palaeoecology and palaeoflora of the western United States and comparable settings in China. She officially retired in 2000, but remained active in research until her death.Leopold recognized the power of scientific credentials in environmental activism. Throughout her career, she promoted palaeobotany as a tool for land protection. She argued that the value of a place was partly the result of its ecological history and how environmental events shape it. One of those events is fire. Using ethnographic and palaeoecological studies, Leopold highlighted the importance of Native American burning practices before European settlement for maintaining the health of prairies and woodland; she actively supported deliberate fire management.
Address the growing urgency of fungal diseases in crops
In 1969, Estella was named conservationist of the year by the Colorado Wildlife Federation; she received the International Cosmos Prize for contributions to conservation in 2010. But those awards, and numerous others, scarcely do justice to the personal influence that she had on students. I met Estella at the US Geological Survey as an undergraduate student and was overjoyed when she accepted me for graduate studies at the University of Washington. Her unbridled enthusiasm for science and environmental protection was inspiring. Estella had what we students called a ‘1,000-volt look’ whenever an idea piqued her interest — to experience this was electrifying.Estella will be remembered for her important contributions to ecology and for a life-long crusade to protect the land. More than most individuals, her scientific interests were inextricably linked to her environmental activism. She was keenly aware of her family heritage and, like her father, advocated simple outdoor living as a way to learn and appreciate nature. As a woman in a male-dominated field, she maintained a strong sense of humour and fearlessness throughout her career; yet, she also had immense grace and generosity. Estella leaves behind colleagues, former students and environmental activists who treasure her influence and their time with her. More

Fifty years ago this week, Gaura Devi, an ordinary woman from a nondescript village in India, hugged a tree, using her body as a shield to stop the tree from being cut down. Little did she know that this simple act of defiance would be a seminal moment in the history of India and the world. Or that Reni village, where she lived, would come to be recognized as the fountainhead of the Chipko environmental movement.Chipko, in Hindi, means ‘to stick’ or ‘to cling’. In the early 1970s, the Western Himalayan regions of Garhwal and Kumaon, where Reni is situated, were in turmoil. Villagers had been using non-violent methods, including tree hugging, to save their local forests from industrial logging for several months by the time Gaura Devi — and about two dozen women from Reni — showed up on the scene1. But the courage of this small group of women, who stood their ground against loggers who hurled threats and abuses at them, shot the movement to international attention.What followed holds lessons for a planet teetering on the edge of a climate crisis: marginalized communities can succeed in catapulting environmental concerns into the global spotlight through innovative protest tactics. The Chipko movement gave rise to India’s Forest Conservation Act of 1980, the express aim of which is to conserve woodlands. A few years later, a new federal environment ministry was set up to act as a nodal agency for the protection of biodiversity and to safeguard the country’s environment1–3. Even the origin of the term tree hugger — which has since acquired pejorative connotations — can be traced back to the grassroots ecological consciousness that surfaced in India’s villages.
The origins of India’s environment movement
The movement and its aftermath hold sobering lessons, too. Villagers who threatened to cling on to trees were voicing concern not just about the state of the forests, but also about their own lives and livelihoods. Their desire was to exercise greater local control over woodland resources. Women such as Gaura Devi, for instance, had to walk long distances to gather firewood once the forests were denuded1,4.Beginning in the late 1960s, activists who took inspiration from the leader of India’s anti-colonial nationalist campaign, Mohandas Gandhi, had begun to mobilize villagers in the Western Himalayas. Their strategy to improve economic opportunity in the region hinged on the Gandhian vision of bottom-up development. A network of cottage industries and cooperatives began to be set up to market forest products. The government’s competing top-down approach of auctioning forests to big private contractors came as an unwelcome intrusion3,5,6.In essence, what the foot soldiers of Chipko wanted was an acknowledgement of their Indigenous rights to access forest resources that were crucial for their survival. What they got instead was a national law and a ministry populated by a new breed of power brokers — who, in the years to come, would decide at times that habitat preservation is possible only by keeping local communities out.The big debateGarhwal and Kumaon, part of the present-day state of Uttarakhand, were at the heart of independent India’s first big debate on environmental justice and equity for a reason. The terrain is mountainous and most of the land is forested. Lives and livelihoods centre heavily around access to land and water resources. Apart from subsistence agriculture, the main source of income in the region 50 years ago was remittance — money sent home from men who had migrated to cities or joined the armed forces2,4,5.Although daily life was economically precarious for the villagers, the hills also presented them with a fragile environment. In the years preceding the Chipko movement, floods and landslides had wreaked havoc. Some of the villages worst affected lay near forests that had been felled1,5,6.
Three climate policies that the G7 must adopt — for itself and the wider world
The idea of ‘commons’ and ‘sacred forests’ had been an intrinsic part of the cultural ethos of rural India, but the colonial period frayed the bonds that villagers tended to have with their immediate environment. The British Raj’s primary source of income was land revenue. As a result, converting forest or common land into agricultural land by getting rid of existing vegetation was very lucrative1,2.Things did not improve after independence — the Indian government’s fourth five-year plan (1969–74) directed the state forest departments to take control of forests and open lands. This policy resulted in more restrictions to access for the locals, who depended on nearby woodlands to meet their needs for food, fruit, fodder, firewood and other raw materials2,3.The spark that ignited Gaura Devi’s tree-hugging protest came when the provincial government handed over ash trees in the Chamoli district of Garhwal to a private contractor to make sports goods. This disregarded the request put forward by a local artisan’s cooperative, the Dashauli Gram Swarajya Sangh (DGSS, Society for Village Self-Rule), which wanted to use the trees to make agricultural implements1,5.
Shade is an essential solution for hotter cities
The manner of protest itself was not new. A year earlier, in March 1973, in the nearby village of Mandal, women and men had come together to prevent the felling of trees under the leadership of a local activist, Chandi Prasad Bhatt, who was associated with the DGSS. As word spread, the act of chipko, or embracing a tree, became an andolan — a movement — which united people across social, caste and age groups, with even children participating in many villages1,5.However, the protest in Reni village is now recognized as a seminal moment. Gaura Devi was an ordinary woman. But her extraordinary act continues to stand as a prominent signpost in the evolution of India’s ecological consciousness, even 50 years later.Surprising savioursOn the day the trees near Reni village were to be felled, neither the DGSS members nor the men of the village were present. This was no coincidence, but a deliberate plan by forest department staff, who had organized meetings elsewhere to minimize the possibility of a large-scale protest. However, what they did not account for was the leadership of Gaura Devi, who headed the village’s mahila mandal (women’s group). On being alerted by a young girl who had seen the bus carrying the loggers, Gaura Devi marshalled the women of the village. They put their bodies in front of the axe-wielding men, eventually forcing the loggers to leave1,5.

In Joshimath, India, cracks developed in homes in January 2023 as the town began to sink.Credit: Brijesh Sati/AFP/Getty

What made these village women, whose roles were conventionally restricted to the home, come out in force to protect the trees? The environmental activist Vandana Shiva, adopting an ecofeminist lens, argues that women, especially in rural areas, share close bonds with nature because their daily tasks are entwined with nature7. For the historian Ramachandra Guha, however, although Chipko did see women participating on a scale like never before, it would be simplistic to reduce it to a women’s movement. For Guha, Chipko is a peasant movement centred on the environment, in which both men and women were involved1,5.Chipko is also synonymous with two men: Bhatt and Sunderlal Bahuguna. Both had strong roots in the community, having worked with voluntary organizations based on the Gandhian ideology of non-violence and satyagraha (which loosely translates as ‘truth force’). Through eco-development camps, Bhatt worked tirelessly to raise awareness about the fragility of the region’s environment. Bahuguna’s padayatras (journeys on foot) across India brought Chipko to the attention of people in other parts of the country and across the world. Chipko thus began to spread3,5,6.In the forests of the Western Ghats in the south Indian state of Karnataka, Chipko inspired similar protests called Appiko (meaning ‘cling’ in the local language, Kannada). Internationally, Bahuguna took Chipko to university lecture halls in western Europe, and the simple idea of hugging trees for protection also resonated with activists in Canada and the United States6. In 1987, the movement was awarded the Right Livelihood Award, known as the alternative Nobel prize, for its impact on the conservation of natural resources in India.The afterlifeOver the years, Chipko has been interpreted and reinterpreted by academics and activists. It has been the subject of many books, peer-reviewed papers and popular articles, and is mentioned in the curriculum of Indian schools. Chipko has a prominent place in the discourse on sustainability, too — as an example of the demand for sustainable development at a regional or local level. In March 2018, to commemorate the 45th anniversary of the movement, an iconic photograph of women joining hands around a tree appeared as a Google doodle, highlighting the movement’s international fame.An immediate effect of the 1974 Reni protest was a 15-year moratorium on tree felling4. A slew of laws and regulations for protecting the forest came into effect. Ironically, Chipko, which had set these laws in motion, resulted in local communities losing access to the very forests that met their livelihood and subsistence needs. Little changed in terms of development or employment opportunities for the locals. With forest protection prioritized, even minor development projects, such as village roads or small irrigation channels, were denied permission. At the same time, large infrastructure projects promoted by the government, such as hydroelectric dams, got the go-ahead2.
The global south is rich in sustainability lessons that students deserve to hear
The fragility of the landscape has steadily worsened. In February 2021, a catastrophic landslide in Chamoli district caused the death of some 200 people. What made the disaster worse were the multiple hydropower plants situated in the path of the landslides. In January 2023, disaster struck again when the town of Joshimath in Chamoli began sinking. Cracks developed on roads and in homes, and people had to be moved to relief camps. The unplanned development of the town on top of an earthquake-induced subsidence zone was a key reason. But a persistent concern in the region is its intrinsic ecological vulnerability, compounded in recent years by climate change.What is the relevance of Chipko today? According to the United Nations, all of us are living amid the triple planetary crises of climate change, biodiversity collapse and air pollution. Humanity has also transgressed six out of the nine ‘planetary boundaries’ that ensure Earth stays in a safe operating space8. In the context of these monumental concerns, it’s remarkable that Chipko continues to inspire.Social and environmental movements in India are still guided by its spirit. It is a strategy used by non-governmental organizations, activists and citizen groups in their fight against development projects that adversely affect tree cover. Thus, hundreds of Chipko-like movements have bloomed in villages and cities across India, inspired by a simple idea — hugging a tree to save it — and by the courage of village folk.A villager from Chamoli, Dhan Singh Rana, wrote a song describing the life and struggles of Gaura Devi, in which he says, “In this world of injustice, show us your miracle again.”3 As the world careens from one crisis to the next, it is more imperative than ever to rekindle the memory of Gaura Devi. It should inspire us to act to save the planet and contribute to sustainable change, putting aside any misgivings about our own limitations as individuals or communities. More

After 15 years of discussion, geologists last week decided that the Anthropocene — generally understood to be the age of irreversible human impacts on the planet — will not become an official epoch in Earth’s geological timeline.The rejected proposal would have codified the end of the current Holocene epoch, which has been in place since the end of the last ice age 11,700 years ago. It suggested that the Anthropocene started in 1952, when plutonium from hydrogen-bomb tests showed up in the sediment of Crawford Lake near Toronto, Canada.The vote has drawn controversy over procedural details, and debate about its legitimacy continues. But whether or not it’s formally approved as a stratigraphic term, the idea of the Anthropocene is now firmly rooted in research. So, how are scientists using the term, and what does it mean to them and their fields?‘It’s a term that belongs to everyone’As head of the Leverhulme Centre for Anthropocene Biodiversity at the University of York, UK, Chris Thomas has perhaps more riding on the term than most. “When the news of this — what sounds like a slightly dodgy vote — happened, I sort of wondered, is it the end of us? But I think not,” he says.For Thomas, the word Anthropocene neatly summarizes the sense that humans are part of Earth’s system and integral to its processes — what he calls indivisible connectedness. “That helps move us away from the notion that somehow humanity is apart from the rest of nature and natural systems,” he says. “It’s undoable — the change is everywhere.”
Geologists reject the Anthropocene as Earth’s new epoch — after 15 years of debate
The concept of an era of human-driven change also provides convenient common ground for him to collaborate with researchers from other disciplines. “This is something that people in the arts and humanities and the social sciences have picked up as well,” he says. “It is a means of enabling communication about the extent to which we are living in a truly unprecedented and human-altered world.”Seen through that lens, the fact that the Anthropocene has been formally rejected because scientists can’t agree on when it began seems immaterial. “Many people in the humanities who are using the phrase find the concept of the articulation of a particular year, based on a deposit in a particular lake, a ridiculous way of framing the concept of a human-altered planet.”Jacquelyn Gill, a palaeoecologist at the University of Maine in Orono, agrees. “It’s a term that belongs to everyone. To people working in philosophy and literary criticism, in the arts, in the humanities, the sciences,” she says. “I think it’s far more meaningful in the way that it is currently being used, than in any attempts that stratigraphers could have made to restrict or define it in some narrow sense.”She adds: “It serves humanity best as a loose concept that we can use to define something that we all widely understand, which is that we live in an era where humans are the dominant force on ecological and geological processes.”Capturing human influencesThe idea of the Anthropocene is especially helpful to make clear that humans have been shaping the planet for thousands of years, and that not all of those changes have been bad, Gill says. “We could do a better job of thinking about human–environment relationships in ways that are not inherently negative all the time,” she says. “People are not a monolith, and neither are our attitudes or relationships to nature.”Some 80% of biodiversity is currently stewarded on Indigenous lands, Gill points out. “Which should tell you something, right? That it’s not the presence of people that’s the problem,” she says. “The solution to those problems is changing the way that many dominant cultures relate to the natural world.”The concept of the Anthropocene is owned by many fields, Gill says. “This reiterates the importance of understanding that the role of people on our planet requires many different ways of knowing and many different disciplines.”
Humans versus Earth: the quest to define the Anthropocene
In a world in which the threat of climate change dominates environmental debates, the term Anthropocene can help to broaden the discussion, says Yadvinder Malhi, a biodiversity researcher at the University of Oxford, UK.“I use it all the time. For me, it captures the time where human influence has a global planetary effect, and it’s multidimensional. It’s much more than just climate change,” he says. “It’s what we’re doing. The oceans, the resources we are extracting, habitats changing.”He adds: “I need that term when I’m trying to capture this idea of humans affecting the planet in multiple ways because of the size of our activity.”The looseness of the term is popular, but would a formal definition help in any way? Malhi thinks it would. “There’s no other term available that captures the global multidimensional impacts on the planet,” he says. “But there is a problem in not having a formal definition if people are using it in different terms, in different ways.”Although the word ‘Anthropocene’ makes some researchers think of processes that began 10,000 years ago, others consider it to mean those of the past century. “I think a formal adoption, like a definition, would actually help to clarify that.” More

Download the Nature Podcast 13 March 2024 In this episode:00:45 Making a map of the human heartThe human heart consists of multiple, specialized structures that all work together to enable the organ to beat for a lifetime. But exactly which cells are present in each part of the heart has been difficult to ascertain. Now, a team has combined molecular techniques to create an atlas of the developing human heart at an individual cell level. Their atlas provides insights into how cell communities communicate and form different structures. They hope that this knowledge will ultimately help in the treatment of congenital heart conditions, often caused by irregular development of the heart.Research article: Farah et al. Nature video: Building a heart atlas08:37 Research HighlightsResidue in ceramic vases suggests that ancient Mesoamerican peoples consumed tobacco as a liquid, and a wireless way to charge quantum batteries.Research Highlight: Buried vases hint that ancient Americans might have drunk tobaccoResearch Highlight: A better way to charge a quantum battery11:11 The evolution of menopause in toothed whalesMenopause is a rare phenomenon, only known to occur in a few mammalian species. Several of these species are toothed whales, such as killer whales, beluga whales and narwhals. But why menopause evolved multiple times in toothed whales has been a long-standing research question. To answer it, a team examined the life history of whales with and without menopause and how this affected the number of offspring and ‘grandoffpsring’. Their results suggest that menopause allows older females to help younger generations in their families and improve their chances of survival.Research Article: Ellis et al.News and Views: Whales make waves in the quest to discover why menopause evolved18:03 Briefing ChatHow the new generation of anti-obesity drugs could help people with HIV, and the study linking microplastics lodged in a key blood vessel with serious health issues.Nature News: Blockbuster obesity drug leads to better health in people with HIVNature News: Landmark study links microplastics to serious health problemsSubscribe to Nature Briefing, an unmissable daily round-up of science news, opinion and analysis free in your inbox every weekday.Never miss an episode. Subscribe to the Nature Podcast on Apple Podcasts, Google Podcasts, Spotify or your favourite podcast app. An RSS feed for the Nature Podcast is available too. More

Northern Australian elder George Milpurrurr shows the next generation how to do a cultural burn.Credit: Penny Tweedie/Alamy

Indigenous Australians have been using fire to shape the country’s northern ecosystems for at least 11,000 years, according to charcoal preserved in the sediment of a sinkhole. The study was published on 11 March in Nature Geoscience1.The practice of cultural burning, also known as ‘fire-stick farming’, is integral to Indigenous Australian culture and history, and is understood to have profoundly altered landscapes across the country.Fire-stick farming involves introducing frequent, low-intensity fires in small areas of the landscape in a patchy, ‘mosaic’ pattern, and is done early in the dry season. The practice is important culturally and environmentally; in particular, it reduces the amount of fuel available for burning and therefore decreases the intensity of wildfires that might spark late in the dry season because of lightning strikes or other triggers.Archaeological evidence indicates that humans have continuously occupied the Australian continent for at least 65,000 years2, but little is known about when the practice of fire-stick farming began.“You need a really long record that goes back before people were here so you can see what the natural world — the definitively unimpacted world, if you’d like — looks like and then you’ve got enough of a record to be able to see if anything changed,” says study co-author Michael Bird, a geologist at James Cook University in Cairns, Australia.The researchers found that record in the sediment of Girraween Lagoon, a permanent water body formed in a collapsed sinkhole near Darwin in the Northern Territory. The lagoon is an important site for the traditional owners of the land, the Larrakia Nation, and was made famous by the crocodile attack scene in the 1986 film Crocodile Dundee.Because the lagoon has remained full, its sediments offer a continuous record of deposition that has not been disturbed by drying out and cracking. Bird and his colleagues were able to extract a core from the bottom of the lagoon that provided a 150,000-year-long record of changes in the type and geochemistry of the deposited charcoal, and in the accumulation of pollen.Change in the charcoalThe team notes that, around 11,000 years ago, the changes in the charcoal deposits point to alterations in the intensity of fires in the area.Without human influence, fires are less frequent but have enough intensity to burn trees and leave behind charcoal, says Bird.“A less-intense fire doesn’t get into the crown — it’s burning what’s on the ground,” he says. The grass, as well as twigs and fallen tree leaves, are more likely to become charcoal than the trees themselves, he adds.Because tree-derived charcoal has higher concentrations of the isotope carbon-13 than does charcoal from grasses, the researchers analysed the composition and geochemistry of the burnt residue in the sample. The authors found a sustained change from low-frequency, high-intensity fires — the ‘natural’ fire regime — to more frequent but less intense ones, which they suggested was the result of Indigenous fire-stick farming.The authors ruled out climate change as the cause of the shift by using the ratio of tree pollen to grass pollen as a type of climate history to show that vegetation changes did not explain the shift in the charcoal record.However, Bird notes that European colonization has mostly brought an end to cultural burning practices, and has shifted fire intensity back towards a natural pattern. “Because we’ve had, 10,000 plus years of a particular fire regime, it’s the release from that fire regime that’s actually creating quite significant issues,” he says, suggesting that this shift has contributed to the return of more high-intensity wildfires.Joe Fontaine, a fire ecologist at Murdoch University in Perth, Australia, says that the growing understanding of how cultural burning has shaped the Australian landscape, particularly in the northern regions, is crucial for contemporary fire-management practices, which to a large extent have excluded Indigenous people and their expertise.“The barriers to doing cultural burning, in our arcane system of laws and bureaucracy,” are challenging to overcome, Fontaine says. There are also many more permanent structures in the landscape nowadays than there were before colonization, he says, so the challenge is to work out where and how cultural burning can be restored as a practice.The continuing work that “puts cultural burning practices out there and establishes it as something that really existed, is crucial to the evolution of contemporary fire management,” he says. More

For more than a decade, Christie Bahlai has been part of a long-running survey of ladybirds. Each summer, she and other scientists send students from their laboratories to a site on Gull Lake, Michigan, about 220 kilometres west of Detroit, to monitor 14 beetle species. Their goal: to track how invasive species are affecting native populations.The ladybird project has been running since 1989, and for 20 years had been directed by Douglas Landis, an entomologist at Michigan State University in East Lansing and Bahlai’s former postdoctoral adviser. But last year, Landis decided to retire. In December, he reached out to Bahlai, a computational ecologist at Kent State University in Ohio, to ask whether she wanted the many boxes of handwritten data sheets stored in his laboratory.
How to digitize your lab notebooks
Bahlai already had digital scans of the documents. Still, she wanted the originals. “What if there’s a note on the data that didn’t come through on the scans, or some other crucial context?” Bahlai explains. “And so, I received my inheritance over Christmas vacation.”Generally, “the easiest and most productive” way to compile data is to type them directly into a spreadsheet, says Miguel Acevedo, an ecologist at the University of Florida in Gainesville. But using a computer, tablet or even a smartphone in the field isn’t always practical. The Puerto Rican rainforest, where Acevedo studies malaria infection in lizards, is prone to unexpected downpours, so his team logs its data in pencil-drawn tables in waterproof notebooks. Bahlai and her colleagues record species counts by hand while working in dusty cornfields, their fingers often covered in sticky insect-trap goo.To be useful, handwritten data must be digitized into a form that can be analysed. But because this is one step removed from data collection, the process is rife with potential for error. Whether carrying over data manually or using software tools such as optical character recognition (OCR), researchers need to think about how to keep damage to a minimum. Here are five tips to do just that.Make a digitization integrity planOne of the first things Acevedo tells his students is that correcting mistakes in data becomes an order of magnitude more difficult with every step towards publication. He calls this the 1/10/100 rule: incorrectly writing down a lizard’s length in millimetres instead of centimetres is easily fixed — a metaphorical $1 mistake. But the cost jumps to $10 if the data point slips through the digitization process, and to $100 after it’s been analysed. Standardized protocols and workflows help to prevent such errors and minimize the cost, he says.In Bahlai’s lab, a “meticulous and reliable” student volunteer transfers the data from the original paper sheets to Google Docs. They annotate anything that they’re unsure of — a smudged number, for example — and tag Bahlai, who will take a closer look. After a second student double-checks the data, Bahlai transfers them into a spreadsheet, for more in-depth quality checks.Acevedo’s set-up is different: students work in pairs, with one reading out the data and the other typing them in. He also insists on including in each notebook a metadata page that contains acronym definitions, units of measurement and other elements. “If somebody is looking at notebooks 20 years from now,” he says, “they’ll know exactly what they’re looking at.”Here’s another must-do, says Joel Correia, a human–environment geographer at Colorado State University in Fort Collins: invest the time and resources upfront to train the people doing the fieldwork. Correia studies the social and ecological effects of long-term land-stewardship practices in three Indigenous nations in the Ecuadorian Amazon. His team teaches members of those communities social-science research methods, such as designing and conducting interviews and surveys in their local language. In such multilingual, multicultural contexts, he says, having shared clarity around the concepts underlying the research is crucial, especially when taking written field notes that will be translated and digitized.Back up your paper, ASAPOnce you’re back from the field, do some rough digitization as soon as you can, Correia advises. Scanning your notebooks to PDFs, or even photocopying them, will safeguard you from the pain of seeing stacks of interviews destroyed by rain, fire or other unforeseen events. “I have not had that experience, but I have certainly heard of other people who have,” he says.Use several pairs of eyesOne common way of reducing errors is by having a number of people input the same data, and then correcting inconsistencies between the versions. How many pairs of eyeballs do you need? Make it an experiment, suggests Acevedo: test your error rate with different numbers of double-checkers, and find the point of diminishing return.

For her research, climatologist Linden Ashcroft often has to digitize historical sources, such as this page of climate data from 1837.Image courtesy of the National Archives of Australia. NAA: PP430/1, VOLUME 4.

But don’t overlook the human element, says Linden Ashcroft, a climatologist at the University of Melbourne, Australia. Ashcroft has run community-science efforts to digitize hand-written records in farmers’ diaries and other historical sources, some going back 200 years. She says that the World Meteorological Organization recommends that such data be double- or triple-keyed — that is, input independently by two or three people. But she knows of projects involving as many as eight individuals. “Is that really a good use of people’s time?”A good rule of thumb, Ashcroft suggests, is to calibrate your error rate to your project goals. “If you’re doing a deep dive into the weather and climate of a particular place, you want to lovingly correct the data,” she says. But if your data will be just a few of a million entries in an international database that researchers use to predict weather patterns, a slightly higher error rate probably won’t affect the outcome.Home in on outliersIf you are working with numbers, you can program your software to flag outliers, improperly formatted values and seemingly illogical data. For instance, Acevedo recalls discovering that lizards measured in one year were an order of magnitude smaller than usual. “I was there, so I knew that the lizards were not particularly small.” After he examined the notebooks from that period, he saw in the metadata that the numbers were recorded in millimetres rather than centimetres, and corrected the data.But that approach doesn’t always work, Ashcroft cautions. Outliers in her data can reflect unusually heavy rain or aberrations in atmospheric conditions, such as temperature or air pressure — real variation that is simply unexpected. “You don’t want the statistical test to kick those [values] out, because extremes are how we’re going to be affected climate change,” she says.Try OCR (and other software)OCR software can be used to convert scanned images into machine-encoded text. Many such tools are available — and most of them can successfully capture data sets in which handwritten text and numbers are written clearly and do not bleed out of their designated columns.But off-the-shelf software often falls short when applied to historical handwriting, in which s’s might look like f’s, for example, says Stuart Middleton, a computer scientist at the University of Southampton, UK. It also performs poorly in the face of image noise, such as creases or shadows in a scanned image or text that spills over from one column of a table into another. In the documents he works with, he says, “there are all sorts of horrors going on.”
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In such cases, researchers with a bit of computer-science savvy can try using different OCR models. Those models — available on the open-source machine-learning platform Hugging Face, for instance — are generally pre-trained on a wide array of images, but feeding them training images that are similar to your data could improve their performance, says Middleton. Scientists with advanced skills in coding and artificial intelligence can also modify the networks to better fit their projects. Middleton’s team is developing more-advanced, multistep OCR solutions for working with historical weather data, including new ways of training, as well as image post-processing.Options exist for digitizing other data types, too. Eliza Grames, an integrative biologist at Binghamton University in New York, uses historical data — largely graphs and charts from studies in the late nineteenth and early twentieth centuries — to map long-term insect-population trends. A program called metaDigitise (and a similar, browser-based program, WebPlotDigitizer) allows her to redraw the plots and calculate the underlying data. She also uses Inkscape, an open-source alternative to Adobe Illustrator, to digitize old species range data into a format that is readable by geographic-information-system mapping software.OCR still requires extensive expert oversight to clean up irregularities and check for errors, Ashcroft warns. She prefers to harness the efforts of volunteers around the world. “To me, the historical weather observations are a really valuable opportunity to engage people with climate science in a fun and easy way,” she says. “People get to be a part of the story.”And OCR is not always worth the trouble. For smaller projects, scanning every page and checking for errors after processing it through software might not yet be more efficient than having students do the job by hand, Acevedo says. But at the rate software is advancing, he says, that could soon change. “Maybe if we have this talk in 2025.” More

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In 1979, ethologist Christophe Boesch and his wife Hedwige Boesch-Achermann began researching the behaviour of a community of wild West African chimpanzees in Taï National Park, Côte d’Ivoire. Their study became the first long-term research on chimpanzees to be conducted in a continuous rainforest, rather than in a mixed savannah habitat such as Gombe National Park, Tanzania, where primatologist Jane Goodall had been working for almost two decades. It led to numerous discoveries about cultural diversity and behavioural variation — revealing, for example, that chimpanzees used hammers to crack nuts, that males cared altruistically for unrelated orphans and how predation by leopards influenced grouping patterns. Boesch argued that, because the Taï population was relatively undisturbed, it yielded a uniquely informative picture of chimpanzee behavioural adaptations. The Taï project remains the only study of a large population of habituated West African chimpanzees (Pan troglodytes verus), a rapidly dwindling subspecies (taichimpproject.org). He has died aged 72.Boesch promoted the conservation of chimpanzees by organizing population surveys, launching chimpanzee-research sites and driving the creation of national parks, including Moyen-Bafing National Park in Guinea. When faced with obstacles, from changing governments and obstructive mining companies to sceptical donor agencies, he had little patience for bureaucracy or unnecessary delays. He envisaged a continuous protected area that stretched from Senegal to Côte d’Ivoire and pursued this goal through the Wild Chimpanzee Foundation (WCF), which he and Boesch-Achermann co-founded in 2000. Under Boesch’s leadership, the WCF engaged local people and lobbied industries and ministries to avert threats from mining activities and infrastructural development. The foundation continues to lead conservation efforts in West Africa.Boesch was born in St Gallen, Switzerland, in 1951. When he was 12 years old, his father, a professor of cultural psychology, gave him King Solomon’s Ring by ethologist Konrad Lorenz, a 1949 book that stimulated Boesch’s lifelong interest in animal behaviour. He attended secondary school in Paris and returned to Switzerland to study biology at the University of Geneva. His first experience of field work with great apes was in Rwanda, studying mountain gorillas as an assistant to US primatologist Dian Fossey.
Chimpanzees are dying from our colds — these scientists are trying to save them
After learning that chimpanzees in Taï use natural hammers to crack open edible nuts, the Boesches spent five years habituating a wild community there to their presence, much of the time in the field spent together with their two young children. At first, the chimpanzees invariably fled, so that for many years the research was, in Boesch’s words, “a study of chimpanzee behinds”. Persistence paid off and led to a PhD from the University of Zurich, Switzerland, in 1984 and to an assistant professorship at the University of Basel in 1991.In 1997, Boesch became one of the founding directors of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. By then, research in Taï was producing rich data on three neighbouring communities, shedding light on intergroup dynamics and social traditions. In 1999, together with Andrew Whiten, Boesch organized a comparison of the behavioural diversity of seven chimpanzee populations. The resulting paper took the study of chimpanzee cultural variation to an increasingly systematic level and galvanized further work throughout Africa (A. Whiten et al. Nature 399, 682–685; 1999). Boesch set up an ambitious project to collect chimpanzee data from more than 50 sites in 18 countries. This project found evidence that chimpanzee cultural diversity had been reduced by human influences, suggesting that the conservation of these animals needs to include the protection of their local traditions.
These animals are racing towards extinction. A new home might be their last chance
Boesch thought that scientists routinely underestimated the cognitive complexity of chimpanzees, for example in their abilities to cooperate, teach their young or use several tool sets; and that studies of chimpanzees in captivity tended to have little relevance to understanding their behaviour in the wild. His pioneering findings often went against prevailing scientific thinking, but he trusted his eyes and never shied away from defending his views.By the 1990s, chimpanzees in Taï were dying from pathogens, such as anthrax, Ebola and respiratory viruses, that decimated Boesch’s study community and endangered human observers. Boesch introduced safety measures and organized studies that led to the first direct evidence of viruses being transmitted from humans to wild apes.In an era when painstaking fieldwork appealed less to students than did seemingly swifter rewards from laboratory experiments, Boesch insisted on the merits of old-fashioned patience: “Go to the field,” he would tell his students. “Observe the chimpanzees and don’t worry about the textbooks — the chimpanzees will teach you!”His passion and enthusiasm for chimpanzee research and conservation were contagious. And Boesch inspired a generation of primatologists. Inza Koné, president of the African Primatological Society, referred to Boesch as the father of primatology in Côte d’Ivoire, a characterization that could fairly be extended to West Africa as a whole. Early in Boesch’s career, he realized that each chimpanzee population is unique and that connecting separate populations is the key to their survival. His more than four decades of devotion to studying and protecting wild chimpanzees leaves a lasting impact on their survival and our knowledge of this species. More

RESEARCH HIGHLIGHT
28 February 2024

In a large US cohort of mother–child dyads, prenatal exposure to phthalate metabolites was associated with varying degrees of negative birth outcomes. More