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VIRGINIE COURTIER ORGOGOZO BIODIVERSITY AND ECOSYSTEMS FEBRUARY 9, 2023 INAUGURAL LECTURE Professors, esteemed colleagues, those of other high positions, ladies and gentlemen, friends, it is a great honor and a genuine pleasure to see so many of you here - other rooms have also been opened - for this inaugural lecture, by Virginie Courtier-Orgogozo,
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the annual chair of biodiversity and ecosystems. Created with support from the Jean-François and Marie-Laure de Clermont-Tonnerre Foundation, this chair is intended to enable progress in research and to illuminate the debate about the living world, the environment and biodiversity, by inviting leading figures, whose scientific work is intended for broad consumption,
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including by the public at large, to the Collège de France. The first row is normally reserved for professors. On behalf of the Collège de France, I sincerely thank the Jean-François and Marie-Laure de Clermont-Tonnerre Foundation, for its support in an essential field, in facing of our current environmental challenges.
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The living world is fascinating. Its complexity surpasses that of the most sophisticated machines that humans have invented over many centuries and that of physical objects, whatever our physicists may say. In the face of the 21st century's challenges, we must try to understand better the living world and its biodiversity, so that our planet may continue to be habitable for humans.
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To understand the living world, we must also understand the evolution of species and the question we may ask, when we look at one another, is whether each species that's currently living on Earth represents the peak of evolution. And that question may be accompanied by another: does evolution occur randomly or is it subject to particular constraints? Since the 2000s,
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genetics has developed in a way that is impressive and spectacular, leading to an explosion of discoveries about genes and their mutations. We have been able to observe that a genome contains fewer possibilities than we imagined, to evolve toward a given form. And those new technologies have also revealed the concept of gene drive.
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So what is the gene drive that is being developed in laboratories? Gene drive has potential applications, first in agriculture and public health, particularly in the fight against malaria, which kills over 400,000 people a year. The method could enable us to make mosquitoes resistant to the parasites that transmit malaria.
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The method obviously also implies risks. It may scare people. To what extent should humans intervene in genetic manipulation? We should reflect deeply on that ethical question and open up a debate, at all levels of society. And to do that, we're lucky to be joined this evening by Virginie Courtier-Orgogozo. An alumna of the École Normale Supérieure,
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and a teacher of earth and life sciences, Virginie Courtier-Orgogozo is a CNRS research director and leads a research team in Paris at the Jacques Monod Institute as well as teaching at the École Polytechnique. She's interested in the mechanisms of the evolution of species, the better to understand our origins and the future of living species. She has a particular interest in the evolution of bioadhesives,
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produced by fruit flies, to stick to various substrates during metamorphosis. She and Arnaud Martin have created a database of the scientifically identified genes and mutations that create natural morphological, physiological, and behavioral differences in plants and animals. And that database has shown - we'll hear further details in a moment -
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that evolution often takes a limited number of genetic paths, indicating that evolution is partly predictable. Virginie has written several articles on the risks and potentials associated with this new gene drive biotechnology, and, as I was glad to discover, you are also productively engaged in philosophy, particularly
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in the concepts of the gene development, identity and change and in 2020 you jointly published the Encyclopedic Dictionary of Identity, with Gallimard. You have received the CNRS's bronze medal and the 2014 Prix Irène-Joliot-Curie for young female scientists. You have been awarded the Ordre National du Mérite and in 2018
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you won the Collège de France's Prix Lacassagne. In your interview with the Collège de France team, to present your teaching for the biodiversity and ecosystems chair, you said you wanted to deconstruct the idea that humans are separate from the rest of nature and that we should remember that we are part of that nature. You intend your classes to show
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that the living world raises questions about ourselves, about matters we thought to be resolved and decisions that we will soon have to take. Virginie, we're keen to hear from you, so I'll hand over. Thank you. The administrator, teachers, colleagues, friends, ladies and gentlemen, I'd like to express my deep gratitude to the teachers at the Collège de France,
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who welcomed me to this prestigious institution. I'm particularly honored and moved, thinking of the great figures of biology, anthropology and medicine that have preceded me. I can't list them all today, but I'd like to mention Jacques Monod, who gave his name to the institute where I have had the good fortune to conduct my research since 2010. I'm also extremely grateful to Professor Edith Heard,
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who worked hard to set up this annual chair of biodiversity and ecosystems, and the Jean-François and Marie-Laure de Clermont-Tonnerre Foundation, which provides financial support. I also thank my research team and all my colleagues, for everything they give me, including the pleasure of working with them. Biodiversity denotes the forms of life on Earth. The word "biodiversity" was coined in 1985,
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by the ecologist Walter Rosen, at the Washington National Forum on Biodiversity, and then popularized by Edward Wilson. David Takacs' analysis shows that biologists took up the concept, with the aim of modifying our social values, our cultural habits, research and political decision-making. The German-American entomologist Thomas Eisner said,
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"The word has proved its use, through its striking meaning, "by which I mean people are now reacting to it." The 1988 report of the National Forum on Biodiversity summarized the situation perfectly. "Biodiversity creates a systematic framework "for analyzing the problem and searching for solutions." But our current relationship with biodiversity is ambivalent.
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It's synonymous with success and progress. Humans have colonized all of the world's habitable areas. They've developed crop and animal farming. They've invented machines, computers, satellites and vaccines and decoded the genomes of thousands of species. But we've also been a part of the degradation of ecosystems, the combustion of fossil fuels, the accelerated disappearance of many species
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and the effects of pollution on humans and other species. That situation should raise questions for all of us. Will we allow ecosystems to degrade, which increasing losses of individuals and species? Will we continue to idealize technological objects, while devaluing nature? What will the consequences be for future generations? What can we do to stop the erosion of biodiversity?
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The IPBES is an international group of biodiversity experts and its 2021 report acknowledges the complexity of the problem of reconciling the conservation of biodiversity, adaptation to climate change and the improvement of people's lives, including the reduction of poverty. I've studied the living world for over 20 years. Living creatures and their complexity fascinate and amaze me.
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But I'm just a biologist, not a politician or an economist and I feel relatively powerless in face of our current challenges. Yet as a biologist, I'd like to make a contribution, to try to find solutions. The failure of life sciences to better limit humankind's negative impact on nature, raises questions for me about my discipline. Albert Einstein said,
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"You can't solve a problem "with the ways of thinking that created it." That approach to problems is the essence of research. It's about entering the unknown trying to see the world differently and attacking problems from a new angle. Perhaps we need to transform our vision of biodiversity, better to understand the living world and to live better with it. In my classes at the Collège de France,
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I wanted to pursue several avenues this year, to think differently about life. The first is to acknowledge the importance of interactions, at various levels, and the interdependencies that underpin life. We humans can't live on another planet or in an environment divested of other forms of life. Life has been able to endure on Earth for so long thanks to those exchanges among living organisms.
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We are all assemblies or mosaics of disparate elements. Second, we need to move beyond the metaphor of the machine and take account of the fact that organisms derive from a historical process. There is no beginning to a living creature's life. We're all at the extremity of a long, living lineage, that has existed for billions of years. Third, it's important to admit
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that nature inspires many humans with admiration, wonder, respect and peace and although it's difficult, using our scientific methods, to understand and quantify that important characteristic of nature, we should not neglect it. In setting out different ways of thinking about life, it is not my ambition to solve the biodiversity crisis, but to help us to understand the living world better.
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The human species likes to make up stories, to give meaning to its surroundings and can believe strongly in some of them. For example, I think that everyone in Europe is convinced that a 100-euro bill is worth double a 50-euro bill. But those bills only display minor differences. I hope that new visions of the living world can help us find solutions to face our current challenges
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and to live better on our planet. In the first part of this lecture, I'll present the current context, with the human impact on ecosystems and the questioning of scientific progress. In the second part, I'll give you an insight into my research into biodiversity, to situate my perspective, as all researchers are influenced by the objects of their study. And in the third part,
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I'll analyze some of our human biases in our understanding of biodiversity. Trying to be aware of and overcome those biases is the first step toward changing how we see the living world. We are currently in the Anthropocene Era, a new epoch, marked by significant human impact on geology and ecosystems. When agriculture began, 10,000 to 12,000 years ago,
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the human population was an estimated few million. Since the industrial revolution, with its accompanying agronomical and medical progress, the global population has been steadily increasing. The latest estimates provided by the United Nations put the current global population at eight billion. The mass of human beings has surpassed that of wild animals and the mass of livestock - cows, pigs, sheep and so on -
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is even higher. The mass of poultry, particularly chickens - is higher than that of wild birds. The current mass of wild animals is a sixth of what it was 100,000 years ago. Crop and animal farming have impoverished plant and animal biodiversity. Of the 6,000 farmed crops, just nine species - sugar cane, corn, rice, wheat, potatoes, soy, manioc, sugar beet and palm oil -
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account for two thirds of plant production. Of the animals for human consumption, fewer than 40 species of bird and animal are farmed by humans and 14 species provide over 90% of the meat used for human food. Since humans appeared on Earth, other species have adapted to them, more or less, and to the environments that humans have transformed, while humans have adapted
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to the new distribution of species on Earth. Humans and other living beings interact constantly, in both directions. Several phenomena characterize the Anthropocene Era: the production of plastics - new polymer-based materials, made by humans - chemical and organic pollution, the intensification of transport,
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the movement of sediment, at rates higher than that of all the rivers combined, intensive agriculture, climate change and the biodiversity crisis. Their effects on the planet demonstrate our species' power and its weakness, as those effects weren't premeditated and our species now struggles to control them. Various perspectives are possible: those effects on ecosystem are caused by particular human activities,
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not by all human beings, which is why Andreas Malm, Donna Haraway and Jason Moore have suggested renaming this period as Capitalocene. But nothing suggests that a non-capitalist economy would have averted the use of fossil fuels and the intensification of transport. Furthermore, those effects only concern a thin layer of our planet's surface,
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while the planet itself has a radius of 7,000km. But that thin crust - the so-called "critical zone" - is home to the biosphere and our living environment, which facilitate human activities, so it's natural that we should be worried. A recent study was made of the use of the Earth's surfaces, over time, by dividing those surfaces into 96km² zones
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and putting them in different categories. The surfaces categorized as wild areas, characterized by a total absence of humans, have not changed. They're deserts and areas covered by ice, where humans couldn't live. In all the other areas with favorable conditions, humans had settled at least 10,000 years ago. The change in those 10,000 years is in the increase in the area covered by towns and villages,
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the reduction of the area covered by inhabited forests and the intensification of animal and crop farming. The biodiversity crisis is commonly thought to stem largely from the human destruction of untouched wilderness, but this study and others show that land was already inhabited 10,000 years ago and that the displacement of indigenous peoples, intensive agriculture and industrialization
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and demographic growth have led to an intensification of the use of land and the destruction of its biodiversity. So humans are not necessarily incompatible with the existence of natural diversity. Humans are currently facing a major biodiversity crisis. In Germany, between 1989 and 2016, insects were caught in traps in protected natural areas
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and the total mass of those insects was measured, in particular places, at different times of the year, between April and November. And that analysis revealed a 75% drop in the insect mass between 1989 and 2016. Another study, conducted with citizens in the UK, counted the number of insects found on car license plates while they were being cleaned,
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after a journey of several miles, in May and June, between 2004 and 2021. Between those two dates, the number of insects decreased by 58%. Various studies, in Europe and North America, have made similar observations of a major loss of insect numbers, in terms of their measured mass and the number of individuals and species. Researchers and enthusiastic amateurs around the world
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recorded the number of individuals in thousands of vertebrate species, of mammals, birds, fish, reptiles and amphibians. And every two years, a group from the WWF and the Zoological Society of London compiles all of that data, to calculate the so-called Living Planet Index, giving a percentage for the average variation in population size.
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Their latest report, from October 2022, places the individual numbers for each species studied at an average of 69% of the number recorded in 1970, which was taken as the benchmark. Those most affected are the specialized species that can only live in a narrow range of environmental and alimentary conditions. The index does not account for plants or invertebrates.
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As for trees, a report published in September 2021, involving over 500 experts, from around the world, who spent five years working on the project, shows that 30% of tree species are at risk of extinction. The greatest number, at over 23,000 tree species, is found in Central and South America, while Madagascar has the greatest number of endangered tree species. Forty-one species of tree
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no longer exist in their natural distribution areas and are only found in botanical gardens and seed collections, though we hope that they may be reintroduced to their natural environments. Other biodiversity crises have occurred through the Earth's history. The problem is not that this crisis is happening faster or that life on Earth will disappear. I don't think life will disappear so easily.
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Certain organisms, such as tardigrades and other micro-organisms, can withstand extreme conditions and will probably survive the crisis. The problem is more that the current situation is moving us toward a trajectory that will bring deep, long term changes in the conditions of life for future generations. So why should we prevent the destruction of biodiversity? First, for spiritual reasons.
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We biologists love nature and are amazed by its beauty and feel a deep moral duty not to destroy it. Second, for material, utilitarian reasons. The living world serves humans and the planet in many ways, providing materials and products, derived from ecosystems, such as food, oil and wood,
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support services, such as the water cycle, soil formation and photosynthesis, regulatory services, such as the recycling of organic waste and the regulation of the climate, and sociocultural services, derived from nature's recreational and esthetic facets. Personally, I don't find that practical approach,
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based on the benefits to human beings, particularly convincing. It encourages us to think that we'll be able to live on Earth so long as we have a few species to provide us with what we need. But do we want the cow soon to become the largest animal on Earth? There are other material reasons for wanting to retain a broad diversity of species and individuals.
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First, we are not yet aware of all of the benefits that nature could bring us. The new research currents in biomimetics or bio-inspiration look to the living world for technological answers to our questions. In my laboratory, we're studying the glue produced by fruit-fly larvae, just before their metamorphosis begins, which enables them to stick to a leaf or stem for several days.
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That glue is made of proteins and isn't environmentally toxic. We hope that our work will lead to industrial or medical applications. There are several thousand species of fruit fly, which have evolved different types of glue, to stick to various substrates, in varied conditions of temperature and humidity. People may think it doesn't matter if we lose a species of fruit fly,
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but when that happens, we also lose a glue that may have unsuspected adhesive properties. We don't know all the consequences of diminished biodiversity. There could be a snowball effect, with the disappearance of species leading to the disappearance of others, because of their interdependency. Some biologists have compared biodiversity to a plane. Losing a few rivets may not affect the plane and its passengers,
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but once a certain number are lost, the others will work lose and the plane may break apart. We don't know whether there's a tipping point, beyond which a planetary catastrophe would ensue, such as a drop in the atmosphere's oxygen concentration, with irreversible consequences for human beings. Five major causes of the erosion of biodiversity
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have been identified: the destruction of habitats, the overexploitation of resources, climate change, pollution and invasive species, and each of those direct causes can be linked to human activities: fishing, agriculture, energy use, drilling, infrastructure creation, forestry, tourism, and to indirect factors, linked to our modes of consumption, finance and governance
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and to demographics and technology, urbanization, migration, conflicts and epidemics. So one way of limiting the loss of biodiversity would be to address those indirect factors. Unfortunately, despite some international and national political commitments and a major rise in public awareness, biodiversity is still in decline, around the world. The atomic bombing of Hiroshima and Nagasaki
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made humans aware of an imminent risk of their own annihilation. Now, with the acceleration of global warming and the biodiversity crisis, a new pending risk of extinction has appeared on the horizon. That risk is lower than that of a nuclear bomb, in that we don't yet know whether the biodiversity crisis could lead to the wholesale destruction of the human race.
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But that risk is also greater, as it involves complex phenomena that are harder to manage than the onset of a nuclear war. The vast negative impact that humans are having on ecosystems is leading people to question the successes of science, by which I mean the processes of knowledge production that help us understand the world and act upon it.
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A section of the public has always been skeptical about the promises and results of science. In the early 19th century, for example, when Edward Jenner introduced his smallpox vaccine, there were cartoons such as this, showing patients who feared that the injection of cowpox pus would lead them to produce calves or cow horns on their heads.
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But I am now interested in the questioning of science by intellectuals themselves. Throughout the 19th and 20th centuries, various negative consequences of science, such as the atomic bomb, eugenics and global warming, led scientists, historians of science and philosophers to question the status of science and the knowledge it produces and to improve the definition of what science actually is.
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Bruno Latour, in France, and Helen Longino, in the USA, have shown how scientific fact is built up gradually, by a community of researchers, who analyze results, compare different points of view and arrive at conclusions. The publication of results in a scientific journal is not enough for those results to become a brick in the edifice of our knowledge. Experimental data and hypotheses
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must be cited, verified, used and modified to gain acceptance in the corpus of our knowledge, to become established science, as opposed to science in progress. Claude Bernard discerned two phases in the research process. Experiments or observations are prepared, bringing into play personal values, preferences and motivations.
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But the process of analyzing the results should be free of preconceived ideas or hypotheses. Yet no researcher can be totally free of all preconceptions, even during that analytical phase. Furthermore, scientific statements are the product of a scientist's willingness to accept that proposition. Much contemporary work in the anthropology, sociology and history of science
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shows that science is socially constructed and I believe that natural sciences have no existence without humans. That new take on natural sciences, as a human creation that is not universal in nature is a blow to science. Not without some pretension, Sigmund Freud liked to say, that human narcissism had endured three major blows. The first was Copernicus' assertion that the Earth is not the center of the universe,
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that it orbits the Sun. The second was the theory of evolution advanced by Darwin and Wallace, showing that humans had evolved from earlier primates. The third was Freud's own discovery that human activity is not controlled solely by the Ego, but also by the unconscious. I believe we are now witnessing a further blow to human self-love.
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The scientific knowledge that humans have accumulated is not as universal as we thought. It's affected by our way of apprehending the world and our language. And human knowledge of the world remains partial by nature. Does that mean that we should abandon science as a way of understanding the world? No, because it's an effective method of understanding the world and designing ways of acting upon it.
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The practices and procedures employed by scientific communities, the pooling of results and knowledge, verification, repeatability, peer review, and the confrontation of divergent views increase our chances of producing reliable scientific consensuses. The workings of the IPCC the UN's International Panel on Climate Change, provides a good example.
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Our trust in science should not be based on a view of the respectability and sagacity of scientists as individuals, but on science as a social process that rigorously verifies hypotheses. When scientists were almost all fair-skinned men, their theories about women and people with black skin were at best incomplete and sometimes disastrous.
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But science gains credibility as a collective endeavor, mixing viewpoints, ideas, theoretical commitments and personal values. Scientists all bring to their work their prejudices, values and underlying hypotheses, but science as a whole can move closer to objectivity, even while individual scientists remain further from it. The more the scientific community is diverse, self-critical and open to alternatives,
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the better its chance of identifying and questioning prejudices. The Collège de France, a secular institution, seems the ideal place to insist on the value of diversity in our approaches and points of view for understanding the world. Its characteristic diversity is one of the leading features of this institution. In the 16th century, its readers were tasked with teaching subjects hitherto disdained by the University of Paris,
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such as Greek, Hebrew or philosophy. It's motto - "docet omnia" - "teach everything" - reflects that diversity well. Professors Lluis Quintana-Murci and Jean-Jacques Hublin used their lectures at the Collège de France to valorize diversity in approach and viewpoint, to understand evolution. And the Collège de France aims to teach emerging forms of knowledge,
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in all fields of literature, science and the arts. Diversity and inclusivity are of growing importance in our present-day societies. Like Helen Longino, I think that all human beings are capable of reason and critical thinking and that the practice of science shouldn't be restricted to professionals. Europe's bird and butterfly populations couldn't have been inventoried and monitored without widespread citizen participation.
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So I'm delighted to be able to give these lectures at the Collège de France, to share my point of view and to bring new perspectives, to illuminate society as a whole. Helen Longino's ideas about plurality affect me personally, not so much because she's a feminist, but because I have always felt different from most of my colleagues for another reason. I'm extremely visual.
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Rather than by manipulating words or concepts, I think by observing nature as it appears in my mind, like Barbara McClintock, who saw genes, switching on and off. I'm reminded of my difference from other people whenever I have to take an online reCAPTCHA test, to check that I'm not a robot. I usually have to redo it three or four times, before I can get to the webpage I want to see.
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I'm very sensitive to detail, so I'd select all the boxes with traffic lights or crosswalks and in this example, I'd select nine squares, when you should only select four. Despite that and other handicaps, it's perhaps thanks to that peculiarity that I've been able to contribute to evolutionary genetics, building an international reputation in that discipline. Today I'd like to present some of the results of my research
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and the properties of life that it's revealed, in its complexity, its rootedness in historical processes and the existence of general laws to be discovered. As with many biologists, throughout my career, my discoveries have emerged from two main activities. First, from my work in the laboratory and in the field, with my research team, keeping me in direct contact with the object of my studies
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and generating new empirical data, to understand the origins and diversity of life forms. Second, through the synthesis of knowledge acquired by the international scientific community, particularly through databases that are open to all, to discover new general laws that govern living matter. For over 20 years my experimental work has focused on the fruit fly,
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which can be easily bred in the laboratory, producing hundreds of individuals within a few days. Just ten days elapse from the laying of the egg to the egg-bearing female. Thousands of global researchers are studying the fruit fly and no multicellular organism is better known to us, genetically. Most of the fruit fly's physiological, neuronal, cellular and molecular characteristics
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are also found in humans and other living beings. Understanding the fly's biology helps us to understand the biology of all living organisms. I was won over by the animal's complexity and by the simplicity of experimenting with it. Our bodies are made up of many cells: neurones, skin cells and muscle cells. I used my thesis to discover how our different body cells are formed
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from the single cell that's formed by the fertilization of an ovule by a spermatozoon. To do that, I studied the formation of the external sensory organs on the surface of the fruit-fly larva. Those organs comprise four cells: a neurone and three different accessory cells. When I began that work, we knew that those four cells came from one mother cell,
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but we didn't know the order of the cell divisions. Our work led us from one surprise to another. We made a detailed examination of increasingly aged embryos, in which we counted the cells, detected with various antibodies. After many hours of microscopy and image analysis, we were surprised to discover that the mother cell did not only produce the four cells of the external sensory organ,
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but also a fifth cell, that migrated a bit further to be differentiated as another isolated neurone, with an independent function from the external sensory organ. So the mother cell produces two sensory organs: an isolated neurone and an external sensory organ, made of a neurone and accessory cells. That initial work showed me that the living work is often more complex that we had imagined
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and that when we study life it's important to remain open to different possibilities. We then started to look at isolated neurones that did not have neighboring external sensory organs and we got a second surprise when we observed that to form that single neurone, nature produces three cells, two or which are eliminated by programmed cell death or apoptosis. That solution is neither intuitive nor optimized.
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An optimal system would just produce one cell, without producing the other two that are then eliminated. And when we used genetic tools to stop those cells from dying during development, we observed an extra external sensory organ, alongside the isolated neurone, which shows that those dying cells have the capacity to form working sensory organs.
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The meaning of the results was revealed through examination in the light of evolution. We discovered a stereotypical sequence of cellar divisions, which forms a basic module that's used in evolution, to form a wide variety of sensory organs in the fruit fly and other insects. The work has shown me how improvisational evolution is. To quote François Jacob,
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"Natural selection doesn't work like an engineer. "It's more like DIY, "using whatever is to hand - "bits of string or wood and old cardboard boxes - "to produce workable results." All life is the product of a long chain, stretching back billions of years, developing through an accumulation of DIY jobs. We're here today
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because those DIY jobs enabled our ancestors to survive and to create offspring that also survived. The same goes for the plants and bacteria around us. To understand better how species and populations evolve over time, I and my colleagues, David Stern and Arnaud Martin, decided to set up a database, of all the genes and mutations identified by the world's researchers
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as having contributed to the natural evolution and domestication of animals and plants, excluding clinical cases. Over 2,500 mutations have been logged in the database at www.gephebase.org. The work in compiling them has been vast, but the results that we have obtained to date, using the Gephebase, are so substantial that I feel compelled to go on. One of our discoveries
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is that evolution occurs via preferential pathways. Evolution often repeats itself in different species in different parts of the world and those repeated evolutionary processes are associated with mutations in the same genes. For example, over 40 insect species have independently evolved a resistance to pyrethroid insecticides, always through mutations in the same gene,
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the para/vgc gene. That means that just a few sites along the chromosome can actually mutate to create particular phenotypical changes. Throughout evolution, humans and dogs have adapted to the same environments. Improved digestion of the starch found in cereals is associated with independent duplications of the same gene in amylase
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in dogs and humans. And adaptation to high altitudes is associated with different mutations in a gene that codes for hemoglobin, in both species. Those observations indicate that evolution is partly predictable. To produce a given change, such as resistance to Warfarin rat poison, predictable mutations will occur in the VKORC1 gene, in rats and mice.
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Evolution involves many random phenomena, such as mutations, the competition of sperm and eggs, for fertilization, the segregation of chromosomes, environmental changes and so on. But in the longer term, predictable phenomena and general laws emerge. That paradox is better understood in comparison with footfall in a museum such as the Pompidou Center.
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We cannot predict whether a particular person will visit on a particular day, but we can predict the busiest times, in terms of the broader population. Evolution is the same. Over a long period of time, predictable phenomena emerge. These recent discoveries about repetitive evolution call into question the widespread idea that evolution could follow a vast array of possible paths
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and that the world we now see is just one of those myriad possibilities. Evolution only occurred once on our planet, so it's very hard, on the basis of that one case, to know what would result if the life on Earth started over or, more realistically, what life forms we may find on other planets. Before I started my evolutionary research,
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I considered human life on Earth as a highly unlikely outcome, the result of a series of chance events. But having discovered all of those predictable phenomena, at the gene level, I'm not so sure. I have a surprising feeling of having progressed in my understanding of life, though I actually feel less certainty than I first did. In short, my biodiversity research has convinced me of the complexity of the living world,
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which is linked to billions of years of evolutionary history and the existence of general laws that remain to be discovered. In my research, I'm trying to find the right balance, searching for general laws, while accounting for the subtlety and complexity of living phenomena. To understand the living world better, I think it's important for us to be aware of our human biases and to attempt to overcome them.
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I'd like to present three of those biases: biases linked to our senses, biases toward organisms of our own size and environment and biases linked to our vision of the world. Some of those biases are only found in particular people and need to be eliminated by broadening the plurality of our viewpoints. Other biases are shared by all human beings and we need to find other ways to overcome them.
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Let us first examine the biases linked to our senses. Those biases are caused by the limitation of our senses. Humans have a limited visual window of perception. The human eye can perceive colors between violet and red, at wavelengths from 400 to 800nm. We can't see infrared or ultraviolet rays.
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Other species have different visual capacities. For example, bees and some fish can see near ultraviolet, at less than 400nm. On the other side of the spectrum, snakes can detect infrared. Human's can perceive on a spatial scale from 0.1mm to several kilometers. While we can detect stars much further away, at several million light years,
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our spatial perception does not exceed a few miles. So the gray area you see here represents an area that is inaccessible to our senses, which humans can only be aware of indirectly, through instruments, calculations and theories. Over the centuries, scientists have developed various tools and methods, to perceive incredibly tiny things and incredibly large things.
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Through the hundred years from 1550 to 1650 the first telescopes and microscopes were built in Europe. Similar diagrams could be created, with other linear parameters, such as time, sound frequency or temperature. We can imagine more complex diagrams, for non-linear parameters, such as smell or chemical molecules. Our physiological sensory limits, in sight, smell, taste, hearing or touch,
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are the results of our evolutionary history. Our senses have been shaped by billions of years of evolution. They have adapted to our life on Earth. They allow us to live and reproduce in a very precise environment, which is ours and our ancestors'. Let's take the example of color and wavelength, to understand that adaptation to our environment. This graph represents light intensity, in terms of wavelength.
00:46:10
Our eyes can see the range between 400 and 800nm. Perfect black-body radiation, at a temperature of 5,900K, such as the Sun, is represented by this curve. The Sun's rays that reach the Earth's surface, after traveling through space and the atmosphere, are represented below. You can see that the light that can been seen by the human eye
00:46:40
matches the peak of the spectrum of the light reaching Earth. But there's also this whole area, which is invisible to the human eye. So some wavelengths are reaching Earth, but we can't see them. By following that explanation, it becomes clear that if we could see a broader wavelength, rainbows would seem wider to us, with extra colors. And bees' perception of rainbows probably differs slightly from ours.
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This picture of a dandelion was taken with a digital camera, adapted to filter and detect ultraviolet light. The monochrome image was colored using a computer, because we can't see those ultraviolet colors, and the dark green patterns visible in the center of the flower would normally be invisible to the human eye. They're nectar guides, which help to attract pollinating insects,
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which can detect ultraviolet light. Humans are facing an unprecedented biodiversity crisis, partly because our understanding is limited, by our senses in particular. Humans were unable to take rapid cognizance of the harmful effects of some of their activities, such as the use of certain pesticides or deforestation, and then to stop them, because they occur at very large or small temporal and spatial levels
00:48:02
that are hard for humans to understand. And it's still hard to evaluate the effects on the living world of certain human activities, as they exceed our primary senses and require analysis on a variety of scales. But this should inspire us with optimism. It means that we still have much to discover. There's still time to change how we see the world and to live on our planet.
00:48:29
I believe that other forms of life have a lot to teach us, not only about how they live, but about how they perceive the world. Another of our human biases appears in our conception of nature, in our preference for animals that share our size and environment. From the time of cave art, thousands of years ago, to the present day, our representations of nature
00:48:57
have only included species of our own size, living in our own environment. It's hard to find a nature charity logo that depicts bacteria. Even with the blob, a myxomycete organism that lives in dead leaves in forests, eyes have been added, although it can find the optimal shortest path to its food, without using eyes. Our biological knowledge is similarly biased,
00:49:26
to organisms of our size, which resemble us. We now have almost complete species inventories for mammals and birds, but they remain very partial for plants, insects, spiders, nematodes and fungi and are even less developed for viruses and bacteria. And we know less about ocean environments than land environments because they're harder to access, as their organisms are microscopic and immobile.
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Perhaps regrettably, it may be the presence of materials of potential industrial use that's now inspiring more attentive studies of the ocean environment. Biology also makes frequent use of model organisms, species that are studied in depth, by many researchers around the world, in the hope that results from those species can be generalized to others. Eight main model organisms are currently used in biology,
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all of which live in close interaction with humans, providing us with a biased vision of life. Those species were chosen as they're easy to raise and to manipulate in the laboratory. Escherichia coli is a bacterium that lives in the human intestines. The lambda phage is a virus that infects bacteria. Saccharomyces cerevisiae is a yeast that humans have used since ancient times,
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in brewing and baking. The Drosophila melanogaster fruit fly and the Caenorhabditis elegans nematode live in rotten fruits that were grown by humans. Arabidopsis thaliana is a weed that grows by roadsides. And mice and rats are commensal organisms, which live around humans. The use of model organisms has proved extremely fruitful in molecular biology, to elucidate the processes involved in the function of cells,
00:51:20
such as the production of proteins, metabolic pathways, intracell molecule transportation and changes in cell shape, as those processes are similar, from one species to another. Focusing on a few experimental organisms has had positive effects in biology, but also tends to restrict our vision of the living world. We still have much to learn about the other organisms that populate the planet. Remember that bacteria living in hot springs at over95 degrees C
00:51:50
enabled the development of PCR tests, which were so useful recently during the Covid-19 pandemic. Other biases in biology are linked to our conception of the world and to our societies. Wolves are a striking case. In the late 1940s, Rudolf Schenkel, the German zoologist, coined the phrase "alpha animal," to describe the highest ranked animal in the pack and the idea of the "alpha male" was quickly popularized
00:52:20
among scientists and non-scientists, forgetting that Rudolf Schenkel was referring to a dominant couple, not just the male. But we now know it is primarily the female in the dominant wolf couple that takes important decisions, such as where to establish a lair, which ties the pack to a place, for six months at a time. And by studying artificial groups among captive wolves, biologists have observed
00:52:46
that some individuals became dominant following a competitive process, similar to what occurs among humans, and concluded that the same thing must take place in nature. But we now know that a typical pack of wolves is a family, whose activities are directed by the adult parents, with the work being systematically shared out. Wolves acquire dominance naturally, through reproduction,
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not through a competitive process that can be observed in zoos, but is not found in nature. Biologicals unconsciously tend to interpret the living world in terms of their own cultures and societies, which affects not only their interpretation of animal behavior, such as here, but potentially every aspect of biology. For example, contemporary biology typically assumes the adult phase to be the most important and the fulfillment of life.
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But that's not always the case. Some insects, such as mayflies, spend three years in the larval phase and just a few hours in the adult phase. Their adult phase represents almost nothing, in terms of time and metabolism. The larval phase is most important in their life cycle. And as farmers well know, with many insect crop blights, the caterpillars are the problem, not the adults. Clown fish take their most important decisions
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during the larval phase. At the age of just two weeks those fish decide where to settle for the rest of their lives. Once they have selected a particular anemone, they'll spend the rest of their lives within ten feet of it. Another of our social biases is to see living matter as machines and to imagine that humans alone
00:54:35
possess a mind, along with their constituent matter. But Philippe Descola, whose colleague I am honored to be for a year, has shown that not all societies share that vision of nature, which he calls "naturalist." That mechanistic vision of life has serious implications nowadays. Émile Baudement, the first professor of zootechnics at the Versailles National Agronomical Institute, from 1849 to 1862,
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saw bovines as no more than "machines to produce meat." Such ideas now sound chilling, but few find it surprising for the CRISPR technique to be called "molecular scissors," although that's a similar machine metaphor. The CRISPR technique enables us to cut DNA at specific places and to insert chosen mutations. Seeing living beings as machines makes it easy to manipulate and modify them.
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In Japan, CRISPR-modified tomatoes have just been marketed, with improved nutritional properties, and two CRISPR-modified fish species have been designed to produce more flesh. And the CRISPR technique was only published ten years ago, in 2012. Genetic applications happen fast. How can we amplify a less mercantile worldview, with greater regard for the long term?
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Biologists are currently envisioning genetic manipulations not only to modify organisms, but to modify natural populations and whole ecosystems. Self-propagating vaccines, that pass from one individual to another have been proposed, to vaccinate wild bat populations against certain viruses, to reduce the risk of emerging infectious diseases
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among humans. With another new biotechnology, known as gene drive, plans are being made to release genetically-modified mosquitoes into the wild, so that they'll breed with natural populations, spreading a DNA fragment throughout the population. The aim is to eradicate particular mosquito-borne diseases. The DNA fragment in question
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can use the CRISPR scissors to copy to the other chromosome and thus to be passed to all of the offspring, unlike a normal gene, which only passes to half the offspring. Gene drive manipulations are currently restricted to the laboratory. The new technology is not yet subject to international regulation and the researchers themselves have defined the best practice
00:57:19
for the use of gene drive in the laboratory. There are two envisaged approaches: either to make the mosquito population resistant to the malaria parasite or to use males to transmit a gene that makes females sterile, which would lead to the total elimination of the mosquito population. Biologists are also planning to use gene drive to eliminate rats and mice in New Zealand,
00:57:48
to prevent the extinction of certain endemic bird species. Self-propagating vaccines and gene drive raise serious ethical questions. The machine metaphor is reaching its limits here, when we become aware of the potential risks. That genetic material could mutate and evolve in ways that are hard to predict. Unlike an insecticide, gene drive and self-propagating vaccines
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cannot be stopped as an insecticide can be withdrawn. The effects on ecosystems are hard to evaluate, as they involve many parameters and will operate in the long term. CRISPR-scissor research recently failed to reproduce the effects of the rin mutation in tomatoes. They wanted to make tomatoes that stay green and firm and don't rot. But the CRISPR mutation had no effect.
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The rin mutation was more complicated than expected, as a dominant-negative allele. While those molecular scissors can be used quite precisely at the molecular level, their effects on the whole organism are harder to predict and even more so at the ecosystem level. Gene drive and self-propagating vaccines have global potential, at the ecosystem level and their regulation
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requires expertise beyond genetics and virology. The One Health concept, which arose in the 2000s and spread in recent years, after the Covid-19 pandemic, shows that human health is directly linked to the health of other animals and ecosystems. Different viewpoints and forms of expertise must be considered, to find better solutions.
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When the Covid-19 pandemic began, I was lucky enough to be a part of AdiosCorona, a self-organized group of enthusiast volunteer scientists, to respond to the public's questions about the pandemic and to offer practical advice. We read and analyzed hundreds of scientific articles, to be able to provide the best advice, based on the available scientific data. With surgical masks,
01:00:03
basing our opinion on various considerations, including environmental pollution from the plastic used to make them and the risk of human contamination from surfaces, we decided to advise the public to reuse masks, by storing them in envelopes, for a week. The emergence of new technologies, such as gene drive requires society to become more involved
01:00:30
in the debate about their usage, which gives rise to two problems. The first was raised by Carl Sagan, in 1996: "We live in a society "exquisitely dependent on science and technology, "in which hardly anyone "knows anything about science and technology." The second problem, raised by Edward Wilson, at a debate at Harvard, in 2009, bears on our institutions and on humans themselves:
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"We have Paleolithic emotions, "medieval institutions and godlike technology. "And it is terrifically dangerous, "and is now approaching a point of crisis overall." To resume and to conclude, human activity is destroying ecosystems and biodiversity. That observation invites us to question the idea of progress commonly associated with science.
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For the first time in the history of life on Earth we can think and make conscious choices to influence the future conditions of life on Earth. To understand biodiversity better, and to find solutions to keep our planet inhabitable, I suggest that at our own level we become aware of our biases and change our viewpoint of the living world. Thank you for your attention.
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Robert Gillan Subtitling: Hiventy by TransPerfect
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