Sixth Extinction Research Articles

The Concept of Extinction: Epistemology, Responsibility, and Precaution

ABSTRACT Extinction is a concept of rapidly growing importance, with the world currently in the sixth mass extinction event and a biodiversity crisis. However, the concept of extinction has itself received surprisingly little attention from philosophers. I will first argue that in practice there is no single unified concept of extinction, but instead that its usage divides between descriptive, epistemic, and declarative concepts. I will then consider the epistemic challenges that arise in ascertaining whether a species has gone extinct, and how these lead to serious limitations on responsibility and accountability for preventing extinctions. I will propose two conceptual engineering changes to our understanding of extinction. Firstly, to use twin epistemic concepts of extinction, corresponding to high and low epistemic demands. Secondly, to explicitly recognize that in many contexts extinction is a thick concept that contains an evaluative component, which therefore motivates explicit ethical considerations such as the use of precautionary principles.

Troubling Modernism at Community College during the Sixth Extinction

“How are we not all talking about this?” a student unmuted to ask in an environmental change-themed writing course, their voice rising to add, “It’s so relevant to what’s going on.” We had just finished reviewing a 2009 profile of climate scientist James Hansen written by Elizabeth Kolbert via then-unfamiliar webinar technology adopted during the first wave of the pandemic.[1]

Domestic Ecology and Autoimmunity: Eugenic Feminism in the Sixth Extinction

Initially hailed as an ur-text for feminist scholarship upon its first reprint in 1973, Charlotte Perkins Gilman’s “The Yellow Wall-Paper” (1892) has undergone a significant historicist reevaluation, beginning in the 1990s, which condemned the story on behalf of its author’s investments in eugenic feminism, the view that women’s reproductive roles should be weaponized as a

Reading Modernism in the Sixth Extinction

1914—a year that looms large in modernist studies for many reasons, including the beginning of the First World War, the “Men of 1914” variant of literary modernism, and the publication of landmark works such as A Portrait of the Artist as a Young Man (in serial form), Tender Buttons, and Des Imagistes—also marks the extinction of the passenger pigeon. Martha, the species

“Enabling Entanglements”: Rethinking Modernist Difficulty in the Sixth Extinction

There’s something incredibly unsettling about the dispassionate description captured in these lines, which the reader encounters midway through “Pinky Agarwalia,” a science fiction narrative written by the British-Indian poet Bhanu Kapil. By Kapil’s account, the story revolves around the destruction of what was once Earth by a thermonuclear war and opens in medias res with the

Witnessing mass extinction: What's invisible, what's visible, what's possible

We are living in the time of the Sixth Mass Extinction. While many details elude us, we know that a mass extinction is underway from comparisons between background and current extinction rates, precipitous drops in wildlife populations, the shrinking of wild places, and the critical endangerment of biodiverse ecologies such as grasslands, tropical forests, wetlands, rivers and lakes, coral reefs, and continental shelves. This paper dissects the underpinnings of the Sixth Mass Extinction, with the intention of joining many other activists and thinkers to disrupt its seeming inevitability. First, I discuss what has been invisible about anthropogenic mass extinction—the event itself—and the factors of silence, ignorance, and denial underlying its invisibility. Then I turn to the visible dimension of the Sixth Mass Extinction, namely, the action orientation of “entitled instrumentalism” that is driving it; I describe entitled instrumentalism as the wholesale assimilation of the natural world into a human-owned domain. I end with considering the possibility of humanity charting an altogether different course. We must recognize mass extinction as the inevitable upshot of nature colonization and awaken to the need to restore and preserve Earth's cosmic wealth.

Iconic 21st Century Activist "T-Shirt and Tote-Bag" Combination Is Hard to Miss These Days!

Iconic 21st Century Activist "T-Shirt and Tote-Bag" Combination Is Hard to Miss These Days!

Macroevolutionary perspectives on Anthropocene extinction

A great deal of macroevolutionary research on extinction has focused on large-scale processes, particularly mass episodes. In contrast, many recent conservation studies focus on Anthropocene dynamics at the population level. We discuss three ways in which a synthesis between these perspectives might illuminate hidden assumptions of value and reveal promising agendas for conservation biology. First, some lineages may have been on extinction trajectories before global change commenced. While it may be difficult to quantify this directly, the potential for pre-existing net-negative diversification rates in lineages or terminal declines in species may have a strong impact on our ethical valuations of biodiversity and consequent management decisions. Second, it is worthwhile to quantify the shape and scale of the Sixth Extinction relative to previous mass extinctions and we outline and model several relevant parameters, including the initial magnitude and subsequent change in diversification rates contributing to recovery. Placing recent estimates of Anthropocene extinction rates into a historical macroevolutionary context may suggest more precise frameworks for interpreting and extrapolating present-day patterns. Third, focusing on recovery dynamics from previous mass extinctions may be valuable, as quantitative models of present-day extinction portend various scenarios for future re-diversification. In this context, “conservation” is less about preserving past or existing states, but rather creating and promoting novel starting points for the near-term function and future evolution of biodiversity, differing from pre-human trajectories. Integrating historical and present-day perspectives on extinction promises a synergistic research program holding potential insights for macroevolution, conservation, and environmental ethics.

Editorial: Mammalian responses to climate change: From organisms to communities

A particularly powerful component of the Anthropocene extinction is global climate change, which, in concert with other elements of anthropogenic forcing, is driving the reorganization of biotic assemblages everywhere on the planet. Rising ambient temperature challenges the adaptive capacity of organisms and for terrestrial animals it can directly cause lethal hyperthermia or dehydration. More generally however, the indirect effects of climate change permeate all facets of the environment including habitat quality (food, water, refuge availability) and risks from predators, competitors, and pathogens (Fig. 1). Chronic exposure to environmental conditions that exceed critical thresholds at critical times of year ultimately result in a convergence of sublethal fitness costs (Pattinson et al. 2022). Such costs could arise from disturbances to physiological processes and behavioral patterns, which become expressed at the population level as changes in vital rates and habitat occupancy. These in turn drive shifts in species ranges or even extinctions, with consequences at community and ecosystem levels. The papers in this Research Topic explore these interactions and their implications.

CHILDREN OF TIME: A POST-APOCALYPTIC STUDY IN WORLDBUILDING AND EVOLUTION OF A NON-HUMAN SPECIES

Children of time is a story that undertakes a herculean endeavor: a fascinating attempt at worldbuilding, creating a snapshot as it were of the evolution of a particular species from simple biological creatures to wise and sentient beings. Aside from being a cogent account of a new world order in which intelligent spiders are at the top of the food chain and humans are the belligerent outsiders and colonizers seeking to seize control from the intelligent arthropods, Adrian Tchaikovsky’s novel also highlights the pertinent issue of ecological damage caused by anthropogenic activities which is rapidly taking the planet toward a cataclysmic event, the Sixth Extinction.

Genetic characterisation of fragmented Asian elephant populations with one recent extinction in its eastern-central Indian range

Habitat fragmentation results in loss of genetic variation in populations and increases inbreeding processes that are measurable by genetic markers. The fragmented forests of Eastern Ghats-Central India support around 3000 Asian elephants ( Elephas maximus L.), of which 2000 are in Odisha state. We obtained samples of fresh elephant dung from four protected areas (PAs) in Odisha: Similipal, Satkosia, Kuldiha and the recently extinct Chandaka population, and assessed levels of genetic variation, gene flow, recent genetic bottleneck, inbreeding and relatedness using 10 polymorphic microsatellite markers. We tested whether the PAs would be similar in levels of genetic variation and inbreeding due to recent fragmentation, using standard methodology for DNA amplification, genotyping, and sex identification. Among the 154 samples collected, 108 individuals were identified, of which 78 were female, 20 male and 10 unclassified. Levels of genetic variation were moderately high overall, and higher within than between the three extant populations. There was no isolation by distance, two long-distance first-generation migrants were detected in Chandaka, and inbreeding and recent bottlenecks were not evident. Bayesian individual-based clustering approaches and multivariate methods identified three populations and Kuldiha was strongly differentiated from the other three. This could partly be explained by missing data and high proportion of full siblings. The sex ratio was female-biased, which could be attributed to higher mortality of males. Our results suggest that elephant populations in Odisha are already undergoing genetic drift and that restoration of habitats and connectivity are urgently needed to avert further population extinctions.

Genetic drift drives rapid speciation of an Arctic insular endemic shrew (Sorex pribilofensis).

Episodes of Quaternary environmental change shaped the genomes of extant species, influencing their response to contemporary environments, which are changing rapidly. Island endemics are among the most vulnerable to such change, accounting for a disproportionate number of recent extinctions. To prevent extinctions and conserve island biodiversity it is vital to combine knowledge of species' ecologies with their complex evolutionary histories. The Bering Sea has a history of cyclical island isolation and reconnection, coupled with modern rates of climate change that exceed global averages. The endangered Pribilof Island shrew (Sorex pribilofensis) is endemic to St. Paul Island, Alaska, which was isolated from mainland Beringia ~14,000 years ago by rising sea levels. Using ~11,000 single nucleotide polymorphisms, 17 microsatellites and mitochondrial sequence data, we test predictions about the evolutionary processes driving shrew speciation across Beringia. Our data show considerable differentiation of S. pribilofensis from mainland sibling species, relative to levels of divergence between mainland shrews. We also find a genome-wide loss of diversity and extremely low Ne for S. pribilofensis. We then show that intraspecific genetic diversity is significantly related to interspecific divergence, and that differentiation between S. pribilofensis and other Beringian shrews is highest across loci that are fixed in S. pribilofensis, indicating that strong drift has driven differentiation of this island species. Our findings show that drift as a consequence of Arctic climate cycling can rapidly reshape insular biodiversity. Arctic island species that lack genomic diversity and have evolved in response to past climate may have limited ability to respond to modern environmental changes.

Are We in a Sixth Mass Extinction? The Challenges of Answering and Value of Asking

Are We in a Sixth Mass Extinction? The Challenges of Answering and Value of Asking

A freshwater perspective on the United Nations decade for ecosystem restoration

AbstractGlobally, ecosystems have suffered from anthropogenic stressors as we enter the sixth mass extinction within the Anthropocene. In response, the UN has declared 2020–2030 the Decade for Ecosystem Restoration, aiming to mitigate ecosystem degradation and biodiversity loss. Freshwater ecosystems are disproportionately impacted relative to marine or terrestrial systems and ecological restoration is needed to preserve biodiversity and ecosystem services. Paradoxically, freshwater is among Earth's most vital ecosystem services. Here we identify meaningful considerations from a freshwater perspective that will lead to progression toward the restoration of freshwater ecosystems: work across terrestrial and freshwater boundaries during restoration, emulate nature, think and act on a watershed scale, design for environmental heterogeneity, mitigate threats alongside restoration, identify bright spots, think long term (a decade is not long enough), and embrace social–ecological systems thinking. Further, we reflect upon the three implementation pathways identified by the UN to translate these considerations into practice in hopes of “bending the curve” for freshwater biodiversity and ecosystems. Pathway 1, building a global movement, could create a network to share experiences and knowledge promoting vicarious learning, ultimately leading to more effective restoration. Pathway 2, generating political support, will be necessary to institutionalize ecosystem protection and restoration by demonstrating the value of freshwater ecosystems and biodiversity. Pathway 3, building technical capacity, aims to improve the current and often ineffective restoration toolbox by incorporating evidence syntheses (i.e., appraisal of evidence base) and Indigenous ways of knowing (i.e., two eyed seeing). Given that freshwater ecosystems are in dire need of repair, it is our hope that these considerations and implementation pathways will contribute to an actionable and productive Decade for Ecosystem Restoration.

The Battle Rages On

The Battle Rages On

The Blue Earth Project: “Is Humanity Settling its own Fate on Ecological Survival?”

This is a report from NoRCELs Blue Earth Project symposium BEP2022 held online on January 8th, 2022. We are reporting the outcome pertaining to the following question: Is Humanity Settling its own Fate on Ecological Survival? A succinct conclusion drawn is that the Earth is facing the sixth mass extinction of flora and fauna; this being different from the previous five extinctions, in that it is entirely due to mankinds activities. Five invited eminent speakers delivered their input, highlighting the fact that there is extensive deterioration of the environment at large, coupled with an unprecedented demise of ecosystems leading to the extinction of species across the globe.

Digging in a 120 years-old lunch: What can we learn from collection specimens of extinct species?

Studying collection specimens is often the only way to unravel information about recent extinctions. These can reveal knowledge on threats and life traits related to extinction, and contribute, by extrapolation, to the conservation of extant species. However, high-throughput sequencing methods have rarely been applied to extinct species to reveal information on their ecology. Insular species are especially prone to extinction. We studied the gut contents of three specimens of the extinct giant skink Chioninia coctei of the Cabo Verde Islands using microscopy and DNA-metabarcoding. The presence of Tachygonetria adult nematodes suggests plants as important diet items. Our metabarcoding approach also identified plants and, additionally, invertebrates, supporting the hypothesis of C. coctei’s generalist diet. The absence of vertebrates in the digestive contents may reflect the decline of seabirds on the Desertas Islands that could have contributed to the debilitation of the giant skink, already depleted by persecution and severe droughts. Even with a small sample size, this study contributes to shedding light on the trophic roles of this enigmatic extinct species and emphasizes the need to develop holistic conservation plans for island threatened taxa. Additionally, it illustrates the potential of integrating up-to-date molecular methods with traditional approaches to studying collection specimens to help to solve ecological puzzles in other ecosystems.

Behavioral responses to spatial heterogeneity in endangered Ganges River dolphins (Platanista gangetica gangetica)

Globally, the threat of endangerment and extinction of small cetaceans was highlighted after the recent extinction of the Chinese River dolphin or Baiji (Lipotes vexillifer). Species with a small population size and a limited geographic range, such as Ganges River dolphins (GRD), are more vulnerable to extinction. The social and behavioral needs of cetaceans have been identified as potential factors increasing their vulnerability to human disturbance. However, little is known about how GRD adapt their behaviors and diel activity patterns to spatiotemporal variation. In this paper, we examined the underwater behavior of GRDs in Nepal by collecting echolocation clicks from three spatially stratified habitats in the Sapta Koshi River system over a six-month period. Our research found that GRDs behave differently in response to spatial heterogeneity, indicating diverse environmental requirements for GRD persistence. Behavioral activity and duration varied across habitats but not across time of day, suggesting that GRD behaviors are likely to be regulated by habitat structure regardless of the time of day. However, GRD consistently exhibited nocturnal activity peaks even when diurnal activity varied substantially. This indicates that river dolphins may favor nocturnal refuges as a reaction to human disturbance in highly regulated rivers. Managing human disturbances in conjunction with habitat heterogeneity can improve the persistence of riverine cetaceans. Here, we document behavioral and ecological information pertaining to GRD, which is essential to the formation of river dolphin recovery plans that link ecological perspectives to planning and management.

Resurrecting biodiversity: advanced assisted reproductive technologies and biobanking.

Biodiversity is defined as the presence of a variety of living organisms on the Earth that is essential for human survival. However, anthropogenic activities are causing the sixth mass extinction, threatening even our own species. For many animals, dwindling numbers are becoming fragmented populations with low genetic diversity, threatening long-term species viability. With extinction rates 1000–10,000 times greater than natural, ex situ and in situ conservation programmes need additional support to save species. The indefinite storage of cryopreserved (−196°C) viable cells and tissues (cryobanking), followed by assisted or advanced assisted reproductive technology (ART: utilisation of oocytes and spermatozoa to generate offspring; aART: utilisation of somatic cell genetic material to generate offspring), may be the only hope for species’ long-term survival. As such, cryobanking should be considered a necessity for all future conservation strategies. Following cryopreservation, ART/aART can be used to reinstate lost genetics back into a population, resurrecting biodiversity. However, for this to be successful, species-specific protocol optimisation and increased knowledge of basic biology for many taxa are required. Current ART/aART is primarily focused on mammalian taxa; however, this needs to be extended to all, including to some of the most endangered species: amphibians. Gamete, reproductive tissue and somatic cell cryobanking can fill the gap between losing genetic diversity today and future technological developments. This review explores species prioritisation for cryobanking and the successes and challenges of cryopreservation and multiple ARTs/aARTs. We here discuss the value of cryobanking before more species are lost and the potential of advanced reproductive technologies not only to halt but also to reverse biodiversity loss.Lay summaryThe world is undergoing its sixth mass extinction; however, unlike previous events, the latest is caused by human activities and is resulting in the largest loss of biodiversity (all living things on Earth) for 65 million years. With an extinction rate 1000–10,000-fold greater than natural, this catastrophic decline in biodiversity is threatening our own survival. As the number of individuals within a species declines, genetic diversity reduces, threatening their long-term existence. In this review, the authors summarise approaches to indefinitely preserve living cells and tissues at low temperatures (cryobanking) and the technologies required to resurrect biodiversity. In the future when appropriate techniques become available, these living samples can be thawed and used to reinstate genetic diversity and produce live young ones of endangered species, enabling their long-term survival. The successes and challenges of genome resource cryopreservation are discussed to enable a move towards a future of stable biodiversity.

Circling the drain: the extinction crisis and the future of humanity.

Humanity has triggered the sixth mass extinction episode since the beginning of the Phanerozoic. The complexity of this extinction crisis is centred on the intersection of two complex adaptive systems: human culture and ecosystem functioning, although the significance of this intersection is not properly appreciated. Human beings are part of biodiversity and elements in a global ecosystem. Civilization, and perhaps even the fate of our species, is utterly dependent on that ecosystem's proper functioning, which society is increasingly degrading. The crisis seems rooted in three factors. First, relatively few people globally are aware of its existence. Second, most people who are, and even many scientists, assume incorrectly that the problem is primarily one of the disappearance of species, when it is the existential threat of myriad population extinctions. Third, while concerned scientists know there are many individual and collective steps that must be taken to slow population extinction rates, some are not willing to advocate the one fundamental, necessary, ‘simple’ cure, that is, reducing the scale of the human enterprise. We argue that compassionate shrinkage of the human population by further encouraging lower birth rates while reducing both inequity and aggregate wasteful consumption—that is, an end to growthmania—will be required.This article is part of the theme issue ‘Ecological complexity and the biosphere: the next 30 years’.