Sixth Extinction Research Articles

Extinction in Public

AbstractThis essay argues that the concept of extinction, polysemous if not overdetermined, is becoming an emergent keyword of contemporary public life as it faces the climate crisis. To make this argument the essay critically considers the ways in which extinction is currently being made public—within and by the environmental humanities but also in the wider public sphere of political and cultural contestation. The essay begins by problematizing the concept of extinction itself, positing that it makes sense to think of the Sixth Extinction as the first historical extinction event—that is, as a social articulation of an organic process in which the causes and impacts are at once natural and social. Then the essay discusses the different extinction imaginaries that have operated across modernity, before finally turning to the writings of the Extinction Studies Working Group, whose conception of extinction as a process rather than event, and whose arguments that mass extinction presents an ethical call to responsibility, have become a template for how extinction is thought about within the field of the environmental humanities. The essay ends by posing some companionly criticisms of the extinction studies project.

Retraction: An Eocene army ant

Retraction: An Eocene army ant

How predictable are mass extinction events?

Many modern extinction drivers are shared with past mass extinction events, such as rapid climate warming, habitat loss, pollution and invasive species. This commonality presents a key question: can the extinction risk of species during past mass extinction events inform our predictions for a modern biodiversity crisis? To investigate if it is possible to establish which species were more likely to go extinct during mass extinctions, we applied a functional trait-based model of extinction risk using a machine learning algorithm to datasets of marine fossils for the end-Permian, end-Triassic and end-Cretaceous mass extinctions. Extinction selectivity was inferred across each individual mass extinction event, before testing whether the selectivity patterns obtained could be used to 'predict' the extinction selectivity exhibited during the other mass extinctions. Our analyses show that, despite some similarities in extinction selectivity patterns between ancient crises, the selectivity of mass extinction events is inconsistent, which leads to a poor predictive performance. This lack of predictability is attributed to evolution in marine ecosystems, particularly during the Mesozoic Marine Revolution, associated with shifts in community structure alongside coincident Earth system changes. Our results suggest that past extinctions are unlikely to be informative for predicting extinction risk during a projected mass extinction.

Pheromones for amphibian conservation – considering new approaches in conservation breeding programmes

Pheromones for amphibian conservation – considering new approaches in conservation breeding programmes

Forty years later: The status of the “Big Five” mass extinctions

Abstract Over 40 years ago, Raup and Sepkoski identified five episodes of elevated extinction in the marine fossil record that were thought to be statistically distinct, thus warranting the term the “Big Five” mass extinctions. Since then, the term has become part of standard vocabulary, especially with the naming of the current biodiversity crisis as the “sixth mass extinction.” However, there is no general agreement on which time intervals should be viewed as mass extinctions, in part because the Big Five turn out not to be statistically distinct from background rates of extinction, and in part, because other intervals of time have even higher extinction rates, in the Cambrian and early Ordovician. Nonetheless, the Big Five represent the five largest events since the early Ordovician, including in analyses that attempt to compensate for the incompleteness of the fossil and rock records. In the last 40 years, we have learned a great deal about the causes of many of the major and minor extinction events and are beginning to unravel the mechanisms that translated the initial environmental disturbances into extinction. However, for many of the events, further understanding will require going back to the outcrop, where the patchy distribution of environments and pervasive temporal gaps in the rock record challenge our ability to establish true extinction patterns. As for the current biodiversity crisis, there is no doubt that the rate of extinction is among the highest ever experienced by the biosphere, perhaps the second highest after the end-Cretaceous bolide impact. However (and fortunately), the absolute number of extinctions is still relatively small – there is still time to prevent this becoming a genuine mass extinction. Given the arbitrariness of calling out the Big Five, perhaps the current crisis should be called the “incipient Anthropocene mass extinction” rather than the “sixth mass extinction.”

A review of recent and future marine extinctions

AbstractBetween 20 and 24 marine extinctions, ranging from algal to mammal species, have occurred over the past 500 years. These relatively low numbers question whether the sixth mass extinction that is underway on land is also occurring in the ocean. There is, however, increasing evidence of worldwide losses of marine populations that may foretell a wave of oncoming marine extinctions. A review of current methods being used to determine the loss of biodiversity from the world’s oceans reveals the need to develop and apply new assessment methodologies that incorporate standardized metrics that allow comparisons to be made among different regions and taxonomic groups, and between current extinctions and past mass extinction events. Such efforts will contribute to a better understanding of extinction risk facing marine flora and fauna, as well as the ways in which it can be mitigated.

The end-Cretaceous plant extinction: Heterogeneity, ecosystem transformation, and insights for the future

Abstract The Cretaceous–Paleogene (K–Pg) mass extinction was geologically instantaneous, causing the most drastic extinction rates in Earth’s History. The rapid species losses and environmental destruction from the Chicxulub impact at 66.02 Ma made the K–Pg the most comparable past event to today’s projected “sixth” mass extinction. The extinction famously eliminated major clades of animals and plankton. However, for land plants, losses primarily occurred among species observed in regional studies but left no global trace at the family or major-clade level, leading to questions about whether there was a significant K–Pg plant extinction. We review emerging paleobotanical data from the Americas and argue that the evidence strongly favors profound (generally >50%), geographically heterogeneous species losses and recovery consistent with mass extinction. The heterogeneity appears to reflect several factors, including distance from the impact site and marine and latitudinal buffering of the impact winter. The ensuing transformations have affected all land life, including true angiosperm dominance in the world’s forests, the birth of the hyperdiverse Neotropical rainforest biome, and evolutionary radiations leading to many crown angiosperm clades. Although the worst outcomes are still preventable, the sixth mass extinction could mirror the K–Pg event by eliminating comparable numbers of plant species in a geologic instant, impoverishing and eventually transforming terrestrial ecosystems while having little effect on global plant-family diversity.

Marine conservation palaeobiology: What does the late Quaternary fossil record tell us about modern-day extinctions and biodiversity threats?

Abstract Near-time conservation palaeobiology uses palaeontological, archaeological and other geohistorical records to study the late Quaternary transition of the biosphere from its pristine past to its present-day, human-altered state. Given the scarcity of data on recent extinctions in the oceans, geohistorical records are critical for documenting human-driven extinctions and extinction threats in the marine realm. The historical perspective can provide two key insights. First, geohistorical records archive the state of pre-industrial oceans at local, regional and global scales, thus enabling the detection of recent extinctions and extirpations as well as shifts in species distribution, abundance, body size and ecosystem function. Second, we can untangle the contributions of natural and anthropogenic processes by documenting centennial-to-millennial changes in the composition and diversity of marine ecosystems before and after the onset of major human impacts. This long-term perspective identifies recently emerging patterns and processes that are unprecedented, thus allowing us to better assess human threats to marine biodiversity. Although global-scale extinctions are not well documented for brackish and marine invertebrates, geohistorical studies point to numerous extirpations, declines in ecosystem functions, increases in range fragmentation and dwindling abundance of previously widespread species, indicating that marine ecosystems are accumulating a human-driven extinction debt.

Australian terrestrial mammals: how many modern extinctions?

This note updates the list of extinct Australian terrestrial mammal species and subspecies and, from published scientific literature, reports 40 species and six subspecies that are presumed to have become extinct since European settlement of Australia.

The Special Issue on the Anthropocene and the Law in Asia The Prevention of the Sixth Mass Extinction: Socio-Legal Responses to Mitigate the Anthropogenic Crises in Asia and Beyond

The Special Issue on the Anthropocene and the Law in Asia The Prevention of the Sixth Mass Extinction: Socio-Legal Responses to Mitigate the Anthropogenic Crises in Asia and Beyond

Prison Zooing and Conservation: Human and Animal Caging in a Time of Ecological Catastrophe

Prisons are responsible for the social and biological death of the humans trapped within them, the animals whom it coerces prisoners to farm and slaughter, free-living animals displaced by prison building, as well as the ecosystems and waters destroyed by prison effluent which makes the lives of those dependent upon these systems and resources for survival, unliveable. In the context of the Sixth Extinction, the prison is at once one of the most resource intensive institutions contributing to Anthropogenic climate change and biodiversity loss, and paradoxically, in the last two decades, sometimes positioned similarly to zoos as an ecological saviour of threatened species. The most established example of this is the Sustainability in Prisons Project that operates in many United States prisons. Specific to conservation, it trains prisoners – often in partnerships with zoos – to captively rear endangered animals and plants. There is also a zoo located on the grounds of a Florida prison in which prisoners care for abandoned animals, which is open to the public for tours. This article argues that the current initiatives of prison zoos and prison conservation programs reflect the trajectory of animal zoo eras and human zoos, with unique implications: two institutions of captivity, the zoo and the prison, now reify each other under the auspices of ecological conservation – a project whose need and operation continues the racialized and anthropocentric projects that gave it rise.

Animal Elegy in Ron Rash’s “In the Valley” (2020)

This paper argues that Ron Rash’s 2020 return to his 2009 bestseller, Serena, and to its eponymous character’s destructive frenzy operates as a pretext for him to deal, in his own poetic way, with the devastating consequences of such ruthless exploitative behaviors and their lethal contribution to the sixth extinction. This paper shows that “In the Valley” partakes of the genre of the poetry of extinction. Focusing on the diverse ways in which the valley’s inexorable emptying is represented, it regards “In the Valley” as an animal elegy that poetically represents the inexorable extinction of numerous species.

Ecological ‘Self’ vs the Ecological ‘Other’: Indigenous Naga Ecotopia for the Dystopic World

Critics have used the colonizer/colonized or the Global North/Global South binaries to restore human rights and freedom. But these planetary or ideological binaries –though theoretically convenient – might not be ecologically sufficient to deal with the ongoing sixth mass extinction (Kolbert, The Sixth Extinction: An Unnatural History). The need of the hour is to critique the existing knowledge systems (science, technology, politics) through the lens of eco-alterity, wherein every agent of environmental disaster is to be identified as the ecological ‘other.’ In this context, the unique indigenous participation of the ecological ‘selves’ is to be deciphered and disseminated: The indigenous ecotopias of the earth might provide insights into ecological sustenance, food sovereignty and coexistence. The present study, therefore, situates the relevance of exploring indigenous ecological knowledge systems by proposing eco-alterity as the tool to liberate victims of ‘slow violence’ (Nixon). In so doing, it seeks to make visible the unique ecotopia of Naga ecological natives – as represented in Kire’s novels – that has survived multiple forms of slow violence.

Diving into a dead-end: asymmetric evolution of diving drives diversity and disparity shifts in waterbirds.

Diving is a relatively uncommon and highly specialized foraging strategy in birds, mostly observed within the Aequorlitornithes (waterbirds) by groups such as penguins, cormorants and alcids. Three key diving techniques are employed within waterbirds: wing-propelled pursuit diving (e.g. penguins), foot-propelled pursuit diving (e.g. cormorants) and plunge diving (e.g. gannets). How many times diving evolved within waterbirds, whether plunge diving is an intermediate state between aerial foraging and submarine diving, and whether the transition to a diving niche is reversible are not known. Here, we elucidate the evolutionary history of diving in waterbirds. We show that diving has been acquired independently at least 14 times within waterbirds, and this acquisition is apparently irreversible, in a striking example of asymmetric evolution. All three modes of diving have evolved independently, with no evidence for plunge diving as an intermediate evolutionary state. Net diversification rates differ significantly between diving versus non-diving lineages, with some diving clades apparently prone to extinction. We find that body mass is evolving under multiple macroevolutionary regimes, with unique optima for each diving type with varying degrees of constraint. Our findings highlight the vulnerability of highly specialized lineages during the ongoing sixth mass extinction.

An Ecological Context That Scars: Reflections on Three Nature Documentaries of 2020

An Ecological Context That Scars: Reflections on Three Nature Documentaries of 2020

The introduction of three cryptic tree frog species in the Dutch coastal dunes challenges conservation paradigms

Abstract Invasive species are considered one of the main drivers of the sixth mass extinction. Conservation solutions depend on whether a species is also indigenous to the country it invades (i.e., beyond its native range). In the case of invasive cryptic species, genetic tools are required to establish their identity. We illustrate these issues with the human-mediated colonization of the Dutch coastal dunes by Hyla tree frogs. Although previously assumed to concern the indigenous common tree frog H. arborea, European tree frogs comprise a complex of allopatric cryptic species, meaning the taxonomic identity of introduced Dutch populations warrants investigation. We sequence mtDNA for 173 individuals from native and introduced populations across the Netherlands and compare our dataset with hundreds of Hyla haplotypes previously barcoded in the Western Palearctic. Two of the dune populations carry an mtDNA haplotype of the native species H. arborea that occurs naturally elsewhere in the Netherlands. In contrast, mtDNA assigned to the eastern tree frog H. orientalis was detected in all three other dune populations. In one of these populations mtDNA of the Italian tree frog H. intermedia was also found. Not one, but three species of tree frogs have thus been introduced to the Dutch coastal dunes, only one of them being native to the Netherlands. This situation causes a conservation conundrum as some introduced populations are lawfully protected but could pose a threat to local biodiversity. Regarding the ‘true’ exotic tree frog species, all conservation options should be considered.

Extinct and Undying Species: Animal Fetishism in Green Lion and How the Dead Dream

With theoretical grounding in a materialist ecocritical approach, this article considers two recent novels that stage human longing for contact with critically endangered species: Henrietta Rose-Innes’s Green Lion (2015) and Lydia Millet’s How the Dead Dream (2007). The article traces parallels between the characters’ animal fetishism—their mystical beliefs in the healing powers of animals—and what Nicole Shukin has theorized as an emerging ethos of neoliberal capitalism that obscures environmental destruction and nonhuman suffering by foregrounding animal vitality and flourishing within the capitalist system. Both novels invite a critical stance towards their respective characters’ animal fetishism, yet through the texts’ own animal representations the novels risk rendering nonhumans as spectral and ahistorical signifiers, contributing to the circulation of commercialized animal imagery. The novels thus risk colluding with a market regime bent on reproducing impressions of “undying animals,” as the sixth mass extinction of species unfolds.

Extinction magnitude of animals in the near future

There have been five major mass extinctions and some minor mass extinctions of animals since early animal diversification 540–520 Myr ago. It is said that a sixth mass extinction is already underway. However, the future extinction magnitude has not been quantitatively estimated. Here, I show that the sixth major mass extinction (defined as > 60% species loss) will be avoided, but a minor mass extinction, 20–50% animal species loss (1% now), will occur when humans cause nuclear war and/or fail to stop increasing greenhouse gas (GHG) emissions, pollution, and deforestation until 2060–2080 CE. When humans decrease GHG emissions, pollution, and deforestation in 40 years and prevent nuclear war in the future, 10–15% animal species loss will occur. Humans should stop not only industrial GHG emissions but also deforestation, environmental pollution, and nuclear war to prevent this mass extinction. When humans fail to stop these processes, significant decreases in biodiversity and the human population and a collapse of ecological balance will occur on Earth.

The context dependency of multiple stressor effects on biodiversity: A commentary on Kefford et al. (2022).

The context dependency of multiple stressor effects on biodiversity: A commentary on Kefford et al. (2022).

Harmony in Conservation

Many authors have noted the role that anthropocentrism has played in creating humanity’s dysfunctional relationship with the natural world. As human hubris (excessive pride or self-confidence) is an ailment that contributes to the anthropogenic sixth mass extinction of Earth’s biodiversity, we argue instead for ‘harmony with nature’. In recent decades, even the conservation discourse has become increasingly anthropocentric. Indeed, justification for nature conservation has in part shifted from nature’s intrinsic value to ‘ecosystem services’ for the benefit of people. Here we call for a transformation to a more harmonious human-nature relationship that is grounded in mutual respect and principled responsibility, instead of utilitarianism and enlightened self-interest. Far from what Tennyson called ‘red in tooth and claw’, we argue nature is a mixture of cooperation as well as competition. We argue that the UN’s ‘Harmony with Nature’ program is an innovative and refreshing path for change. If we are to achieve harmony with nature, modern industrial society will need to abandon its anthropocentric ‘human supremacy’ mindset and adopt an ecocentric worldview and ecological ethics. We conclude it is thus both appropriate (and essential) for conservationists to champion harmony with nature.