scholarly journals Introductory Chapter: The Present Global Ecological Crisis in the Light of the Mass Extinctions of Earth History

2020 ◽  
Author(s):  
Levente Hufnagel ◽  
Melinda Pálinkás ◽  
Ferenc Mics ◽  
Réka Homoródi
Keyword(s):  
Ecological Crisis ◽  
Mass Extinctions ◽  
Earth History

Milankovitch cycles and their effects on species in ecological and evolutionary time

Paleobiology ◽  
1990 ◽  
Vol 16 (1) ◽  
pp. 11-21 ◽  
Author(s):  
K. D. Bennett
Keyword(s):  
Time Scales ◽  
Climatic Changes ◽  
Milankovitch Cycles ◽  
Mass Extinctions ◽  
Geological Time ◽  
Evolutionary Time ◽  
Abiotic Environment ◽  
Earth History ◽  
Microevolutionary Change ◽  
Second Tier

The Quaternary ice ages were paced by astronomical cycles with periodicities of 20–100 k.y. (Milankovitch cycles). These cycles have been present throughout earth history. The Quaternary fossil record, marine and terrestrial, near to and remote from centers of glaciation, shows that communities of plants and animals are temporary, lasting only a few thousand years at the most. Response of populations to the climatic changes of Quaternary Milankovitch cycles can be taken as typical of the way populations have behaved throughout earth history. Milankovitch cycles thus force an instability of climate and other aspects of the biotic and abiotic environment on time scales much less than typical species durations (1–30 m.y.). Any microevolutionary change that accumulates on a time scale of thousands of years is likely to be lost as communities are reorganized following climatic changes. A four-tier hierarchy of time scales for evolutionary processes can be constructed as follows: ecological time (thousands of years), Milankovitch cycles (20–100 k.y.), geological time (millions of years), mass extinctions (approximately 26 m.y.). “Ecological time” and “geological time” are defined temporally as the intervals between events of the second and fourth tiers, respectively. Gould's (1985) “paradox of the first tier” can be resolved, at least in part, through the undoing of Darwinian natural selection at the first tier by Milankovitch cycles at the second tier.

scholarly journals Estimates of the magnitudes of major marine mass extinctions in earth history

2016 ◽  
Vol 113 (42) ◽  
pp. E6325-E6334 ◽  
Author(s):  
Steven M. Stanley
Keyword(s):  
Mass Extinction ◽  
Marine Species ◽  
Ecological Diversity ◽  
Mass Extinctions ◽  
Late Permian ◽  
Marine Animals ◽  
Earth History ◽  
Enormous Amount ◽  
Terminal Permian ◽  
Combined Data

Procedures introduced here make it possible, first, to show that background (piecemeal) extinction is recorded throughout geologic stages and substages (not all extinction has occurred suddenly at the ends of such intervals); second, to separate out background extinction from mass extinction for a major crisis in earth history; and third, to correct for clustering of extinctions when using the rarefaction method to estimate the percentage of species lost in a mass extinction. Also presented here is a method for estimating the magnitude of the Signor–Lipps effect, which is the incorrect assignment of extinctions that occurred during a crisis to an interval preceding the crisis because of the incompleteness of the fossil record. Estimates for the magnitudes of mass extinctions presented here are in most cases lower than those previously published. They indicate that only ∼81% of marine species died out in the great terminal Permian crisis, whereas levels of 90–96% have frequently been quoted in the literature. Calculations of the latter numbers were incorrectly based on combined data for the Middle and Late Permian mass extinctions. About 90 orders and more than 220 families of marine animals survived the terminal Permian crisis, and they embodied an enormous amount of morphological, physiological, and ecological diversity. Life did not nearly disappear at the end of the Permian, as has often been claimed.

Do all mass extinctions represent an ecological crisis? Evidence from the Late Ordovician

2001 ◽  
Vol 36 (3-4) ◽  
pp. 329-340 ◽  
Author(s):  
P. J. Brenchley ◽  
J. D. Marshall ◽  
C. J. Underwood
Keyword(s):  
Late Ordovician ◽  
Ecological Crisis ◽  
Mass Extinctions

Human Competence and Ecological Crisis

1979 ◽  
Vol 24 (6) ◽  
pp. 468-469
Author(s):  
GARY W. EVANS
Keyword(s):  
Ecological Crisis

Making the Différance: Between Derrida and Stiegler

Derrida Today ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 1-16
Author(s):  
Francesco Vitale
Keyword(s):  
Natural Condition ◽  
Ecological Crisis ◽  
Human Being ◽  
Effective Response ◽  
Life On Earth

This paper intends to verify the extent and effectiveness of the transforming appropriation of the Derridean concept of ‘differance’ by Stiegler with respect to the problems that, according to Stiegler, make this creative critical operation necessary; in particular with respect to the most recent question concerning the possibility of thinking about and putting into practice a ‘neganthropological différance’ capable of facing the ecological crisis that today seems to threaten the very existence of life on earth. The paper goes back to Technics and Time 1. to analyze the distinction between ‘vital difference’ and ‘noetic difference’ that constitutes the condition of possibility of the ‘neganthropological différance.’ In this perspective, the distinction proposed by Stiegler seems to re-propose the hierarchically oriented oppositional structure that characterizes metaphysical thought and in particular the opposition between man and animal, attributing to the human being the ability to free himself from the constraints of his biological-natural condition. Finally, the paper attempts to account for the repercussions of this approach on the very possibility of an effective response to the ecological crisis, concluding with a provocation regarding the role that theory can and must play with regard to such an urgent and far-reaching problem.

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