Sixth Mass Extinction Academic Bun Fight: Tracking Ecological Change in Egypt Over 6k Years

Collapse of an ecological network in Ancient Egypt

Authors:

Yeakel et al

Abstract:

The dynamics of ecosystem collapse are fundamental to determining how and why biological communities change through time, as well as the potential effects of extinctions on ecosystems. Here, we integrate depictions of mammals from Egyptian antiquity with direct lines of paleontological and archeological evidence to infer local extinctions and community dynamics over a 6,000-y span. The unprecedented temporal resolution of this dataset enables examination of how the tandem effects of human population growth and climate change can disrupt mammalian communities. We show that the extinctions of mammals in Egypt were nonrandom and that destabilizing changes in community composition coincided with abrupt aridification events and the attendant collapses of some complex societies. We also show that the roles of species in a community can change over time and that persistence is predicted by measures of species sensitivity, a function of local dynamic stability. To our knowledge, our study is the first high-resolution analysis of the ecological impacts of environmental change on predator–prey networks over millennial timescales and sheds light on the historical events that have shaped modern animal communities.

Retort:

Mammalian extinction in ancient Egypt, similarities with the southern Levant

Authors:

Bar-Oz et al

Exert:

Yeakel et al. (1) find that wild mammal extinction in ancient Egypt during the Holocene was nonrandom and coincided with abrupt climatic changes and a local cultural collapse. The authors provide compelling evidence that the deterioration of the natural Egyptian ecosystem gradually progressed during the Holocene. The extinction patterns provided vividly show that decreasing predator and prey (ungulates) diversity mirror increased desertification, human population growth, and political instability. We see strong ecological logic in Yeakel et al.’s (1) scenario and point to the advantages of conducting detailed comparisons of local extinction data to illuminate particularities and to better fine-tune broader hypotheses concerning Holocene extinctions

Second Retort:

Ancient Egypt’s fluctuating fauna: Ecological events or cultural constructs?

Author:

Evans

Exert:

Yeakel et al. present an innovative examination of Egypt’s ecological history (1), in which they rely upon paleontological evidence and artistic representations of animals to reconstruct patterns of species extinctions over six millennia. Focusing on ungulates and their mammalian predators, and drawing upon mammalogist Dale Osborn’s 1998 volume, The Mammals of Ancient Egypt (2), Yeakel et al. (1) report dramatic changes in predator–prey ratios corresponding to periods in which Egypt may have experienced extreme aridification.

Yeakel et al.’s (1) efforts to link science and the humanities are valuable; indeed, the abundant depictions of animals found in ancient Egyptian cultural remains, especially in detailed tomb paintings, offer a ready source of material that can be approached in this way (3). However, scientific evaluation must be balanced with a clear understanding of Egyptian art, which was heavily constrained by both graphic and cultural rules (4).

Response:

Reply to Evans and Bar-Oz et al.: Recovering ecological pattern and process in Ancient Egypt

Authors:

Yeakel et al

Exert:

Our recent paper used artistic depictions of animals and fossil evidence to examine the community-level effects of local extinction events over 6,000 y of Egyptian history (1). We found that local extinctions were nonrandom, that changes to community structure (quantified by the species predator/prey ratio) seemed to correspond to local aridification pulses, and that the decline in species richness throughout Egyptian history resulted in a drop in dynamic stability because of the elimination of smaller-bodied herbivores.