The biotic crisis overtaking our planet is likely to precipitate a major …

• Abstract
• Introduction
• The Core Concept
• Lessons from the Past?
• Recovery Processes
• Conservation Responses
• References

Biology Articles » Evolutionary Biology » The biotic crisis and the future of evolution » Introduction

Introduction

- The biotic crisis and the future of evolution

Human activities have brought the Earth to the brink of biotic crisis. Many biologists (e.g., refs. 1-5) consider that coming decades will see the loss of large numbers of species. Fewer scientistswitness the lack of professional papers addressing the issueappear to have recognized that, in the longer term, these extinctions will alter not only biological diversity but also the evolutionary processes by which diversity is generated. Thus, current and predicted environmental perturbations form a double-edged sword that will slice into both the legacy and future of evolution.

A simple consideration of time underscores the magnitude of the challenge to scientists and public alike (cf. ref. 6). Episodes of mass extinction documented in the geological record were followed by protracted intervals of rediversification and ecological reorganization; five million years can be considered a broadly representative recovery time, although durations varied from one extinction to another (7). Suppose, too, that the average number of people on Earth during the recovery period is 2.5 billion (by contrast with the 6 billion today). Under these conditions, the total number of people affected by what we do (or do not do) during the next few decades will be in the order of 500 trillion10,000 times more people than have existed until now. We are thus engaged in by far the largest "decision" ever taken by one human community on the unconsulted behalf of future societies.

The question of how current threats to biological diversity will affect the future of evolution was first raised by one of us in the mid-1980s (8). It attracted virtually zero interest from fellow biologists. Thirteen years later, he revisited the question, this time with more detailed analysis, although still in exploratory form (9). This latter publication elicited attention from the National Academy of Sciences, which undertook to sponsor a Colloquium in March 2000. As a "scene setter" for Colloquium participants, we drafted an overview account of topics to be tackled, and that draft makes up the bulk of this paper. We hope that it may serve the same purpose for readers of this special section of PNAS.