Human populations and their use of land have transformed most of the terrestrial biosphere into anthropogenic biomes (anthromes), causing a variety of novel ecological patterns and processes to emerge. To assess whether human populations and their use of land have directly altered the terrestrial biosphere sufficiently to indicate that the Earth system has entered a new geological epoch, spatially explicit global estimates of human populations and their use of land were analysed across the Holocene for their potential to induce irreversible novel transformation of the terrestrial biosphere. Human alteration of the terrestrial biosphere has been significant for more than 8000 years. However, only in the past century has the majority of the terrestrial biosphere been transformed into intensively used anthromes with predominantly novel anthropogenic ecological processes. At present, even were human populations to decline substantially or use of land become far more efficient, the current global extent, duration, type and intensity of human transformation of ecosystems have already irreversibly altered the terrestrial biosphere at levels sufficient to leave an unambiguous geological record differing substantially from that of the Holocene or any prior epoch. It remains to be seen whether the anthropogenic biosphere will be sustained and continue to evolve.

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Anthropogenic transformation of the terrestrial biosphere

In this book, Robert L. Kelly challenges the preconceptions that hunter-gatherers were Paleolithic relics living in a raw state of nature, instead crafting a position that emphasizes their diversity, and downplays attempts to model the original foraging lifeway or to use foragers to depict human nature stripped to its core. Kelly reviews the anthropological literature for variation among living foragers in terms of diet, mobility, sharing, land tenure, technology, exchange, male-female relations, division of labor, marriage, descent and political organization. Using the paradigm of human behavioral ecology, he analyzes the diversity in these areas and seeks to explain rather than explain away variability, and argues for an approach to prehistory that uses archaeological data to test theory rather than one that uses ethnographic analogy to reconstruct the past.

The Lifeways of Hunter-Gatherers: The Foraging Spectrum

Chimpanzee and hunter-gatherer intergroup aggression differ in important ways, including humans having the ability to form peaceful relationships and alliances among groups. This paper nevertheless evaluates the hypothesis that intergroup aggression evolved according to the same functional principles in the two species—selection favoring a tendency to kill members of neighboring groups when killing could be carried out safely. According to this idea chimpanzees and humans are equally risk-averse when fighting. When self-sacrificial war practices are found in humans, therefore, they result from cultural systems of reward, punishment, and coercion rather than evolved adaptations to greater risk-taking. To test this “chimpanzee model,” we review intergroup fighting in chimpanzees and nomadic hunter-gatherers living with other nomadic hunter-gatherers as neighbors. Whether humans have evolved specific psychological adaptations for war is unknown, but current evidence suggests that the chimpanzee model is an appropriate starting point for analyzing the biological and cultural evolution of warfare.

Intergroup Aggression in Chimpanzees and War in Nomadic Hunter-Gatherers

In this paper I reexamine the Boserup model of agricultural intensification and archaeological reaction to it. Although causes have been extensively debated, little attention has been paid to process, and even those who reject the causal efficacy of population may adopt other aspects of the Boserup model. These “unexamined aspects” include the assumption that intensification proceeds along a single course, characterized by gradual decreases in the frequency of cropping. I suggest that the course of intensification is complex and variable and that, only by breaking down the process of intensification into its component strategies, can we come to an understanding of both the causes and the courses of intensification.

Stefan Seitz

Papers

Hunter-Gatherers and Their Neighbors from Prehistory to the Present [and Comments and Replies]