Nicole M. Herzog

The pyrophilic primate hypothesis

Members of genus Homo are the only animals known to create and control fire. The adaptive significance of this unique behavior is broadly recognized, but the steps by which our ancestors evolved pyrotechnic abilities remain unknown. Many hypotheses attempting to answer this question attribute hominin fire to serendipitous, even accidental, discovery. Using recent paleoenvironmental reconstructions, we present an alternative scenario in which, 2 to 3 million years ago in tropical Africa, human fire dependence was the result of adapting to progressively fire‐prone environments. The extreme and rapid fluctuations between closed canopy forests, woodland, and grasslands that occurred in tropical Africa during that time, in conjunction with reductions in atmospheric carbon dioxide levels, changed the fire regime of the region, increasing the occurrence of natural fires. We use models from optimal foraging theory to hypothesize benefits that this fire‐altered landscape provided to ancestral hominins and link these benefits to steps that transformed our ancestors into a genus of active pyrophiles whose dependence on fire for survival contributed to its rapid expansion out of Africa.

Starch Grain Analysis in California and the Great Basin

Abstract Understanding variability in prehistoric diets requires data on plant and animal remains. While zooarchaeological approaches continue to provide fine-grained information on the animal components of diet, plant use is difficult to track within a wide range of archaeological contexts. Starch grain analysis is a proven method for identifying the taxonomic relationships of plant microfossils deposited on archaeological artifacts. Here I report on practical and methodological considerations for the application of starch research to California and Great Basin archaeobotanical remains. The study examines the feasibility of the approach in identifying plant use on a small set (n = 8) of ground stone artifacts recovered from the Leonard Hot Spring locality, Surprise Valley, northeastern California. The exercise yielded a total of 111 starch grains. Of these, 52 were diagnostic of edible plant taxa. The possibilities for monitoring past patterns of plant consumption and variation therein through time and space are clearly indicated. The study also highlighted three requirements for greater methodological accuracy: (1) analytical categorization of comparative samples enabling identification of species with overlapping morphological and size features, (2) expanded comparative libraries, and (3) experimental processing. Results indicate the strength of the method in identifying plant remains where other methods are unavailable or inconclusive.

Savanna Chimpanzees at Fongoli, Senegal, Navigate a Fire Landscape

Savanna chimpanzees (Pan troglodytes verus) at Fongoli, Senegal, appear to be able to predict the “behavior” of wildfires of various intensities. Although most wildfires are avoided, even the most intense fires are met with relative calm and seemingly calculated movement by apes in this arid, hot, and open environment. In addition to reviewing instances of such behavior collected during the course of the Fongoli study, we also report chimpanzees’ use of burned landscapes during the dry season, when more than 75% of these apes’ home range may be burned annually. In burned areas, chimpanzees spent more time foraging and traveling than in unburned areas. Chimpanzees’ behavior in a fire context can help inform paleoanthropological hypotheses regarding early members of our own lineage and can provide insight into the ability of early hominins to conceptualize the behavior of fire and thus set the stage for our lineage’s use of fire.

What's burning got to do with it? Primate foraging opportunities in fire-modified landscapes

OBJECTIVES Anecdotal and formal evidence indicate that primates take advantage of burned landscapes. However, little work has been done to quantify the costs and benefits of this behavior. Using systematic behavioral observations from a population of South African vervet monkeys (Chlorocebus aethiops pygerythrus), we evaluate differences in food availability and energetics before and after controlled burns altered vegetation near their home range. We aim to determine whether burned habitats offer improved foraging opportunities. METHODS We collected feeding data from foraging individuals and analyzed common plant foods for their energetic content. We then used the feeding and energetic data to calculate postencounter profitabilities and encounter rates for food types. Using negative binomial and mixed linear regression models we compared data from burned and unburned habitats. RESULTS Our results show significantly improved encounter rates in burned landscapes for two prey items, invertebrates and grasses. However, postencounter profitabilities in burned areas were not significantly different than those achieved in unburned areas. CONCLUSIONS Results suggest that improved encounters alone can motivate changes in foraging behavior. These foraging benefits enable the exploitation of burned savanna habitats, likely driving postburn range expansions observed among populations of vervet monkeys. Thus quantified, these results may serve as a foundation for hypotheses regarding the evolution of fire-use in our own lineage.