paleoanthropology, evolution and genetics

Photo Credit: Hillside above the Rising Star cave system, South Africa. John Hawks CC-BY-NC-ND

Monkey pyrophiles

Nicole Herzog and colleagues spent half a year following a troop of vervet monkeys during the controlled burn season at Loskop Dam Nature Reserve in South Africa. They found that the vervets took readily to newly-burned landscapes, substantially increasing their home range to make use of burned habitat.

The study did not include any kind of observation or analysis of the foods the vervets were eating in the burned landscape, so it is not clear whether they were eating new green shoots or insects and other invertebrates that were exposed in the burn zone. It's also unclear the extent to which the monkeys became more terrestrial to use the burned zone. But their use of space greatly increased, and they biased their behavior within their older pre-burn range toward the edges of the burned area.

The paper includes a nice synopsis of behaviors of other primates in relation to fire, including some discussion of the Fongoli chimpanzees (Pruetz and LaDuke 2010). Like those chimpanzees, these vervet monkeys approached the fire to investigate as it was happening, showed no alarm at the approaching flames, and made extensive use of the burned area after the fire. The paper cites studies of macaques and baboons also using burned areas.

Smoke over Rising Star
Smoke from fire near Rising Star site, June 2014

They conclude with some implications for human evolution, proposing that our greater reliance on terrestrial resources and controlled use of fire may be part of a longer heritage of "pyrophilia":

While the importance of fire in human evolutionary history has long been acknowledged (Clark and Harris, 1985; Goudsblom, 1986; James et al., 1989; Pyne, 1995; Wrangham et al., 1999; Burton, 2009; Wrangham, 2009), how and why early hominins came to use this force is largely unknown. Descriptions of primates' exploitation of burned landscapes provide strong evidence that they understand fire and attendant changes to travel and foraging opportunities. That even the most terrestrially constrained of savanna-dwelling primates expand into burned territory suggests a deep phylogenetic history of fire tolerance and pyrophilic tendencies. Pruetz and LaDuke (2010) argue that savanna chimpanzees' ability to “conceptualize” fire is a synapomorphic trait within the human–chimpanzee clade. We agree, but given that our vervet subjects exhibited a similarly “conceptualized” response to fire—they did not flee but instead calmly monitored the approaching blaze as the flames, noise, and smoke drew near—argue for an even deeper history of the trait within the primate clade. The fire-positive adaptations detailed in this and other savanna-dwelling primate populations provide clues to understanding the foundation for complex pyrotechnological innovations in our own lineage. If burned landscapes represent novel foraging opportunities, consistent and controlled use of these patches would have contributed to the selective pressures that shaped the unique morphology, mobility, and behavior of our genus.

Primates are curious and learn readily about natural phenomena that surround them. It may not be a stretch to imagine that the human lineage became fire-users by developing a knowledge and consciousness about the occurrence of fire upon the landscape. Maybe even controlled burning has a longer history than we typically think.

References:

Herzog, N. M., Parker, C. H., Keefe, E. R., Coxworth, J., Barrett, A. and Hawkes, K. (2014), Fire and home range expansion: A behavioral response to burning among savanna dwelling vervet monkeys (Chlorocebus aethiops). Am. J. Phys. Anthropol., 154: 554–560. doi: 10.1002/ajpa.22550

Pruetz JD, LaDuke TC. 2010. Brief communication: reaction to fire by savanna chimpanzees (Pan troglodytes verus) at Fongoli, Senegal: conceptualization of “fire behavior” and the case for a chimpanzee model. Am J Phys Anthropol 141:646–650.