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Posts Tagged ‘human evolution’

Smoke and human evolution

August 31st, 2016 1 comment

In this blog we have discussed that some plants have evolved seeds with sensitivity to chemicals produced by fire in such a way that these chemicals stimulate the germination of the plants after a fire; we call this process smoke-stimulated germination [1-3]. Well, plants are not the only organisms that have evolved in response to chemicals present in the smoke, humans too! A recent paper show that modern humans are the only primates (including early hominids as Nearthentals and Denisovans) that carry a mutation increasing tolerance to smoke chemicals produced by fires [4]. This mutation could have given an evolutionary advantage to modern humans in relation to other hominids as allowed them to use fire for many important activities (e.g., cooking, hunting, defense, heating, agriculture). This high exposure to smoke would have also increased the susceptibility to pulmonary infections, and even the evolution of some of them (tuberculosis [5]). The tolerance to smoke also allowed modern humans to have some tolerance to pollution and to smoke cigarettes! That is, the ability to smoke could be a side effect (an exaptation, if you’d like) of been adapted to use fire, and in fact, it currently acts as a secondary sexual character!

woody-allen-smoking
Smoking as a secondary sexual character (Woody Allen in Manhattan, 1979).

References
[1] Moreira B., Tormo J., Estrelles E., Pausas J.G. 2010. Disentangling the role of heat and smoke as germination cues in Mediterranean Basin flora. Annals of Botany 105: 627-635. [doi | pdf | post]

[2] Tormo, J., B. Moreira, and J. G. Pausas. 2014. Field evidence of smoke-stimulated seedling emergence and establishment in Mediterranean Basin flora. Journal of Vegetation Science 25: 771-777. [doi | wiley | pdf | post]

[3] Smoke-stimulated germination, jgpausas.blogs.uv.es/2011/12/02/

[4] Hubbard, T.D., Murray, I.A., Bisson, W.H., Sullivan, A.P., Sebastian, A., Perry, G.H., Jablonski, N.G. & Perdew, G.H. (2016) Divergent Ah receptor ligand selectivity during hominin evolution. Mol. Biol. Evol., 33:2648-2658.

[5] Chisholm, R.H., Trauer, J.M., Curnoe, D. & Tanaka, M.M. (2016). Controlled fire use in early humans might have triggered the evolutionary emergence of tuberculosis. Proc. Natl. Acad. Sci. USA, 113, 9051-9056.

Fire in the root of humans (2)

January 16th, 2016 No comments

Many people have the idea that fires scare animals and fled them in panic. However this is not always true, some species react still and calm and move away to safe sites. Some time ago I mentioned a study demonstrating that chimps in wild, when they see a wildfire, they react calmly, predict their behaviour and move accordantly without any stress or fear, suggesting that they have some understanding of fire behaviour [1]. Few days ago I came across other studies [2,3] suggesting that different species of primates not only react calmly to fire but after a fire, they increase their home range to include the area burned and used it for searching food, including ‘cooked’ fruits! So wildfires were very important in the history of humans [4], they could have contribute to the first step towards humanity from our ancestors …


Figure: In captivity, some apes are able to light a fire a roast vegetables (see youtube1, youtube2). Photo from www.dailymail.co.uk

References
[1] Fire in the root of humans, jgpausas.blogs.uv.es 19-1-2010.

[2] Jaffe KE, Isbell LA 2009. After the fire: benefits of reduced ground cover for vervet monkeys (Cercopithecus aethiops). Am. J. Primatol. 71:252-260.

[3] Herzog NM, Parker CH, Keefe ER, Coxworth J, Barrett A, 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.

[4] Pausas J.G. & Keeley J.E. 2009. A burning story: The role of fire in the history of life. BioScience 59: 593-601 [doijstor | BioOne | pdfpost]

 

Fire in the roots of humans

January 19th, 2010 No comments

One key difference between animals and humans is the use of fire; in fact, during the evolution, fire made us humans. For instance, cooking implied higher food energy, as well as an increased the diversity of available food (detoxifying effects of heating, etc…). Furthermore, cooking implied a delay in food consumption, which required the development of social abilities for the distribution of tasks within the group (e.g., collection, accumulation, cooking, defense, even stealing). These factors are thought to have prompted the evolution of large brains and bodies, small teeth, modern limb proportions, and other human traits, including many social aspects of human-associated behavior. However, the moment in which humans started to use fire is still debated. It is often believed that the rise of Homo erectus from its more primitive ancestors was fueled by the ability use fire.

Although the use and control of fire is a human trait, a recent study has demonstrated that chimpanzees have the ability to understand wildfires and predict their behavior (Pruetz & LaDuke 2010). Chimps calmly observed wildfires around them, predict their behaviour and move accordantly without any stress or fear. This suggest that the conceptualization of fire may be a old trait, in the hominids group.

To what extent current humans are losing this trait is another debate, but we may be better off at managing our fire-prone landscapes by learning from chimps!

References

  • Pausas J.G. & Keeley J.E. 2009. A burning story: The role of fire in the history of life. BioScience 59: 593-601 [doi] [pdf]
  • Pruetz JD & TC LaDuke 2010. 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 Phy Anthropol (in press) [doi]
  • Wrangham RW, Jones JH, Laden G, Pilbeam D, Conklin-Brittain NL. 1999. The raw and the stolen: Cooking and the ecology of human origins. Current Anthropol 40: 567–590.
  • Control of fire by early humans [Wikipedia]

chimpanzee

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