Savannah chimpanzees, a model for understanding human evolution
Chimpanzees –Pan troglodytes– are the closest living evolutionary relatives to our species, since we share with them about 98.7% of the DNA, and we have in common an ancestor that lived approximately between 4.5 and 6 million years ago. Despite this closeness, these primates lack some of the biological and cultural traits that humans possess to adapt to extreme heat, such as the numerous eccrine sweat glands, the relative lack of hair, or the ability to create artifacts such as containers. of water or hats to mitigate dehydration and heat stroke.
Also, to thrive, most great apes, such as chimpanzees, bonobos, and gorillas, need swaths of lush forest in Africa, or in the case of orangutans, in Southeast Asia.However, some groups of chimpanzees survive in the savannas, areas characterized by a climate with high temperatures and very seasonal and scarce rainfall. The ecology and way of life of these chimpanzees is far from that of their jungle counterparts, and that is why now the professor at the Faculty of Psychology of the University of Barcelona, Adriana hernandez, has co-directed the work of an international team of primatologists who have reviewed the existing scientific literature regarding the behavior and ecology of chimpanzees in the savannas to understand how they adapt to these extreme conditions.
According to the researchers, the environmental conditions of these places would provoke a specific type of behaviors and physiological responses in these chimpanzees, such as resting in caves or digging to extract water that do not occur in those of their congeners that live in wooded areas, where the conditions environmental are not so extreme. “What we call savanna environment effect has important implications when it comes to reconstructing the behavior of the first humans who lived in similar habitats and, therefore, it helps us better understand our own evolution “says Hernández, whose work is published this week in the magazine Evolutionary Antropology under the title Chimpanzees (Pan troglodytes) in savanna landscapes.
Chimpanzees that live in the savannah are taxonomically indistinguishable from other chimpanzees. For this reason, comparisons of behavior, morphology and ecology with respect to their relatives of forested landscapes provide key information to generate hypotheses or test theories about how early humans were able to adapt millions of years ago as African forests receded and gave way to savannas.
“We know that early hominins adapted to savanna environments similar to those occupied by chimpanzees, and it is thought that lsavanna conditions caused adaptations in our ancestors, such as brain development or tolerance to high temperatures “, explains Hernández, who is also co-director of Research at the Jane Goodall Institute in Spain. “Therefore, understanding how our genetically closest relatives adapt to a dry, hot, seasonal and open environment, very similar to those where early hominins lived, helps us to analyze how our ancestors might have adapted and how they might have emerged. the characteristics that define us as humans, “he adds.
Among the characteristics collected by the study, the following stand out: Savanna Chimpanzee Strategies to Tolerate High Temperatures. “Understanding how they cope with heat can help us understand how the strategies that we employ came about. Some are probably the same for chimpanzees and hominins, such as using caves or diving into water to cool off,” continues the researcher.
Another prominent example refers to how chimpanzees try to hydrate during the late dry season, for example by digging for water when the presence of this is reduced to only a few points on the ground, something that the first hominids also had to face during part of the year.
The work has also confirmed that social groups of savanna chimpanzees are distributed in unusually large areas, around 100 km², while chimpanzees that inhabit more wooded areas have ranges of between 3 and 30 km². However, although the size of the groups is similar in both types of chimpanzees, in the savannah they show a much lower population density, something that could be explained by the low availability of food in the habitat.
Although we now know much more than ever about savanna chimpanzees, their exact number is unknown, although according to researchers there are fewer than those that inhabit forested areas, since the total area they occupy is much smaller. “It should also be taken into account that there are far fewer sites where savanna chimpanzees have been studied, since there are only two places in the savannah where chimpanzees are habituated to humans and their behavior can be observed directly. In contrast, there are more wooded sites with chimpanzees totally used to researchers; environments in which these primates have been studied for decades, “explains Adriana Hernández.
Keys to understanding adaptation to climate change
Another of the relevant contributions of this research is that it contributes to understanding the possible effects of climate change on the species. “The adaptation of these chimpanzees to extreme climates can help us model how chimpanzees currently living in forests could adapt to changes that climate studies project will make their environments drier and warmer.
This is important as the species is endangered and the West African subspecies –Pan troglodytes verus– is critically threatened “, reports the researcher, from whose team they take the opportunity to emphasize the need for more research on the biological and cultural aspects of the savanna environment, and thus be able to address the effects on the species of the expected future increase in the frequency of heat waves and dry spells.
- You enjoy history? Are you a photography lover? Do you want to keep up to date with the latest scientific advances? Do you love to travel? ¡Apúntate gratis a nuestras newsletter National Geographic!