The article “Chimpanzee carrying behavior and the origins of human bipedalism” by Carvalho and colleagues (2012) investigates the hypothesis of bipedalism in early hominins as an adaptation to carrying valuable and unpredictable resources. In the researchers’ view, environmental uncertainty, along with the competition for resources significantly contributed to bipedalism development as a means of efficiently transporting food and water (Carvalho et al., pg. 1). The theoretical framework follows the wild chimpanzees who are the closest living relatives to humans and exhibit an increased proportion of bipedal walking with possessions of valuable items.
To find out if their assumption was true, Carvalho and colleagues conducted forest field experiments at the Bossou forest in Guinea, where they studied chimpanzees in their natural habitat. The chimpanzees were offered two different types of nuts. One of them is the very valuable and somewhat challenging to find, coula nuts, and the other one, is a more available oil-palm nut (Carvalho et al., pg. 2). The researchers manipulated the availability of these resources and carefully observed chimpanzee behavior to discover whether the availability of these resources affected their mode of carrying and frequency.
The article’s findings support the notion that chimpanzees walk bipedally in most cases when carrying unpredictable and valuable resources. The explanation presented is that as chimpanzees carry items that are valuable and unpredictable, they walk bipedally more often (Carvalho et al., pg. 2). The researchers discovered a very powerful link between bipedalism amongst chimpanzees and threatening competition for coula nuts or during the time of high growth of coula nuts. Moreover, chimpanzees showed a preference for bipedalism when carrying more items at a time while walking, which can be linked to an increase in the number of items carried (Carvalho et al., pg. 2). The behavior, that has been observed, perfectly supports the prognosis that early hominins may have assumed erect posture to overcome the problem of accessing and moving around objects of value in those environments where there were often other competitors.
This research’s direct observation of wild chimpanzee behavior in the natural habitat where most of their closest relatives spent millions of years provides more information about their evolutionary history. A good deal of effort has been invested in designing experiments in which resource availability would be manipulated and an assessment of the role carried behavior in contributing to the pool of valid findings has been made. Furthermore, the scientists designed additional investigations of chimpanzee interactions in crop-raiding occasions while bringing the initial hypothesis into further support (Selinger et al., pg. 7). Nevertheless, the research helps evaluate the chimpanzee behavior though it does not directly describe what could have transpired for the early hominins. Also, chimpanzees are not direct ancestors of humans and therefore their behavior might not be quite the same as that of early hominins. Moreover, the study emphasizes a particular chimpanzee population, which is one geographic location stopping the study’s outcome from being applied to other chimpanzees elsewhere, and observational data is prone to subjective orientations that bias the result.
In comparison, the proposed selective advantages for bipedality in this article are similar to that carrying behavior in The Natural Detective by Lovejoy (1984) on the mysterious origin of human bipedality, both asserting similar grounds. Lovejoy’s hypothesis on bipedalism came along in the early hominins as a response to the dropping of objects, especially foods, while the hands were freed for other tasks (Lovejoy, pg. 2). Carvalho and colleagues (2012) speak to the fact that bipedalism could have taken effect to enable the efficient transportation of some valuable yet, unpredictable resources. That is exactly the part where the two theories agree that function environment and competition play a significant part in the emergence of bipedal locomotion. Concerns about the theory that Lovejoy put out have been raised by some researchers, who challenge the possibility of bipedalism being only to carry. Besides, other theories give a different reason for selective pressure for bipedality like keeping body temperature or saving energy as well as taking a long way (Selinger et al., pg. 4). Although the read source brings to light the association between bipedalism and resource taking among chimpanzees, there may be different theories or criticism similar to that found in the context of scientific research.
Ultimately, Carvalho and colleagues explore the role of resource-carrying and its association with bipedality. Through a series of observations of how chimpanzees behave in the wild, these investigators put forth powerful evidence of increased bipedalism when they have to transport important and possibly unpredictable resources in competitive environments where other chimps might want to steal them. However the article has some limitations like direct observation and experimental design despite confronting the two, so further research is required to wholly understand the roots of bipedalism in early hominins classification. The comparison between this theory of Lovejoy and those in the existing literature underscores the overlap in selective pressures for bipedality while creating room for further investigation of alternative hypotheses.
Works Cited
Carvalho, Susana, et al. “Chimpanzee carrying behaviour and the origins of human bipedality.” Current Biology 22.6 (2012): R180-R181.
Lovejoy, C. Owen. “The natural detective.” Natural History 93.10 (1984): 24.
Selinger, Jessica C., et al. “Running in the wild: Energetics explain ecological running speeds.” Current Biology 32.10 (2022): 2309-2315.
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