Both bonobos and chimpanzees are primarily frugivorous, but chimpanzees display more variety in their diets. Bonobos inhabit the lowland forests south of the Congo River while chimpanzees inhabit a variety of environments north of the Congo River including woodland-savannah and dry forest as well as moist evergreen forests typical of bonobos. It’s not immediately obvious why an environment would select for paedomorphism, but examining the bonobo’s habitat can provide some clues to reconstructing its phylogentic history. Perhaps the first observers of the bonobos were not so far off when they mistook a bonobo skull for a juvenile chimp. This theory implies that at least part of the mutation responsible for the speciation of bonobos suppresses the onotological process necessary to derive adult chimpanzees from children. He suggests that comparisons between bonobo and chimpanzee anatomy are suggestive of paedomorphism, or the retention of juvenile characteristics in the adult form. Blount (1990) offers a theory for the mechanism by which speciation might have occurred. Furuichi (2011) postulates that small genetic changes altered one or a few crucial features during the bottleneck period, resulting in development of the bonobo social system, including its sexual behavior “if genetic changes occurred in the physiology of females, causing them to show estrus during nonconceptive periods, this whole social system may have developed in an environment with abundant and dense food resources”. The question left for modern ethologists is the nature of the mutation that caused speciation. Comparison of the banded chromosomes in humans, chimpanzees, and bonobos demonstrated that Pan paniscus is the most chromosomally specialized species (Stayon et al. Male chimpanzees express dominance over their female counterparts by contrast, dominance is not strictly ordered by gender in bonobo society despite the fact that female bonobos are smaller than males (de Waal 1995).Ĭontrary to the proposition that speciation in the Pan linage derived the common chimpanzee from the bonobo when the chimpanzee entered the open savannah (der Waal 1989), genetic testing gives credence to the notion that a genetic mutation derived the bonobo from the chimpanzee when the bonobo entered the protected forests (Furuichi 2011). The differences in the behavior of these two species, however, is not limited to sex. Together, these differences in behavior suggests that sex in bonobo society serves a fundamentally different purpose than in chimpanzees that is not limited to reproduction. These interactions reflect a much broader sexual lexicon in bonobos than in chimpanzee in addition to vaginal, bonobos utilize oral and manual stimulation in a variety of copulation positions, preferring ventro-ventral position as in humans. Furthermore, sexual interactions among bonobos occur in every possible partner combination regardless of age or gender with the notable exception incest among siblings. The rate of sexual interactions is higher among bonobos than chimpanzees, yet both maintain the same rate of reproduction. There are, however, profound differences between the two species (Cf. It is estimated that the two species within the Pan genus diverged 1,000,000 years ago, which reflects similarities in both the anatomy and behavior (such as male philopatry) between the species (Przeworski 2007). In fact, “pygmy chimpanzees” are just as large as some subspecies of the common chimpanzee (De Waal 1995). paniscus as an independent species following a detailed morphological study. paniscus skull was first thought to belong to a juvenile chimpanzee. Ernest Schwarz, a German anatomist in a Belgian colonial museum first documented Pan paniscus in 1929.
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