Paper Example on Promiscuity in Chimpanzees

Introduction

By definition, promiscuous breeding is a breeding type that involves both the males and the females of a certain population who mate randomly and with multiple partners. For chimpanzees, mating is a rather free process which is characterized by a high degree of male to male competition. Although chimpanzees are closely related to humans and have similar behaviors and genetic makeup, the chimps are considered far more promiscuous as compared to the humans, and this is substantiated by the impressive size of their testes (Tutin, 1979). Stumpf and Boesch (2004) contend that, relative to their body size, the testes of a male chimpanzee are ten times larger than a man's, and they have a prolific sperm production to match. This being the case, the core intent of this essay is to discuss the diverse nature of chimpanzees extensively.

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To begin with, the promiscuous nature of the chimpanzees is evidenced by the fact that the females do not stand by their male counterparts. Instead, they usually have multiple partners, and this means that the male chimps ought to live up to the standards by producing as many sperms as possible. This, in essence, gives them the best chance of fathering multiple offspring during the ensuing sperm war. On the other hand, for the female chimpanzees, besides their ability to maximize their chances of reproducing with what they consider as genetically superior male, they also benefit from the prevalence of a paternity confusion. For instance, there are very low chances of a male killing a young chimp if there is a chance he fathered it.

According to research, the promiscuity of chimpanzees is characterized by the use of violence by the males. In particular, male chimpanzees are known to have always possessed the desire to control female reproduction, and for this reason, they use either violence of the fear of violence as a control mechanism. Besides, the males can be overly aggressive towards their female counterparts especially before mating. Barnard (2011) contends that male chimpanzees use punishment and intimidation as a means of reducing promiscuity among the females and also to promote their own mating interests. With reference to the research conducted in the Kibale National Park in Uganda, female promiscuity among the chimps is one of the key features of their mating. More specifically, this research substantiates that male chimpanzees achieve high mating success with the females whom they are highly aggressive with. Besides, according to Muller, Kahlenberg, Emery Thompson and Wrangham (2007), the promiscuity among chimpanzees is characterized by three types of sexual coercion, which includes, forced copulation, harassment, and intimidation. For instance, forced copulation involves violent restraint which leads to immediate mating while the harassment involves a series of attempts to copulate, which imposes costs of females and hence inducing the eventual submission by the females. Intimidation, which is the final strategy, is characterized by the physical punishment of female refusal to mate. This, as a result, increases the chances of submission in the future.

Similarly, the sexual behavior of a majority of the chimpanzees is primarily tied to the female's reproductive cycle, in which case, females are only receptive to males when they are in estrus. More specifically, estrus is characterized by certain behavioral changes which hint that the female is receptive. According to studies, for many chimpanzees, like in apes and Old World monkeys, the estrus is accompanied by swelling and changes in the color of the skin around the female's genital areas. This, in essence, serves as a visual cue that the female is ready to mate. Regardless of this particular situation, the nature and the extent of the female chimpanzee's choice in promiscuously mating primates is overly uncertain. Nonetheless, studies have shown that there is considerable interest in the idea that a promiscuous strategy predominates only in a female's early follicular phase, a phase when there a very low to no chances of conception. During this time, females exert a preference for certain males around the ovulation time, and hence attempting to concentrate paternity in those individuals.

Besides, a growing body of research on primates has increasingly contended that promiscuity among the female chimpanzees serves as a strategy to stop the males from killing their offspring. According to scientists, it is common for male mammals to kill infants in the species where the females live in social groups that are dominated by one of a few males. Usually, for chimpanzees, their social lives are characterized by issues such as rival males may take over a group, killing the young chimps in the group. Stumpf and Boesch (2004) highlight that the primary reason why these male chimpanzees do this is to ensure that he can produce his own offspring. In the same vein, studies substantiate that for some female chimpanzees, promiscuity is exemplified when they mate as much as possible in the shortest time possible. This, in essence, makes it unclear who the father of their offspring is and the male chimps usually fear the risk of killing the chimps that they have fathered.

Why Chimpanzees Are Not Monogamous Like Orang-Utans

Monogamy, which involves having one mate at a time, is rare in a majority of primates. However, in those species which it has evolved, like among orang-utans, monogamy was always preceded by a breeding system which is non-monogamous and one which was characterized by very high risks of incoming males killing the infants of their rival males. For chimpanzees, this strategy has been prevalent over the years since it gives the incoming males the chance to take over their rival females.

Statistics substantiate that approximately 3% of mammal species are essentially monogamous. Although there is no concrete evidence as to why monogamy evolved in some primates and not others, (Muller, Thompson, Kahlenberg and Wrangham (2010) point out that gorillas and promiscuous chimpanzees are polygamous. For instance, unlike other primates such as orangutans, chimpanzees live in communities or multi-male, multi-female unit-groups. According to modern day literature, chimpanzees are deemed the most polygamous primates. For instance, Newton-Fisher (2014) argues that chimps live in groups that consist of approximately 40 adult and adolescent members alongside associated juveniles and infants. However, the population is characterized by female biasnes of a ratio of 1:6.

Owing to the promiscuous nature of the chimpanzees, and the gender imbalance between the males and the females, polygamy is inevitable. According to Muller et al., (2010) the reason why chimpanzees are not as monogamous like other primates such as orang-utans can be highly attributed to their behavioral mechanisms. For instance, for the chimps, their behavioral mechanism gives their females a certain degree of genetic choice. Besides, the fact that a disproportionate number of conceptions can occur during consortships suggests that these mechanisms are successfully operative. Also, polygamy among the chimpanzees is common owing to the mating characteristics of the females. In particular, various aspects of the female reproductive physiology function in a way that allows an intimate female experience with every other adult male in the community before the female becomes likely to conceive. Thus, based on this premise, the distribution of the female core areas means that by cooperating to maintain a certain community range, the male chimpanzees gain access to many females. This, in essence, increases the reproductive potential of the male chimpanzees.

Polygamy among the chimps is also highly attributed to the fact that they live in communities that consist of community members who are in close contact. Particularly, chimpanzees are tied to a particular locale where migration for most of them, is not common. This being the case, a certain kind of aloofness from other troops is created hence preventing a high concentration of individuals. Besides, in these communities, the chimpanzees avoid each other and are aggressive towards other outsider groups or communities. Thus, this being the case, and owing to the fact that there is a gender imbalance between the promiscuous females and the males, the males often tend to have more than two sexual partners.

Conclusion

In conclusion, promiscuity among chimpanzees is a unique trait that especially characterizes them as primates. Although different scholars have different contentions about the promiscuous nature of these mammals, it is evident that female chimpanzees appear to have a strong incentive to search for mates to counter issues related to their infanticide risk. Besides, promiscuity among female chimpanzees serves as a means of promoting their post-copulatory mate choice through sperm competition and hence leading to their polygamous nature.

References

Barnard, C. (2011). Animal behaviour: Mechanism, development, function, and evolution. Mexico: Pearson Educacion.

Muller, M. N., Kahlenberg, S. M., Emery Thompson, M., & Wrangham, R. W. (2007). Male coercion and the costs of promiscuous mating for female chimpanzees. Proceedings of the Royal Society B: Biological Sciences, 274(1612), 1009-1014. doi:10.1098/rspb.2006.0206

Muller, M. N., Thompson, M. E., Kahlenberg, S. M., & Wrangham, R. W. (2010). Sexual coercion by male chimpanzees shows that female choice may be more apparent than real. Behavioral Ecology and Sociobiology, 65(5), 921-933. doi:10.1007/s00265-010-1093-y

Newton-Fisher, N. E. (2014). Roving females and patient males: a new perspective on the mating strategies of chimpanzees. Biological Reviews, 89(2), 356-374. doi:10.1111/brv.12058

Stumpf, R. M., & Boesch, C. (2004). Does promiscuous mating preclude female choice? Female sexual strategies in chimpanzees (Pan troglodytes verus) of the Ta National Park, Cote d' Ivoire. Behavioral Ecology and Sociobiology, 57(5), 511-524. doi:10.1007/s00265-004-0868-4

Tutin, C. E. (1979). Mating patterns and reproductive strategies in a community of wild chimpanzees (Pan troglodytes schweinfurthii). Behavioral Ecology and Sociobiology, 6(1), 29-38. doi:10.1007/bf00293242