Intersexual selection is selection for traits that enhance the ability of one sex to attract the other (“intersexual” = between the sexes). Figure 6.24b Hamadryas baboon at Giza Zoo by Hatem Moushir 36 by Hatem Moushir is used under a CC BY-SA 3.0 License. Food abundance is either plentiful (Figure 6.7a) or scarce (Figure 6.7b). Malden, Massachusetts: John Wiley & Sons. Mobbing involves two or more individuals making repeated advances on a predator, often while vocalizing and/or displaying. Unlike the small group, mortality in larger groups was almost entirely due to predation, and this highlights another set of costs and benefits of group living. Dominant (high-ranking) females spend more time feeding and eat more ripe fruit than subordinates (low-ranking), so they consume more nutrients. Because male chimpanzees cannot keep others from mating with females, producing greater quantities of sperm is perhaps their best way to ensure paternity. It is not just the sheer number of cultural traditions that make chimpanzee culture so fascinating. Boston: Houghton Mifflin. 2008. “Social Correlates of Testosterone and Ornamentation in Male Mandrills.” Hormones and Behavior 54 (3): 365–372. Grey-cheeked mangabeys in Kibale National Park, Uganda, exert female choice in multiple ways (Arlet et al. If this rate of loss is not curtailed, the Bornean orangutan will go extinct in less than 15 years. 1983). In such cases, females may not be choosing mates based on direct (resource-based) or indirect (genetic) benefits but, rather, ensuring that any male who might be in close proximity to her infant after birth will not kill it. This behavior, which Goodall compared to human warfare, is now known to be typical of wild chimpanzees and is another behavior we share with our closest relatives. Big Sky has been full of surprising and shocking moments so far.Episode 9 in particular holds quite a few of those. Alarm-calling behavior is widespread in primates. assess key features of their habitat and use this information to alter their behavior and maximize their chance of escape. Natal dispersal: Emigrating from the group into which one is born. So why do subordinate females remain in the group? The systematic use of signals to refer to objects in the environment. Howler group roars may act to maintain distance between neighboring groups or keep extra-group males from entering the home range (Schön Ybarra 1986; Sekulic 1982). Redness of male mandrill faces is correlated with androgen levels. 2017). Intersexual selection: The selection for traits that enhance the ability of the members of one sex to attract the attention of the other. Whether or not a primate is group-living or solitary, it engages in some form of vigilance, or watchful behavior to detect potential danger. Day-range length: The distance traveled in a day. Boesch, Christophe. Indirect competition can take many forms, but in all cases, the males do not interact; they may, in fact, never even see each other. Figure 6.3a Female patas monkey with infant by Karin Enstam Jaffe is under a CC BY-NC 4.0 License. How much food is available in a given area. Selection for traits that enhance the ability of members of one sex to compete amongst themselves. Figure 6.8 Food distribution patterns by Karin Enstam Jaffe original to Explorations: An Open Invitation to Biological Anthropology is under a CC BY-NC 4.0 License. When this happens, usually it is the large-bodied species that supplants the small-bodied species. Submissive males respond by fleeing or presenting their hindquarters. Lastly, males may compete indirectly by committing infanticide. Survey work has revealed that the Grauer gorilla population has declined significantly since the 1990s, due almost entirely to illegal hunting. Male gelada baboons use “lip flips,” in which the gums and teeth are exposed by flipping the upper lip up over the nostrils (Figure 6.26), and “raised eyelids,” in which the pale eyelids are exposed by pulling the scalp back as threatening gestures (Aich et al. Because of their large body size, gorillas have  a much lower metabolic rate than tarsiers, so they can consume low-quality food, like leaves, and take their time digesting it, so long as they get enough (Figure 6.6b). Fossey, Dian. Gautier-Hion, Annie, René Quris, and Jean-Pierre Gautier. Arriving at the Gombe Stream Reserve in Tanzania in 1960, Jane Goodall (Figure 6.23a) was the first scientist to conduct a long-term study of wild nonhuman primates. Having a diet consisting primarily of leaves. Trivers, Robert L. 1972. “Parental Investment and Sexual Selection.” In Sexual Selection and the Descent of Man, 1871–1971, edited by Bernard Campbell, 136–179. As our closest living relatives, primates provide important insights into the evolution of human social behavior, language, and culture. Male gorillas who are able to monopolize a group of females (through direct competition with other males) do not need to compete with sperm, and so they do not need to produce it in large amounts. Polyspecific associations have been documented in many New World and Old World primate communities. As discussed in the previous section, when species feed on high-quality, scarce food (like fruit), larger groups mean there are more individuals competing for access to the resource. Although they cannot run as fast, when they hear an alarm call they run back toward the river, by-passing the short trees, just like the patas do (Enstam and Isbell 2002). Carnivores: Organisms whose diet consists primarily of animal tissue. She eventually manages it, seeing Erik is in the passenger seat with tape on his mouth and tape strapping him in. Raising one’s hair or fur in an effort to look bigger. It is that each chimpanzee community displays a unique cultural profile defined by a subset of the known traditions. Figure 6.4a and 6.4b A female vervet (left). In the, In some species, facial coloration provides information about individual health or status. Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff, Eds. 1999. “Males as Infant Protectors in Hanuman Langurs (Presbytis entellus) Living in Multimale Groups: Defence Pattern, Paternity, and Sexual Behaviour.” Behavioral Ecology and Sociobiology 46 (5): 350–356. Not surprisingly, when vervets are near the river, they climb the tall trees to seek refuge from such predators. Because they encounter food sites together, they avoid visiting a site that might have been depleted by one of the other species if they were foraging separately (Gautier-Hion et al. The attack, which consisted of loud alarm calls, along with multiple individuals biting and scratching the snake’s body and head, resulted in the snake releasing the female sifaka, who survived (Gardner et al. The result? iscuss these behaviors in a later section, entitled “Why do Primates Live in Groups?”, the next section). 2002. “Male Demography, Female Mating Behavior, and Infanticide in Wild Patas Monkeys (Erythrocebus patas).” International Journal of Primatology. Despite this, squirrel monkeys maintain the association because the capuchins can crack open palm nuts that squirrel monkeys cannot. Research on a variety of animals, including fish, rodents, birds, and monkeys indicate the transmission of a single behavior pattern through social learning, resulting in cultural variation. Lastly, males may compete indirectly by committing infanticide. Figure 6.15d Fosa fotovideo by Bertal is used under a CC BY-SA 3.0 License. Frugivores who do not eat leaves must travel farther distances in search of food because they can only feed in some trees (i.e., those producing fruit). Figure 6.29 Lemur catta 004 by Alex Dunkel (Visionholder) is used under a CC BY-SA 3.0 License. Arlington, VA: IUCN SSC Primate Specialist Group (PSG), International Primatological Society (IPS), Conservation International (CI), and Bristol Zoological Society. Reproductive suppression: The prevention or inhibition of reproduction of healthy adults. Figure 6.28a Uakari by Coada dragos is used under a CC BY-SA 4.0 License. Stanford, Craig B. In many species, females actively choose to mate with multiple males. I’ve observed vervets opportunistically killing lizards by smashing them against a rock or tree trunk and eating them (much as this lion-tailed macaque has done; Figure 6.14a). Charleston, Rhode Island: Pogonias Press. Biologists study primates as examples of evolutionary theories like natural selection or parental investment. Because not every tree contains fruit, it is less plentiful than leaves. Direct fitness: An individual’s genetic contribution to future generations that is due to offspring production. Enstam, Karin L., and Lynne A. Isbell. Her suggestions, along with comments made by two anonymous reviewers on an earlier version of this chapter, improved the final version considerably. Monkeys and apes also use a diversity of facial expressions in visual communication. We educate ourselves as well as our friends, families, and communities about the plight of endangered primates. For example, although sweet potato washing started in freshwater, it gradually shifted to seawater, apparently to add salt for flavor. Individuals may break up into smaller feeding groups (fission) and combine into larger groups (fusion). species. Harmful genetic effects of breeding between relatives. Dominance hierarchy: The ranked organization of individuals established by the outcome of aggressive-submissive interactions. They must also ensure that they consume more calories than they burn. By the end of the 1980s, the population had begun to recover and continues to increase. Describe the variety of social and mating systems observed in primates. They present their hindquarters (which signals interest in mating) significantly more to high-ranking and immigrant males; they refuse to mate with some males; and most mate with multiple males when they are receptive. However, polyspecific associations are different. In other cases, females reject advances by some males and not others. Primate Info Net (http://pin.primate.wisc.edu/) is an information service of the National Primate Research Center at the University of Wisconsin, Madison. Schwitzer, Christoph, Russell A. Mittermeier, Anthony B. Rylands, Federica Chiozza, Elizabeth A. Williamson, Elizabeth J. Macfie, Janette Wallis, and Alison Cotton. It is often used in reference to male-male competition, such as when two less-competitive males join forces against a more-competitive male. Davis studying vervet and patas monkey anti-predator behavior. The difference in these male strategies is illustrated by the gibbon, orangutan, chimpanzee, and tamarin. The point of mobbing is to drive off or distract the predator long enough for others to escape. Such examples clearly illustrate the benefits of group living. She earned her Ph.D. in Anthropology from U.C. A male who has some degree of paternity certainty, or confidence that he is the father, is more likely to invest in an offspring than a male who does not because any investment in the offspring may increase his own reproductive success. All living organisms that occur in an area that includes primates. As we discussed in the “Parental Investment” section, due to their rapid reproductive rate and propensity for twinning (Figure 6.21a–b), breeding females need help from all group members to raise their offspring, and they suppress reproduction in other females in their group, effectively making breeding females solitary. If detected, however, the slow loris will attempt to escape by releasing its grip and falling off the branch or biting in defense. In non-rainforest habitats, like Kenya’s open woodland, which is home to four species (Figure 6.11a–d), there are fewer niches for multiple species to occupy. 1998). Within 30 years, it had spread across generations, and 46 of 57 monkeys in the group engaged in the behavior. 2006. “Signal Content of Red Facial Coloration in Female Mandrills (Mandrillus sphinx).” Proceedings of the Royal Society B: Biological Sciences 273 (1599): 2395–2400. Organisms whose diets consist primarily of insects. Their physical adaptations for speed, like their long legs, combined with the lack of arboreal escape routes, makes fleeing on the ground their best option. But what do vervets do when they are away from the river and the safety of their tall trees? Although there are many examples of multiple males living in groups with multiple females (we’ll discuss some examples below), it is rare for multiple males to live with a single breeding female, a mating system referred to as polyandry (Figure 6.22d). 1980a. These exhibits are among the most popular because the babies are so cute and so much fun to watch. Crypsis: The ability to avoid detection by other organisms. This is only possible by consuming food that is easily digestible, like insects. It is important to recognize that primate reproductive strategies have evolved to maximize individual reproductive success. Because it is difficult to see others in the dark, and because nocturnal primates avoid predators by remaining quiet, species like the slow loris and the aye-aye rely heavily on scent-marking to communicate with conspecifics. Secondary sexual characteristics: Characteristics that appear at time of sexual maturity. Here are some helpful navigation tips and features. Unlike their Tanzanian counterparts, they form hunting parties to search for red colobus monkeys and, once located, anticipate the prey’s movement and coordinate with other hunters to drive, isolate, and capture prey (Boesch 2002). Captive female primates, including gorillas and chimpanzees, who have not had the opportunity to observe their mother or other females care for infants do not know how to care for their own offspring. Whether they supplement their high-fruit diet with insects or leaves also depends on their size. Bands, Businesses, Restaurants, Brands and Celebrities can create Pages in order to connect with their fans and customers on Facebook. It is certainly not a perfect rule, and males may sometimes invest in an offspring they did not father. When their trees deteriorated, vervets in Amboseli National Park, in Tanzania, began to shift home ranges. An important aspect of primate communities is the predators that also occupy them. When males and females of a species have similar morphological traits. A dedicated teacher-scholar, Dr. Jaffe has won several teaching, scholarship, and mentoring awards, including SSU’s Excellence in Teaching Award, Educational Experience Enhancement Award, and the President’s Excellence in Scholarship Award. Emigrating from the group into which one is born. Gorillas in the Mist. Bioarchaeology and Forensic Anthropology, 16. Gaining the gorillas’ trust was difficult as they were fearful of humans they had known only as poachers. In some cases, one species may be particularly good at detecting a specific type of predator and may alert the other species to its presence. Perhaps the most common explanation for dispersal of at least one sex from the perspective of reproductive success is to avoid inbreeding, or mating with close relatives. Figure 6.23a Jane Goodall HK by Jeekc is used under a CC BY-SA 3.0 License. These strategies are divided into those dealing with offspring production and care (parental investment) and those that maximize mating success (sexual selection). 2003). Santana, Sharlene E., Jessica Lynch Alfaro, and Michael E. Alfaro. But in Gambia, they use modified twigs to extract honey from holes in trees. 2003. “Social Structure of the Solitary Slow Loris Nycticebus coucang (Lorisidae).” Journal of Zoology 261 (1): 35–46. Perhaps the best way to avoid predation is to avoid being detected by predators in the first place, and some primates use crypsis to great effect. … Figure 6.23b US-223658 Dian Fossey (2925879356) by Mary-Lynn is used under a CC BY 2.0 License. Figure 6.22d Polyandry in species like tamarins and marmosets. White-faced capuchins hunt more often during the dry season, when other food is scarce, and sometimes work together to chase, surround, and capture small mammals like young squirrels or coatis (Fedigan 1990). We did not see the subadult male again and assume he died. Figure 6.23c Dr Birute Galdikas by Simon Fraser University – University Communications is used under a CC BY 2.0 License. What are the costs and benefits of group living? Infanticide occurs in many primate species, including red howler monkeys, chacma baboons, crab-eating macaques, diademed sifakas, ring-tailed lemurs, Hanuman langurs, and mountain gorillas. This is similar to the way a female dominance hierarchy determines a female’s priority of access to food. Sekulic, Ranka. Inbreeding depression: Harmful genetic effects of breeding between relatives. Intrasexual selection most often operates on males. Chapman, Colin A., and Carlos A. Peres. Both the explosion and the chase were diversions so Ronald could get away in his truck. Having a diet consisting primarily of fruit. Similarly, some insects, like termites in a termite mound (Figure 6.10), are found in clumps, similar to the way a single fruit tree is a “clump” of fruit surrounded by trees with no fruit. Second edition, New York: Oxford University Press. When food is scarce, the group “fissions” and females travel independently, with their dependent offspring, in their own range but still within the community territory. Female choice is often more subtle than male-male competition, so it can be more difficult to study. During my fieldwork in Kenya, I observed the first suspected case of infanticide in patas monkeys (Enstam et al. 2006. “Male Aggression toward Females in Hamadryas Baboons: Conditioning, Coercion, and Control.” In Sexual Coercion in Primates and Humans, edited by Martin N. Muller and Richard W. Wrangham, 244–268. While there are many threats to primates, habitat destruction and hunting are the leading causes of population decline (Figure 6.18a–b). Because some males monopolize multiple females, many male orangutans do not have access to females. Under such circumstances, females benefit from competing with one another for “priority of access” to the resource, and dominance hierarchies result. It is clear that this strategy helps the breeding female’s reproductive success. The sexual swelling reaches its maximum size at ovulation. Conspecifics: Members of the same species. As you learned in Chapter 5, insects are a high-quality food. So how is it that two species can have the same mating system and different social systems or, alternately, the same social system and different mating systems? In other cases, maturing individuals may choose to leave their group because they are attracted to individuals in another group. We will discuss sexual dimorphism in greater detail in the next section. Figure 6.25 Mandrill 08 by SuperJew is used under a CC BY-SA 4.0 License. Like foraging benefits discussed above, anti-predator benefits are variable. Five New World Primates: A Study in Comparative Ecology. Because female primates invest more in offspring production and care than males (see the “Parental Investment” section), they pay a significantly higher cost if the offspring dies before maturity or reaches maturity but does not reproduce. I wanted to know: How would the structure of these habitats affect the responses of vervets and patas monkeys to alarm calls that signal the approach of a terrestrial predator like a lion? 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