Evolutionary Anthropology 15:123 124 (2006) NEWS Integrative Primate Biology he annual meeting of the Society for Integrative and Comparative Biology (SICB) was held in Orlando, Florida, on January 4 8, 2006. Although the conference hotel was located in the Walt Disney World Resort, not all of the presentations focused on mouse models named Mickey. Biologists from around the world presented their research on a range of topics that included the digging biomechanics of shovel-nosed lobsters, environmental effects on turtle bone density, conservation of Brazilian bats, and the grooming behavior of mantis shrimp. Within this varied spectrum of research, we report on several topics of interest to physical anthropologists studying primate functional morphology and behavior. T LONG LIMBS AND SHORT THUMBS The evolution of long limbs was a popular topic at the 2006 SICB meetings. One presentation of particular interest to students of human evolution was by David Carrier (Utah). Carrier s research focused on the selective pressures in uencing limb length in australopithecines. Australopithecines had shorter hindlimbs than did later hominins, a trait often cited as an adaptation to arboreal locomotion. Nevertheless, reduced hindlimb length may also have been advantageous during bouts of physical aggression: By lowering the center of mass and decreasing the ground reaction force moment arm, short limbs also increase stability and permit greater acceleration. To test the hypothesis that short hindlimbs in australopithecines were selected for increased ghting ability, Carrier examined the relationship between hindlimb length (normalized to body mass) and sexual size dimorphism, his proxy for aggressive behavior, in Hominoidea. Results showed that relative hindlimb length was strongly negatively corre 2006 Wiley-Liss, Inc. lated with measures of sexual size dimorphism even when controlling for body size. Carrier s results indicate that pressures to improve ghting ability may have selected for reduced limb length in australopithecines and other hominoids, suggesting that the link between aggression and body proportions in primates deserves further examination. The study of limb lengths is not restricted to bipedal hominins. Most nonhuman primates have relatively long limb bones. This is especially true of the hands and feet of arboreal monkeys. However, colobine monkeys typically have shorter thumbs than do cercopithecine monkeys. Michael Selby (Kent State) and co-workers examined pollical reduction in colobines using mouse models. They found that mutant mice lacking expression of the Hoxa13 gene have a reduced pollex, as do colobines. Thus, down-regulation of this Hox gene in colobines may allow elongation of the other digits while keeping the pollex relatively short. Although a possible mechanism for colobine thumb reduction seems to have been found, what remains to be understood is the adaptive bene t of thumb reduction in this group of primates. We look forward to future studies that will offer a behavioral and ecological context for the evolution of thumb reduction. be related to locomotor preferences, as Delacour s langurs engage in more leaping and bounding than do their congeners. Further work deserves to be done on the locomotor behavior of this understudied group of primates. While Stevens and colleagues studied locomotion in more naturalistic environments, Kristian Carlson (Zurich) presented the results of experimental work conducted at Stony Brook University on arboreal locomotion in Eulemur rubriventer. Using a different approach than have previous studies of simulated arboreal locomotion, Carlson examined the kinematics and kinetics of nonlinear locomotion. He found that as animal subjects walked with more abducted limb postures, as if bridging between arboreal supports, substrate reaction forces appeared more like those experienced during terrestrial locomotion. For example, the mediolateral component of the substrate reaction forces went from a laterally directed force in linear locomotion to a more medially directed force when the instrumented arboreal support was offset from a linear position. Thus, forces experienced by nonhuman primates during quadrupedal locomotion may be more complex than is usually described, making future studies of primate locomotion even more important. LEMUR BIOLOGY Unlike anthropoid primates, many strepsirhine taxa are characterized by social systems in which females are philopatric and dominant to males. Among spotted hyenas (Crocuta crocuta), another mammalian group characterized by a similar social system, female social dominance is associated with somatic masculinization in females, a process induced by exposure to large amounts of maternal androgens in utero. Christine Drea (Duke) presented research testing whether somatic masculinization and increased prenatal androgen exposure might also correlate with female dominance in ring-tailed lemurs (Lemur catta). Ring-tailed lemur females are size monomorphic with ARBOREAL LOCOMOTION Nancy Stevens (Ohio University) and colleagues presented pilot data on the vertebral kinematics of Delacour s langurs (Trachypithecus delacouri) and Hatinh langurs (T. laotum hatinhensis), two similarly sized Asian colobines housed at the Endangered Primate Research Center in Vietnam. The animals were lmed walking across horizontal supports placed in semi-naturalistic enclosures. Results showed signi cant differences in back movements during locomotion. While Hatinh langurs walked with a relatively at back, Delacour s langurs maintained substantial vertebral exion throughout each stride. Differences in back posture may DOI 10.1002/evan.20106 Published online in Wiley InterScience (www.interscience.wiley.com). 124 NEWS males and display pendulous clitorises, suggesting that masculinization may be present. Drea found that female testosterone and androstenedione levels rose during the breeding season and early in pregnancy, during the time when genitalia are differentiating. Nevertheless, androgen levels were consistently higher when litters contained at least one male infant than when litters consisted solely of females. These data are consistent with partial masculinization in female ring-tailed lemurs, suggesting an interesting hormonal and morphological link to the strepsirhines unique social system. Elizabeth Scordato and Christine Drea (Duke) presented interesting research on sex-speci c variation in Lemur catta olfactory communication. They examined scent-marking behaviors of adult males and females, including the speci c glands used, the chemical composition of gland secretions, the timing of secretions (for example, breeding versus nonbreeding), and the behavioral response to these secretions. Males were found to respond more strongly than did females. Furthermore, males responded with different behaviors depending on which gland secretion was examined. Females tended to respond more to other females. The data tend to support functional differences between scent glands, suggesting that scent marking by males serves in intrasexual competition, whereas female scent marking is a form of reproductive competition. FEEDING BIOLOGY Over the last 30 years, a great deal of progress has been made on the mechanics of chewing in primates. Chris Vinyard (NEOUCOM) and collaborators presented work to help answer the question of whether jaw-muscle activity patterns are correlated with masticatory apparatus morphology among primate species, as well to determine whether neuromuscular systems in the masticatory system are conserved in evolution. They reported that differences in balancing-side and workingside jaw-muscle adductor activity patterns (for example, recruitment and ring patterns) differ between anthropoid and strepsirrhine primates and that these different patterns correlate with differences in jaw and tooth mor- phologies between the two groups. Thus, primate jaw-muscle activity patterns appear to be an integrated and evolving component of the masticatory apparatus. These results may help resolve the mechanical reasons why anthropoids, as compared to strepsirhine primates, have deep jaws with greater symphyseal strength. While Vinyard and colleagues focused on primates, a presentation on alpacas (Lama pacos) by Susan Williams (Ohio University) and her colleagues tested the hypothesis that mandibular symphysis fusion is related to jaw-muscle activity and symphyseal bone strain patterns. While activity in the working-side deep masseter muscle, which has a large transverse component to its force and acts partially independently of the other jaw muscles, supports the link between symphyseal fusion and transverse masticatory forces, the activity in this muscle appeared to be small. The laterally directed force from the delayed activity of the balancing-side deep masseter muscle results in twisting of the symphysis about a transverse axis. Thus, the relationship between form of the mandible and function of the chewing muscles is just as complicated in alpacas as it is in primates. Future work by these two groups of researchers will de nitely prove useful in providing better understanding of mandibular form and, in turn, better understanding of the evolution of the primate masticatory complex. Barth Wright (George Washington) and his colleagues, who reported on new research on leaf material properties and food processing behaviors in captive Vietnamese leaf monkeys. This naturalistic research will provide further insight into the complex nature of primate feeding and how it relates to different craniodental anatomies in primates. ries of analyses usi...