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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2009.01.020 Byline: E.V. Lonsdorf (a)(b), S.R. Ross (a), S.A. Linick (a), M.S. Milstein (a), T.N. Melber (a) Abstract: Studies of ape tool use have been conducted in captivity since the early 1900s and in the wild since the 1960s. Chimpanzees are the most prolific tool users among the apes, and are known to use more tools than any other nonhuman animal. In contrast, reports of gorilla tool use are rare both in wild and captive settings. Studies of the processes involved in tool use learning have been limited in the wild by the lack of ability to control several unpredictable variables, and in captivity by tool use opportunities that are often presented in non-naturalistic contexts. We attempted to address both of these limitations by providing naA[macron]ve subjects with a naturalistic tool use device (built to simulate a termite mound) while housed in a more natural social setting to approximate how learning would occur in the wild. Both gorillas and chimpanzees participated in the experiment to allow comparative analyses of acquisition of tool behaviour and the factors that may affect acquisition. Both species showed low frequencies of interaction with the mound in the baseline condition, before baiting with a food reward. Once baited, chimpanzees both attempted and succeeded to extract the reward more quickly than did gorillas. The number of social group members at the mound was significantly higher for chimpanzees than for gorillas and may have affected skill acquisition. We advocate that comparative approaches to skill acquisition and learning are valuable, but that researchers need to be cognizant of species differences in social structure that may affect results. Author Affiliation: (a) The Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, U.S.A. (b) Committee on Evolutionary Biology, University of Chicago, U.S.A. Article History: Received 14 July 2008; Revised 10 October 2008; Accepted 26 January 2009 Article Note: (miscellaneous) MS. number: A08-00446R

The order in which ectocranial sutures undergo fusion displays species-specific variation among primates. However, the precise relationship between suture closure and phylogenetic affinities is poorly understood. In this study, we used Guttman Scaling to determine if the modal progression of suture closure differs among Homo sapiens, Pan troglodytes, and Gorilla gorilla. Because DNA sequence homologies strongly suggest that P. troglodytes and Homo sapiens share a more recent common ancestor than either does with G. gorilla, we hypothesized that this phylogenetic relationship would be reflected in the suture closure patterns of these three taxa. Results indicated that while all three species do share a similar lateral-anterior closure pattern, G. gorilla exhibits a unique vault pattern, which, unlike humans and P. troglodytes, follows a strong posterior-to-anterior gradient. P. troglodytes is therefore more like Homo sapiens in suture synostosis. KEY WORDS cranial suture; synostosis; variation; phylogeny; Guttman analysis

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2008.01.008 Byline: Yasmin Mobius, Christophe Boesch, Kathelijne Koops, Tetsuro Matsuzawa, Tatyana Humle Abstract: Behavioural diversity in the predation pattern of army ants (Dorylus spp.) by different populations of wild chimpanzees, Pan troglodytes, has been proposed to reflect different cultural traditions. Chimpanzees use either stick tools (known as ant dipping) or simply their hands to prey on two groups of army ants (epigaeic and intermediate species). A recent analysis has shown that, contrary to the cultural hypothesis, the tool length and associated harvesting technique used by chimpanzees in different populations is to a large extent influenced by characteristics of the ants themselves. However, in line with the cultural hypothesis, chimpanzees at two long-term study sites in West Africa (Bossou, Guinea, and TaA[macron] National Park, CA[acute accent]te d'Ivoire) prey on the same five army ant species but adopt different strategies to do so. We conducted controlled human simulations of ant dipping and an ant survey at these two sites to evaluate alternative ecological explanations related to ant behaviour and ecology that could account for the observed differences in chimpanzee predation behaviour. Ant speed explained differences in tool length within Bossou but not between Bossou and TaA[macron]. Our results do not support an ecological basis underlying the lack of dipping at ant trails in TaA[macron] chimpanzees. Finally, neither ant aggressiveness (measured as speed and persistence) nor yield when using tools could explain why, unlike Bossou chimpanzees, TaA[macron] chimpanzees do not use tools to harvest epigaeic species. We conclude that an interaction of cultural and ecological factors shapes the differences in army ant predation between TaA[macron] and Bossou chimpanzees. Author Affiliation: (a) Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Germany (a ) Leverhulme Centre for Human Evolutionary Studies, Department of Biological Anthropology, University of Cambridge, U.K. (a ) Primate Research Institute, Kyoto University, Japan Article History: Received 21 September 2007; Revised 12 November 2007; Accepted 18 January 2008 Article Note: (miscellaneous) MS. number: 9519

The authors argue that differentiation of hominids from great apes cannot be based strictly on a 'Pan troglodytes' model. An examination of four features of chimpanzee society reveals that other nonhumans also engage in analogous behaviors, which is relevant for reconstructions of hominid behavioral evolution.

We develop the theory for computing the joint frequency spectra of alleles in two closely related species. We allow for arbitrary population growth in both species after they had a common ancestor. We focus on the case in which a single chromosome is sequenced from one of the species. We use classical diffusion theory to show that, if the ancestral species was at equilibrium under mutation and drift and a chromosome from one of the descendant species carries the derived allele, the frequency spectrum in the other species is uniform, independently of the demographic history of both species. We also predict the expected densities of segregating and fixed sites when the chromosome from the other species carries the ancestral allele. We compare the predictions of our model with the site-frequency spectra of SNPs in the tour HapMap populations of humans when the nucleotide present in the Neanderthal DNA sequence is ancestral or derived, using the chimp genome as the outgroup.

Most phenotypic differences between human and chimpanzee are likely to result from differences in gene regulation, rather than changes to protein-coding regions. To date, however, only a handful of human-chimpanzee nucleotide differences leading to changes in gene regulation have been identified. To hone in on differences in regulatory elements between human and chimpanzee, we focused on 10 genes that were previously found to be differentially expressed between the two species. We then designed reporter gene assays for the putative human and chimpanzee promoters of the 10 genes. Of seven promoters that we found to be active in human liver cell lines, human and chimpanzee promoters had significantly different activity in four cases, three of which recapitulated the gene expression difference seen in the microarray experiment. For these three genes, we were therefore able to demonstrate that a change in cis influences expression differences between humans and chimpanzees. Moreover, using site-directed mutagenesis on one construct, the promoter for the DDA3 gene, we were able to identify three nucleotides that together lead to a cis regulatory difference between the species. High-throughput application of this approach can provide a map of regulatory element differences between humans and our close evolutionary relatives.

Byline: Sarah-Jane Vick (1), Bridget M. Waller (2), Lisa A. Parr (3), Marcia C. Smith Pasqualini (4), Kim A. Bard (2) Keywords: Comparative anatomy; Chimpanzees; Facial action coding system (FACS); Facial morphology Abstract: A comparative perspective has remained central to the study of human facial expressions since Darwin's [(1872/1998). The expression of the emotions in man and animals (3rd ed.). New York: Oxford University Press] insightful observations on the presence and significance of cross-species continuities and species-unique phenomena. However, cross-species comparisons are often difficult to draw due to methodological limitations. We report the application of a common methodology, the Facial Action Coding System (FACS) to examine facial movement across two species of hominoids, namely humans and chimpanzees. FACS [Ekman & Friesen (1978). Facial action coding system. CA: Consulting Psychology Press] has been employed to identify the repertoire of human facial movements. We demonstrate that FACS can be applied to other species, but highlight that any modifications must be based on both underlying anatomy and detailed observational analysis of movements. Here we describe the ChimpFACS and use it to compare the repertoire of facial movement in chimpanzees and humans. While the underlying mimetic musculature shows minimal differences, important differences in facial morphology impact upon the identification and detection of related surface appearance changes across these two species. Author Affiliation: (1) Scottish Primate Research Group, Department of Psychology, University of Stirling, Stirling, FK9 4LA, UK (2) Centre for the Study of Emotion, Department of Psychology, University of Portsmouth, King Henry I St., Portsmouth, UK (3) Divison of Psychiatry and Behavioral Sciences, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA (4) Department of Psychology, Avila University, Kansas City, MO, USA Article History: Registration Date: 06/10/2006 Online Date: 15/12/2006

A comparative perspective has remained central to the study of human facial expressions since Darwin's [(1872/1998). The expression of the emotions in man and animals (3rd ed.). New York: Oxford University Press] insightful observations on the presence and significance of cross-species continuities and species-unique phenomena. However, cross-species comparisons are often difficult to draw due to methodological limitations. We report the application of a common methodology, the Facial Action Coding System (FACS) to examine facial movement across two species of hominoids, namely humans and chimpanzees. FACS [Ekman & Friesen (1978). Facial action coding system. CA: Consulting Psychology Press] has been employed to identify the repertoire of human facial movements. We demonstrate that FACS can be applied to other species, but highlight that any modifications must be based on both underlying anatomy and detailed observational analysis of movements. Here we describe the ChimpFACS and use it to compare the repertoire of facial movement in chimpanzees and humans. While the underlying mimetic musculature shows minimal differences, important differences in facial morphology impact upon the identification and detection of related surface appearance changes across these two species. Keywords Comparative anatomy * Chimpanzees * Facial action coding system (FACS) * Facial morphology

A comparison of segmental duplications in humans and chimpanzees is presented as they might help in understanding the origins of phenotypic difference between humans and their closest relatives. Comparisons revealed that a total of approximately 80 Mb of segmentally duplicated DNA in humans and 65 Mb in chimpanzees.

This study investigates the evolution of human growth by analyzing differences in body mass growth trajectories among three populations: the Ache of eastern Paraguay, the US (NHANES, 1999-2000), and captive chimpanzees. The relative growth statistic 'A' from the mammalian growth law is allowed to vary with age and proves useful for comparing growth across different ages, populations, and species. We demonstrate ontogenetic separation between chimpanzees and humans, and show that interspecific differences are robust to variable environmental conditions. The human pattern of slow growth during the lengthened period from weaning to the beginning of the adolescent growth spurt is found among the Ache (low energy availability and high disease load) and also in the US (high energy availability and low disease load). The human growth pattern contrasts with that of the chimpanzee, where absolute growth rates and relative 'A' values are faster and less prolonged. We suggest that selection has acted to decrease human growth rates to allow more time for increased cognitive development with lower body-maintenance costs. KEY WORDS growth rates; Ache foragers; chimpanzees; human life history

The article seeks to clarify the extent of chimpanzee's ecological diversity by scrutinizing sympatric mammalian fauna.

The importance of daytime, as a confounding variable of primate endocrine function is emphasized. The diurnal pattern of steroid excretion in Chimpanzees and human is compared and studied.

Researchers have compared the braincase of a new hominid find, Homo floresiensis to modern humans as well as to chimps and others hominids to determine if it is indeed a new species of diminutive hominid that lived 18,000 years ago. Researchers found that the combination of traits is responsible for elucidating a specimen's identity than a single trait such as brain size.

It has been a generally held belief that there is just a one percent genetic difference between humans and chimpanzees, but a report released in early 2004 refutes this claim, saying that there may not be many similarities. Researchers in Japan, who came up with these findings, say that comparative analysis between human beings and chimpanzees is no easy task and that there is still some way to go before one can conclusively conclude anything about this.

The target article by Corballis presents an interesting and novel theoretical perspective on the evolution of language, speech, and handedness. There are two specific aspects of the article that will be addressed in this commentary: (a) the link between Broca's area and gestural communication in chimpanzees, and (b) the issue of population-level handedness in great apes, notably chimpanzees.

The consensus view of fossil and molecular data places the human-chimpanzee divergence at ~6 Ma and the hominoid-cercopithecoid divergence at ~25 Ma. Some recent molecular publications run counter to this consensus, suggesting that these divergences occurred substantially earlier. If true, these earlier dates would suggest a major reappraisal of the fossil evidence and require a recontextualization of these events in substantially different paleoenvironments. Date estimation from molecular data poses significant methodological challenges that have not yet been fully evaluated. Furthermore, there is no widely accepted methodology accounting for these challenges. Unfortunately, some recent publications relevant to primate divergence times have methodological shortcomings. We performed extensive analyses of simulated and real sequence alignments to determine factors having the greatest impact on primate divergence date estimates. Our results show that the best results derive from (1) choosing a local calibration point--early primate divergence times incompatible with fossil findings often result from calibration outside the primates, (2) correction for rate variation across lineages--there is considerable variation across primate lineages and between primates and other mammals, and (3) accounting for rate variation across nucleotide sites--variation across sites within a single locus and between loci produces substantial error if loci are concatenated. We have developed methods for the estimation of divergence dates from molecular data. We have evaluated the precision and accuracy of these methods. Reanalysis of recently published data following this methodology results in date estimates more compatible with current interpretations of the fossil record. Supported by NIH_R01_GM60760