Ectocranial suture closure in Pan troglodytes and Gorilla gorilla: pattern and phylogeny

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.     

Comparative analysis of the fragments of highly repeated DNA of Homo, Pan, Macaca and Cercopithecus

In the present paper the restriction patterns of Homo, Pan troglodytes, Macaca fascicularis and Cercopithecus aethiops, obtained by digestion with Eco RI endonuclease, were compared. All these species showed two common bands at 0.3 and 0.6 Kb. In this region another band at 0.5 Kb was present in Macaca fascicularis and Cercopithecus aethiops. Furthermore Macaca fascicularis, Cercopithecus aethiops and Pan troglodytes showed a series of bands not present in humans. The distance matrix shows a strong similarity between Homo and Pan and a decreasing similarity with Macaca fascicularis and Cercopithecus aethiops. No intraspecific variability was observed.     

Electromyography of pronators and supinators in great apes.

We obtained electromyographic recordings from the supinator, biceps brachii, pronator quadratus, and pronator teres muscles of a chimpanzee and a gorilla and from the supinator, pronator quadratus, and biceps brachii muscles of an orangutan as they stood and walked quadrupedally on horizontal and inclined surfaces, engaged in suspensory behavior, reached overhead, and manipulated a variety of foods and artifacts. In Pan troglodytes and Pan gorilla, as in Homo sapiens, the supinator muscle is the prime supinator, with the biceps brachii muscle serving to augment speed or force of supination. Primary of the pronator quadratus muscle over the pronator teres muscle during pronation is less clear in the African apes than in humans. Possibly, pongid radial curvature or forelimb elongation or both factors are related to the somewhat different patterns of activity that we observed in the pronator muscles of Pan versus those reported for Homo sapiens. In Pongo pygmaeus, as in P. troglodytes and P. gorilla, the pronator quadratus muscle acts as a pronator and the supinator muscle acts to supinate the hand at the radioulnar joints. The biceps brachii muscle is active at low levels as the orangutan supinates its hand with the elbow flexed.     

Comparison of cranial ontogenetic trajectories among great apes and humans

Molecular data suggest that humans are more closely related to chimpanzees than either is to the gorillas, yet one finds the closest similarity in craniofacial morphology to be among the great apes to the exclusion of humans. To clarify how and when these differences arise in ontogeny, we studied ontogenetic trajectories for Homo sapiens, Pan paniscus, Pan troglodytes, Gorilla gorilla and Pongo pygmaeus. A total of 96 traditional three-dimensional landmarks and semilandmarks on the face and cranial base were collected on 268 adult and sub-adult crania for a geometric morphometric analysis. The ontogenetic trajectories are compared by various techniques, including a new method, relative warps in size-shape space. We find that adult Homo sapiens specimens are clearly separated from the great apes in shape space and size-shape space. Around birth, Homo sapiens infants are already markedly different from the great apes, which overlap at this age but diverge among themselves postnatally. The results suggest that the small genetic differences between Homo and Pan affect early human ontogeny to induce the distinct adult human craniofacial morphology. Pure heterochrony does not sufficiently explain the human craniofacial morphology nor the differences among the African apes.     

Functional capabilities of modern and fossil hominid hands: three-dimensional analysis of trapezia

Three-dimensional (3D) trapezium models from Homo sapiens, Gorilla gorilla, Pan troglodytes, Australopithecus afarensis (A.L.333-80), and Homo habilis (O.H.7-NNQ) were acquired through laser digitizing. Least-square planes were generated for each articular surface, and the angles between the planes were compared. Each extant species displays an overall pattern that distinguishes it from the others. The observed angles in G. gorilla and P. troglodytes are more similar to one other than either is to H. sapiens. Our results, obtained from using new 3D modeling and analytical tools, raise interesting questions about the functional capabilities of the fossil trapezia. Multivariate statistical analyses indicate that A.L.333-80 is morphologically more similar to that of modern humans, whereas the O.H.7 trapezium is more similar to that of the gorilla. Significant differences between A.L.333-80 and the extant species occur, but some similarities to humans suggest the ability to form the distinctively human forceful pad-to-side and three-jaw chuck grips. Some key morphological differences from humans highlighted and quantified by our research suggest limitations in the functional capabilities of the O.H.7 trapezium, particularly in those that facilitate pronation at the base of the second metacarpal. If the O.H.7 trapezium represents part of the hand responsible for manufacturing and using the stone tools found at Olduvai, our results suggest that the hand manipulated the stones in a way for which we have no modern analog. Alternative considerations are that the O.H.7 trapezium is not representative of other trapezia from its species (i.e., N=1), or that it represents another primate or hominid species.     

Qualitative analysis of constitutive heterochromatin and primate evolution

The results of qualitative heterochromatin analysis in 16 species of primates: Homo sapiens , Pan troglodytes and Gorilla gorilla (F. Hominidae), Hylobates syndactilus (F. Hylobatidae), Macaca fascicularis , M. tibetana , Mandrillus sphinx , M. leucophaeus , Cercopithecus aethiops , C. sabaeus and C. albogularis (F. Cercopithecidae), Cebus apella , Ateles belzebuth hybridus , Aotus azarae , Saimiri sciureus and Lagothrix lagothricha (F. Cebidae) are presented in this work. We characterized heterochromatin using: (a) in situ digestion with restriction enzymes AluI, HaeIII, RsaI and Sau3A, and (b) chromosome staining with DA/DAPI on unbanded chromosomes, on C-banded chromosomes and on sequentially G-C-banded chromosomes. The aim of this work was to relate the qualitative characteristics of constitutive heterochromatin observed with the cytogenetic evolutive processes in the primate group. Results obtained show that (1) in the family Cercopithecidae, Papionini species do not present chromosomal rearrangements when their karyotypes are compared and the heterochromatin characteristics are uniform, while Cercopithecini species show a high number of chromosomal reorganizations, but they have the same heterochromatic characteristics; (2) the Platyrrhini species analysed show variability in their karyological and heterochromatic characteristics; (3) the Hominoidea present two different situations: Pan , Gorilla and Homo with few chromosomal reorganizations among their karyotypes but with a high variability in their heterochromatin characteristics, and Hylobates with low heterochromatin variability and a highly derived karyotype. Speciation processes related to chromosome changes and heterochromatin variations in different groups of primates are discussed.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 107–124.     

A complete sequence of the mitochondrial genome of the western lowland gorilla

The complete mitochondrial DNA (mtDNA) molecule of the gorilla was sequenced. The entire sequence, 16,412 nucleotides, was determined by analysis of natural (not polymerase chain reaction) restriction fragments covering the whole molecule. The sequence was established from one individual and thus nonchimeric. After comparison with the COII gene of gorilla specimens with known geographical origin, the sequence was identified as characteristic of the Western lowland gorilla, Gorilla gorilla gorilla. With the exception of the NADH2 gene, all genes have a methionine start codon. The inferred start codon of NADH2 is ATT (isoleucine). The COIII, NASDH4, and cytochrome b genes are not terminated by a stop codon triplet, and the COI gene is probably terminated by an AAA triplet rather than by a regular stop codon. The great majority of genic sequences (rRNAs, peptide-coding genes, tRNAs) of the complete mtDNAs of Gorilla, Pan, and Homo show a greater similarity between Pan and Homo than between either of these genera to Gorilla. The analysis of the peptide-coding genes suggest that relative to comparison between Homo and Pan a certain degree of transition saturation has taken place in codon position 3 in comparisons between Gorilla to either Homo or Pan.      

Phylogeny, neoteny and growth of the cranial base in hominoids

This study tests the hypothesis that there is a general pattern in the growth of the cranial base of Homo sapiens that is 'essentially neotenous' [Gould, 1977]. Juvenile and adult crania of Homo sapiens, Gorilla gorilla, Pan troglodytes and Pongo pygmaeus were studied and the cross-sectional growth curves for 10 measurements made on the cranial base (as viewed in norma basilaris) were compared. The results of this study suggest that relatively simple modifications to the timing or pattern of growth are insufficient to explain the observed morphological differences between the cranial base of modern Homo sapiens and the great apes.     

Patterns of mandibular variation in Pan and Gorilla and implications for African ape taxonomy

Pan and Gorilla taxonomy is currently in a state of flux, with the number of existing species and subspecies of common chimpanzee and gorilla having been recently challenged. While Pan and Gorilla systematics have been evaluated on the basis of craniometric and odontometric data, only a handful of studies have evaluated multivariate craniometric variation within P. troglodytes, and none have evaluated in detail mandibular variation in either P. troglodytes or Gorilla gorilla. In this paper, we examine ontogenetic and adult mandibular variation in Pan and Gorilla. We test the hypothesis that patterns and degrees of mandibular variation in Pan and Gorilla closely correspond to those derived from previous analyses of craniometric variation. We then use these data to address some current issues surrounding Pan and Gorilla taxonomy. Specifically, we evaluate the purported distinctiveness of P.t. verus from the other two subspecies of Pan troglodytes, and the recent proposals to recognize Nigerian gorillas as a distinct subspecies, Gorilla gorilla diehli, and to acknowledge mountain and lowland gorillas as two separate species. Overall, patterns and degrees of multivariate mandibular differentiation parallel those obtained previously for the cranium and dentition. Thus, differences among the three conventionally recognized gorilla subspecies are somewhat greater than among subspecies of common chimpanzees, but differences between P. paniscus and P. troglodytes are greater than those observed between any gorilla subspecies. In this regard, the mandible does not appear to be more variable, or of less taxonomic value, than the face and other parts of the cranium. There are, however, some finer differences in the pattern and degree of morphological differentiation in Pan and Gorilla, both with respect to cranial and dental morphology, and in terms of the application and manner of size adjustment. Mandibular differentiation supports the conventional separation of bonobos from chimpanzees regardless of size adjustment, but size correction alters the relative alignment of taxa. Following size correction, intergroup distances are greatest between P.t. verus and all other groups, but there is considerable overlap amongst chimpanzee subspecies. Amongst gorillas, the greatest separation is between eastern and western gorillas, but adjustment relative to palatal vs. basicranial length results in a greater accuracy of group classification for G.g. gorilla and G.g. graueri, and more equivalent intergroup distances amongst all gorilla groups. We find no multivariate differentiation of the Nigerian gorillas based on mandibular morphology, suggesting that the primary difference between Nigerian and other western lowland gorillas lies in the nuchal region. Though intergroup distances are greatest between P.t. verus and other chimpanzee subspecies, the degree of overlap amongst all three groups does not indicate a markedly greater degree of distinction in mandibular, as opposed to other morphologies. Finally, mandibular differentiation corroborates previous craniodental studies indicating the greatest distinction amongst gorillas is between eastern and western groups. Thus, patterns and degrees of mandibular variation are in agreement with other kinds of data that have been used to diagnose eastern and western gorillas as separate species.     

Chimpanzee fetal G gamma and A gamma globin gene nucleotide sequences provide further evidence of gene conversions in hominine evolution

The fetal globin genes G gamma and A gamma from one chromosome of a chimpanzee (Pan troglodytes) were sequenced and found to be closely similar to the corresponding genes of man and the gorilla. These genes contain identical promoter and termination signals and have exons 1 and 2 separated by the conserved short intron 1 (122 bp) and exons 2 and 3 separated by the more rapidly evolving, larger intron 2 (893 bp and 887 bp in chimpanzee G gamma and A gamma, respectively). Each intron 2 has a stretch of simple sequence DNA (TG)n serving possibly as a "hot spot" for recombination. The two chimpanzee genes encode polypeptide chains that differ only at position 136 (glycine in G gamma and alanine in A gamma) and that are identical to the corresponding human chains, which have aspartic acid at position 73 and lysine at 104 in contrast to glycine and arginine at these respective positions of the gorilla A gamma chain. Phylogenetic analysis by the parsimony method revealed four silent (synonymous) base substitutions in evolutionary descent of the chimpanzee G gamma and A gamma codons and none in the human and gorilla codons. These Homininae (Pan, Homo, Gorilla) coding sequences evolved at one-tenth the average mammalian rate for nonsynonymous and one-fourth that for synonymous substitutions. Three sequence regions that were affected by gene conversions between chimpanzee G gamma and A gamma loci were identified: one extended 3' of the hot spot with G gamma replaced by the A gamma sequence, another extended 5' of the hot spot with A gamma replaced by G gamma, and the third conversion extended from the 5' flanking to the 5' end of intron 2, with G gamma replaced here by the A gamma sequence. A conversion similar to this third one has occurred independently in the descent of the gorilla genes. The four previously identified conversions, labeled C1-C4 (Scott et al. 1984), were substantiated with the addition of the chimpanzee genes to our analysis (C1 being shared by all three hominines and C2, C3, and C4 being found only in humans). Thus, the fetal genes from all three of these hominine species have been active in gene conversions during the descent of each species.      

Issues in Bonobo (Pan paniscus) Sexual Behavior

Sexual behavior is one of the reported similarities between Pan paniscus and Homo sapiens that has stimulated recent interest in the phylogeny of the Pan and the Australopithecus/Homo genera. Similarities do exist, but an understanding of the forms and functions of Van paniscus sexual behavior is best achieved through a comparison to Pan troglodytes. Pan paniscus shows increased female receptivity, variability in copulatory position, male or female initiation of sexual behavior, differential male and female preferences for copulatory position, and association of food sharing and sexual behavior. Their sexual behavior appears to function in proximate terms as a tension-reduction mechanism. Lowered tension, in turn, facilitates multi-male, multi-female social groups. Lowered levels of aggression and increased sexual activity appear to be associated with paedomorphism, and the behavioral and anatomical/physiological characteristics of the species appear to be a consequence of a feeding ecology that promotes large groupings of the animals at preferential and comparatively rich feeding sites.     

Early hominin speciation at the Plio/Pleistocene transition

Over the last half-decade or so, there has been an explosion in the recognition of hominin genera and species. We now have the late Miocene genera Orrorin and Sahelanthropus, the mid Pliocene genus Kenyanthropus, three new Pliocene species of Australopithecus (A. anamensis, A. garhi and A. bahrelghazali) and a sub species of Ardipithecus (Ar. r. kadabba) to contend with. Excepting also the more traditional species allocated to Paranthropus, Australopithecus and early Homo we are approaching around 15 species over 5 million years (excluding hominin evolution over the last one million years). Can such a large number of hominin species be justified? An examination of extant hominid (Gorilla gorilla, Pan troglodytes, and Pan paniscus) anatomical variability indicates that the range of fossil hominin variability supports the recognition of this large number of fossil species. It is also shown that not all hominins are directly related to the emergence of early Homo and as such have become extinct. Indeed the traditional australopithecine species 'A'. anamensis, 'A'. afarensis and 'A'. garhi are considered here to belong to a distinct genus Praeanthropus. They are also argued not be hominins, but rather an as yet undefined hominid group from which the more derived hominins evolved. The first hominin is represented by A. africanus or a hominin very much like it. The Paranthropus clade is defined by a derived heterochronic condition of peramorphosis, associated with sequential progenesis (contraction of successive growth stages) in brain and dental development, but a mixture of peramorphic and paedomorphic features in its craniofacial anatomy. Conversely, Kenyanthropus and Homo both share a pattern of peramorphosis, associated with sequential hypermorphosis (prolongation of successive growth stages) in brain development, and paedomorphosis processes in cranial, facial and dental development. This suggests, that these two clades share an important synapomorphy not recognised in the parsimony analyses, suggesting that they may form a sister group relationship to the exclusion of Paranthropus. This highlights the need to re-interpret phylogenetic results in terms of function and development. The rapid speciation and extinction as argued here is in keeping with other fossil groups in Africa at the Plio/Pleistocene transition. This emphasises that we must approach the pre-australopithecines and hominins as part of the endemic African fauna, and not in isolation to the evolutionary and climatic processes that were operating all around them.     

Fluorescent (F) bodies in the spermatozoa of man and the great apes

Mature spermatozoa of the chimpanzee (Pan troglodytes), the gorilla (Gorilla gorilla), and the orangutan (Pongo pygmaeus) were stained with quinacrine dihydrochloride. Fluorescent (F) bodies were visualized in the spermatozoa of the chimpanzee and gorilla but were absent in the orangutan, in which there is no brilliant fluorescence in any chromosome. The F bodies appeared to be randomly located in the sperm heads of these two species, as they usually are in human spermatozoa. However, the proportion of sperm showing one or more F bodies in the chimpanzee and gorilla was not comparable to what is usually found in man. The F bodies in the chimpanzee presumably represent brilliant regions in the autosomes, since the Y chromosome has no brilliant fluorescence in this species. This is contrary to man, in which the F body is an useful indicator of the Y chromosome. In the gorilla, the F bodies probably correspond to both the Y chromosome and to some brilliant regions in the autosomes.     

Status of large mammals in the mountain sector of Kahuzi-Biega National Park, Democratic Republic of Congo, in 1996

Kahuzi-Biega National Park, located in eastern Democratic Republic of Congo, harbours an abundance of endemic species and maintains important populations of Grauer's gorilla ( Gorilla gorilla graueri ) and elephants ( Loxodonta africana ). This paper reports on the status of large mammals within the mountain sector of the park in 1996, 2 years after the arrival of half a million Rwandan refugees in the area immediately adjacent to the sector. Large mammal surveys found that gorilla populations had remained stable and that elephants were concentrated within a subsector of the area. However, although chimpanzees ( Pan troglodytes ), blue monkeys ( Cercopithecus mitis ), and owl-faced monkeys ( C. hamlyni ) were abundant and widespread, most terrestrial mammal species were found in very low densities and had been subjected to poaching. Nevertheless, important mammal populations remained and complemented the biodiversity conservation value of the park.     

Species association of hepatitis B virus (HBV) in non-human apes; evidence for recombination between gorilla and chimpanzee variants

Hepatitis B virus (HBV) infections are widely distributed in humans, infecting approximately one third of the world's population. HBV variants have also been detected and genetically characterised from Old World apes; Gorilla gorilla (gorilla), Pan troglodytes (chimpanzee), Pongo pygmaeus (orang-utan), Nomascus nastusus and Hylobates pileatus (gibbons) and from the New World monkey, Lagothrix lagotricha (woolly monkey). To investigate species-specificity and potential for cross species transmission of HBV between sympatric species of apes (such as gorillas and chimpanzees in Central Africa) or between humans and chimpanzees or gorillas, variants of HBV infecting captive wild-born non-human primates were genetically characterised. 9 of 62 chimpanzees (11.3%) and two from 11 gorillas (18%) were HBV-infected (15% combined frequency), while other Old world monkey species were negative. Complete genome sequences were obtained from six of the infected chimpanzee and both gorillas; those from P. t .ellioti grouped with previously characterised variants from this subspecies. However, variants recovered from P. t. troglodytes HBV variants also grouped within this clade, indicative of transmission between sub-species, forming a paraphyletic clade. The two gorilla viruses were phylogenetically distinct from chimpanzee and human variants although one showed evidence for a recombination event with a P.t.e.-derived HBV variant in the partial X and core gene region. Both of these observations provide evidence for circulation of HBV between different species and sub-species of non-human primates, a conclusion that differs from the hypothesis if of strict host specificity of HBV genotypes.     

A quantitative method for the evaluation of three-dimensional structure of temporal bone pneumatization

Temporal bone pneumatization has been included in lists of characters used in phylogenetic analyses of human evolution. While studies suggest that the extent of pneumatization has decreased over the course of human evolution, little is known about the processes underlying these changes or their significance. In short, reasons for the observed reduction and the potential reorganization within pneumatized spaces are unknown. Technological limitations have limited previous analyses of pneumatization in extant and fossil species to qualitative observations of the extent of temporal bone pneumatization. In this paper, we introduce a novel application of quantitative methods developed for the study of trabecular bone to the analysis of pneumatized spaces of the temporal bone. This method utilizes high-resolution X-ray computed tomography (HRXCT) images and quantitative software to estimate three-dimensional parameters (bone volume fractions, anisotropy, and trabecular thickness) of bone structure within defined units of pneumatized spaces. We apply this approach in an analysis of temporal bones of diverse but related primate species, Gorilla gorilla, Pan troglodytes, Homo sapiens, and Papio hamadryas anubis, to illustrate the potential of these methods. In demonstrating the utility of these methods, we show that there are interspecific differences in the bone structure of pneumatized spaces, perhaps reflecting changes in the localized growth dynamics, location of muscle attachments, encephalization, or basicranial flexion.     

Sexual Dimorphism and Facial Growth Beyond Dental Maturity in Great Apes and Gibbons

The great apes and gibbons are characterized by extensive variation in degree of body size and cranial dimorphism, but although some studies have investigated how sexual dimorphism in body mass is attained in these species, for the majority of taxa concerned, no corresponding work has explored the full extent of how sexual dimorphism is attained in the facial skeleton. In addition, most studies of sexual dimorphism combine dentally mature individuals into a single “adult” category, thereby assuming that no substantial changes in size or dimorphism take place after dental maturity. We investigated degree and pattern of male and female facial growth in Pan troglodytes troglodytes, Pan paniscus, Gorilla gorilla gorilla, Pongo pygmaeus, and Hylobates lar after dental maturity through cross-sectional analyses of linear measurements and geometric mean values of the facial skeleton and age-ranking of individuals based on molar occlusal wear. Results show that overall facial size continues to increase after dental maturity is reached in males and females of Gorilla gorilla gorilla and Pongo pygmaeus, as well as in the females of Hylobates lar. In male Pongo pygmaeus, adult growth patterns imply the presence of a secondary growth spurt in craniofacial dimensions. There is suggestive evidence of growth beyond dental maturity in the females of Pan troglodytes troglodytes and Pan paniscus, but not in the males of those species. The results show the presence of statistically significant facial size dimorphism in young adults of Pan paniscus and Hylobates lar, and of near statistical significance in Pan troglodytes troglodytes, but not in older adults of those species; adults of Gorilla gorilla gorilla and Pongo pygmaeus are sexually dimorphic at all ages after dental maturity. The presence of sex-specific growth patterns in these hominoid taxa indicates a complex relationship between socioecological selective pressures and growth of the facial skeleton.     

Dental topography and diets of Australopithecus afarensis and early Homo

Diet is key to understanding the paleoecology of early hominins. We know little about the diets of these fossil taxa, however, in part because of a limited fossil record, and in part because of limitations in methods available to infer their feeding adaptations. This paper applies a new method, dental topographic analysis, to the inference of diet from fossil hominin teeth. This approach uses laser scanning to generate digital 3D models of teeth and geographic information systems software to measure surface attributes, such as slope and occlusal relief. Because it does not rely on specific landmarks that change with wear, dental topographic analysis allows measurement and comparison of variably worn teeth, greatly increasing sample sizes compared with techniques that require unworn teeth. This study involved comparison of occlusal slope and relief of the lower second molars of Australopithecus afarensis (n=15) and early Homo (n=8) with those of Gorilla gorilla gorilla (n=47) and Pan troglodytes troglodytes (n=54). Results indicate that while all groups show reduced slope and relief in progressively more worn specimens, there are consistent differences at given wear stages among the taxa. Early Homo shows steeper slopes and more relief than chimpanzees, whereas A. afarensis shows less slope and relief than any of the other groups. The differences between the two hominin taxa are on the same order as those between the extant apes, suggesting similar degrees of difference in diet. Because these chimpanzees and gorillas differ mostly in fallback foods where they are sympatric, results suggest that the early hominins may likewise have differed mostly in fallback foods, with A. afarensis emphasizing harder, more brittle foods, and early Homo relying on tougher, more elastic foods.     

Phylogenetic relationships amongHomo sapiens and related species based on restriction site variations in rDNA spacers

A rapid method, using 12 restriction enzymes, was employed to analyze variations in ribosomal DNA (rDNA) spacers in a study of phylogenetic relationships betweenHomo sapiens and related species. We mapped restriction sites in the external and internal spacer regions and compared the arrangements of sites. The estimated sequence divergence betweenHomo sapiens andPan troglodytes, Pan paniscus, Gorilla gorilla, Pongo pygmaeus, Hylobates lar, H. agilis, andMacaca fuscata was 2.7, 2.3, 3.8, 7.3, 6.8, 7.8, and 14.1%, respectively. The genetic relationships inferred from these distances generally correspond to those inferred from analyses of other molecular markers in the literature. The divergence betweenH. lar andH. agilis and betweenH. lar andH. syndactylus was 0.34 and 2.4%, respectively.This study was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Science and Culture, Japan, and also by the Cooperative Research Program of the Primate Research Institute, Kyoto University.