The expression of aggression in old world monkeys

The expression of agonistic behavior in adult and juvenile members of both sexes was studied in groups of from 23 to 93 animals representing Macaca mulatta, M. arctoides, M. nemestrina, M. nigra, and Cercocebus atys. Data were collected using focal animal techniques over a period of 1 year for each group. Adult male biting was notably infrequent in all cases, and adult male participation in agonistic encounters was less frequent than for any other age-sex class, especially in the groups with the highest agonistic rates. Adult male agonistic behavior was often expressed as aggression but seldom involved contact forms of aggression, and biting constituted the smallest proportion of contact aggression for all age-sex classes. Adult males were also seldom the targets of aggression and had the highest rates for shaking of objects and bouncing displays. A tendency for the most severe forms of aggressive expression to be most frequent in those animals least capable of inflicting injury was noted in all groups, along with a tendency for aggression to be directed toward immature animals. Sex differences in aggressive expression and responses to aggression were noted, but the frequency of receipt of aggression was not directly reflected in the wounding noted. Different means to achieve the same consequence, infrequent adult male damaging attacks, are suggested to operate in the several groups studied.     

Allomothering behaviour of new and old world monkeys

The holding or transferring of newborn infants at less than 1 month old by individuals other than the mothers was studied in 24 species of New and Old World monkeys under captive conditions. The observed monkey species could be divided into two types. Group A included eight species of three families where the mothers were tolerant to ‘infant transfer’ and readily retrieved their infants from other individuals, the frequency of infant transfer being high. The infant transfer of this group was termed allomothering behaviour. Group B included 16 species of two families where infant transfer did not occur at all or its frequency was very low and the mothers were possessive of their infants. Once transfer did occur, the infant could not be reclaimed with ease. The relationships between the two groups and taxonomic status, life forms and social types were evaluated in a total of 45 species from the present study and the literature. Correspondences were found with social type and taxonomic status. That is, species of Group A were seen only in the family or one-male type, except for one species, although none of this group appeared in the Cercopithecinae regardless of social types. The significance of infant transfer is discussed in relation to the participants' responses to it and the correlations between the two groups and social types.     

Animal behaviour: old world monkeys build new world order

New experimental evidence shows that policing behaviour by dominant monkeys stabilizes and integrates macaque societies.     

Life history patterns of new world monkeys

Allometric methods are used to investigate the life history patterns of New World monkeys. These patterns are compared to those found in other haplorhines and links with ecology are explored. The life history characteristics of the cebid monkeys suggest that these species are primarily slow breeding and slow developing for primates of their size. I suggest that these characteristics arose during a long period of adaptation to stable rainforest habitats. The capuchins and squirrel monkeys are a notable exception to the general rule that genera found outside primary forests will have a “fast” life history. In the marmosets and tamarins selection for small size and high birth rate has occurred, probably as a result of their adapting to more secondary habitats. It is this selection for rapid breeding, combined with the preadaptation of paternal care, that has probably led to twinning in these species. The evidence presented indicates that it is unlikely that twinning arose as a direct result of the mechanical constraints of small size but is more probably due to selection for increased reproductive output.     

Hearing of old world monkeys (Cercopithecinae)

The characteristics of normal hearing were examined in the laboratory for seven species of Old World monkeys. Operant conditioning procedures, coupled with standard audiometric testing methods, were used to assess thresholds of hearing, frequency range of hearing, and differential sensitivity to auditory intensity and frequency. To produce tonal stimulation, an animal was trained to touch and maintain manual contact with a contact-sensitive key and to report hearing the tone by lifting his hand from the key; this response was followed by food reinforcement. When the reporting response occurred without the auditory signal, the animal was punished by a short suspension from the experiment. Additional contingencies were added to ensure stable and reliable responding, and threshold and differential acuity determinations were then made. Threshold was defined as the stimulus value responded to correctly 50% of the time. The frequency range of hearing of all the cercopithecoids tested extended from 60 to 40,000 Hz, an octave above the upper bound of 20,000 Hz for man but well below the 60–70,000 Hz limit for some prosimians. Absolute sensitivity for tonal stimulation in the most sensitive frequency range (1–8 kHz) was about 2 × 10^?4 microbars, comparable to that of other primates tested, including man. Thus, the Old World monkey appears only slightly less sensitive than man to small changes in intensity and frequency of acoustic stimulation. At 1000 Hz at 60 dB above the threshold of audibility, his limit of resolution is about 5 Hz for frequency and 2 dB for intensity.     

Positional behavior in five sympatric old world monkeys

Observations of positional behavior and habitat use were recorded on focal individuals of five species of Old World monkeys at Kibale Forest, Uganda, through the dry season of 1990 and 1991. Cercopithecus ascanius, Cercopithecus mitis, Cercocebus albigena, Colobus badius, and Colobus guereza commonly utilize five similar types of positional behavior (i.e., quadrupedalism, leaping, climbing, sitting, and standing), but in varying frequencies and situations. As a group, colobines use oblique supports and leap more often, and cover greater linear distances during leaps than do cercopithecines. Colobines also prefer to sit (about 90% of all postures), while cercopithecines stand more frequently. Body size differences between the sexes of a species are not reflected in positional behavior. The two small-bodied species climb more and leap less often than the three larger species, which is the reverse of what we would expect. Leaping is the most common method of crossing open spaces within the canopy; but most spatial gaps and leaps are over short distances, usually one meter or less. All five species, regardless of body size or the availability of forest supports, prefer mediumsized supports. Incorporating our work from Uganda with previous investigations of positional behavior reveals few consistent trends with respect to body size or habitat use across primates. © 1995 Wiley-Liss, Inc.     

Zebrafish and fly Nkx6 proteins have similar CNS expression patterns and regulate motoneuron formation

Genes belonging to the Nkx, Gsh and Msx families are expressed in similar dorsovental spatial domains of the insect and vertebrate central nervous system (CNS), suggesting the bilaterian ancestor used this genetic program during CNS development. We have investigated the significance of these similar expression patterns by testing whether Nkx6 proteins expressed in ventral CNS of zebrafish and flies have similar functions. In zebrafish, Nkx6.1 is expressed in early-born primary and later-born secondary motoneurons. In the absence of Nkx6.1, there are fewer secondary motoneurons and supernumerary ventral interneurons, suggesting Nkx6.1 promotes motoneuron and suppresses interneuron formation. Overexpression of fish or fly Nkx6 is sufficient to generate supernumerary motoneurons in both zebrafish and flies. These results suggest that one ancestral function of Nkx6 proteins was to promote motoneuron development.     

Model life tables for the larger old world monkeys

Mortality statistics for 25 populations of the larger Old World monkeys (members of the subfamily Cercopithecinae) were evaluated with a competing hazard model of mortality. The best eight of these life tables were combined to generate a standard model life table representative of the mortality patterns of these primates. Two applications of the standard model to smooth, graduate, and compare life tables based on limited and defective data are presented.     

Jaw morphology and function in living and fossil old world monkeys

This allometric investigation on a sample of 29 cercopithecine and 22 colobine taxa augments the data and implications of prior work on subfamilial variation in mandibular form and function in recent Cercopithecidae. To increase the size range encompassed by living cercopithecines and colobines, I included many of the larger-bodied fossil specimens. These analyses serve to fill a gap in our understanding of size-related changes in masticatory function and symphyseal morphology and curvature in extant and extinct Old World monkeys. Results of subfamilial scaling comparisons indicate that for a given jaw length, colobines possess significantly more robust corpora and symphyses than those of cercopithecines, especially at smaller sizes. Following from previous work, the most plausible explanation for why the subfamilies differ in relative corporeal and symphyseal dimensions is that colobine mandibles experience elevated loads and greater repetitive loading during mastication due, on average, to processing a diet of tough leaves and/or seeds. Although colobines have relatively larger symphyses, subfamilial analyses of symphyseal curvature demonstrate that they evince less symphyseal curvature vis-à-vis cercopithecines of a common size. Moreover, both subfamilies exhibit similar allometric changes in the degree of curvature, such that larger-bodied Old World monkeys have more curved symphyses than those of smaller taxa. Subfamilial scaling analyses also indicate that colobines possess a shorter M2 bite-point length relative to masseter lever-arm length, but not versus temporalis lever-arm length. Thus, as compared to cercopithecines, colobines can recruit less masseter-muscle force to produce similar bite forces during mastication. In both clades, M² bite-point length scales with positive allometry relative to masseter lever-arm length, such that larger species are less efficient at generating molar bite forces. This seems especially important due to the lack of subfamily difference in M² bite-point:temporalis lever-arm scaling (which is isometric across cercopithecids). A consideration of extinct cercopithecids indicates that many of the large-bodied papionins have more robust corpora, due perhaps to a diet which was of similar toughness to that of extant and extinct colobines. However, the biomechanical arrangements of the masseter and temporalis in all but one fossil cercopithecine and all of the fossil colobine specimens are much as predicted for a subfamilial member of its skull size. That most large-bodied papionins with tougher diets nonetheless maintain a less efficient jaw-muscle configuration may be due to stronger offsetting selection for increased relative canine size and gape.     

A biomechanical analysis of mandibular scaling in old world monkeys

Scaling of mandibular dimensions in male Old World monkeys was investigated. Mandibular condyle length, width, and area were regressed separately against body mass and mandibular length for a total of 14 species of Cercopithecoids. Scaling of mandibular depth and width against both body mass and mandibular length were also investigated. When results of regression analysis using the two different independent variables (body mass and mandibular length) were compared, there were significant pattern differences in scaling of cercopithecines versus colobines. Compared to body mass, male cercopithecines had relatively large mandibles (length, width, and depth) and also relatively large condyles (length, width, and area). However, compared to mandibular length, cercopithecines had relatively transversely thin and shallow mandibles and relatively narrow condyles. It is shown that a “biomechanical” interpretation of mandibular scaling patterns against body mass in Old World monkeys demonstrates only that cercopithecines have prognathic faces, an already well-known and well-documented condition. When the biomechanical effects of prognathic faces are controlled for (by scaling against mandibular length), it is shown that cercopithecines possess special adaptations in condyle length while colobines possess special adaptations in condyle width and mandibular depth and width. These results clearly demonstrate the importance of selecting a relevant reference variable in scaling studies where biomechanical interpretations are attempted.     

Karyotypic fission theory and the evolution of old world monkeys and apes

The karyotypes of living catarrhines are correlated with the current concepts of their fossil record and systematic classification. A phylogeny, beginning at the base of the Oligocene, for those animals and their chromosome numbers is presented. Todd? (1970) theory of karyotypic fissioning is applied to this case — three fissioning events are hypothesized. A late Eocene event (the primary catarrhine fissioning) is hypothesized to underlie the diversification of the infraorder Catarrhini into its extant families, the second fissioning underlies the radiation of the Pongidae/Hominidae in the Miocene and the third accounts for the high chromosome numbers (54–72) and the Neogene (Miocene-Pliocene-Pleistocene) radiation of members of the genus Cercopithecus. Published catarrhine chromosome data, including that for “marked” chromosomes (those with a large achromatic region that is the site for ribosomal RNA genes) are tabulated and analysed. The ancestral X chromosome is always retained in the unfissioned metacentric state. The Pongidae/Hominidae have 15 pairs of mediocentric chromosomes that survived the second fissioning whereas the other chromosomes (besides the X) are thought to be fission-derived acrocentrics. Both the detailed karyology and the trend from low to high numbers is best interpreted to support Todd? concept of adaptive radiations correlated with karyotypic fissioning in ancestral populations.     

Chromosome phylogenies of man,great apes,and old world monkeys

The karyotypes of man and of the closely related Pongidae — chimpanzee, gorilla, and orangutan — differ by a small number of well known rearrangements, mainly pericentric inversions and one fusion which reduced the chromosome number from 48 in the Pongidae to 46 in man. Dutrillaux et al. (1973, 1975, 1979) reconstructed the chromosomal phylogeny of the entire primate order. More and more distantly related species were compared thus moving backward in evolution to the common ancestors of the Pongidae, of the Cercopithecoidae, the Catarrhini, the Platyrrhini, the Prosimians, and finally the common ancestor of all primates. Descending the pyramid it becomes possible to assign the rearrangements that occurred in each phylum, and the one that led to man in particular.The main conclusions are that this phylogeny is compatible with the occurrence during evolution of simple chromosome rearrangements — inversions, fusions, reciprocal translocation, acquisition or loss of heterochromatin — and that it is entirely consistent with the known primate phylogeny based on physical morphology and molecular evolution. If heterochromatin is not taken into account, man has in common with the other primates practically all of his chromosomal material as determined by chromosome banding. However, it is arranged differently, according to species, on account of chromosome rearrangements. This interpretation has been confirmed by comparative gene mapping, which established that the same chromosome segments, identified by banding, carry the same genes (Finaz et al., 1973; Human Gene Mapping 8, 1985).A remarkable observation made by Dutrillaux is that different primate phyla seem to have adopted different chromosome rearrangements in the course of evolution: inversions for the Pongidae, Robertsonian fusions for the lemurs, etc. This observation may raise many questions, among which is that of an organized evolution. Also, the breakpoints of chromosomal rearrangements observed during evolution, in human chromosomal diseases, and after ionizing irradiation do not seem to be distributed at random.Chromosomal rearrangements observed in evolution are known to be harmful in humans, leading to complete or partial sterility through abnormal offspring in the heterozygous state but not in the homozygous state. They then become a robust reproductive barrier capable of creating new species, far more powerful than gene mutations advocated by neo-Darwinism. The homozygous state may be achieved especially through inbreeding, which must have played a major role during primate evolution. Whether new species derive from unique individuals or couples (Adam and Eve), or through a populational process, remains a matter for discussion.     

Do old female monkeys have a specific social role?

The role of the aged in human society has received much attention from gerontologists, and the notion of a social role for aged monkeys is common in primatology. Four hundred and fifty hours of focal animal data were collected on a sample of 40 adult female Japanese monkeys. The animals are semi-free ranging and of known age. These data were analyzed in an attempt to determine whether old females constitute a behaviorally distinct subgroup. Very little behavioral variation based on age could be documented. Where age related variation occurs, it is better explained as a function of youth, rather than as a function of old age. The expectation that old monkeys will occupy a distinct social role because of their advanced age is discussed in terms of biological versus social aging, human versus non human aging, the evolution of behavioral change in old age, and the application of the social role concept to old female monkeys. It is concluded that there is little evidence that the behavior of the aged females differs significantly from that of the other adult females, and it does not appear that the fact of biological aging creates any radically different social situation which would cue the onset of specific role behavior for aged animals.     

Molecular evolution of growth hormone gene family in old world monkeys and hominoids

Growth hormone is a classic molecule in the study of the molecular clock hypothesis as it exhibits a relatively constant rate of evolution in most mammalian orders except primates and artiodactyls, where dramatically enhanced rate of evolution (25–50-fold) has been reported. The rapid evolution of primate growth hormone occurred after the divergence of tarsiers and simians, but before the separation of old world monkeys (OWM) from new world monkeys (NWM). Interestingly, this event of rapid sequence evolution coincided with multiple duplications of the growth hormone gene, suggesting gene duplication as a possible cause of the accelerated sequence evolution. Here we determined 21 different GH-like sequences from four species of OWM and hominoids. Combining with published sequences from OWM and hominoids, our analysis demonstrates that multiple gene duplications and several gene conversion events both occurred in the evolutionary history of this gene family in OWM/hominoids. The episode of recent duplications of CSH-like genes in gibbon is accompanied with rapid sequence evolution likely resulting from relaxation of purifying selection. GHN genes in both hominoids and OWM are under strong purifying selection. In contrast, CSH genes in both lineages are probably not. GHV genes in OWM and hominoids evolved at different evolutionary rates and underwent different selective constraints. Our results disclosed the complex history of the primate growth hormone gene family and raised intriguing questions on the consequences of these evolutionary events.