ABSTRACT
Nursery rearing has well-known consequences for primate species. Relative to some other primate species, research has indicated a reduced impact of nursery rearing on squirrel monkeys, particularly in terms of rates, severity, and persistence of abnormal behavior. We administered the Primate Neonatal Neurobehavioral Assessment to 29 dam-reared and 13 nursery-reared squirrel monkeys (Saimiri boliviensis boliviensis) at 2 and 6 weeks of age. Mixed-model ANOVAs comparing composite scores and individual assessment items across age, rearing status, and sex revealed a number of developmental differences. Dam-reared infants scored higher on all four composite measures compared to nursery-reared infants (p < .05) indicating that nursery-reared animals had slower motor development, were less active and attentive, and were more passive than their dam-reared counterparts. Consistent with infant rhesus macaques, nursery-reared squirrel monkeys showed an increased sensitivity to tactile stimulation (p < .05). Altogether, these results suggest a disruption of species-typical development when squirrel monkey infants are reared in a nursery setting, with activity, orientation, and state control areas most affected, though experimental research is needed to determine if this is a causal relationship. Contrary to previous behavioral research, there are likely developmental differences between dam-reared infant squirrel monkeys and those reared in a nursery setting.
Subject(s)
Animals, Newborn/psychology , Saimiri/psychology , Social Environment , Age Factors , Animals , Animals, Newborn/growth & development , Female , Male , Neuropsychological Tests , Saimiri/growth & developmentABSTRACT
Broadening our knowledge of olfactory communication in strictly monogamous systems can inform our understanding of how chemosignals may facilitate social and reproductive behavior between the sexes. Compared to other social and mating systems, relatively little is known about olfactory communication in strictly monogamous non-human primates. Furthermore, platyrrhines are not well represented in chemical analyses of glandular secretions. We conducted semi-quantitative headspace gas chromatography with mass spectrometry to investigate the chemical components of glandular secretions from the subcaudal and pectoral glands of a strictly pair-living platyrrhine, the owl monkey (Aotus spp.). In this study, the first chemical analysis of a wild platyrrhine population, our goals were to (1) conduct a robust analysis of glandular secretions from both captive and wild owl monkey populations and (2) identify whether biologically relevant traits are present in glandular secretions. We also compared and contrasted the results between two Aotus species in different environmental contexts: wild Aotus azarae (N = 33) and captive A. nancymaae (N = 104). Our findings indicate that secretions from both populations encode sex, gland of origin, and possibly individual identity. These consistent patterns across species and contexts suggest that secretions may function as chemosignals. Our data also show that wild A. azarae individuals are chemically discriminated by age (adult or subadult). Among the captive A. nanycmaae, we found chemical differences associated with location, possibly caused by dietary differences. However, there was no noticeable effect of contraception on the chemical profiles of females, nor evidence that closely related individuals exhibit more similar chemical profiles in A. nancymaae. Overall, our data suggest that glandular secretions of both wild and captive Aotus convey specific information. Future studies should use behavioral bioassays to evaluate the ability of owl monkeys to detect signals, and consider whether odor may ultimately facilitate social and sexual relationships between male and female owl monkeys.
Subject(s)
Aotidae/physiology , Pheromones/chemistry , Scent Glands/metabolism , Age Factors , Animal Communication , Animals , Argentina , Bodily Secretions/chemistry , Bodily Secretions/metabolism , Ecosystem , Female , Gas Chromatography-Mass Spectrometry/veterinary , Male , Pheromones/metabolism , Sex Factors , SmellABSTRACT
In polygynous primates, a greater reproductive variance in males have been linked to their reduced life expectancy relative to females. The mortality patterns of monogamous pair-bonded primates, however, are less clear. We analyzed the sex differences in mortality within wild (NMales = 70, NFemales = 73) and captive (NMales = 25, NFemales = 29) populations of Azara's owl monkeys (Aotus azarae), a socially and genetically monogamous primate exhibiting biparental care. We used Bayesian Survival Trajectory Analysis (BaSTA) to test age-dependent models of mortality. The wild and captive populations were best fit by the logistic and Gompertz models, respectively, implying greater heterogeneity in the wild environment likely due to harsher conditions. We found that age patterns of mortality were similar between the sexes in both populations. We calculated life expectancy and disparity, the latter a measure of the steepness of senescence, for both sexes in each population. Males and females had similar life expectancies in both populations; the wild population overall having a shorter life expectancy than the captive one. Furthermore, captive females had a reduced life disparity relative to captive males and to both sexes in the wild. We interpret this pattern in light of the hazards associated with reproduction. In captivity, where reproduction is intensely managed, the risks associated with gestation and birth are tempered so that there is a reduction in the likelihood of captive females dying prematurely, decreasing their overall life disparity.
Subject(s)
Animals, Zoo/physiology , Aotidae/physiology , Longevity , Animals , Argentina , Bayes Theorem , Female , Life Expectancy , Male , Pair Bond , Reproduction , Sex Characteristics , TexasABSTRACT
Due to many physiological and genetic characteristic similarities to humans, squirrel monkeys provide an ideal animal model specifically for studying malaria, and transmissible spongiform encephalopathies (Creutzfeldt-Jacob disease). While squirrel monkeys three years and older are generally considered adult subjects suitable for use in medical research studies, little is known about the functional properties of lymphocytes in relation to the age of these animals, which could significantly impact the quality and quantity of innate and adaptive immune responses. In this study, we investigated differences in the phenotype and function of lymphocytes subsets of young (3-4 years), adult (8-10 years) and aged (16-19 years) squirrel monkeys. In general, animals in all three age groups exhibited comparable numbers of different lymphocyte subsets except for CD20+ B cells that were significantly lower in aged relative to young animals and T cells subsets expressing both CD4 and CD8 (double positive) were significantly higher in aged relative to young animals. With increasing age, phenotypic differences in central and effector memory T cells subsets were observed, that were more pronounced for the CD8+ T cells. Despite equal proportions of CD3+ T cells among the three age groups, responses of peripheral blood mononuclear cells to T cell mitogens PHA and Con A showed lower IFN-γ producing cells in the aged group than that in the young group. Furthermore, aged animals showed significantly higher plasma levels of inflammatory cytokines IL-6, IFN-γ, TNF-α, IL-10 and IL-12. These findings suggest that while the squirrel monkeys in general share phenotypic and functional similarities of lymphocyte subsets with humans in relation to age, specific differences exist in immune function of lymphocytes between young and old animals that could potentially impact experimental outcomes for which the measurement of immunologic endpoints are critical.
Subject(s)
Lymphocytes/physiology , Saimiri/immunology , Adaptive Immunity , Age Factors , Animals , Animals, Laboratory/immunology , Antigens, CD20/metabolism , Bolivia , Cytokines/blood , Enzyme-Linked Immunospot Assay , Female , Immunity, Innate , Interferon-gamma/metabolism , Lymphocytes/cytology , Phenotype , Saimiri/physiologyABSTRACT
Density-dependence is hypothesized as the major mechanism of population regulation. However, the lack of long-term demographic data has hampered the use of density-dependent models in nonhuman primates. In this study, we make use of the long-term demographic data from Cayo Santiago's rhesus macaques to parameterize and analyze both a density-independent and a density-dependent population matrix model, and compare their projections with the observed population changes. We also employ a retrospective analysis to determine how variance in vital rates, and covariance among them, contributed to the observed variation in long-term fitness across different levels of population density. The population exhibited negative density-dependence in fertility and the model incorporating this relationship accounted for 98% of the observed population dynamics. Variation in survival and fertility of sexually active individuals contributed the most to the variation in long-term fitness, while vital rates displaying high temporal variability exhibited lower sensitivities. Our findings are novel in describing density-dependent dynamics in a provisioned primate population, and in suggesting that selection is acting to lower the variance in the population growth rate by minimizing the variation in adult survival at high density. Because density-dependent mechanisms may become stronger in wild primate populations due to increasing habitat loss and food scarcity, our study demonstrates that it is important to incorporate variation in population size, as well as demographic variability into population viability analyses for a better understanding of the mechanisms regulating the growth of primate populations.
Subject(s)
Macaca mulatta/physiology , Animals , Fertility , Population Density , Population Dynamics , Puerto RicoABSTRACT
The chemical investigation of specimens of the Jamaican brown alga Stypopodium zonale led to the isolation of a cytotoxic compound, zonaquinone acetate (1), along with known compounds flabellinone, not previously identified in S. zonale, stypoldione, 5',7'-dihydroxy-2'-pentadecylchromone and sargaol. The structures of the metabolites were established by analysis of the spectral data including 1D and 2D NMR experiments while the stereochemistry of 1 was assessed by VCD measurements. Cytotoxic activity was reported in vitro for 1 against breast cancer and colon cancer cell lines at IC(50) values of 19.22-21.62 µM and 17.11-18.35 µM respectively, comparing favorably with standard treatments tamoxifen (17.22-17.32 µM) and fluorouracil (27.03-31.48 µM). When tested with liver cancer cells (Hep G2), no activity was observed. Weak antioxidant activity was observed with 1 but sargaol exhibited high activity.
Subject(s)
Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Phaeophyceae/chemistry , Cell Line, Tumor , Diterpenes/chemistry , Diterpenes/pharmacology , Humans , Terpenes/chemistry , Terpenes/pharmacologyABSTRACT
The chemical composition of the essential oil obtained from the aerial parts of Cleome serrata by hydrodistillation was analyzed by employing GC-FID, GC-MS and RI. Fourteen compounds comprising 90.4% of the total oil composition were characterized. The main components identified were (Z)-phytol (53.0%) and di(2-ethylhexyl)-phthalate (DEHP) (14.7%). The oil was evaluated for its in vitro antimicrobial activities against nine pathogenic microorganisms using the filter paper disc diffusion method. Moderate antimicrobial activity was observed against five of the pathogens assayed. In addition, the essential oil was tested against the sweet potato weevil, Cylas formicarius elegantulus. Strong knockdown insecticidal activity was observed.
Subject(s)
Cleome/chemistry , Oils, Volatile/analysis , Bacteria/drug effects , Jamaica , Oils, Volatile/pharmacologyABSTRACT
Five different essential oil extractions of the aerial parts of Cleome spinosa Jacq. were examined. The oils obtained by hydrodistillation of the whole aerial parts, aerial parts without flowers (fruit, leaves and stem), flowers, fruits and leaves have been examined by GC-FID and GC-MS. The chemical profiles of the oils reveal the dominance of oxygenated sesqui- and diterpenes, with the exception of the fruit oil, which contained a high content of fatty acids. The most abundant compounds from the whole aerial parts were (Z)-phytol (31.3%), integerrimine (5.5%) and incensole (4.0%). The major compounds from the aerial portion without flowers were caryophyllene oxide (10.5%), (-)-spathulenol (7.5%) and Z-phytol (6.9%). In the flower oil, the main components were 7-alpha-hydroxy manool (23.8%), incensole (9.2%) and sclareol (8.7%). The chief constituents in the fruit oil were tetradecanoic acid (40.6%), (Z)-phytol (6.58%) and sclareol (4.5%). In the leaf oil, (Z)-phytol (19.5%), 7-alpha-hydroxy manool (6.8%) and caryophyllene oxide (4.36%) were the predominant compounds. Antimicrobial activity of the oil obtained from the whole aerial part was evaluated against nine microbial strains using a filter paper disc-diffusion method. The volatile oil showed moderate action against seven of the eight bacteria strains used, with significant inhibitory activity against Streptococcus pyogenes Group A when compared with the standard antibiotics, ampicillin and gentamicin. The fungus, Candida albicans was less sensitive to the essential oil. The oils showed moderate insecticidal activity against Cylas formicarius elegantalus, but possessed no antioxidant activity as indicated by the DPPH method. This represents the first report on the chemical composition of the essential oils from C. spinosa found in Jamaica and the in vitro antioxidant, insecticidal and antimicrobial potential of the oil from the aerial parts.
Subject(s)
Anti-Infective Agents/pharmacology , Cleome/chemistry , Oils, Volatile/analysis , Animals , Antioxidants/pharmacology , Chromatography, Gas , Gas Chromatography-Mass Spectrometry , Insecticides/pharmacology , Oils, Volatile/pharmacology , WeevilsABSTRACT
Fractionation of the MeOH/CH2Cl2 extract of the sponge Amphimedon compressa afforded the secondary metabolite amphitoxin (1), the structure of which was elucidated by interpretation of 1H- and 13C-NMR data. The crude extract and the fractions containing the metabolite 1 were assessed for ichthyotoxic and insecticidal activity towards Xiphophorus variatus (moon fish) and Cylas formicarius elegantulus (sweet potato weevil), respectively. In addition, the ability of 1 to cause mortality (toxicity and lethal effect) in the rodent Rattus norvegicus (Norway rat) was examined. Moderate insecticidal activity was observed, while the toxicity towards the moon fish was evidenced by the high mortality rates for all the fractions tested. In contrast, the rodent was not affected by the metabolite.
Subject(s)
Insecticides/pharmacology , Porifera/chemistry , Pyridinium Compounds/pharmacology , Weevils/drug effects , Animals , Fishes , Insecticides/chemistry , Insecticides/toxicity , Jamaica , Magnetic Resonance Spectroscopy , Molecular Structure , Pyridinium Compounds/chemistry , Pyridinium Compounds/toxicity , RatsABSTRACT
Changes in the yields of the oleoresin and content of pungent bioactive principles: [6], [8], [10] gingerols and [6] shogaol of Jamaican ginger ( Zingiber officinale) were investigated during different stages of maturity (7-9 months). Ethanolic oleoresin extracts were prepared (95%, w/w) by cold maceration of dried ginger powder, and their percentage yields were calculated (w/w). The pungent bioactive principles in the ginger oleoresin were extracted with methanol and quantitatively analyzed by high performance liquid chromatography (HPLC). Ginger harvested at 8 months from Bourbon, Portland had the highest oleoresin yield (8.46 +/- 0.46%). [6] Gingerol was found to be the most abundant pungent bioactive principle in all the oleoresin samples investigated, with the 9 months sample from Bourbon, Portland containing the highest level (28.94 +/- 0.39%). The content of [6] gingerols was also found to be consistently high (7-9 months) in oleoresin samples from Johnson Mountain, St. Thomas (15.12 +/- 0.39 to 16.02 +/- 0.95%). The results suggest that Bourbon in Portland may be the most ideal location for cultivating ginger for high yields and quality, however, Johnson Mountain in St. Thomas could prove to be the least restrictive location, allowing for harvesting of good quality material throughout the maturity period (7-9 months).
Subject(s)
Plant Extracts/analysis , Zingiber officinale/chemistry , Zingiber officinale/growth & development , Catechols/analysis , Chromatography, High Pressure Liquid , Environment , Fatty Alcohols/analysis , Jamaica , Odorants/analysis , Time FactorsABSTRACT
Aromatic diarylheptanoid compounds from Curcuma longa Linn grown in Jamaica were quantified by UV-vis spectrophotometry and high-performance liquid chromatographic (HPLC) analyses. The oleoresin yields from ethanolic extracts were quantified and evaluated with regard to the effects of the type of postharvesting process and the type of extraction method conducted on the plant material. Fresh samples that were hot solvent extracted provided the highest oleoresin yields of 15.7% +/- 0.4 ( n = 3), and the lowest oleoresin yields of 7.8% +/- 0.2 ( n = 3) were from the dried milled samples that were cold solvent extracted. Data from the ASTA spectrophotometer assay confirmed that dried samples contained the highest curcuminoid content of 55.5% +/- 2.2 ( n = 6) at the fifth month of storage, and the fresh samples showed a curcuminoid content of 47.1% +/- 6.4 ( n = 6) at the third month of storage. A modified HPLC analysis was used to quantify curcumin content. Data from the HPLC analysis confirmed that the dried treated, hot extracted, room temperature stored samples had the highest curcumin content of 24.3%. A novel high-performance thin layer chromatography (HPTLC) method provided a chemical fingerprint of the C. longa with the use of a commercial curcumin standard.
Subject(s)
Curcuma/chemistry , Curcuma/growth & development , Curcumin/analysis , Food Handling/methods , Food Preservation/methods , Plant Extracts/analysis , Chromatography, High Pressure Liquid , Cold Temperature , Hot Temperature , Jamaica , Plant Extracts/chemistryABSTRACT
Squirrel monkeys (genus Saimiri) give birth to relatively large neonates with large, fast-growing brains. Maternal energy expenditure during gestation and infant development is argued to be high, but may be offset by the provisioning of offspring by females other than the mother (allonursing). Milk composition is an important component of maternal energy expenditure, but has been examined in only a small number of primate species. Here, we report on the milk composition from laboratory-housed Bolivian squirrel monkey (Saimiri boliviensis boliviensis) dams (n = 6) and allomothers (n = 2). Milk samples (n = 16) representing mid-lactation were assayed for fat, sugar, dry matter (DM), crude protein (CP), and fatty acids. Gross energy (GE) was calculated from these constituents (excepting fatty acids). The goals of this project were: (1) to provide descriptive data on milk composition of squirrel monkeys, including the range of intraspecific variation; (2) to determine if milk produced by allomothers differs from milk from dams; and (3) to compare squirrel monkey milk to that of other small New World monkeys, the callitrichines. Squirrel monkey samples averaged 4.56% fat, 3.59% CP, 6.98% sugar, 16.59% DM, and 0.91 kcal/g. The proportion of the medium chain fatty acids 8:0 and 10:0 was 40 times greater than that reported for human milk samples, and 18:1 and 18:2n-6 comprise more than 60% of total fatty acids. Milk from allomothers was lower than dams in fat, DM, and GE, which may relate to variation in maternal condition between these two groups. Excluding allomothers, milk from squirrel monkeys was higher in mean GE than captive common marmosets, but did not differ in the proportion of energy from fat, CP, and sugar relative to total GE. The consistency in energy from protein between species suggests this may be a shared-derived trait of New World monkeys.
Subject(s)
Milk/chemistry , Saimiri/physiology , Animals , Female , LactationABSTRACT
New World squirrel monkeys (Saimiri spp.) have high circulating cortisol levels but normal electrolytes and blood pressures. The goal of the present study was to gain insight into adaptive mechanisms used by Bolivian squirrel monkeys to minimize the effects of high cortisol on mineralocorticoid receptor (MR) activity and electrolyte and water balance. Aldosterone levels in serum from 10 squirrel monkeys were 17.7 +/- 3.4 ng/dl (normal range in humans, 4 to 31 ng/dl), suggesting that squirrel monkeys do not exhibit a compensatory increase in aldosterone. The squirrel monkey MR was cloned and expressed in COS-7 cells and found to have similar responsiveness to cortisol and aldosterone as human MR, suggesting that squirrel monkey MR is not inherently less responsive to cortisol. To determine whether altered metabolism of cortisol might contribute to MR protection in squirrel monkeys, serum and urinary cortisol and cortisone were measured, and a comprehensive urinary corticosteroid metabolite profile was performed in samples from anesthetized and awake squirrel monkeys. The levels of cortisone exceeded those of cortisol in serum and urine, suggesting increased peripheral 11beta-hydroxysteroid dehydrogenase 2 activity in squirrel monkeys. In addition, a significant fraction (approximately 20%) of total corticosteroids excreted in the urine of squirrel monkeys appeared as 6beta-hydroxycortisol, compared with that in man (1%). Therefore, changes in cortisol metabolism likely contribute to adaptive mechanisms used by Bolivian squirrel monkeys to minimize effects of high cortisol.
Subject(s)
Hydrocortisone/analogs & derivatives , Saimiri/metabolism , Amino Acid Sequence , Animals , Aotidae/genetics , Aotidae/metabolism , COS Cells , Chlorocebus aethiops , Cloning, Molecular , Cortisone/blood , Cortisone/metabolism , Cortisone/urine , Hydrocortisone/blood , Hydrocortisone/metabolism , Hydrocortisone/urine , Molecular Sequence Data , Receptors, Mineralocorticoid/drug effects , Receptors, Mineralocorticoid/genetics , Receptors, Mineralocorticoid/metabolism , Saimiri/geneticsABSTRACT
The chemical composition of the essential oil obtained by hydrodistillation from the aerial parts of Hyptis verticillata Jacq. was elucidated by a combination of GC and GC-MS analyses. The oil was dominated by the sesquiterpenoids cadina-4,10(15)-dien-3-one (15.1%) (1) and aromadendr-1(10)-en-9-one (squamulosone) (30.7%) (2). The oil exhibited chemosterilant activities against the cattle tick, Boophilus microplus Canest., and toxic action against adult Cylas formicarius elegantulus Summer, the most destructive pest of sweet potato (Ipomoea species).
Subject(s)
Hyptis/chemistry , Insecticides , Oils, Volatile/chemistry , Animals , Chromatography, Gas , Coleoptera , Gas Chromatography-Mass Spectrometry , IxodidaeSubject(s)
21003 , Humans , Anti-Infective Agents/isolation & purification , Arthropods , Anti-Infective Agents/toxicity , Bacteria/drug effects , Fungi/isolation & purification , Fungi/drug effects , Jamaica , Larva , Microbial Sensitivity Tests , Nematoda , Population Density , Seasons , StrongyloidesABSTRACT
The methanol extract obtained from the leaves and stems of Euphorbia hirta inhibited the activity of angiotensin converting enzyme (ACE) by 90 percent and 50 percent at 500 ug and 160 ug respectively using enzyme linked immunosorbent assay (ELISA). The effect of the extract on thirst was examined using Wistar rats. Intraperitoneal administration of 10mg/100mg body wt of the extract significantly (p<0.05) decreased the amount of water consumed by rats. This effect lasted for 2 h.(AU)
Subject(s)
Rats , 21003 , Methanol/chemical synthesis , Enzyme-Linked Immunosorbent Assay , Peptidyl-Dipeptidase A/analysis , Plant Extracts/analysis , Thirst/drug effectsABSTRACT
While preparing a routine sagittal section of the human head and neck for the teaching of anatomy, 3 mature Ascaris lumbricoides worms were seen in the maxillary sinus and 3 in the sphenoidal sinus. Of the worms in the maxillary sinus, 2 were males and one was female, while in the sphenoidal sinus all 3 worms were females. The worms measured 7 - 11 cm in length Light microscope examination of the maxillary sinus wall revealed a few eggs of the parasite in close relation to the epithelium. The migratory abilities of A. Lumbricoides adult worms are well documented and most often involve the bile and pancreatic ducts (Asrat & Rogers, 1995). In a endemic area of Kashmir, India, A. Lumbricoides was the cause of acute pancreatis in 23 percent of 256 patients (Khuroo et al., 1992). Worm extraction and biliary drainage were indicated in 32 percent of 156 patients who had acute hepatobiliary and pancreatic ascariasis, and this resulted in rapid relief of symptoms in most patients (Khuroo et al., 1993). In the case represented, the ostia of the sinuses were between 3 and 4 mm in width and were therefore large enough for the passage of the worms as adults. We are not aware of any other report of ectopic ascariasis involving the sinuses. Clinical data on the current case were not available to us. A. Lumbricoides has high fecundity and the fact that only a few eggs were seen in the sinuses suggests that the worms were immature or that there was a reduction in egg production due to overcrowding or lack of adequate nutrition.(AU)
Subject(s)
Humans , 21003 , Ascaris lumbricoides/isolation & purification , Paranasal Sinuses/parasitologyABSTRACT
The novel assingment of 13C and 1HNMR data for cadina-4,10(15)-dien-3-one obtained from Hyptis verticillata is presented. The study revealed that cadina-4,10(15)-dien-3-one possesses chemosterilant activities against the economically important cattle tick, Boophilus microplus, and toxic action against adult Cylas formicarius the most destructive pest of sweet potato (I pomoea sp.) (AU)
Subject(s)
21003 , Female , Male , Coleoptera , Insecticides , Naphthalenes/chemistry , Ticks , Carbon Isotopes , Cattle , Hydrogen , Molecular Structure , Naphthalenes/isolation & purification , Naphthalenes/toxicity , Magnetic Resonance Spectroscopy , PlantsABSTRACT
Allomaternal behavior is defined as maternal-like interactions between an infant and some animal other than its natural mother. The occurrence of allomothering can have a profound influence on the life of the infant and on the animal with which the infant interacts. Allomaternal interactions were studied during the first 6 months of life in 50 Bolivian squirrel monkeys in two different social settings. Allomaternal interactions began during the first week of life. Sampling indicated that the infants spent 30% of their time on allomothers during the first 6 months of life. Dorsal clinging on allomothers occurred most frequently when the infants were younger and more dependent, and declined with the infant's growing independence. In addition, squirrel monkey infants nursed on allomothers, though the rates were lower than nursing on their dam. Four- to six-year-old young adult females accounted for most of the allomaternal interactions (53%), while adult females 7 to 9 years old provided 21% of the allomaternal interactions. A similar age-related pattern was found for allomaternal nursing; however, reproductive status had a profound influence. Those females with a reproductive failure for the year provided 86% of the allomaternal nursing bouts. Allomaternal interactions were not based solely on kinship relationships. Future studies need to be directed toward establishing the proximal causes of allomaternal behavior in the squirrel monkey. © 1994 Wiley-Liss, Inc.