1
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Wilson VAD, Masilkova M. Does the primate face cue personality? PERSONALITY NEUROSCIENCE 2023; 6:e7. [PMID: 38107779 PMCID: PMC10725780 DOI: 10.1017/pen.2023.5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/24/2023] [Accepted: 05/31/2023] [Indexed: 12/19/2023]
Abstract
When looking at others, primates primarily focus on the face - detecting the face first and looking at it longer than other parts of the body. This is because primate faces, even without expression, convey trait information crucial for navigating social relationships. Recent studies on primates, including humans, have linked facial features, specifically facial width-to-height ratio (fWHR), to rank and Dominance-related personality traits, suggesting these links' potential role in social decisions. However, studies on the association between dominance and fWHR report contradictory results in humans and variable patterns in nonhuman primates. It is also not clear whether and how nonhuman primates perceive different facial cues to personality traits and whether these may have evolved as social signals. This review summarises the variable facial-personality links, their underlying proximate and evolutionary mechanisms and their perception across primates. We emphasise the importance of employing comparative research, including various primate species and human populations, to disentangle phylogeny from socio-ecological drivers and to understand the selection pressures driving the facial-personality links in humans. Finally, we encourage researchers to move away from single facial measures and towards holistic measures and to complement perception studies using neuroscientific methods.
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Affiliation(s)
- Vanessa A D Wilson
- Department of Comparative Cognition, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Department of Comparative Language Science, University of Zurich, Zurich, Switzerland
- Center for the Interdisciplinary Study of Language Evolution (ISLE), University of Zurich, Zurich, Switzerland
| | - Michaela Masilkova
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic
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2
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Hamilton MI, Fernandez DP, Nelson SV. Using strontium isotopes to determine philopatry and dispersal in primates: a case study from Kibale National Park. ROYAL SOCIETY OPEN SCIENCE 2021; 8:200760. [PMID: 33972840 PMCID: PMC8074638 DOI: 10.1098/rsos.200760] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 01/15/2021] [Indexed: 06/12/2023]
Abstract
Strontium isotope ratios (87Sr/86Sr) allow researchers to track changes in mobility throughout an animal's life and could theoretically be used to reconstruct sex-biases in philopatry and dispersal patterns in primates. Dispersal patterns are a life-history variable that correlate with numerous aspects of behaviour and socio-ecology that are elusive in the fossil record. The present study demonstrates that the standard archaeological method used to differentiate between 'local' and 'non-local' individuals, which involves comparing faunal isotopic ratios with environmental isotopic minima and maxima, is not always reliable; aspects of primate behaviour, local environments, geologic heterogeneity and the availability of detailed geologic maps may compromise its utility in certain situations. This study instead introduces a different methodological approach: calculating offset values to compare 87Sr/86Sr of teeth with that of bone or local environments. We demonstrate this method's effectiveness using data from five species of primates, including chimpanzees, from Kibale National Park, Uganda. Tooth-to-bone offsets reliably indicate sex-biases in dispersal for primates with small home ranges while tooth-to-environment offset comparisons are more reliable for primates with larger home ranges. Overall, tooth-to-environment offsets yield the most reliable predictions of species' sex-biases in dispersal.
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Affiliation(s)
- Marian I. Hamilton
- Department of Anthropology, University of Northern Colorado, Greeley, CO, 80639-6900, USA
- Department of Anthropology, University of New Mexico, Albuquerque, NM, 87111, USA
| | - Diego P. Fernandez
- Department of Geology and Geochemistry, University of Utah, Salt Lake City, UT, USA
| | - Sherry V. Nelson
- Department of Anthropology, University of New Mexico, Albuquerque, NM, 87111, USA
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3
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Baxter A, Wood EK, Witczak LR, Bales KL, Higley JD. Sexual Dimorphism in Titi Monkeys' Digit (2D:4D) Ratio is Associated with Maternal Urinary Sex Hormones During Pregnancy. Dev Psychobiol 2020; 62:979-991. [PMID: 31372988 PMCID: PMC7871332 DOI: 10.1002/dev.21899] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 06/15/2019] [Accepted: 06/28/2019] [Indexed: 12/23/2022]
Abstract
The second-to-fourth digit (2D:4D) ratio is a sexually-dimorphic biomarker for prenatal sex hormone exposure. We investigated whether titi monkeys (Plecturocebus cupreus) exhibit sexually-dimorphic 2D:4D ratio, and whether variation in 2D:4D ratio correlates with maternal testosterone and estrogen levels during early pregnancy. Subjects were 61 adult titi monkeys (32 males, 29 females). For 26 subjects, maternal urine samples were collected approximately 15-20 weeks before birth and assayed for testosterone and estrone conjugate (E1 C). Titi monkeys exhibited a human-like pattern of sexual dimorphism in right-hand 2D:4D ratio, with females exhibiting higher 2D:4D ratio than males (β = -0.29, p = 0.023). For left-hand 2D:4D ratio, high levels of maternal E1 C predicted low offspring 2D:4D ratio (β = -0.48, p = 0.009). For right-hand 2D:4D ratio, high levels of testosterone (β = -0.53, p = 0.005) and testosterone-to-E1 C ratio (β = -0.41, p = 0.028) predicted low offspring 2D:4D ratio. For 2D:4D ratio asymmetry (right-hand - left-hand), high levels of testosterone (β = -0.43, p = 0.03) and testosterone-to-E1 C ratio (β = -0.53, p = 0.003) predicted low (right-biased) asymmetry. This is the first report of sexually-dimorphic 2D:4D ratio in New World monkeys, and the results support a growing literature suggesting prenatal sex hormones may modulate offspring 2D:4D ratio.
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Affiliation(s)
- Alexander Baxter
- Department of Psychology, Brigham Young University, Provo, Utah
- Department of Psychology, University of California, Davis, California
- California National Primate Research Center, Davis, California
| | | | - Lynea R Witczak
- Department of Psychology, University of California, Davis, California
- California National Primate Research Center, Davis, California
| | - Karen L Bales
- Department of Psychology, University of California, Davis, California
- California National Primate Research Center, Davis, California
| | - J Dee Higley
- Department of Psychology, Brigham Young University, Provo, Utah
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4
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Wood EK, Jarman P, Cash E, Baxter A, Capitanio JP, Higley JD. Masculinized Second-to-Fourth Digit Ratio (2D:4D Ratio) Is Associated With Lower Cortisol Response in Infant Female Rhesus Monkeys ( Macaca mulatta). Front Behav Neurosci 2020; 14:94. [PMID: 33088262 PMCID: PMC7497207 DOI: 10.3389/fnbeh.2020.00094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 05/18/2020] [Indexed: 01/02/2023] Open
Abstract
The second-to-fourth digit ratio (2D:4D ratio) is considered a postnatal proxy measure for the degree of prenatal androgen exposure (PAE), which is the primary factor responsible for masculinizing the brain of a developing fetus. Some studies suggest that the organizational effects of PAE may extend to the hypothalamic-pituitary-adrenal (HPA) axis response to stress. This study investigates the relationship between 2D:4D ratio and HPA axis functioning using a rhesus monkey (Macaca mulatta) model. Subjects were N = 268 (180 females, 88 males) rhesus monkey infants (3–4 months of age). Plasma cortisol concentrations were assayed from two blood samples obtained during a 25-h experimental social separation stressor at 2- and 7-h post-separation. Subjects’ 2D:4D ratio was measured later in life (Mage = 6.70 years). It was hypothesized that infant rhesus monkeys that exhibited a more masculine-like 2D:4D ratio would show lower levels of circulating cortisol after a social separation and relocation stressor. The results showed that there was a sex difference in the left-hand 2D:4D ratio. The results also showed that there was an overall sex difference in cortisol concentrations and that female, but not male, monkeys that exhibited a more masculine-like right- and left-hand 2D:4D ratio exhibited lower mean stress-induced cortisol concentrations early in life. These findings suggest that higher levels of prenatal androgens in females, as measured by 2D:4D ratio, may be related to an attenuated HPA axis stress-response, as measured by plasma cortisol levels. To the extent that these findings generalize to humans, they suggest that the organizational effects of PAE extend to the infant HPA axis, modulating the HPA axis response, particularly in females.
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Affiliation(s)
- Elizabeth K Wood
- Department of Psychology, Brigham Young University, Provo, UT, United States
| | - Parker Jarman
- Department of Psychology, Brigham Young University, Provo, UT, United States
| | - Elysha Cash
- Department of Psychology, Brigham Young University, Provo, UT, United States
| | - Alexander Baxter
- Department of Psychology, University of California, Davis, Davis, CA, United States.,California National Primate Research Center (CNPRC), Davis, CA, United States
| | - John P Capitanio
- Department of Psychology, University of California, Davis, Davis, CA, United States.,California National Primate Research Center (CNPRC), Davis, CA, United States
| | - J Dee Higley
- Department of Psychology, Brigham Young University, Provo, UT, United States
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5
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Kaczmarski M, Ziemblińska K, Tryjanowski P. Sand lizards Lacerta agilis with higher digit ratios are more likely to autotomy. J Anat 2020; 237:1103-1113. [PMID: 32659045 DOI: 10.1111/joa.13277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 05/16/2020] [Accepted: 06/18/2020] [Indexed: 12/21/2022] Open
Abstract
Digit ratio is a morphological feature regarded as a biomarker of the balance of sex hormones during early development. The exposure of embryos to a set of sex hormones and the mutual relations between those hormones cause the emergence of individual morphological and/or behavioural characteristics as well as differences between sexes. We have thus hypothesised that differences in one of these morphological traits-digit ratio-may be a proxy representing a tendency towards tail autotomy. The aim of this study is to investigate the digit ratio (2D:3D, 2D:4D, 3D:4D) of the sand lizard, Lacerta agilis, Lacertidae, a species characterised by well-developed sexual dimorphism, whereby females are larger than males. We also tested associations between patterns in digit ratio and caudal autotomy, a common defensive mechanism among lizards. To our knowledge, the relationship between a tendency towards autotomy and digit ratio pattern has never been researched. To date, studies on autotomy have mainly focused on the consequences, costs or evolutionary background of tail loss. Hence, researchers examined mostly the frequency of autotomy in the context of predatory pressure or habitat conditions, omitting an individual's behavioural tendency to shed its tail. However, behavioural traits can affect an individual's exposure to predator attack and consequently the need to use an anti-predator strategy. Thus, following this logic, dropping the tail may be the result of the lizard's intraspecific personality characteristics, resulting from the effect of hormones on behaviour or innate traits. Therefore, we suggest that the inclusion of autotomy as a factor explaining observed digit ratio patterns and their variability between taxa has great potential. We used computerised measurements of photographed limbs to determine the length of digits. We found that the digit ratios for all four limbs were significantly lower in females than in males, excluding the 3D:4D ratio for the right hindlimbs. Therefore, the results confirmed the pattern already observed for most lizards. The novel element in our study is the detection of the relationship between a tendency towards caudal autotomy and digit ratio. Individuals with a tendency towards autotomy have a higher 2D:4D ratio in the right forelimbs and a lower 2D:3D ratio in the right hindlimbs. Obtained results suggest that these morphological characteristics are most likely related to intraspecific differences (between bold and shy individuals) which consequently may determine an individual's reaction or susceptibility to be a prey and escape behaviour. Thus, our results are probably the first attempt to link digit ratio to the susceptibility of lizards to tail autotomy.
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Affiliation(s)
- Mikołaj Kaczmarski
- Institute of Zoology, Poznań University of Life Sciences, Poznań, Poland
| | - Klaudia Ziemblińska
- Department of Meteorology, Poznań University of Life Sciences, Poznań, Poland
| | - Piotr Tryjanowski
- Institute of Zoology, Poznań University of Life Sciences, Poznań, Poland.,Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Prague 6, Czech Republic
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6
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Teichroeb JA, Stead SM, Edwards PD, Landry F, Palme R, Boonstra R. Anogenital distance as a measure of male competitive ability in Rwenzori Angolan colobus. Am J Primatol 2020; 82:e23111. [PMID: 32083334 DOI: 10.1002/ajp.23111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 01/15/2020] [Accepted: 02/09/2020] [Indexed: 01/08/2023]
Abstract
Anogenital distance (AGD) is positively correlated to fetal androgen exposure and developmental masculinization in mammals. Independent of overall body size, AGD shows a strong positive correlation with male fertility and in rodents, AGD is a good indicator of male competitive ability and is associated with female choice. We hypothesized that AGD will also predict male competitive ability in non-human primates. To test this, we measured AGD noninvasively with a parallel laser in a wild population of Angolan colobus monkeys (Colobus angolensis ruwenzorii) in Uganda and correlated to it to their social structure. C. angolensis ruwenzorii form a multilevel society with both one-male/multifemale units (OMUs) and multimale/multifemale units (MMUs). We compared AGD in males from five OMUs and six MMUs and related it to their fecal androgen metabolite concentrations, dominance rank and body size, and to the number of females in their unit. Males in OMUs had greater access to females, so were predicted to have longer AGDs, but this was not found. AGD also did not correlate overall with mean fecal androgen metabolites in MMUs. However, AGD was correlated with dominance rank in MMUs, demonstrating that higher-ranking males in these multimale units had longer AGDs. Body size did not show the same relationship with dominance rank, suggesting that male rank was not just a reflection of absolute male size. Our findings indicate that AGD predicts male competitive ability in this species and that it may be a useful correlate throughout the non-human primates. These results also support the idea that prenatal androgen exposure increases the likelihood of the expression of behaviors that maintain high dominance rank.
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Affiliation(s)
- Julie A Teichroeb
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Samantha M Stead
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Phoebe D Edwards
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Florence Landry
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Rupert Palme
- Unit of Physiology, Pathophysiology and Experimental Endocrinology, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Rudy Boonstra
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
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7
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Paukner A. Digit ratio (2D:4D) and its behavioral correlates in infant rhesus macaques (Macaca mulatta). Dev Psychobiol 2019; 62:992-998. [PMID: 31512755 DOI: 10.1002/dev.21917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 08/16/2019] [Accepted: 08/17/2019] [Indexed: 11/11/2022]
Abstract
2D:4D ratios are typically lower in adult human males than females and are linked to numerous sex-differentiated behaviors. 2D:4D ratios are considered an indicator of prenatal androgen exposure; if so, children's 2D:4D ratios would arguably be even better indicators of prenatal androgen exposure since children have experienced fewer postnatal influences than adults. However, sex differences in 2D:4D ratios as well as associations between 2D:4D ratios and sex-typed behaviors in children have been inconsistent. Several studies also report sex differences and behavioral correlates of 2D:4D ratios in adult non-human primates, but little is known about 2D:4D ratios in infant non-human primates. This study examined sex differences in 2D:4D ratios over the first month of life, and associations with behavioral outcomes at 12-24 weeks of age, in N = 304 infant rhesus macaques. An increase in 2D:4D ratios over the first month of life was found, as well as associations with aggression and play behaviors, but no sex differences in 2D:4D ratios were observed. These results highlight the need for future developmental studies of 2D:4D ratios in order to determine not only their stability and predictive value, but also to discern the mechanism connecting prenatal androgen exposure, 2D:4D ratios, and behavioral outcomes.
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Affiliation(s)
- Annika Paukner
- Psychology Department, Nottingham Trent University, Nottingham, UK
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8
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Li W, Luo LY, Yang X, He Y, Lian B, Qu CH, Wu QY, Zhang JG, Xie P. Depressed female cynomolgus monkeys (Macaca fascicularis) display a higher second-to-fourth (2D:4D) digit ratio. Zool Res 2019; 40:219-225. [PMID: 31011132 PMCID: PMC6591159 DOI: 10.24272/j.issn.2095-8137.2019.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
This research aimed to provide evidence of a relationship between digit ratio and depression status in the cynomolgus monkey (Macaca fascicularis). In stable cynomolgus monkey social groups, we selected 15 depressed monkeys based on depressive-like behavioral criteria and 16 normal control monkeys. All animals were video recorded for two weeks, with the duration and frequency of the core depressive behaviors and 58 other behaviors in 12 behavioral categories then evaluated via behavioral analysis. Finger lengths from the right and left forelimb hands of both groups were measured by X-ray imaging. Finger length and digit ratio comparisons between the two groups were conducted using Student’s t-test. In terms of the duration of each behavior, significant differences emerged in “Huddling” and five other behavioral categories, including Ingestive, Amicable, Parental, Locomotive, and Resting. In addition to the above five behavioral categories, we found that depressed monkeys spent less time in parental and rubbing back and forth behaviors than the control group. Furthermore, the 4th fingers were significantly longer in the left and right hands in the control group relative to the depressed monkeys. The second-to-fourth (2D:4D) digit ratio in the left and right forelimb hands was significantly lower in the control group than that in the depressed group. Our findings revealed significant differences in finger lengths and digit ratios between depressed monkeys and healthy controls, which concords with our view that relatively high fetal testosterone exposure may be a protective factor against developing depressive symptoms (or that low fetal testosterone exposure is a risk factor).
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Affiliation(s)
- Wei Li
- Department of Neurology, Army Medical Center of PLA, Chongqing 400042, China.,Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Neurobiology of Chongqing Medical University, Chongqing 400016, China
| | - Ling-Yun Luo
- Department of Neurology, the Third Affiliated Hospital of Sun Yat-Sen Universlty Yuedong Hospital, Guangzhou Guangdong 514700, China
| | - Xun Yang
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Neurobiology of Chongqing Medical University, Chongqing 400016, China
| | - Yong He
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Neurobiology of Chongqing Medical University, Chongqing 400016, China
| | - Bin Lian
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Neurobiology of Chongqing Medical University, Chongqing 400016, China
| | - Chao-Hua Qu
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Neurobiology of Chongqing Medical University, Chongqing 400016, China
| | - Qing-Yuan Wu
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China
| | - Jian-Guo Zhang
- Chongqing Key Laboratory of Neurobiology of Chongqing Medical University, Chongqing 400016, China
| | - Peng Xie
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, China.,Chongqing Key Laboratory of Neurobiology of Chongqing Medical University, Chongqing 400016, China
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9
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Baxter A, Wood EK, Jarman P, Cameron AN, Capitanio JP, Higley JD. Sex Differences in Rhesus Monkeys' Digit Ratio (2D:4D Ratio) and Its Association With Maternal Social Dominance Rank. Front Behav Neurosci 2018; 12:213. [PMID: 30297989 PMCID: PMC6160532 DOI: 10.3389/fnbeh.2018.00213] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 08/27/2018] [Indexed: 01/30/2023] Open
Abstract
Prenatal androgen exposure (PAE) plays a pivotal role in masculinizing the developing body and brain, and extreme exposure may contribute to autism, anxiety disorder and schizophrenia. One commonly used biomarker for PAE is the pointer-to-ring-finger digit length (2D:4D) ratio. Although this biomarker is widely used in human studies, relatively few studies have investigated 2D:4D ratio in nonhuman primates, particularly rhesus macaques (Macaca mulatta), one of the most commonly used animals in biomedical research. Thus far, data suggest that sexual dimorphism in 2D:4D ratio may be in the opposite direction in some monkey species, when compared to the pattern exhibited by humans and great apes. Using a large sample size, we investigated whether rhesus monkeys' 2D:4D ratio shows the same sex-differentiated pattern present in other Old World monkey species. We also investigated whether individual differences in 2D:4D ratio are associated with the social dominance rank of subjects' mothers during pregnancy, and the social dominance rank the subjects attained as adults. Subjects were 335 rhesus monkeys between 3 years and 24 years of age (M = 6.6). Maternal dominance rank during pregnancy and subjects' adult dominance rank were categorized into tertiles (high, middle and low). Results showed that, across both hands, male rhesus monkeys exhibited higher 2D:4D ratio than females, a pattern consistent with other monkey species and a reversal from the pattern typically observed in humans and apes. This sex difference was modulated by maternal dominance rank, with female offspring of high-ranking and middle-ranking mothers exhibiting masculinized 2D:4D ratio, indicating that maternal dominance rank during pregnancy may influence levels of PAE. There was no association between subjects' 2D:4D ratio and the social dominance rank they attained as adults. These findings show a consistent sex difference in Old World monkeys' 2D:4D ratio that diverges from the pattern observed in apes and humans, and suggest maternal social dominance rank modulates PAE in rhesus monkeys.
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Affiliation(s)
- Alexander Baxter
- Department of Psychology, Brigham Young University, Provo, UT, United States
| | - Elizabeth K. Wood
- Department of Psychology, Brigham Young University, Provo, UT, United States
| | - Parker Jarman
- Department of Psychology, Brigham Young University, Provo, UT, United States
| | - Ashley N. Cameron
- California National Primate Research Center (CNPRC), Davis, CA, United States
| | - John P. Capitanio
- California National Primate Research Center (CNPRC), Davis, CA, United States
- Department of Psychology, University of California, Davis, Davis, CA, United States
| | - J. Dee Higley
- Department of Psychology, Brigham Young University, Provo, UT, United States
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10
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Selected Psychological Aspects of Meat Consumption-A Short Review. Nutrients 2018; 10:nu10091301. [PMID: 30223443 PMCID: PMC6165406 DOI: 10.3390/nu10091301] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/10/2018] [Accepted: 09/12/2018] [Indexed: 01/01/2023] Open
Abstract
Eating meat is deeply entrenched in Western culture. It is often associated with wealth and a highly nutritional diet; and for many people it is also an established habit that is difficult to change. The second half of the 20th century was a period of rapid growth in meat consumption, which resulted in intensified meat production. At the same time, eating meat has recently become subject to criticism for health-related, environmental or humanitarian reasons. This review aims to signal the potential consequences of a change of diet or switching to diets that are rich/poor in certain ingredients on the functioning of the hormonal and nervous system, which translates into changes in mood and behavior. This paper discusses the psychological phenomena which underlie the difficulty of changing one's food preferences and problems encountered while adding new products to the daily diet. Finally, this study summarizes the limitations of modifying eating habits that have resulted from established attitudes and habits.
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11
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Huber HF, Li C, Nathanielsz PW. 2D:4D digit ratio is not a biomarker of developmental programming in baboons (Papio hamadryas species). J Med Primatol 2018; 47:78-80. [PMID: 29034475 PMCID: PMC5771970 DOI: 10.1111/jmp.12318] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2017] [Indexed: 01/18/2023]
Abstract
We hypothesized second-to-fourth hand digit ratio (2D:4D) is a biomarker of developmental programming in 3 baboon groups: intrauterine growth restriction (7 females, 8 males), exposure during fetal life to synthetic glucocorticoids (4 females, 5 males), and controls (66 females, 20 males). 2D:4D was similar between sexes and groups.
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Affiliation(s)
- Hillary F. Huber
- Department of Animal Science, University of Wyoming, Laramie, WY, USA
| | - Cun Li
- Department of Animal Science, University of Wyoming, Laramie, WY, USA
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Peter W. Nathanielsz
- Department of Animal Science, University of Wyoming, Laramie, WY, USA
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA
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12
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Falcon RG. Stay, stray or something in-between? A comment on Wlodarski et al. Biol Lett 2018; 12:rsbl.2015.1069. [PMID: 27220857 DOI: 10.1098/rsbl.2015.1069] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 03/08/2016] [Indexed: 11/12/2022] Open
Affiliation(s)
- Rachael G Falcon
- Department of Psychology, University of New Mexico, Albuquerque, NM 87131, USA
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13
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Modlinska K, Pisula W. Exploratory Analysis of the Links among Food Consumption Profiles, Prenatal Androgens, and Selected Measures of Quality of Life. Front Public Health 2016; 4:240. [PMID: 27833908 PMCID: PMC5080284 DOI: 10.3389/fpubh.2016.00240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 10/13/2016] [Indexed: 11/13/2022] Open
Abstract
Prenatal sex steroids play a vital role in the development of the whole organism, and therefore also the brain. Exposure of the fetus to testosterone seems to be of special importance both for typical development and pathology. The key factor impacting offspring development (including prenatal androgen levels) appears to be diet, both in terms of shortage and excessive intake of certain food products. Prenatal steroid levels are measured using the ratio of the lengths of the second and fourth fingers (2D:4D). So far, the digit ratio (2D:4D) has been shown to correlate negatively with prenatal testosterone and positively with prenatal estrogen. Numerous correlational studies found relationships between the 2D:4D phenotype and differences in magnitude of many psychological traits. Certain social and demographic variables also correlate with the digit ratio. The present paper offers a preliminary analysis of correlations between diet, prenatal hormones’ levels (established based on the digit ratio), and selected social variables. One of the findings is that countries with high meat consumption present the so-called masculine digit ratio, while countries with plant-based diets – a feminine digit ratio.
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Affiliation(s)
- Klaudia Modlinska
- Institute of Psychology, Polish Academy of Sciences , Warsaw , Poland
| | - Wojciech Pisula
- Institute of Psychology, Polish Academy of Sciences , Warsaw , Poland
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14
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Ryckmans J, Millet K, Warlop L. The Influence of Facial Characteristics on the Relation between Male 2D:4D and Dominance. PLoS One 2015; 10:e0143307. [PMID: 26600255 PMCID: PMC4657903 DOI: 10.1371/journal.pone.0143307] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 11/02/2015] [Indexed: 11/19/2022] Open
Abstract
Although relations between 2D:4D and dominance rank in both baboons and rhesus macaques have been observed, evidence in humans is mixed. Whereas behavioral patterns in humans have been discovered that are consistent with these animal findings, the evidence for a relation between dominance and 2D:4D is weak or inconsistent. The present study provides experimental evidence that male 2D:4D is related to dominance after (fictitious) male-male interaction when the other man has a dominant, but not a submissive or neutral face. This finding provides evidence that the relationship between 2D:4D and dominance emerges in particular, predictable situations and that merely dominant facial characteristics of another person are enough to activate supposed relationships between 2D:4D and dominance.
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Affiliation(s)
- Jan Ryckmans
- Faculty of Economics and Business, Research Center for Marketing and Consumer Science, KU Leuven, Leuven, Belgium
| | - Kobe Millet
- Department of Marketing, VU University Amsterdam, Amsterdam, Netherlands
- * E-mail:
| | - Luk Warlop
- Faculty of Economics and Business, Research Center for Marketing and Consumer Science, KU Leuven, Leuven, Belgium
- Department of Marketing, BI Norwegian Business School, Oslo, Norway
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15
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Wlodarski R, Manning J, Dunbar RIM. Stay or stray? Evidence for alternative mating strategy phenotypes in both men and women. Biol Lett 2015; 11:20140977. [PMID: 25652222 PMCID: PMC4360109 DOI: 10.1098/rsbl.2014.0977] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In all comparative analyses, humans always fall on the borderline between obligate monogamy and polygamy. Here, we use behavioural indices (sociosexuality) and anatomical indices (prenatal testosterone exposure indexed by 2D : 4D digit ratio) from three human populations to show that this may be because there are two distinct phenotypes in both sexes. While males are more promiscuous and display higher prenatal testosterone exposure than females overall, our analyses also suggest that the within-sex variation of these variables is best described by two underlying mixture models, suggesting the presence of two phenotypes with a monogamous/promiscuous ratio that slightly favours monogamy in females and promiscuity in males. The presence of two phenotypes implies that mating strategy might be under complex frequency-dependent selection.
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Affiliation(s)
- Rafael Wlodarski
- Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, UK
| | - John Manning
- Department of Psychology, Northumbria University, Newcastle-upon-Tyne, UK
| | - R I M Dunbar
- Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, UK
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16
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Manning J, Kilduff L, Cook C, Crewther B, Fink B. Digit Ratio (2D:4D): A Biomarker for Prenatal Sex Steroids and Adult Sex Steroids in Challenge Situations. Front Endocrinol (Lausanne) 2014; 5:9. [PMID: 24523714 PMCID: PMC3906590 DOI: 10.3389/fendo.2014.00009] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 01/16/2014] [Indexed: 11/13/2022] Open
Abstract
Digit ratio (2D:4D) denotes the relative length of the second and fourth digits. This ratio is considered to be a biomarker of the balance between fetal testosterone (T) and estrogen (E) in a narrow window of early ontogeny. Evidence for this assertion is derived from direct and indirect measures of prenatal hormonal exposure (in experimental animals, via amniotic fluid samples and in the study of sex-typical traits) in relation to 2D:4D. In contrast, the relationships between 2D:4D and levels of sex steroids in adults are less clear, as many correlational studies of 2D:4D and adult sex steroids have concluded that this association is statistically non-significant. Here, we suggest that in order to understand the link between 2D:4D and sex hormones, one must consider both fetal organizing and adult activating effects of T and E. In particular, we hypothesize that 2D:4D correlates with organizing effects on the endocrine system that moderate activating effects in adulthood. We argue that this is particularly evident in "challenging" conditions such as aggressive and sexual encounters, in which individuals show increased levels of T. We discuss this refinement of the 2D:4D paradigm in relation to the links between 2D:4D and sports performance, and aggression.
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Affiliation(s)
- John Manning
- Department of Psychology, Northumbria University, Newcastle upon Tyne, UK
- *Correspondence: John Manning, Department of Psychology, Northumbria University, Newcastle upon Tyne NE1 8ST, UK e-mail:
| | - Liam Kilduff
- Applied Sports Technology, Exercise and Medicine Research Centre, Swansea University, Swansea, UK
| | - Christian Cook
- School of Sport, Health and Exercise Science, Bangor University, Gwynedd, UK
| | | | - Bernhard Fink
- Department of Biological Personality Psychology and Assessment, University of Göttingen, Göttingen, Germany
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17
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Abbott AD, Colman RJ, Tiefenthaler R, Dumesic DA, Abbott DH. Early-to-mid gestation fetal testosterone increases right hand 2D:4D finger length ratio in polycystic ovary syndrome-like monkeys. PLoS One 2012; 7:e42372. [PMID: 22927929 PMCID: PMC3425513 DOI: 10.1371/journal.pone.0042372] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 07/05/2012] [Indexed: 01/03/2023] Open
Abstract
A smaller length ratio for the second relative to the fourth finger (2D:4D) is repeatedly associated with fetal male-typical testosterone (T) and is implicated as a biomarker for a variety of traits and susceptibility to a number of diseases, but no experimental human studies have been performed. The present study utilizes the rhesus monkey, a close relative of humans, and employs discrete gestational exposure of female monkeys to fetal male-typical T levels for 15-35 days during early-to-mid (40-76 days; n = 7) or late (94-139 days; n = 7) gestation (term: 165 days) by daily subcutaneous injection of their dams with 10 mg T propionate. Such gestational exposures are known to enhance male-typical behavior. In this study, compared to control females (n = 19), only early-to-mid gestation T exposure virilizes female external genitalia while increasing 2D:4D ratio in the right hand (RH) by male-like elongation of RH2D. RH2D length and 2D:4D positively correlate with androgen-dependent anogenital distance (AG), and RH2D and AG positively correlate with duration of early-to-mid gestation T exposure. Male monkeys (n = 9) exhibit a sexually dimorphic 2D:4D in the right foot, but this trait is not emulated by early-to-mid or late gestation T exposed females. X-ray determined phalanx measurements indicate elongated finger and toe phalanx length in males, but no other phalanx-related differences. Discrete T exposure during early-to-mid gestation in female rhesus monkeys thus appears to increase RH2D:4D through right-side biased, non-skeletal tissue growth. As variation in timing and duration of gestational T exposure alter male-like dimensions of RH2D independently of RH4D, postnatal RH2D:4D provides a complex biomarker for fetal T exposure.
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Affiliation(s)
- Andrew D Abbott
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, Wisconsin, United States of America.
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18
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Ferdenzi C, Lemaître JF, Leongómez JD, Roberts SC. Digit ratio (2D:4D) predicts facial, but not voice or body odour, attractiveness in men. Proc Biol Sci 2011; 278:3551-7. [PMID: 21508034 DOI: 10.1098/rspb.2011.0544] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
There is growing evidence that human second-to-fourth digit ratio (or 2D:4D) is related to facial features involved in attractiveness, mediated by in utero hormonal effects. The present study extends the investigation to other phenotypic, hormone-related determinants of human attractiveness: voice and body odour. Pictures of faces with a neutral expression, recordings of voices pronouncing vowels and axillary odour samples captured on cotton pads worn for 24 h were provided by 49 adult male donors. These stimuli were rated on attractiveness and masculinity scales by two groups of 49 and 35 females, approximately half of these in each sample using hormonal contraception. Multivariate regression analyses showed that males' lower (more masculine) right 2D:4D and lower right-minus-left 2D:4D (Dr-l) were associated with a more attractive (and in some cases more symmetrical), but not more masculine, face. However, 2D:4D and Dr-l did not predict voice and body odour masculinity or attractiveness. The results were interpreted in terms of differential effects of prenatal and circulating testosterone, male facial shape being supposedly more dependent on foetal levels (reflected by 2D:4D ratio), whereas body odour and vocal characteristics could be more dependent on variation in adult circulating testosterone levels.
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Affiliation(s)
- Camille Ferdenzi
- Swiss Centre for Affective Sciences, University of Geneva, 7 rue des Battoirs, 1205 Geneva, Switzerland.
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19
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Nelson E, Rolian C, Cashmore L, Shultz S. Digit ratios predict polygyny in early apes, Ardipithecus, Neanderthals and early modern humans but not in Australopithecus. Proc Biol Sci 2010; 278:1556-63. [PMID: 21047863 DOI: 10.1098/rspb.2010.1740] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Social behaviour of fossil hominoid species is notoriously difficult to predict owing to difficulties in estimating body size dimorphism from fragmentary remains and, in hominins, low canine size dimorphism. Recent studies have shown that the second-to-fourth digit ratio (2D : 4D), a putative biomarker for prenatal androgen effects (PAEs), covaries with intra-sexual competition and social systems across haplorrhines; non-pair-bonded polygynous taxa have significantly lower 2D : 4D ratios (high PAE) than pair-bonded monogamous species. Here, we use proximal phalanx ratios of extant and fossil specimens to reconstruct the social systems of extinct hominoids. Pierolapithecus catalaunicus, Hispanopithecus laietanus and Ardipithecus ramidus have ratios consistent with polygynous extant species, whereas the ratio of Australopithecus afarensis is consistent with monogamous extant species. The early anatomically modern human Qafzeh 9 and Neanderthals have lower digit ratios than most contemporary human populations, indicating increased androgenization and possibly higher incidence of polygyny. Although speculative owing to small sample sizes, these results suggest that digit ratios represent a supplementary approach for elucidating the social systems of fossil hominins.
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Affiliation(s)
- Emma Nelson
- School of Archaeology, Classics and Egyptology, University of Liverpool, Hartley Building, Brownlow Street, Liverpool L69 3GS, UK.
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