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Gómez-Robles A, Nicolaou C, Smaers JB, Sherwood CC. The evolution of human altriciality and brain development in comparative context. Nat Ecol Evol 2024; 8:133-146. [PMID: 38049480 PMCID: PMC10781642 DOI: 10.1038/s41559-023-02253-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 10/18/2023] [Indexed: 12/06/2023]
Abstract
Human newborns are considered altricial compared with other primates because they are relatively underdeveloped at birth. However, in a broader comparative context, other mammals are more altricial than humans. It has been proposed that altricial development evolved secondarily in humans due to obstetrical or metabolic constraints, and in association with increased brain plasticity. To explore this association, we used comparative data from 140 placental mammals to measure how altriciality evolved in humans and other species. We also estimated how changes in brain size and gestation length influenced the timing of neurodevelopment during hominin evolution. Based on our data, humans show the highest evolutionary rate to become more altricial (measured as the proportion of adult brain size at birth) across all placental mammals, but this results primarily from the pronounced postnatal enlargement of brain size rather than neonatal changes. In addition, we show that only a small number of neurodevelopmental events were shifted to the postnatal period during hominin evolution, and that they were primarily related to the myelination of certain brain pathways. These results indicate that the perception of human altriciality is mostly driven by postnatal changes, and they point to a possible association between the timing of myelination and human neuroplasticity.
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Affiliation(s)
- Aida Gómez-Robles
- Department of Anthropology, University College London, London, UK.
- Department of Genetics, Evolution and Environment, University College London, London, UK.
| | | | - Jeroen B Smaers
- Department of Anthropology, Stony Brook University, Stony Brook, NY, USA
| | - Chet C Sherwood
- Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, DC, USA
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Bard KA, Keller H, Ross KM, Hewlett B, Butler L, Boysen ST, Matsuzawa T. Joint Attention in Human and Chimpanzee Infants in Varied Socio-Ecological Contexts. Monogr Soc Res Child Dev 2022; 86:7-217. [PMID: 35355281 DOI: 10.1111/mono.12435] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Joint attention (JA) is an early manifestation of social cognition, commonly described as interactions in which an infant looks or gestures to an adult female to share attention about an object, within a positive emotional atmosphere. We label this description the JA phenotype. We argue that characterizing JA in this way reflects unexamined assumptions which are, in part, due to past developmental researchers' primary focus on western, middle-class infants and families. We describe a range of cultural variations in caregiving practices, socialization goals, and parenting ethnotheories as an essential initial step in viewing joint attention within inclusive and contextualized perspectives. We begin the process of conducting a decolonized study of JA by considering the core construct of joint attention (i.e., triadic connectedness) and adopting culturally inclusive definitions (labeled joint engagement [JE]). Our JE definitions allow for attention and engagement to be expressed in visual and tactile modalities (e.g., for infants experiencing distal or proximal caregiving), with various social partners (e.g., peers, older siblings, mothers), with a range of shared topics (e.g., representing diverse socialization goals, and socio-ecologies with and without toys), and with a range of emotional tone (e.g., for infants living in cultures valuing calmness and low arousal, and those valuing exuberance). Our definition of JE includes initiations from either partner (to include priorities for adult-led or child-led interactions). Our next foundational step is making an ecological commitment to naturalistic observations (Dahl, 2017, Child Dev Perspect, 11(2), 79-84): We measure JE while infants interact within their own physical and social ecologies. This commitment allows us to describe JE as it occurs in everyday contexts, without constraints imposed by researchers. Next, we sample multiple groups of infants drawn from diverse socio-ecological settings. Moreover, we include diverse samples of chimpanzee infants to compare with diverse samples of human infants, to investigate the extent to which JE is unique to humans, and to document diversity both within and between species. We sampled human infants living in three diverse settings. U.K. infants (n = 8) were from western, middle-class families living near universities in the south of England. Nso infants (n = 12) were from communities of subsistence farmers in Cameroon, Africa. Aka infants (n = 10) were from foraging communities in the tropical rain forests of Central African Republic, Africa. We coded behavioral details of JE from videotaped observations (taken between 2004 and 2010). JE occurred in the majority of coded intervals (Mdn = 68%), supporting a conclusion that JE is normative for human infants. The JA phenotype, in contrast, was infrequent, and significantly more common in the U.K. (Mdn = 10%) than the other groups (Mdn < 3%). We found significant within-species diversity in JE phenotypes (i.e., configurations of predominant forms of JE characteristics). We conclude that triadic connectedness is very common in human infants, but there is significant contextualization of behavioral forms of JE. We also studied chimpanzee infants living in diverse socio-ecologies. The PRI/Zoo chimpanzee infants (n = 7) were from captive, stable groups of mixed ages and sexes, and included 4 infants from the Chester Zoo, U.K. and 3 from the Primate Research Institute, Kyoto University, Japan. The Gombe chimpanzee infants (n = 12) were living in a dynamically changing, wild community in the Gombe National Park, Tanzania, Africa. Additionally, we include two Home chimpanzee infants who were reared from birth by a female scientist, in the combined U.S., middle-class contexts of home and university cognition laboratory. JE was coded from videotaped observations (taken between 1993 and 2006). JE occurred during the majority of coded intervals (Mdn = 64%), consistent with the position that JE is normative for chimpanzee infants. The JA phenotype, in contrast, was rare, but more commonly observed in the two Home chimpanzee infants (in 8% and 2% of intervals) than in other chimpanzee groups (Mdns = 0%). We found within-species diversity in the configurations comprising the JE phenotypes. We conclude that triadic connectedness is very common in chimpanzee infants, but behavioral forms of joint engagement are contextualized. We compared JE across species, and found no species-uniqueness in behavioral forms, JE characteristics, or JE phenotypes. Both human and chimpanzee infants develop contextualized social cognition. Within-species diversity is embraced when triadic connectedness is described with culturally inclusive definitions. In contrast, restricting definitions to the JA phenotype privileges a behavioral form most valued in western, middle-class socio-ecologies, irrespective of whether the interactions involve human or chimpanzee infants. Our study presents a model for how to decolonize an important topic in developmental psychology. Decolonization is accomplished by defining the phenomenon inclusively, embracing diversity in sampling, challenging claims of human-uniqueness, and having an ecological commitment to observe infant social cognition as it occurs within everyday socio-ecological contexts. It is essential that evolutionary and developmental theories of social cognition are re-built on more inclusive and decolonized empirical foundations.
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Affiliation(s)
- Kim A Bard
- Department of Psychology, University of Portsmouth
| | - Heidi Keller
- Department of Human Sciences, Osnabrück University
| | | | - Barry Hewlett
- Department of Anthropology, Washington State University, Vancouver
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3
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Bründl AC, Tkaczynski PJ, Nohon Kohou G, Boesch C, Wittig RM, Crockford C. Response to the commentary 'Becoming uniquely human? Comparing chimpanzee to human infancy'. Dev Sci 2021; 25:e13143. [PMID: 34196441 DOI: 10.1111/desc.13143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 06/10/2021] [Indexed: 11/30/2022]
Affiliation(s)
- Aisha C Bründl
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.,Department of Neuropsychology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.,Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
| | - Patrick J Tkaczynski
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.,Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
| | - Grégoire Nohon Kohou
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
| | - Christophe Boesch
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire.,Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Roman M Wittig
- Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire.,Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Catherine Crockford
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.,Taï Chimpanzee Project, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire.,The Great Ape Social Mind Lab, Institut des Sciences Cognitives, CNRS, Lyon, France
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Berecz B, Cyrille M, Casselbrant U, Oleksak S, Norholt H. Carrying human infants - An evolutionary heritage. Infant Behav Dev 2020; 60:101460. [PMID: 32569907 DOI: 10.1016/j.infbeh.2020.101460] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 05/21/2020] [Accepted: 06/03/2020] [Indexed: 02/08/2023]
Abstract
We propose that infant carrying is a biological norm for human caregiving, given that human infants have evolved a capacity to cling onto an upright caregiver whose body co-evolved to enable offspring carrying. The origins of this mutual adaptation may date back 4 million years, with the emergence of bipedalism, which precluded the infant horizontal and gravity-supported position on the back of a quadrupedal caregiver. We describe infant cooperative reflexes and behaviors, including the carrying-induced calming response and discuss hypotheses for the invention of infant carrier tools. Carrying involves several physiological and behavioral parent-infant co-adaptations that imply it is an evolutionarily conserved strategy. Epigenetic transmission of reproductive behavior through generations affects the development of the offspring, as well as the mental health of the parent. Carrying might have contributed to the evolution of Hominidae, potentially aiding dexterity, handedness, language acquisition, and social interactions. We review the evolutionary milestones and time points where the infant-caregiver interactions might have changed, exploring infant carrying as it intersects with biological and cultural evolution. We briefly summarize the effects of infant carrying on physiological, epigenetic, and socio-emotional outcomes.
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Affiliation(s)
- Bernadett Berecz
- Eotvos Lorand University, Institute of Biology, Pazmany Peter stny. 1/C. H-1117, Budapest, Hungary.
| | | | | | - Sarah Oleksak
- University of Maryland Eastern Shore, Lift Me Up, Inc., United States
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Bründl AC, Tkaczynski PJ, Nohon Kohou G, Boesch C, Wittig RM, Crockford C. Systematic mapping of developmental milestones in wild chimpanzees. Dev Sci 2020; 24:e12988. [DOI: 10.1111/desc.12988] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 04/17/2020] [Accepted: 05/05/2020] [Indexed: 01/29/2023]
Affiliation(s)
- Aisha C. Bründl
- Department of Human Behavior, Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig Germany
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
| | - Patrick J. Tkaczynski
- Department of Human Behavior, Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig Germany
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
| | - Grégoire Nohon Kohou
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
| | - Christophe Boesch
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
- Department of Primatology Max Planck Institute for Evolutionary Anthropology Leipzig Germany
| | - Roman M. Wittig
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
- Department of Primatology Max Planck Institute for Evolutionary Anthropology Leipzig Germany
| | - Catherine Crockford
- Department of Human Behavior, Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig Germany
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques Abidjan Côte d’Ivoire
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7
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Clay AW, Bard KA, Bloomsmith MA. Effects of sex and early rearing condition on adult behavior, health, and well-being in captive chimpanzees (Pan troglodytes). Behav Processes 2018; 156:58-76. [DOI: 10.1016/j.beproc.2017.06.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 06/29/2017] [Indexed: 02/07/2023]
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Bard KA, Hopkins WD. Early Socioemotional Intervention Mediates Long-Term Effects of Atypical Rearing on Structural Covariation in Gray Matter in Adult Chimpanzees. Psychol Sci 2018; 29:594-603. [PMID: 29381427 PMCID: PMC5902648 DOI: 10.1177/0956797617740685] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Atypical rearing has deleterious effects on chimpanzee behavior during development, some of which can be ameliorated with a responsive care intervention (RCI). Here, we obtained in vivo magnetic resonance images of adult brains of 27 chimpanzees given institutional care, with and without RCI, and compared them with those of 16 chimpanzees mother-reared from birth. We found significant long-term rearing effects on structural covariation and gray matter volume, specifically in the basal forebrain (i.e., caudate, putamen, nucleus accumbens, rectus gyrus, and orbital prefrontal cortex), indicating that RCI prevented brain changes due to atypical rearing. A significant correlation between covariation in these brain areas and caregiver nurturing, experienced in the first month of life, suggests a possible developmental mechanism for the effect of early experience on brain networks. We identified an early intervention that prevents changes in the basal forebrain that otherwise emerge as a consequence of institutionalized rearing without species-typical socioemotional experiences.
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Affiliation(s)
- Kim A Bard
- 1 Department of Psychology, University of Portsmouth
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9
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Bard KA. Dyadic interactions, attachment and the presence of triadic interactions in chimpanzees and humans. Infant Behav Dev 2017; 48:13-19. [DOI: 10.1016/j.infbeh.2016.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 11/01/2016] [Accepted: 11/01/2016] [Indexed: 10/20/2022]
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Mother-infant interactions in captive and wild chimpanzees. Infant Behav Dev 2016; 48:20-29. [PMID: 27887738 DOI: 10.1016/j.infbeh.2016.11.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 11/02/2016] [Accepted: 11/02/2016] [Indexed: 11/20/2022]
Abstract
We review studies on mother-infant interactions in chimpanzees, our closest living relatives, in captive and wild environments. Infant cognitive development is formed through mother-infant interactions during the long dependent period, which is approximately 5 years. Patterns of interaction between mothers and infants are different from those observed in adult chimpanzees. Mother-infant interactions are relatively altruistic, although solicitation by infants is almost always required. Active teaching has rarely been reported in chimpanzees; instead, infants socially learn new skills through long-term observation. Case studies describing rearing of a disabled infant by a multiparous but inexperienced chimpanzee, and the carrying of dead infants in the wild chimpanzees of Bossou reveal the strong affectionate bond between mothers and infants. Characteristics of human mother-infant interaction are highlighted through comparisons with chimpanzees.
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Primate sociality to human cooperation. Why us and not them? HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE 2015; 25:28-48. [PMID: 24307447 DOI: 10.1007/s12110-013-9184-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Developmental psychologists identify propensities for social engagement in human infants that are less evident in other apes; Sarah Hrdy links these social propensities to novel features of human childrearing. Unlike other ape mothers, humans can bear a new baby before the previous child is independent because they have help. This help alters maternal trade-offs and so imposes new selection pressures on infants and young children to actively engage their caretakers' attention and commitment. Such distinctive childrearing is part of our grandmothering life history. While consequences for other cooperative activities must surely follow, the novel rearing environments set up by helpful grandmothering can explain why natural selection escalated preferences and motivations for interactivity in our lineage in the first place, and why, unlike other aspects of infant development, social sensitivities are not delayed in humans compared with genus Pan.
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Wilson VAD, Weiss A. Social Relationships in Nonhuman Primates: Potential Models of Pervasive Disorders. ACTA ACUST UNITED AC 2014. [DOI: 10.1007/978-1-4939-2250-5_11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Abstract
It is a truism to say that primates develop, but it is also important to acknowledge that development occurs across many domains, including motor behavior, socioemotional behavior, communication, and cognition. In this review, we focus on those aspects of development that impact social cognition outcomes in infancy. Triadic engagements, such as those of joint attention, cooperation, and intentional communication, develop in the first year of life in chimpanzees and humans. Joint attention, for example, occurs when infants coordinate their attention to a social partner while also attending to an object or event. Hominoids are strongly influenced by experiences during early development, especially experiences that are foundational for these coordinated triadic engagements. Purported species differences in triadic engagements are highlighted in current evolutionary theories of primate social cognition, but conclusions about species differences are unfounded when development is ignored. Developmental experiences must be matched, controlled, or systematically varied in experimental designs that make cross-species comparisons. Considerations of development, across species and across rearing experiences, would contribute to more accurate evolutionary theories of primate social cognition.
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Affiliation(s)
- Kim A. Bard
- Psychology Department, University of Portsmouth, Portsmouth, Hampshire PO1 2DY, United Kingdom
| | - David A. Leavens
- School of Psychology, University of Sussex, Falmer, East Sussex BN1 9QH, United Kingdom
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Bard KA, Bakeman R, Boysen ST, Leavens DA. Emotional engagements predict and enhance social cognition in young chimpanzees. Dev Sci 2014; 17:682-96. [PMID: 24410843 PMCID: PMC4116479 DOI: 10.1111/desc.12145] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Accepted: 09/29/2013] [Indexed: 11/26/2022]
Abstract
Social cognition in infancy is evident in coordinated triadic engagements, that is, infants attending jointly with social partners and objects. Current evolutionary theories of primate social cognition tend to highlight species differences in cognition based on human-unique cooperative motives. We consider a developmental model in which engagement experiences produce differential outcomes. We conducted a 10-year-long study in which two groups of laboratory-raised chimpanzee infants were given quantifiably different engagement experiences. Joint attention, cooperativeness, affect, and different levels of cognition were measured in 5- to 12-month-old chimpanzees, and compared to outcomes derived from a normative human database. We found that joint attention skills significantly improved across development for all infants, but by 12 months, the humans significantly surpassed the chimpanzees. We found that cooperativeness was stable in the humans, but by 12 months, the chimpanzee group given enriched engagement experiences significantly surpassed the humans. Past engagement experiences and concurrent affect were significant unique predictors of both joint attention and cooperativeness in 5- to 12-month-old chimpanzees. When engagement experiences and concurrent affect were statistically controlled, joint attention and cooperation were not associated. We explain differential social cognition outcomes in terms of the significant influences of previous engagement experiences and affect, in addition to cognition. Our study highlights developmental processes that underpin the emergence of social cognition in support of evolutionary continuity.
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Affiliation(s)
- Kim A Bard
- Centre for Comparative and Evolutionary Psychology, University of PortsmouthUK
| | - Roger Bakeman
- Department of Psychology, Georgia State UniversityUSA
| | - Sarah T Boysen
- Centre for Comparative and Evolutionary Psychology, University of PortsmouthUK
- Department of Psychology, The Ohio State UniversityUSA
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15
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The developmental cognitive neuroscience of action: semantics, motor resonance and social processing. Exp Brain Res 2014; 232:1585-97. [DOI: 10.1007/s00221-014-3924-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 03/19/2014] [Indexed: 10/25/2022]
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