scholarly journals Understanding primate brain evolution

2007 ◽  
Vol 362 (1480) ◽  
pp. 649-658 ◽  
Author(s):  
R.I.M Dunbar ◽  
Susanne Shultz
Keyword(s):  
Life History ◽  
Path Analysis ◽  
Group Size ◽  
Brain Size ◽  
Brain Evolution ◽  
Primate Brain ◽  
The Social ◽  
Large Brain ◽  
Brain Data ◽  
The Relationship

We present a detailed reanalysis of the comparative brain data for primates, and develop a model using path analysis that seeks to present the coevolution of primate brain (neocortex) and sociality within a broader ecological and life-history framework. We show that body size, basal metabolic rate and life history act as constraints on brain evolution and through this influence the coevolution of neocortex size and group size. However, they do not determine either of these variables, which appear to be locked in a tight coevolutionary system. We show that, within primates, this relationship is specific to the neocortex. Nonetheless, there are important constraints on brain evolution; we use path analysis to show that, in order to evolve a large neocortex, a species must first evolve a large brain to support that neocortex and this in turn requires adjustments in diet (to provide the energy needed) and life history (to allow sufficient time both for brain growth and for ‘software’ programming). We review a wider literature demonstrating a tight coevolutionary relationship between brain size and sociality in a range of mammalian taxa, but emphasize that the social brain hypothesis is not about the relationship between brain/neocortex size and group size per se ; rather, it is about social complexity and we adduce evidence to support this. Finally, we consider the wider issue of how mammalian (and primate) brains evolve in order to localize the social effects.

scholarly journals The relationship between egg size and helper number in cooperative breeders: a meta-analysis across species

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4028 ◽  
Author(s):  
Tanmay Dixit ◽  
Sinead English ◽  
Dieter Lukas
Keyword(s):  
Life History ◽  
Social Environment ◽  
Group Size ◽  
Egg Size ◽  
Reproductive Investment ◽  
Maternal Investment ◽  
Differential Allocation ◽  
The Social ◽  
Cooperatively Breeding ◽  
The Relationship

BackgroundLife history theory predicts that mothers should adjust reproductive investment depending on benefits of current reproduction and costs of reduced future reproductive success. These costs and benefits may in turn depend on the breeding female’s social environment. Cooperative breeders provide an ideal system to test whether changes in maternal investment are associated with the social conditions mothers experience. As alloparental helpers assist in offspring care, larger groups might reduce reproductive costs for mothers or alternatively indicate attractive conditions for reproduction. Thus, mothers may show reduced (load-lightening) or increased (differential allocation) reproductive investment in relation to group size. A growing number of studies have investigated how cooperatively breeding mothers adjust pre-natal investment depending on group size. Our aim was to survey these studies to assess, first, whether mothers consistently reduce or increase pre-natal investment when in larger groups and, second, whether these changes relate to variation in post-natal investment.MethodsWe extracted data on the relationship between helper number and maternal pre-natal investment (egg size) from 12 studies on 10 species of cooperatively breeding vertebrates. We performed meta-analyses to calculate the overall estimated relationship between egg size and helper number, and to quantify variation among species. We also tested whether these relationships are stronger in species in which the addition of helpers is associated with significant changes in maternal and helper post-natal investment.ResultsAcross studies, there is a significant negative relationship between helper number and egg size, suggesting that in most instances mothers show reduced reproductive investment in larger groups, in particular in species in which mothers also show a significant reduction in post-natal investment. However, even in this limited sample, substantial variation exists in the relationship between helper number and egg size, and the overall effect appears to be driven by a few well-studied species.DiscussionOur results, albeit based on a small sample of studies and species, indicate that cooperatively breeding females tend to produce smaller eggs in larger groups. These findings on prenatal investment accord with previous studies showing similar load-lightening reductions in postnatal parental effort (leading to concealed helper effects), but do not provide empirical support for differential allocation. However, the considerable variation in effect size across studies suggests that maternal investment is mitigated by additional factors. Our findings indicate that variation in the social environment may influence life-history strategies and suggest that future studies investigating within-individual changes in maternal investment in cooperative breeders offer a fruitful avenue to study the role of adaptive plasticity.

scholarly journals Experts in action: why we need an embodied social brain hypothesis

2021 ◽  
Vol 377 (1844) ◽  
Author(s):  
Louise Barrett ◽  
S. Peter Henzi ◽  
Robert A. Barton
Keyword(s):  
Social Life ◽  
Cognitive Skills ◽  
Social Evolution ◽  
Brain Size ◽  
Large Body ◽  
The Body ◽  
Social Brain ◽  
Primate Brain ◽  
The Social ◽  
Large Brain

The anthropoid primates are known for their intense sociality and large brain size. The idea that these might be causally related has given rise to a large body of work testing the ‘social brain hypothesis'. Here, the emphasis has been placed on the political demands of social life, and the cognitive skills that would enable animals to track the machinations of other minds in metarepresentational ways. It seems to us that this position risks losing touch with the fact that brains primarily evolved to enable the control of action, which in turn leads us to downplay or neglect the importance of the physical body in a material world full of bodies and other objects. As an alternative, we offer a view of primate brain and social evolution that is grounded in the body and action, rather than minds and metarepresentation. This article is part of the theme issue ‘Systems neuroscience through the lens of evolutionary theory’.

scholarly journals WHATEVER YOU WANT: INCONSISTENT RESULTS IS THE RULE, NOT THE EXCEPTION, IN THE STUDY OF PRIMATE BRAIN EVOLUTION

2018 ◽  
Author(s):  
Andreas Wartel ◽  
Patrik Lindenfors ◽  
Johan Lind
Keyword(s):  
Body Size ◽  
Brain Evolution ◽  
Data Sets ◽  
Data Set ◽  
Scientific Rigor ◽  
Explanatory Variables ◽  
Primate Brain ◽  
Residual Variation ◽  
The Many ◽  
Brain Data

AbstractPrimate brains differ in size and architecture. Hypotheses to explain this variation are numerous and many tests have been carried out. However, after body size has been accounted for there is little left to explain. The proposed explanatory variables for the residual variation are many and covary, both with each other and with body size. Further, the data sets used in analyses have been small, especially in light of the many proposed predictors. Here we report the complete list of models that results from exhaustively combining six commonly used predictors of brain and neocortex size. This provides an overview of how the output from standard statistical analyses changes when the inclusion of different predictors is altered. By using both the most commonly tested brain data set and a new, larger data set, we show that the choice of included variables fundamentally changes the conclusions as to what drives primate brain evolution. Our analyses thus reveal why studies have had troubles replicating earlier results and instead have come to such different conclusions. Although our results are somewhat disheartening, they highlight the importance of scientific rigor when trying to answer difficult questions. It is our position that there is currently no empirical justification to highlight any particular hypotheses, of those adaptive hypotheses we have examined here, as the main determinant of primate brain evolution.

Social Networks and Social Complexity in Female-bonded Primates

2010 ◽  
Author(s):  
Julia Lehmann ◽  
Katherine Andrews ◽  
Robin Dunbar
Keyword(s):  
Social Network ◽  
Social Relationships ◽  
Social Complexity ◽  
Social Bonds ◽  
Primate Brain ◽  
The Social ◽  
Group Members ◽  
Primate Group ◽  
Network Metrics ◽  
The Relationship

Most primates are intensely social and spend a large amount of time servicing social relationships. The social brain hypothesis suggests that the evolution of the primate brain has been driven by the necessity of dealing with increased social complexity. This chapter uses social network analysis to analyse the relationship between primate group size, neocortex ratio and several social network metrics. Findings suggest that social complexity may derive from managing indirect social relationships, i.e. relationships in which a female is not directly involved, which may pose high cognitive demands on primates. The discussion notes that a large neocortex allows individuals to form intense social bonds with some group members while at the same time enabling them to manage and monitor less intense indirect relationships without frequent direct involvement with each individual of the social group.

scholarly journals Experience of adults with cystic fibrosis: a perspective based on social phenomenology

2018 ◽  
Vol 71 (6) ◽  
pp. 2891-2898
Author(s):  
Samara Macedo Cordeiro ◽  
Maria Cristina Pinto de Jesus ◽  
Renata Evangelista Tavares ◽  
Deise Moura de Oliveira ◽  
Miriam Aparecida Barbosa Merighi
Keyword(s):  
Cystic Fibrosis ◽  
Life History ◽  
Qualitative Study ◽  
Health Professionals ◽  
Daily Life ◽  
The Social ◽  
The World ◽  
Social Prejudice ◽  
The Relationship ◽  
Social Phenomenology

ABSTRACT Objective: To understand the experience of adults living with cystic fibrosis. Method: A qualitative study based on the social phenomenology by Alfred Schütz, carried out with 12 adults interviewed in 2016. The statements were analyzed and organized into concrete categories. Results: The following categories were evidenced: “The biopsychosocial impact of the disease on daily life”, “Social prejudice as a generator of embarrassment”, “Coping strategies” and “Fear, uncertainties and the desire to carry out life projects”. Final considerations: The understanding of the experience lived by adults with cystic fibrosis allowed unveiling intersubjective aspects experienced by this public that should be considered by health professionals in the care of this group. It is up to the professionals involved in assisting these people to develop care strategies aimed at completeness, respect for the world of meanings of each individual, their life history, and intersubjectivity that is specially built in the relationship between professionals and people with cystic fibrosis.

scholarly journals Maternal investment, life histories and the evolution of brain structure in primates

2019 ◽  
Vol 286 (1911) ◽  
pp. 20191608 ◽  
Author(s):  
Lauren E. Powell ◽  
Robert A. Barton ◽  
Sally E. Street
Keyword(s):  
Life History ◽  
Life Histories ◽  
Brain Size ◽  
Developmental Trajectories ◽  
Adult Life ◽  
Maternal Investment ◽  
Brain Evolution ◽  
Brain Structures ◽  
Juvenile Period ◽  
Adult Lifespan

Life history is a robust correlate of relative brain size: larger-brained mammals and birds have slower life histories and longer lifespans than smaller-brained species. The cognitive buffer hypothesis (CBH) proposes an adaptive explanation for this relationship: large brains may permit greater behavioural flexibility and thereby buffer the animal from unpredictable environmental challenges, allowing for reduced mortality and increased lifespan. By contrast, the developmental costs hypothesis (DCH) suggests that life-history correlates of brain size reflect the extension of maturational processes needed to accommodate the evolution of large brains, predicting correlations with pre-adult life-history phases. Here, we test novel predictions of the hypotheses in primates applied to the neocortex and cerebellum, two major brain structures with distinct developmental trajectories. While neocortical growth is allocated primarily to pre-natal development, the cerebellum exhibits relatively substantial post-natal growth. Consistent with the DCH, neocortical expansion is related primarily to extended gestation while cerebellar expansion to extended post-natal development, particularly the juvenile period. Contrary to the CBH, adult lifespan explains relatively little variance in the whole brain or neocortex volume once pre-adult life-history phases are accounted for. Only the cerebellum shows a relationship with lifespan after accounting for developmental periods. Our results substantiate and elaborate on the role of maternal investment and offspring development in brain evolution, suggest that brain components can evolve partly independently through modifications of distinct developmental phases, and imply that environmental input during post-natal maturation may be particularly crucial for the development of cerebellar function. They also suggest that relatively extended post-natal maturation times provide a developmental mechanism for the marked expansion of the cerebellum in the apes.

scholarly journals phylopath: Easy phylogenetic path analysis in R

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4718 ◽  
Author(s):  
Wouter van der Bijl
Keyword(s):  
Experimental Data ◽  
Path Analysis ◽  
Observational Data ◽  
Brain Size ◽  
R Package ◽  
Causal Models ◽  
Binary Variables ◽  
The Relationship

Confirmatory path analysis allows researchers to evaluate and compare causal models using observational data. This tool has great value for comparative biologists since they are often unable to gather experimental data on macro-evolutionary hypotheses, but is cumbersome and error-prone to perform. I introducephylopath, an R package that implements phylogenetic path analysis (PPA) as described by von Hardenberg & Gonzalez-Voyer (2013). In addition to the published method, I provide support for the inclusion of binary variables. I illustrate PPA andphylopathby recreating part of a study on the relationship between brain size and vulnerability to extinction. The package aims to make the analysis straight-forward, providing convenience functions, and several plotting methods, which I hope will encourage the spread of the method.

scholarly journals Neocortex evolution in primates: the ‘social brain’ is for females

2005 ◽  
Vol 1 (4) ◽  
pp. 407-410 ◽  
Author(s):  
Patrik Lindenfors
Keyword(s):  
Group Size ◽  
Social Intelligence ◽  
Social Evolution ◽  
Female Group ◽  
Male And Female ◽  
Social Intelligence Hypothesis ◽  
Male Group ◽  
The Social ◽  
Size Limits ◽  
The Relationship

According to the social intelligence hypothesis, relative neocortex size should be directly related to the degree of social complexity. This hypothesis has found support in a number of comparative studies of group size. The relationship between neocortex and sociality is thought to exist either because relative neocortex size limits group size or because a larger group size selects for a larger neocortex. However, research on primate social evolution has indicated that male and female group sizes evolve in relation to different demands. While females mostly group according to conditions set by the environment, males instead simply go where the females are. Thus, any hypothesis relating to primate social evolution has to analyse its relationship with male and female group sizes separately. Since sex-specific neocortex sizes in primates are unavailable in sufficient quantity, I here instead present results from phylogenetic comparative analyses of unsexed relative neocortex sizes and female and male group sizes. These analyses show that while relative neocortex size is positively correlated with female group size, it is negatively, or not at all correlated with male group size. This indicates that the social intelligence hypothesis only applies to female sociality.

scholarly journals Coevolution of cultural intelligence, extended life history, sociality, and brain size in primates

2017 ◽  
Vol 114 (30) ◽  
pp. 7908-7914 ◽  
Author(s):  
Sally E. Street ◽  
Ana F. Navarrete ◽  
Simon M. Reader ◽  
Kevin N. Laland
Keyword(s):  
Life History ◽  
Social Learning ◽  
Group Size ◽  
Social Group ◽  
Brain Volume ◽  
Brain Size ◽  
Research Effort ◽  
Human Cognition ◽  
Primate Species ◽  
Brain Expansion

Explanations for primate brain expansion and the evolution of human cognition and culture remain contentious despite extensive research. While multiple comparative analyses have investigated variation in brain size across primate species, very few have addressed why primates vary in how much they use social learning. Here, we evaluate the hypothesis that the enhanced reliance on socially transmitted behavior observed in some primates has coevolved with enlarged brains, complex sociality, and extended lifespans. Using recently developed phylogenetic comparative methods we show that, across primate species, a measure of social learning proclivity increases with absolute and relative brain volume, longevity (specifically reproductive lifespan), and social group size, correcting for research effort. We also confirm relationships of absolute and relative brain volume with longevity (both juvenile period and reproductive lifespan) and social group size, although longevity is generally the stronger predictor. Relationships between social learning, brain volume, and longevity remain when controlling for maternal investment and are therefore not simply explained as a by-product of the generally slower life history expected for larger brained species. Our findings suggest that both brain expansion and high reliance on culturally transmitted behavior coevolved with sociality and extended lifespan in primates. This coevolution is consistent with the hypothesis that the evolution of large brains, sociality, and long lifespans has promoted reliance on culture, with reliance on culture in turn driving further increases in brain volume, cognitive abilities, and lifespans in some primate lineages.

scholarly journals The multiple contexts of brain scaling: Phenotypic integration in brain and behavioral evolution

2022 ◽  
Author(s):  
Barbara L. Finlay
Keyword(s):  
Life History ◽  
Brain Size ◽  
Brain Evolution ◽  
Phenotypic Integration ◽  
Extended Evolutionary Synthesis ◽  
Brain Mass ◽  
Mammalian Retina ◽  
General Perspective ◽  
Duration Of Development

Understanding the adaptive functions of increasing brain size have occupied scientists for decades. Here, taking the general perspective of the Extended Evolutionary Synthesis, the question of how brains change in size will be considered in two developmental frameworks. The first framework will consider the particular developmental mechanisms that control and generate brain mass, concentrating on neurogenesis in a comparative vertebrate context. The consequences of limited adult neurogenesis in mammals, and the dominating role of duration of neurogenesis for mammalian evolution will be discussed for the particular case of the teleost versus mammalian retina, and for paths of brain evolution more generally. The second framework examines brain mass in terms of life history, particularly the features of life history that correlate highly, if imperfectly, with brain mass, including duration of development to adolescence, duration of parental care, body and range size, and longevity. This covariation will be examined in light of current work on genetic causes and consequences of covariation in craniofacial bone groupings. The eventual development of a multivariate structure for understanding brain evolution which specifically integrates formerly separate layers of analysis is the ultimate goal.

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