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Rantala MJ, Luoto S, Borráz-León JI, Krams I. Schizophrenia: the new etiological synthesis. Neurosci Biobehav Rev 2022; 142:104894. [PMID: 36181926 DOI: 10.1016/j.neubiorev.2022.104894] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 08/25/2022] [Accepted: 09/25/2022] [Indexed: 10/31/2022]
Abstract
Schizophrenia has been an evolutionary paradox: it has high heritability, but it is associated with decreased reproductive success. The causal genetic variants underlying schizophrenia are thought to be under weak negative selection. To unravel this paradox, many evolutionary explanations have been suggested for schizophrenia. We critically discuss the constellation of evolutionary hypotheses for schizophrenia, highlighting the lack of empirical support for most existing evolutionary hypotheses-with the exception of the relatively well supported evolutionary mismatch hypothesis. It posits that evolutionarily novel features of contemporary environments, such as chronic stress, low-grade systemic inflammation, and gut dysbiosis, increase susceptibility to schizophrenia. Environmental factors such as microbial infections (e.g., Toxoplasma gondii) can better predict the onset of schizophrenia than polygenic risk scores. However, researchers have not been able to explain why only a small minority of infected people develop schizophrenia. The new etiological synthesis of schizophrenia indicates that an interaction between host genotype, microbe infection, and chronic stress causes schizophrenia, with neuroinflammation and gut dysbiosis mediating this etiological pathway. Instead of just alleviating symptoms with drugs, the parasite x genotype x stress model emphasizes that schizophrenia treatment should focus on detecting and treating possible underlying microbial infection(s), neuroinflammation, gut dysbiosis, and chronic stress.
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Affiliation(s)
- Markus J Rantala
- Department of Biology, University of Turku, FIN-20014 Turku, Finland.
| | - Severi Luoto
- School of Population Health, University of Auckland, 1023 Auckland, New Zealand
| | | | - Indrikis Krams
- Institute of Ecology and Earth Sciences, University of Tartu, 51014 Tartu, Estonia; Department of Zoology and Animal Ecology, Faculty of Biology, University of Latvia, 1004, Rīga, Latvia
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2
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Quinn EA. Centering human milk composition as normal human biological variation. Am J Hum Biol 2021; 33:e23564. [DOI: 10.1002/ajhb.23564] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 11/25/2020] [Accepted: 12/23/2020] [Indexed: 02/06/2023] Open
Affiliation(s)
- Elizabeth A. Quinn
- Department of Anthropology Washington University in St. Louis Saint Louis Missouri USA
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3
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Kuziez D, Harkey J, Burack S, Borja J, Quinn EA. Maternal birth weight is associated with milk epidermal growth factor in Filipino women. Am J Hum Biol 2020; 32:e23403. [DOI: 10.1002/ajhb.23403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 01/27/2020] [Accepted: 01/29/2020] [Indexed: 12/17/2022] Open
Affiliation(s)
- Duaa Kuziez
- Saint Louis University School of Medicine, Saint Louis University Saint Louis Missouri
| | - Jamie Harkey
- Department of Anthropology Washington University in St. Louis Saint Louis Missouri
| | - Sarah Burack
- Department of Anthropology Washington University in St. Louis Saint Louis Missouri
| | - Judith Borja
- Office of Population Studies University of San Carlos Cebu Philippines
| | - Elizabeth A. Quinn
- Department of Anthropology Washington University in St. Louis Saint Louis Missouri
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Abstract
Humans show marked variation in body size around the world, both within and among populations. At present, the tallest people in the world are from the Netherlands and the Balkan countries, while the shortest populations are central African Pygmies. There are genetic, genetic plasticity, developmental, and environmental bases for size variation in Homo sapiens from the recent past and the present. Early populations of Homo species also have shown considerable size variation. Populations from the present and the past are also marked by sexual dimorphism, which, itself, shows group variation. There is abundant evidence for the effects of limited food and disease on human growth and resultant adult body size. This environmental influence has been reflected in "secular trends" (over a span of years) in growth and adult size from socioeconomic prosperity or poverty (availability of resources). Selective and evolutionary advantages of small or large body size also have been documented. Heritability for human height is relatively great with current genome-wide association studies (GWAS) identifying hundreds of genes leading to causes of growth and adult size variation. There are also endocrinological pathways limiting growth. An example is the reduced tissue sensitivity to human growth hormone (HGH) and insulin-like growth factor (IGF-1) in Philippine and African hunter-gatherer populations. In several short-statured hunter-gatherer populations (Asian, African, and South American), it has been hypothesized that short life expectancy has selected for early maturity and truncated growth to enhance fertility. Some island populations of humans and other mammals are thought to have been selected for small size because of limited resources, especially protein. The high-protein content of milk as a staple food may contribute to tall stature in East African pastoral peoples. These and other evolutionary questions linked to life history, male competition, reproduction, and mobility are explored in this paper.
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The Ecology of Breastfeeding and Mother-Infant Immune Functions. THE MOTHER-INFANT NEXUS IN ANTHROPOLOGY 2020. [DOI: 10.1007/978-3-030-27393-4_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Miller EM. Ecological immunity of human milk: Life history perspectives from the United States and Kenya. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 167:389-399. [DOI: 10.1002/ajpa.23639] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Revised: 06/04/2018] [Accepted: 06/06/2018] [Indexed: 12/15/2022]
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Veile A. Hunter-gatherer diets and human behavioral evolution. Physiol Behav 2018; 193:190-195. [PMID: 29800635 DOI: 10.1016/j.physbeh.2018.05.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 05/15/2018] [Accepted: 05/15/2018] [Indexed: 11/30/2022]
Abstract
Human behavior and physiology evolved under conditions vastly different from those which most humans inhabit today. This paper summarizes long-term dietary studies conducted on contemporary hunter-gatherer populations (sometimes referred to as foragers). Selected studies for the most part that use evolutionary theoretical perspectives and data collection methods derived from the academic field of human behavioral ecology, which derives relatively recently from the fields of evolutionary biology, ethology, population biology and ecological anthropology. I demonstrate how this body of research illuminates ancestral patterns of food production, consumption and sharing, infant feeding, and juvenile subsistence contributions in hunter-gatherer economies. Insights from hunter-gatherer studies are then briefly discussed within the context of better-studied human populations that are Westernized, Educated, Industrialized, Rich, and Democratic (WEIRD).
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Affiliation(s)
- Amanda Veile
- Department of Anthropology, Purdue University, USA; Center on Aging and the Life Course, Purdue University, USA.
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Power ML, Schulkin J, Drought H, Milligan LA, Murtough KL, Bernstein RM. Patterns of milk macronutrients and bioactive molecules across lactation in a western lowland gorilla (Gorilla gorilla) and a Sumatran orangutan (Pongo abelii). Am J Primatol 2016; 79:1-11. [DOI: 10.1002/ajp.22609] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 09/02/2016] [Accepted: 09/06/2016] [Indexed: 01/08/2023]
Affiliation(s)
- Michael L. Power
- Smithsonian Conservation Biology Institute, Conservation Ecology Center; Nutrition; Laboratory, National Zoological Park; Washington District of Columbia
- Research Department; American College of Obstetricians and Gynecologists; Washington District of Columbia
| | - Jay Schulkin
- Research Department; American College of Obstetricians and Gynecologists; Washington District of Columbia
- Department of Neuroscience; Georgetown University; Washington District of Columbia
| | - Heather Drought
- Department of Anthropology, The George Washington University; Washington District of Columbia
| | - Lauren A. Milligan
- Smithsonian Conservation Biology Institute, Conservation Ecology Center; Nutrition; Laboratory, National Zoological Park; Washington District of Columbia
- Anthropology Department, Mira Costa College; Oceanside California
| | - Katie L. Murtough
- Smithsonian Conservation Biology Institute, Conservation Ecology Center; Nutrition; Laboratory, National Zoological Park; Washington District of Columbia
- College of Computer, Mathematical, and Natural Sciences; University of Maryland; College Park Maryland
| | - Robin M. Bernstein
- Department of Anthropology; University of Colorado Boulder; Boulder Colorado
- Health and Society Program; Institute of Behavioral Science, University of Colorado Boulder; Boulder Colorado
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Quinn EA, Childs G. Ecological pressures and milk metabolic hormones of ethnic Tibetans living at different altitudes. Ann Hum Biol 2016; 44:34-45. [DOI: 10.3109/03014460.2016.1153144] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Elizabeth A. Quinn
- Department of Anthropology, Washington University in St. Louis, St. Louis, MO, USA
| | - Geoff Childs
- Department of Anthropology, Washington University in St. Louis, St. Louis, MO, USA
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Bernstein RM, Hinde K. Bioactive factors in milk across lactation: Maternal effects and influence on infant growth in rhesus macaques (Macaca mulatta). Am J Primatol 2016; 78:838-50. [PMID: 27029025 DOI: 10.1002/ajp.22544] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 02/23/2016] [Accepted: 02/25/2016] [Indexed: 12/31/2022]
Abstract
Among mammals, numerous bioactive factors in milk vary across mothers and influence offspring outcomes. This emerging area of research has primarily investigated such dynamics within rodent biomedical models, domesticated dairy breeds, and among humans in clinical contexts. Less understood are signaling factors in the milk of non-human primates. Here, we report on multiple bioactive components in rhesus macaque (Macaca mulatta) milk and their associations with maternal and infant characteristics. Milk samples were collected from 59 macaques at multiple time points across lactation in conjunction with maternal and infant morphometrics and life-history animal records. Milk was assayed for adiponectin (APN), epidermal growth factor (EGF) and its receptor (EGF-R), and transforming growth factor beta 2 (TGF-β2 ). Regression models were constructed to assess the contributions of maternal factors on variation in milk bioactives, and on the relationship of this variation to infant body mass and growth. Maternal body mass, parity, social rank, and infant sex were all predictive of concentrations of milk bioactives. Primiparous mothers produced milk with higher adiponectin, but lower EGF, than multiparous mothers. Heavier mothers produced milk with lower EGF and EGF-R, but higher TGF-β2 . Mothers of daughters produced milk with higher TGF-β2 . Mid-ranking mothers produced milk with higher mean EGF and adiponectin concentrations than low-ranking mothers. Milk EGF and EGF-R were positively associated with infant body mass and growth rate. Importantly, these signaling bioactives (APN, EGF, EGF-R, and TGF-β2 ) were significantly correlated with nutritional values of milk. The effects of milk signals remained after controlling for the available energy in milk revealing the added physiological role of non-nutritive milk bioactives in the developing infant. Integrating analyses of energetic and other bioactive components of milk yields an important perspective for interpreting the magnitude, sources, and consequences of inter-individual variation in milk synthesis. Am. J. Primatol. 78:838-850, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Robin M Bernstein
- Department of Anthropology, University of Colorado Boulder, Boulder, Colorado.,Health and Society Program, Institute of Behavioral Science, University of Colorado Boulder, Boulder, Colorado
| | - Katie Hinde
- School of Human Evolution and Social Change, Arizona State University, Arizona.,Center for Evolution and Medicine, Arizona State University, Arizona.,Brain, Mind, and Behavior Unit, California National Primate Research Center, California
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Anderson J, McKinley K, Onugha J, Duazo P, Chernoff M, Quinn EA. Lower levels of human milk adiponectin predict offspring weight for age: a study in a lean population of Filipinos. MATERNAL AND CHILD NUTRITION 2015; 12:790-800. [PMID: 26446289 DOI: 10.1111/mcn.12216] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Prior studies have reported a significant, inverse association between adiponectin in human milk and offspring growth velocity. Less is known about this association in populations characterised by a loss of weight for age z-scores (WAZs) in early life. We investigated the association between maternal body composition and milk adiponectin in a sample of Filipino mothers. We then tested for an association between milk adiponectin and size for age in their infants. A total of 117 Filipino mothers nursing infants from 0 to 24 months were recruited from Cebu, Philippines. Anthropometrics, interviews and milk samples were collected and analysed using standard protocols. Mean milk adiponectin in this sample was 7.47 ± 5.75 ng mL(-1) . Mean infant WAZ and weight for length (WLZ) decreased with age. Maternal body composition was not associated with milk adiponectin content. Milk adiponectin had a significant, positive association with infant WAZ and WLZ. Prior reports have found an inverse association between milk adiponectin and infant WAZ. Here, we report that in lean populations with lower milk adiponectin, there is a positive association with infant WAZ, possibly reflecting pleiotropic biological functions of adiponectin for post-natal growth. This study increases the understanding of normal biological variation in milk adiponectin and the consequences of low levels of milk adiponectin for offspring growth.
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Affiliation(s)
- Justine Anderson
- Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Kassielle McKinley
- Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jason Onugha
- Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Paulita Duazo
- Office of Population Studies, University of San Carlos, Cebu, Philippines
| | - Meytal Chernoff
- Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Elizabeth A Quinn
- Office of Population Studies, University of San Carlos, Cebu, Philippines.
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Quinn EA, Diki Bista K, Childs G. Milk at altitude: Human milk macronutrient composition in a high-altitude adapted population of tibetans. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 159:233-43. [DOI: 10.1002/ajpa.22871] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 09/04/2015] [Accepted: 09/06/2015] [Indexed: 12/20/2022]
Affiliation(s)
- Elizabeth A. Quinn
- Department of Anthropology; Washington University in St. Louis; St. Louis Missouri 63130
| | | | - Geoff Childs
- Department of Anthropology; Washington University in St. Louis; St. Louis Missouri 63130
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Ulijaszek SJ. Concluding remarks: what's in a name? "Negritos" in the context of the human prehistory of Southeast Asia. Hum Biol 2015; 85:495-xx. [PMID: 24297239 DOI: 10.3378/027.085.0323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2013] [Indexed: 11/05/2022]
Abstract
The "negrito" hypothesis posits that various indigenous groups throughout Island and Mainland Southeast Asia have a shared phenotype due to common descent from a putative ancestral population, representing a pre-agricultural substrate of humanity in the region. This has been examined and tested many times in the past, with no clear resolution. With many new resources to hand, the articles in this volume reexamine this hypothesis in a range of different ways. The evidence presented in this double issue of Human Biology speaks more against the category of "negrito" than for it. While populations with the negrito phenotype form a small proportion of all contemporary populations in this region, they have remained a persistent presence. And without a fascination about their origins, there would not be such a depth of knowledge about the human biology of this region more broadly as there is now.
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Affiliation(s)
- Stanley J Ulijaszek
- School of Anthropology, University of Oxford and St. Cross College, Oxford, UK
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Endicott P. Introduction: revisiting the "negrito" hypothesis: a transdisciplinary approach to human prehistory in southeast Asia. Hum Biol 2015; 85:7-20. [PMID: 24297218 DOI: 10.3378/027.085.0301] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2013] [Indexed: 11/05/2022]
Abstract
The "negrito" hypothesis predicts that a shared phenotype among various contemporary groups of hunter-gatherers in Southeast Asia--dark skin, short stature, tight curly hair--is due to common descent from a region-wide, pre-Neolithic substrate of humanity. The alternative is that their distinctive phenotype results from convergent evolution. The core issues of the negrito hypothesis are today more relevant than ever to studies of human evolution, including the out-of-Africa migration, admixture with Denisovans, and the effects of environment and ecology on life-history traits. Understanding the current distribution of the negrito phenotype dictates a wide-ranging remit for study, including the articulation of the relationship between foragers and farmers in the present, the development of settled agriculture in the mid-Holocene, and terminal Pleistocene population expansions. The consensus reached by the contributors to this special double issue of Human Biology is that there is not yet conclusive evidence either for or against the negrito hypothesis. Nevertheless, the process of revisiting the problem will benefit the knowledge of the human prehistory of Southeast Asia. Whether the term negrito accurately reflects the all-encompassing nature of the resulting inquiry is in itself questionable, but the publication of this double issue is testament to the enduring ability of this hypothesis to unite disparate academic disciplines in a common purpose.
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Affiliation(s)
- Phillip Endicott
- Musée de l'Homme, Paris, France and Museum National d'Historie Naturelle, 57 rue Cuvier, Paris, 75005 France
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Lye TP. Making friends in the rainforest: "negrito" adaptation to risk and uncertainty. Hum Biol 2013; 85:417-44. [PMID: 24297236 DOI: 10.3378/027.085.0320] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2013] [Indexed: 11/05/2022]
Abstract
The so-called negritos adapt not just to a tropical forest environment but also to an environment characterized by perturbations and fluctuations. As with other hunter-gatherers in the region and, indeed, throughout the world, they use both social and ecological methods to enhance their chances of survival in this changing environment: socially, they have developed networks of trading and marriage partners; ecologically, they maintain patches of key resources that are available for future harvesting. As evidenced in the case of the Batek (Orang Asli), patterns of forest structure and composition are sometimes direct outcomes of intentional resource concentration and enrichment strategies. While little of the above is controversial anthropologically, what has drawn some debate is the nature of the relationship with partner societies. Conventional wisdom posits relations of inequality between foragers and "others": foragers and farmers are often construed as hierarchical dyads where foragers supply products or labor to farmers in exchange for agricultural harvests and other trade goods. This kind of adaptation appears to be one of divergent specialization. However, there are cases, such as in the relationship between Batek and Semaq Beri, where both societies follow a roughly similar mode of adaptation, and specialization has not materialized. In sum, while not denying that hierarchy and inequality exist, I suggest that they have to be contextualized within a larger strand of relationships that includes both hierarchy and egality. Further, such relationships are part of the general portfolio of risk reduction strategies, following which access to widely scattered environmental resources, and passage from one location to another, is enhanced not by competing with and displacing neighbors but by maintaining a flexible regime of friendly exchange partners.
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Affiliation(s)
- Tuck-Po Lye
- School of Social Sciences, Universiti Sains Malaysia, Penang, Malaysia
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Benjamin G. Why Have the Peninsular “Negritos” Remained Distinct? Hum Biol 2013; 85:445-84. [DOI: 10.3378/027.085.0321] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2013] [Indexed: 11/05/2022]
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