The uniqueness of the human brain: a review.

The purpose of this review is to highlight the most important aspects of the anatomical and functional uniqueness of the human brain. For this, a comparison is made between our brains and those of our closest ancestors (chimpanzees and bonobos) and human ancestors. During human evolution, several changes occurred in the brain, such as an absolute increase in brain size and number of cortical neurons, in addition to a greater degree of functional lateralization and anatomical asymmetry. Also, the cortical cytoarchitecture became more diversified and there was an increase in the number of intracortical networks and networks extending from the cerebral cortex to subcortical structures, with more neural networks being invested in multisensory and sensory-motor-affective-cognitive integration. These changes permitted more complex, flexible and versatile cognitive abilities and social behavior, such as shared intentionality and symbolic articulated language, which, in turn, made possible the formation of larger social groups and cumulative cultural evolution that are characteristic of our species.

Esta revisão se propõe a relatar os aspectos mais importantes da singularidade anatômica e funcional do cérebro humano. Para isso, faz-se uma comparação entre o nosso cérebro e os de nossos parentes evolutivos mais próximos (chimpanzés e bonobos) e os ancestrais humanos. Durante a evolução humana ocorreu aumento absoluto do tamanho do cérebro e do número de neurônios corticais cerebrais, maior grau de lateralização funcional e assimetria anatômica cerebral, citoarquitetura cortical mais diversificada e aumento das redes neurais intracorticais e do córtex cerebral para as estruturas subcorticais acompanhada de mudança em direção ao investimento de redes neurais na integração multissensorial e sensório-motora-afetiva-cognitiva. Essas mudanças possibilitaram capacidades cognitivas e comportamentos sociais complexos, flexíveis e versáteis, destacando-se a intencionalidade compartilhada e a linguagem articulada simbólica, que permitiram a formação de grupos sociais maiores e a evolução cultural cumulativa característica de nossa espécie.

The uniqueness of the human brain: a review / A singularidade do cérebro humano: uma revisão

ABSTRACT The purpose of this review is to highlight the most important aspects of the anatomical and functional uniqueness of the human brain. For this, a comparison is made between our brains and those of our closest ancestors (chimpanzees and bonobos) and human ancestors. During human evolution, several changes occurred in the brain, such as an absolute increase in brain size and number of cortical neurons, in addition to a greater degree of functional lateralization and anatomical asymmetry. Also, the cortical cytoarchitecture became more diversified and there was an increase in the number of intracortical networks and networks extending from the cerebral cortex to subcortical structures, with more neural networks being invested in multisensory and sensory-motor-affective-cognitive integration. These changes permitted more complex, flexible and versatile cognitive abilities and social behavior, such as shared intentionality and symbolic articulated language, which, in turn, made possible the formation of larger social groups and cumulative cultural evolution that are characteristic of our species.

RESUMO Esta revisão se propõe a relatar os aspectos mais importantes da singularidade anatômica e funcional do cérebro humano. Para isso, faz-se uma comparação entre o nosso cérebro e os de nossos parentes evolutivos mais próximos (chimpanzés e bonobos) e os ancestrais humanos. Durante a evolução humana ocorreu aumento absoluto do tamanho do cérebro e do número de neurônios corticais cerebrais, maior grau de lateralização funcional e assimetria anatômica cerebral, citoarquitetura cortical mais diversificada e aumento das redes neurais intracorticais e do córtex cerebral para as estruturas subcorticais acompanhada de mudança em direção ao investimento de redes neurais na integração multissensorial e sensório-motora-afetiva-cognitiva. Essas mudanças possibilitaram capacidades cognitivas e comportamentos sociais complexos, flexíveis e versáteis, destacando-se a intencionalidade compartilhada e a linguagem articulada simbólica, que permitiram a formação de grupos sociais maiores e a evolução cultural cumulativa característica de nossa espécie.

Sleep tight! Adolescent sleep quality across three distinct sleep ecologies.

Background and objectives: Good sleep quality, associated with few arousals, no daytime sleepiness and self-satisfaction with one's sleep, is pivotal for adolescent growth, maturation, cognition and overall health. This article aims to identify what ecological factors impact adolescent sleep quality across three distinct sleep ecologies representing a gradient of dense urbanity to small, rural environments with scarce artificial lighting and no Internet. Methodology: We analyze variation of sleep efficiency, a quantitative measure of sleep quality-defined as the ratio of total time spent asleep to total time dedicated to sleep-in two agricultural indigenous populations and one post-industrial group in Mexico (Campeche = 44, Puebla = 51, Mexico City = 50, respectively). Data collection included actigraphy, sleep diaries, questionnaires, interviews and ethnographic observations. We fit linear models to examine sleep efficiency variation within and between groups. Results: We found that sleep efficiency varied significantly across sites, being highest in Mexico City (88%) and lowest in Campeche (75%). We found that variation in sleep efficiency was significantly associated with nightly exposure to light and social sleep practices. Conclusions and implications: Our findings point toward contextual cost-benefits of sleep disruption in adolescence. We highlight the need to prioritize research on adolescent sleep quality across distinct developmental ecologies and its impact on health to improve adolescent wellbeing through evidence-based health practices.

The Natural Tendency for Wide and Careful Listening: Exploring the Relationship Between Open-Mindedness and Psychological Science.

We take open-mindedness to be a component of intellectual humility, as much of the recent empirical literature regarding intellectual humility does but contrary to what some philosophers think. More particularly, we understand intellectual humility as having a self-directed component, which is concerned primarily with the regulation of confidence we have on our own epistemic goods and capacities, and an other-directed component, which is concerned primarily with one's epistemic openness to others so to improve one's epistemic situation. Given that the open-minded person is disposed give new ideas serious consideration, it is crucial that she both listens widely and carefully to other's ideas. In this paper, we examine whether there is evidence to suggest that we have a natural, evolved tendency for this wide and careful listening related to open-mindedness. We conclude that there is indication of a natural tendency for wide listening, especially an in-group tendency. However, careful listening lacks more substantive empirical studies. It seems that human infants are much more inclined to be charitable and attentive to in-group cues or opinions. This is important evidence to deconstruct the idea of a natural tendency of virtuous intellectual humility that opens up the discussion for the role of social learning in cultivating and maintaining a virtuous life.

The Evolution of Playfulness, Play and Play-Like Phenomena in Relation to Sexual Selection.

By conceptualizing Sexual Selection, Darwin showed a way to analyze intra-specific individual differences within an evolutionary perspective. Interestingly, Sexual Selection is often used to investigate the origins of sports, arts, humor, religion and other phenomena that, in several languages, are simply called "play." Despite their manifested differences, these phenomena rely on shared psychological processes, including playfulness. Further, in such behaviors there is usually considerable individual variability, including sex differences, and positive relationship with mating success. However, Sexual Selection is rarely applied in the study of play, with exception to what is concerned as infant training behavior for adult sex roles. We offer an integrated grounding of playful phenomena aligning evolutionary propositions based on sexual selection, which might stimulate further exploration of playfulness within evolutionary perspective.

Effects of Social Distancing During the COVID-19 Pandemic on Anxiety and Eating Behavior-A Longitudinal Study.

As social animals, humans need to live in groups. This contact with conspecifics is essential for their evolution and survival. Among the recommendations to reduce transmission of the new coronavirus (SARS-CoV-2) responsible for COVID-19 are social distancing and home confinement. These measures may negatively affect the social life and, consequently, the emotional state and eating behavior of individuals. We assessed the impact of the COVID-19 pandemic on the anxiety, premenstrual symptoms, and eating behavior of young women. Data collection was conducted in person (prepandemic-from March to December 2019) and online (during the pandemic-August 2020). A total of 71 participants, average age of 21.26 years (SD = 0.41), took part in the study. Trait anxiety during the pandemic was significantly lower than in the prepandemic period. Investigation of the "anxiety/stress" symptom of the Premenstrual Symptoms Screening Tool (PSST) revealed that this symptom was more severe before the pandemic. There was a decline in the desire for sweet and fatty foods during the pandemic. However, craving for traditional foods rose significantly in the same period. Uncontrolled and emotional eating were significantly lower during the pandemic. The results suggest that the pandemic may have had a positive impact on anxiety and eating behavior of the participants, which may be due to differences between urban and rural populations and the latter living with their families. These findings are important for raising a discussion regarding the effects of the current environment on the regulation of cognitive and dietary adaptations.

Computed tomography shows high fracture prevalence among physically active forager-horticulturalists with high fertility.

Modern humans have more fragile skeletons than other hominins, which may result from physical inactivity. Here, we test whether reproductive effort also compromises bone strength, by measuring using computed tomography thoracic vertebral bone mineral density (BMD) and fracture prevalence among physically active Tsimane forager-horticulturalists. Earlier onset of reproduction and shorter interbirth intervals are associated with reduced BMD for women. Tsimane BMD is lower versus Americans, but only for women, contrary to simple predictions relying on inactivity to explain skeletal fragility. Minimal BMD differences exist between Tsimane and American men, suggesting that systemic factors other than fertility (e.g. diet) do not easily explain Tsimane women's lower BMD. Tsimane fracture prevalence is also higher versus Americans. Lower BMD increases Tsimane fracture risk, but only for women, suggesting a role of weak bone in women's fracture etiology. Our results highlight the role of sex-specific mechanisms underlying skeletal fragility that operate long before menopause.

Gain of transcription factor binding sites is associated to changes in the expression signature of human brain and testis and is correlated to genes with higher expression breadth.

The gain of transcription factor binding sites (TFBS) is believed to represent one of the major causes of biological innovation. Here we used strategies based on comparative genomics to identify 21,822 TFBS specific to the human lineage (TFBS-HS), when compared to chimpanzee and gorilla genomes. More than 40% (9,206) of these TFBS-HS are in the vicinity of 1,283 genes. A comparison of the expression pattern of these genes and the corresponding orthologs in chimpanzee and gorilla identified genes differentially expressed in human tissues. These genes show a more divergent expression pattern in the human testis and brain, suggesting a role for positive selection in the fixation of TFBS gains. Genes associated with TFBS-HS were enriched in gene ontology categories related to transcriptional regulation, signaling, differentiation/development and nervous system. Furthermore, genes associated with TFBS-HS present a higher expression breadth when compared to genes in general. This biased distribution is due to a preferential gain of TFBS in genes with higher expression breadth rather than a shift in the expression pattern after the gain of TFBS.

The Influence of the Evolutionary Past on the Mind: An Analysis of the Preference for Landscapes in the Human Species.

According to some evolutionary psychologists, landscapes preferences in the human species are influenced by their evolutionary past. Because the Pleistocene savanna is the least inhospitable landscape, it was the most suitable environment for survival and influenced the evolution of hominids in such a way that even today the human being has a universal preference for these environments. However, there is controversy regarding this statement, because in some studies it was evidenced that people prefer images of landscapes that are similar to those of the environment where they live. In this sense, we want to test whether there is indeed a preference for images of the savanna landscape and how the current environmental context may influence this preference. We performed a study in three environmental contexts with different landscapes in order to be able to observe the influence of the familiar landscape on landscape preference, of which two rural communities - one presenting a landscape similar to the deciduous seasonal forest and another presenting a savanna-like landscape - that totaled 132 participants and one urban community with 189 participants. The stimulus consisted of 12 images representing the six major terrestrial biomes and two images of urban landscapes. The variables analyzed were the emotional responses and the preference of the participants in relation to the images of landscapes. We analyzed the data using the Kruskal-Wallis test. The obtained result did not corroborate the idea of universal preference for images of savanna landscape. The image of Rainforest landscape was the preferred one among all the three environmental contexts studied. In this way, the preference for landscape may have been shaped at different periods of human evolutionary history, and not just during the period when hominids lived on the savannah. As much as selective pressures of the Pleistocene savanna have shaped the human mind during the evolutionary history, other factors and different types of environments may have influenced human preferences for landscapes. Thus, evolutionary psychologists who analyze human preferences for images of landscapes, guided by the idea of the past influencing the present, must be cautious before generalizing their results, especially if other variables such as the cultural ones are not controlled.

Influence of fruit and invertebrate consumption on the gut microbiota of wild white-faced capuchins (Cebus capucinus).

OBJECTIVES: Invertebrate consumption is thought to be an integral part of early hominin diets, and many modern human populations regularly consume insects and other arthropods. This study examines the response of gut microbial community structure and function to changes in diet in wild white-faced capuchins (Cebus capucinus), a primate that incorporates a large proportion of invertebrates in its diet. The goal of the study is to better understand the role of both fruit and invertebrate prey consumption on shaping primate gut microbiomes. MATERIALS AND METHODS: Fecal samples (n = 169) and dietary data were collected over 12 months. The V3-V5 region of microbial 16S rRNA genes was amplified and sequenced. The IM-TORNADO pipeline was used to analyze sequences. RESULTS: White-faced capuchin gut bacterial communities were characterized primarily by Firmicutes (41.6%) and Proteobacteria (39.2%). There was a significant relationship between the invertebrate diet composition of individual capuchins and their gut microbiome composition. However, there was no relationship between the fruit diet composition of individual capuchins and their gut microbiome composition, even when examining multiple timescales. DISCUSSION: The results of our study indicate that there is a stronger relationship between gut microbial community structure and invertebrate diet composition than between gut microbial community structure and fruit consumption. As invertebrates and other animal prey play an important role in the diet of many primates, these results give important insight into the role of faunivory in shaping the evolution of host-microbe interactions in primates.

Detecting Long-Term Balancing Selection Using Allele Frequency Correlation.

Balancing selection occurs when multiple alleles are maintained in a population, which can result in their preservation over long evolutionary time periods. A characteristic signature of this long-term balancing selection is an excess number of intermediate frequency polymorphisms near the balanced variant. However, the expected distribution of allele frequencies at these loci has not been extensively detailed, and therefore existing summary statistic methods do not explicitly take it into account. Using simulations, we show that new mutations which arise in close proximity to a site targeted by balancing selection accumulate at frequencies nearly identical to that of the balanced allele. In order to scan the genome for balancing selection, we propose a new summary statistic, ß, which detects these clusters of alleles at similar frequencies. Simulation studies show that compared with existing summary statistics, our measure has improved power to detect balancing selection, and is reasonably powered in non-equilibrium demographic models and under a range of recombination and mutation rates. We compute ß on 1000 Genomes Project data to identify loci potentially subjected to long-term balancing selection in humans. We report two balanced haplotypes-localized to the genes WFS1 and CADM2-that are strongly linked to association signals for complex traits. Our approach is computationally efficient and applicable to species that lack appropriate outgroup sequences, allowing for well-powered analysis of selection in the wide variety of species for which population data are rapidly being generated.

The Mitonuclear Dimension of Neanderthal and Denisovan Ancestry in Modern Human Genomes.

Some human populations interbred with Neanderthals and Denisovans, resulting in substantial contributions to modern-human genomes. Therefore, it is now possible to use genomic data to investigate mechanisms that shaped historical gene flow between humans and our closest hominin relatives. More generally, in eukaryotes, mitonuclear interactions have been argued to play a disproportionate role in generating reproductive isolation. There is no evidence of mtDNA introgression into modern human populations, which means that all introgressed nuclear alleles from archaic hominins must function on a modern-human mitochondrial background. Therefore, mitonuclear interactions are also potentially relevant to hominin evolution. We performed a detailed accounting of mtDNA divergence among hominin lineages and used population-genomic data to test the hypothesis that mitonuclear incompatibilities have preferentially restricted the introgression of nuclear genes with mitochondrial functions. We found a small but significant underrepresentation of introgressed Neanderthal alleles at such nuclear loci. Structural analyses of mitochondrial enzyme complexes revealed that these effects are unlikely to be mediated by physically interacting sites in mitochondrial and nuclear gene products. We did not detect any underrepresentation of introgressed Denisovan alleles at mitochondrial-targeted loci, but this may reflect reduced power because locus-specific estimates of Denisovan introgression are more conservative. Overall, we conclude that genes involved in mitochondrial function may have been subject to distinct selection pressures during the history of introgression from archaic hominins but that mitonuclear incompatibilities have had, at most, a small role in shaping genome-wide introgression patterns, perhaps because of limited functional divergence in mtDNA and interacting nuclear genes.

Adult sex ratios and partner scarcity among hunter-gatherers: implications for dispersal patterns and the evolution of human sociality.

Small populations are susceptible to high genetic loads and random fluctuations in birth and death rates. While these selective forces can adversely affect their viability, small populations persist across taxa. Here, we investigate the resilience of small groups to demographic uncertainty, and specifically to fluctuations in adult sex ratio (ASR), partner availability and dispersal patterns. Using 25 years of demographic data for two Savannah Pumé groups of South American hunter-gatherers, we show that in small human populations: (i) ASRs fluctuate substantially from year to year, but do not consistently trend in a sex-biased direction; (ii) the primary driver of local variation in partner availability is stochasticity in the sex ratio at maturity; and (iii) dispersal outside of the group is an important behavioural means to mediate locally constrained mating options. To then simulate conditions under which dispersal outside of the local group may have evolved, we develop two mathematical models. Model results predict that if the ASR is biased, the globally rarer sex should disperse. The model's utility is then evaluated by applying our empirical data to this central prediction. The results are consistent with the observed hunter-gatherer pattern of variation in the sex that disperses. Together, these findings offer an alternative explanation to resource provisioning for the evolution of traits central to human sociality (e.g. flexible dispersal, bilocal post-marital residence and cooperation across local groups). We argue that in small populations, looking outside of one's local group is necessary to find a mate and that, motivated by ASR imbalance, the alliances formed to facilitate the movement of partners are an important foundation for the human-typical pattern of network formation across local groups.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'.

Population genetic structure of Helicobacter pylori strains from Portuguese-speaking countries.

BACKGROUND: The human gastric colonizer Helicobacter pylori is useful to track human migrations given the agreement between the bacterium phylogeographic distribution and human migrations. As Portugal was an African and Brazilian colonizer for over 400 years, we hypothesized that Portuguese isolates were likely genetically closer with those from countries colonized by Portuguese in the past. We aimed to characterize the population structure of several Portuguese-speaking countries, including Portugal, Brazil, Angola, and Cape Verde. MATERIALS AND METHODS: We included strains isolated in Portugal from Portuguese and from former Portuguese colonies. These strains were typed by multilocus sequence typing (MLST) for seven housekeeping genes. We also retrieved from Multi Locus Sequence Typing Web site additional housekeeping gene sequences, namely from Angola and Brazil. RESULTS: We provided evidence that strains from Portuguese belong to hpEurope and that the introgression of hpEurope in non-European countries that speak Portuguese is low, except for Brazil and Cape Verde, where hpEurope accounted for one quarter and one half of the population, respectively. We found genetic similarity for all strains from Portuguese-speaking countries that belong to hpEurope population. Moreover, these strains showed a predominance of ancestral Europe 2 (AE2) over ancestral Europe 1 (AE1), followed by ancestral Africa 1. CONCLUSIONS: H. pylori is a useful marker even for relative recent human migration events and may become rapidly differentiated from founder populations. H. pylori from Portuguese-speaking countries assigned to hpEurope appears to be a hybrid population resulting from the admixture of AE1, AE2 and ancestral hpAfrica1.

Morphological affinities of Homo naledi with other Plio-Pleistocene hominins: a phenetic approach

ABSTRACT Recent fossil material found in Dinaledi Chamber, South Africa, was initially described as a new species of genus Homo, namely Homo naledi. The original study of this new material has pointed to a close proximity with Homo erectus. More recent investigations have, to some extent, confirmed this assignment. Here we present a phenetic analysis based on dentocranial metric variables through Principal Components Analysis and Cluster Analysis based on these fossils and other Plio-Pleistocene hominins. Our results concur that the Dinaledi fossil hominins pertain to genus Homo. However, in our case, their nearest neighbors are Homo habilis and Australopithecus sediba. We suggest that Homo naledi is in fact a South African version of Homo habilis, and not a new species. This can also be applied to Australopithecus sediba.

Human Brain Expansion during Evolution Is Independent of Fire Control and Cooking.

What makes humans unique? This question has fascinated scientists and philosophers for centuries and it is still a matter of intense debate. Nowadays, human brain expansion during evolution has been acknowledged to explain our empowered cognitive capabilities. The drivers for such accelerated expansion remain, however, largely unknown. In this sense, studies have suggested that the cooking of food could be a pre-requisite for the expansion of brain size in early hominins. However, this appealing hypothesis is only supported by a mathematical model suggesting that the increasing number of neurons in the brain would constrain body size among primates due to a limited amount of calories obtained from diets. Here, we show, by using a similar mathematical model, that a tradeoff between body mass and the number of brain neurons imposed by dietary constraints during hominin evolution is unlikely. Instead, the predictable number of neurons in the hominin brain varies much more in function of foraging efficiency than body mass. We also review archeological data to show that the expansion of the brain volume in the hominin lineage is described by a linear function independent of evidence of fire control, and therefore, thermal processing of food does not account for this phenomenon. Finally, we report experiments in mice showing that thermal processing of meat does not increase its caloric availability in mice. Altogether, our data indicate that cooking is neither sufficient nor necessary to explain hominin brain expansion.

Functional test of PCDHB11, the most human-specific neuronal surface protein.

BACKGROUND: Brain-expressed proteins that have undergone functional change during human evolution may contribute to human cognitive capacities, and may also leave us vulnerable to specifically human diseases, such as schizophrenia, autism or Alzheimer's disease. In order to search systematically for those proteins that have changed the most during human evolution and that might contribute to brain function and pathology, all proteins with orthologs in chimpanzee, orangutan and rhesus macaque and annotated as being expressed on the surface of cells in the human central nervous system were ordered by the number of human-specific amino acid differences that are fixed in modern populations. RESULTS: PCDHB11, a beta-protocadherin homologous to murine cell adhesion proteins, stood out with 12 substitutions and maintained its lead after normalizing for protein size and applying weights for amino acid exchange probabilities. Human PCDHB11 was found to cause homophilic cell adhesion, but at lower levels than shown for other clustered protocadherins. Homophilic adhesion caused by a PCDHB11 with reversion of human-specific changes was as low as for modern human PCDHB11; while neither human nor reverted PCDHB11 adhered to controls, they did adhere to each other. A loss of function in PCDHB11 is unlikely because intra-human variability did not increase relative to the other human beta-protocadherins. CONCLUSIONS: The brain-expressed protein with the highest number of human-specific substitutions is PCDHB11. In spite of its fast evolution and low intra-human variability, cell-based tests on the only proposed function for PCDHB11 did not indicate a functional change.

El dilema obstétrico / Obstetric dilemma

Resumen: La teoría darwiniana indica que los seres humanos somos producto de la evolución y la selección natural, que ha tomado millones de años para traernos a nuestra situación actual. En el transcurso de ese tiempo el cuerpo de los animales que nos precedieron y del humano mismo cambiaron en varias formas, y una de los cambios más trascendentales fue el paso de la locomoción cuadrúpeda a bípeda. Ese cambio requirió numerosas adaptaciones entre las que están las del esqueleto de la pelvis y las extremidades inferiores, que redujeron el tamaño del anillo pélvico, por lo que si el feto esperara a nacer hasta que su cerebro madurara completamente, su gran cabeza no pasaría por ese anillo. La solución a este problema, que se ha llamado el dilema obstétrico, fue que el nacimiento ocurriera cuando la cabeza del feto aún no es demasiado grande, lo que implica que el cerebro todavía no está completamente maduro; aun así, el feto pasa con dificultades por el canal y el anillo pélvico. Al momento del nacimiento el cerebro del neonato no está completamente desarrollado y tiene que terminar de madurar fuera del útero, lo que toma tomar alrededor de 20 años. Esto puede explicar no solamente el comportamiento desorganizado de los adolescentes en general, sino también el inicio temprano de algunas enfermedades neurológicas cuyas consecuencias no se ven hasta la edad adulta, cuando la maduración del cerebro ha terminado.

Abstract: Darwinian theory indicates that human beings are products of evolution and natural selection, processes that have taken millions of years. During that time animals and humanoids changed in many ways and one of the most remarkable is the transition of a quadrupedal to a bipedal gait. Such a change required numerous adaptations, many of which are in the skeleton and lower limbs, that reduced the diameter of the pelvis in such a way that if the fetus had to wait to be completely developed to be born his large head would not pass through the pelvic channel. This problem is known as the 'obstetrics dilemma' and its solution was to allow the birth of an immature fetus, which implies a long process of extra uterus development. Even so, to be born the fetus has many difficulties to negociate the pelvic channel. At birth the fetus brain is incompletely developed and has to finish developing out of the uterus, a process that takes about 20 years. This delay might explain no only some unpredictable adolescent behaviors, but also the onset of some diseases whose consequences are seen until the adult years, when brain development has finished.

Ácido docosahexaenoico (DHA), un ácido graso esencial a nivel cerebral / Docosahexaenoic acid (DHA), an essential fatty acid at the brain

Docosahexaenoic acid (C22: 6 -3, DHA) is a long-chain polyun-saturated fatty acid of marine origin essential for the formation and function of the nervous system, particularly the brain and the retina of humans. It has been proposed a remarkable role of DHA during the human evolution, mainly on the growth and development of the brain, effect that allowed the emergence of the first cognitive skills that differentiated our specie from other animals. Currently, DHA is considered a critical nutrient during pregnancy and breastfeeding due to it active participation at both, the structural and functional development of the nervous system in early life. DHA and specifically one of its derivatives known as neuroprotectin D-1 (NPD-1), has neuroprotective properties against brain aging, neurodegenerative diseases and injury caused by the damage generated during brain ischemia-reperfusion episodes. This paper reviews and discusses the importance of DHA in the human brain given the importance of this fatty acid in the development of the tissue and as neuroprotective agent. It also includes a critical view about the use of this noble fatty acid in the population.

El ácido docosahexaenoico (C22:6 ω-3, DHA) es un ácido graso poliinsaturado de cadena larga de origen marino fundamental para la formación y funcionalidad del sistema nervioso, especialmente para el cerebro y la retina de los humanos. Es destacable el rol trascendental que se propone tuvo este ácido graso en la evolución humana, principalmente en el crecimiento y desarrollo cerebral, efecto que permitió el surgimiento de las primeras habilidades cognitivas y de inteligencia que diferenciaron a nuestra especie de otros animales. Actualmente se considera al DHA como un nutriente crítico durante el embarazo y la lactancia debido a su activa participación en el desarrollo del sistema nervioso tanto a nivel estructural como funcional en los primeros años de vida. DHA y específicamente uno de sus derivados conocidos como neuroprotectina D-1 (NPD-1), presenta propiedades neuroprotectoras frente al envejecimiento cerebral, algunas enfermedades neurodegenerativas y a la injuria causada por el daño durante episodios de isquemia-reperfusión cerebral. En este trabajo se revisa y discute la relevancia del DHA a nivel cerebral, considerando la importancia de este ácido graso tanto en el desarrollo cerebral como en los efectos neuroprotectores que presenta. Se incluye, además, una visión crítica sobre el consumo de este noble ácido graso en la población.

Insights on the HLA-G evolutionary history provided by a nearby Alu insertion.

The AluyHG element belongs to the AluYb8 subfamily. It is a polymorphic insertion, located approximately 20 kb from the HLA-G 3'-untranslated region (3'-UTR), which has been used for evolution studies because it exhibits identity for descendants and it is still polymorphic in the human genome. To understand the evolutionary mechanisms acting on HLA-G, we evaluated the presence or absence of the AluyHG element, associating this variable site with others observed at HLA-G coding, 3'-UTR, or both regions in four distinct populations (Brazilian, French, Congolese, and Senegalese). The results were compared with the 1000Genomes Consortium data. The worldwide AluyHG frequencies showed an increment, starting lower in Africa and increasing following distance and time of human dispersion out of Africa. The same haplotype pattern was observed in all populations, indicating that most of the HLA-G haplotypes already detected were originated earlier in Africa, before Homo sapiens dispersion. The AluyHG insertion was associated with the G*01:01:01:01/UTR-1 haplotype, with rare recombinants. Despite its high frequency in worldwide populations, the G*01:01:01:01/UTR-1 haplotype should be very recent. The low frequency of recombinants indicates that the rate of recombination at the HLA-G gene is very low.