A Paleogenomic Reconstruction of the Deep Population History of the Andes.

There are many unanswered questions about the population history of the Central and South Central Andes, particularly regarding the impact of large-scale societies, such as the Moche, Wari, Tiwanaku, and Inca. We assembled genome-wide data on 89 individuals dating from ∼9,000-500 years ago (BP), with a particular focus on the period of the rise and fall of state societies. Today's genetic structure began to develop by 5,800 BP, followed by bi-directional gene flow between the North and South Highlands, and between the Highlands and Coast. We detect minimal admixture among neighboring groups between ∼2,000-500 BP, although we do detect cosmopolitanism (people of diverse ancestries living side-by-side) in the heartlands of the Tiwanaku and Inca polities. We also highlight cases of long-range mobility connecting the Andes to Argentina and the Northwest Andes to the Amazon Basin. VIDEO ABSTRACT.

A global analysis of matches and mismatches between human genetic and linguistic histories.

Human history is written in both our genes and our languages. The extent to which our biological and linguistic histories are congruent has been the subject of considerable debate, with clear examples of both matches and mismatches. To disentangle the patterns of demographic and cultural transmission, we need a global systematic assessment of matches and mismatches. Here, we assemble a genomic database (GeLaTo, or Genes and Languages Together) specifically curated to investigate genetic and linguistic diversity worldwide. We find that most populations in GeLaTo that speak languages of the same language family (i.e., that descend from the same ancestor language) are also genetically highly similar. However, we also identify nearly 20% mismatches in populations genetically close to linguistically unrelated groups. These mismatches, which occur within the time depth of known linguistic relatedness up to about 10,000 y, are scattered around the world, suggesting that they are a regular outcome in human history. Most mismatches result from populations shifting to the language of a neighboring population that is genetically different because of independent demographic histories. In line with the regularity of such shifts, we find that only half of the language families in GeLaTo are genetically more cohesive than expected under spatial autocorrelations. Moreover, the genetic and linguistic divergence times of population pairs match only rarely, with Indo-European standing out as the family with most matches in our sample. Together, our database and findings pave the way for systematically disentangling demographic and cultural history and for quantifying processes of shifts in language and social identities on a global scale.

Intravenous methylprednisolone pulses in hospitalised patients with severe COVID-19 pneumonia: a double-blind, randomised, placebo-controlled trial.

RATIONALE: Pulse glucocorticoid therapy is used in hyperinflammation related to coronavirus disease 2019 (COVID-19). We evaluated the efficacy and safety of pulse intravenous methylprednisolone in addition to standard treatment in COVID-19 pneumonia. METHODS: In this multicentre, randomised, double-blind, placebo-controlled trial, 304 hospitalised patients with COVID-19 pneumonia were randomised to receive 1 g of methylprednisolone intravenously for three consecutive days or placebo in addition to standard dexamethasone. The primary outcome was the duration of patient hospitalisation, calculated as the time interval between randomisation and hospital discharge without the need for supplementary oxygen. The key secondary outcomes were survival free from invasive ventilation with orotracheal intubation and overall survival. RESULTS: Overall, 112 (75.4%) out of 151 patients in the pulse methylprednisolone arm and 111 (75.2%) of 150 in the placebo arm were discharged from hospital without oxygen within 30 days from randomisation. Median time to discharge was similar in both groups (15 days, 95% CI 13.0-17.0 days and 16 days, 95% CI 13.8-18.2 days, respectively; hazard ratio (HR) 0.92, 95% CI 0.71-1.20; p=0.528). No significant differences between pulse methylprednisolone and placebo arms were observed in terms of admission to intensive care unit with orotracheal intubation or death (20.0% versus 16.1%; HR 1.26, 95% CI 0.74-2.16; p=0.176) or overall mortality (10.0% versus 12.2%; HR 0.83, 95% CI 0.42-1.64; p=0.584). Serious adverse events occurred with similar frequency in the two groups. CONCLUSIONS: Methylprenisolone pulse therapy added to dexamethasone was not of benefit in patients with COVID-19 pneumonia.

A genomic history of Aboriginal Australia.

The population history of Aboriginal Australians remains largely uncharacterized. Here we generate high-coverage genomes for 83 Aboriginal Australians (speakers of Pama-Nyungan languages) and 25 Papuans from the New Guinea Highlands. We find that Papuan and Aboriginal Australian ancestors diversified 25-40 thousand years ago (kya), suggesting pre-Holocene population structure in the ancient continent of Sahul (Australia, New Guinea and Tasmania). However, all of the studied Aboriginal Australians descend from a single founding population that differentiated ~10-32 kya. We infer a population expansion in northeast Australia during the Holocene epoch (past 10,000 years) associated with limited gene flow from this region to the rest of Australia, consistent with the spread of the Pama-Nyungan languages. We estimate that Aboriginal Australians and Papuans diverged from Eurasians 51-72 kya, following a single out-of-Africa dispersal, and subsequently admixed with archaic populations. Finally, we report evidence of selection in Aboriginal Australians potentially associated with living in the desert.

Insulin sensitivity depends on the route of glucose administration.

AIMS/HYPOTHESIS: The small intestine plays an important role in hepatic and whole-body insulin sensitivity, as shown by bariatric surgery. Our goal was to study whether routes and dose of glucose administration have an acute impact on insulin sensitivity. The primary endpoint of this proof-of-concept study was the difference in insulin-mediated metabolic clearance rate (MCR/I) of glucose between the oral and intravenous routes of glucose administration. Secondary endpoints were differences in insulin effect on proteolysis, ketogenesis, lipolysis and glucagon levels. METHODS: In this parallel cohort study, we administered multiple oral glucose loads to 23 participants (aged between 18 and 65 years) with morbid obesity and with normal or impaired glucose tolerance or type 2 diabetes. In a different session, we administered isoglycaemic intravenous glucose infusions (IGIVI) to match the plasma glucose levels observed during the oral challenges. Glucose rate of appearance (Ra) and disappearance (Rd) and endogenous glucose production (EGP) were calculated by infusing [6,6-2H2]glucose with or without oral [U-13C6]glucose. Plasma small polar metabolites were measured by gas chromatography and time-of-flight mass spectrometry. Lipids were measured by ultra-HPLC and quadrupole mass spectrometry. Glucagon-like peptide-1, insulin, C-peptide and glucagon were also measured. Participants, caregivers, people doing measurements or examinations, and people assessing the outcomes were unblinded to group assignment. RESULTS: Glucose MCR/I was significantly higher during IGIVI than during oral glucose administration, independently of glycaemic status (12 ± 6 for IGIVI vs 7.4 ± 3 ml min-1 kg-1 per nmol/l for oral, p< 0.001 from paired t test). Insulin secretion was higher during oral administration than during IGIVI (p< 0.001). The disposition index was significantly lower during the oral procedure: 4260 ± 1820 vs 5000 ± 2360 (ml min-1 kg-1 (nmol/l)-1 pmol/min; p = 0.005). Insulin clearance was significantly higher when glucose was infused rather than ingested (2.53 ± 0.82 vs 2.16 ± 0.49 l/min in intravenous and oral procedure, respectively, p = 0.006). The efficacy of insulin in inhibiting lipolysis and proteolysis was decreased after oral glucose loads. A heat map diagram showed a different pattern for the metabolites between the two routes of glucose administration. CONCLUSIONS/INTERPRETATION: Our study shows that insulin sensitivity depends on the route of glucose administration, the oral route leading to increased insulin secretion and compensatory insulin resistance compared with the intravenous route. The efficacy of insulin in blocking lipolysis and protein breakdown is lower after oral glucose loads vs the intravenous route. Our findings suggest that, while the glucose-mediated incretin release is followed by an increase in insulin release, the effect of the released insulin is limited by an increase in insulin resistance. TRIAL REGISTRATION: ClinicalTrials.gov NCT03223129. Graphical abstract.

The Current Genomic Landscape of Western South America: Andes, Amazonia, and Pacific Coast.

Studies of Native South American genetic diversity have helped to shed light on the peopling and differentiation of the continent, but available data are sparse for the major ecogeographic domains. These include the Pacific Coast, a potential early migration route; the Andes, home to the most expansive complex societies and to one of the most widely spoken indigenous language families of the continent (Quechua); and Amazonia, with its understudied population structure and rich cultural diversity. Here, we explore the genetic structure of 176 individuals from these three domains, genotyped with the Affymetrix Human Origins array. We infer multiple sources of ancestry within the Native American ancestry component; one with clear predominance on the Coast and in the Andes, and at least two distinct substrates in neighboring Amazonia, including a previously undetected ancestry characteristic of northern Ecuador and Colombia. Amazonian populations are also involved in recent gene-flow with each other and across ecogeographic domains, which does not accord with the traditional view of small, isolated groups. Long-distance genetic connections between speakers of the same language family suggest that indigenous languages here were spread not by cultural contact alone. Finally, Native American populations admixed with post-Columbian European and African sources at different times, with few cases of prolonged isolation. With our results we emphasize the importance of including understudied regions of the continent in high-resolution genetic studies, and we illustrate the potential of SNP chip arrays for informative regional-scale analysis.

Mechanisms for increased risk of diabetes in chronic liver diseases.

OBJECTIVE: Patients with chronic liver disease (CLD), both non-alcoholic fatty liver disease (NAFLD) and chronic hepatitis C (CHC), are at high risk of diabetes (T2D), but mechanisms are still unknown. Muscle/liver insulin resistance (IR) and pancreatic dysfunction are the major metabolic defects leading to T2D. However, if the risk of T2D in CLD patients is because of reduced insulin response and/or to IR, and the impact of liver histology has not been investigated. DESIGN: We studied 220 non-T2D patients with chronic liver disease (129 NAFLD, BMI = 27.3 kg/m2 ; 91 CHC, BMI = 25.0 kg/m2 ) that received a 75-gram oral glucose tolerance test (OGTT) with the measurement of glucose and insulin concentrations for 2 hours, glucose tolerance (NGT vs IGT) and liver biopsy. The results were compared to 26 controls (CT-NGT, BMI = 25.6 kg/m2 ). We evaluated peripheral insulin sensitivity (OGIS), OGTT-insulin response (ΔAUC-I/ΔAUC-G) and disposition-index (DI = OGIS∙ΔAUC-I/ΔAUC-G) for the risk to develop T2D. RESULTS: NAFLD had increased muscle IR (associated to NASH, steatosis and fibrosis), higher than in CHC or CT-NGT (OGIS = 8.9 vs 11.3 and 10.5 mL/min kg, P < .0001). In NAFLD, OGTT-insulin response (ΔAUC-I/ΔAUC-G) was the highest while it was significantly decreased in CHC (2.2 vs 1.1 and 1.6, NAFLD vs. CHC and CT-NGT, P < .005). The highest T2D risk (low DI) was observed in CHC-IGT (7.5), CHC-NGT (13.5) and NAFLD-IGT (10.8) vs CT-NGT (14.9, all P < .0001), but not in NAFL-NGT or NASH-NGT. CONCLUSION: We observed an increased T2D risk in NAFLD-IGT, CHC-IGT and CHC-NGT mainly because of reduced OGTT-insulin response, while insulin response in NAFLD-NGT compensates the IR thus maintaining normal glycaemia.

Efficacy of tocilizumab in patients with COVID-19 ARDS undergoing noninvasive ventilation.

BACKGROUND: The severity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is extremely variable, ranging from asymptomatic patients to those who develop severe acute respiratory distress syndrome (ARDS). As for now, there are still no really effective therapies for coronavirus disease 2019 (COVID-19). Some evidences suggest that tocilizumab (TCZ) may avoid the progression of severe COVID-19. The aim of this retrospective case-control study was to analyze the efficacy and safety of TCZ in patients with COVID-19 ARDS undergoing noninvasive mechanical ventilation (NIV). METHODS: Seventy-nine consecutive patients with severe COVID-19 pneumonia and worsening acute respiratory failure (ARF) were admitted to the Pulmonology Unit of Azienda USL of Reggio Emilia-IRCCS. All patients were inflamed (elevated CRP and IL-6 levels) and received NIV at admission according to the presence of a pO2/FiO2 ratio ≤ 200 mmHg. The possibility of being treated with TCZ depended on the drug availability. The primary outcome was the in-hospital mortality rate. A secondary composite outcome of worsening was represented by the patients who died in the pulmonology unit or were intubated. RESULTS: Out of 79 patients, 41 were treated with TCZ. Twenty-eight patients received intravenous (IV) TCZ and 13 patients received subcutaneous (SC) TCZ. In-hospital overall mortality rate was 38% (30/79 patients). The probabilities of dying and being intubated during the follow-up using Kaplan-Meier method were significantly lower in total patients treated with TCZ compared to those of patients not treated with TCZ (log-rank p value = 0.006 and 0.036, respectively). However, using Cox multivariate analyses adjusted for age and Charlson comorbidity index only the association with the reduced risk of being intubated or dying maintained the significance (HR 0.44, 95%CI 0.22-0.89, p = 0.022). Two patients treated with TCZ developed cavitating lung lesions during the follow-up. CONCLUSIONS: This study shows that TCZ treatment may be effective in COVID-19 patients with severe respiratory impairment receiving NIV. More data on safety are required. Randomized controlled trials are needed to confirm these results.

Inferring patterns of folktale diffusion using genomic data.

Observable patterns of cultural variation are consistently intertwined with demic movements, cultural diffusion, and adaptation to different ecological contexts [Cavalli-Sforza and Feldman (1981) Cultural Transmission and Evolution: A Quantitative Approach; Boyd and Richerson (1985) Culture and the Evolutionary Process]. The quantitative study of gene-culture coevolution has focused in particular on the mechanisms responsible for change in frequency and attributes of cultural traits, the spread of cultural information through demic and cultural diffusion, and detecting relationships between genetic and cultural lineages. Here, we make use of worldwide whole-genome sequences [Pagani et al. (2016) Nature 538:238-242] to assess the impact of processes involving population movement and replacement on cultural diversity, focusing on the variability observed in folktale traditions (n = 596) [Uther (2004) The Types of International Folktales: A Classification and Bibliography. Based on the System of Antti Aarne and Stith Thompson] in Eurasia. We find that a model of cultural diffusion predicted by isolation-by-distance alone is not sufficient to explain the observed patterns, especially at small spatial scales (up to [Formula: see text]4,000 km). We also provide an empirical approach to infer presence and impact of ethnolinguistic barriers preventing the unbiased transmission of both genetic and cultural information. After correcting for the effect of ethnolinguistic boundaries, we show that, of the alternative models that we propose, the one entailing cultural diffusion biased by linguistic differences is the most plausible. Additionally, we identify 15 tales that are more likely to be predominantly transmitted through population movement and replacement and locate putative focal areas for a set of tales that are spread worldwide.

Immune reconstitution inflammatory syndrome in tuberculous pleurisy and ulcerative colitis: a case report.

We present the case of a 46-year-old Caucasian male, affected by ulcerative colitis, who developed tuberculous pleurisy during immunosuppressive therapy; despite proper therapy, worsening of the radiological findings was observed. The case was discussed among an online group of Italian physicians and diagnosis of immune reconstitution inflammatory syndrome (IRIS) tuberculosis was established. Therapy was continued and full recovery was obtained. IRIS is a syndrome initially described during opportunistic infections in HIV infected after being placed in anti-retroviral therapy. It reveals itself through a wide variety of manifestations, including fever, lymphadenopathies, worsening of lung infiltrates, pleural or pericardial effusion, central nervous system involvement. Few data are available regarding the best therapeutic options. IRIS is an insidious and potentially serious complication of opportunistic infections in immunocompromised patients. The always wider diffusion of immunosuppressive therapies increases the number of patients at risk, therefore physicians need to be aware of the issue.

High-resolution mitochondrial DNA analysis sheds light on human diversity, cultural interactions, and population mobility in Northwestern Amazonia.

OBJECTIVES: Northwestern Amazonia (NWA) is a center of high linguistic and cultural diversity. Several language families and linguistic isolates occur in this region, as well as different subsistence patterns, with some groups being foragers and others agriculturalists. In addition, speakers of Eastern Tukanoan languages are known for practicing linguistic exogamy, a marriage system in which partners are taken from different language groups. In this study, we use high-resolution mitochondrial DNA sequencing to investigate the impact of this linguistic and cultural diversity on the genetic relationships and population structure of NWA groups. METHODS: We collected saliva samples from individuals representing 40 different NWA ethnolinguistic groups and sequenced 439 complete mitochondrial genomes to an average coverage of 1,030×. RESULTS: The mtDNA data revealed that NWA populations have high genetic diversity with extensive sharing of haplotypes among groups. Moreover, groups who practice linguistic exogamy have higher genetic diversity, while the foraging Nukak have lower genetic diversity. We also find that rivers play a more important role than either geography or language affiliation in structuring the genetic relationships of populations. DISCUSSION: Contrary to the view of NWA as a pristine area inhabited by small human populations living in isolation, our data support a view of high diversity and contact among different ethnolinguistic groups, with movement along rivers probably facilitating this contact. Additionally, we provide evidence for the impact of cultural practices, such as linguistic exogamy, on patterns of genetic variation. Overall, this study provides new data and insights into a remote and little-studied region of the world.

Genetic structure and sex-biased gene flow in the history of southern African populations.

OBJECTIVES: We investigated the genetic history of southern African populations with a special focus on their paternal history. We reexamined previous claims that the Y-chromosome haplogroup E1b1b (E-M293) was brought to southern Africa by pastoralists from eastern Africa, and investigated patterns of sex-biased gene flow in southern Africa. MATERIALS AND METHODS: We analyzed previously published complete mtDNA genome sequences and ∼900 kb of NRY sequences from 23 populations from Namibia, Botswana, and Zambia, as well as haplogroup frequencies from a large sample of southern African populations and 23 newly genotyped Y-linked STR loci for samples assigned to haplogroup E1b1b. RESULTS: Our results support an eastern African origin for Y-chromosome haplogroup E1b1b (E-M293); however, its current distribution in southern Africa is not strongly associated with pastoralism, suggesting more complex demographic events and/or changes in subsistence practices in this region. The Bantu expansion in southern Africa had a notable genetic impact and was probably a rapid, male-dominated expansion. Our finding of a significant increase in the intensity of the sex-biased gene flow from north to south may reflect changes in the social dynamics between Khoisan and Bantu groups over time. CONCLUSIONS: Our study shows that the population history of southern Africa has been complex, with different immigrating groups mixing to different degrees with the autochthonous populations. The Bantu expansion led to heavily sex-biased admixture as a result of interactions between Khoisan females and Bantu males, with a geographic gradient which may reflect changes in the social dynamics between Khoisan and Bantu groups over time.

Refining the Y chromosome phylogeny with southern African sequences.

The recent availability of large-scale sequence data for the human Y chromosome has revolutionized analyses of and insights gained from this non-recombining, paternally inherited chromosome. However, the studies to date focus on Eurasian variation, and hence the diversity of early-diverging branches found in Africa has not been adequately documented. Here, we analyze over 900 kb of Y chromosome sequence obtained from 547 individuals from southern African Khoisan- and Bantu-speaking populations, identifying 232 new sequences from basal haplogroups A and B. We identify new clades in the phylogeny, an older age for the root, and substantially older ages for some individual haplogroups. Furthermore, while haplogroup B2a is traditionally associated with the spread of Bantu speakers, we find that it probably also existed in Khoisan groups before the arrival of Bantu speakers. Finally, there is pronounced variation in branch length between major haplogroups; in particular, haplogroups associated with Bantu speakers have significantly longer branches. Technical artifacts cannot explain this branch length variation, which instead likely reflects aspects of the demographic history of Bantu speakers, such as recent population expansion and an older average paternal age. The influence of demographic factors on branch length variation has broader implications both for the human Y phylogeny and for similar analyses of other species.

Ancient substructure in early mtDNA lineages of southern Africa.

Among the deepest-rooting clades in the human mitochondrial DNA (mtDNA) phylogeny are the haplogroups defined as L0d and L0k, which are found primarily in southern Africa. These lineages are typically present at high frequency in the so-called Khoisan populations of hunter-gatherers and herders who speak non-Bantu languages, and the early divergence of these lineages led to the hypothesis of ancient genetic substructure in Africa. Here we update the phylogeny of the basal haplogroups L0d and L0k with 500 full mtDNA genome sequences from 45 southern African Khoisan and Bantu-speaking populations. We find previously unreported subhaplogroups and greatly extend the amount of variation and time-depth of most of the known subhaplogroups. Our major finding is the definition of two ancient sublineages of L0k (L0k1b and L0k2) that are present almost exclusively in Bantu-speaking populations from Zambia; the presence of such relic haplogroups in Bantu speakers is most probably due to contact with ancestral pre-Bantu populations that harbored different lineages than those found in extant Khoisan. We suggest that although these populations went extinct after the immigration of the Bantu-speaking populations, some traces of their haplogroup composition survived through incorporation into the gene pool of the immigrants. Our findings thus provide evidence for deep genetic substructure in southern Africa prior to the Bantu expansion that is not represented in extant Khoisan populations.

Between Andes and Amazon: the genetic profile of the Arawak-speaking Yanesha.

The Yanesha are a Peruvian population who inhabit an environment transitional between the Andes and Amazonia. They present cultural traits characteristic of both regions, including in the language they speak: Yanesha belongs to the Arawak language family (which very likely originated in the Amazon/Orinoco lowlands), but has been strongly influenced by Quechua, the most widespread language family of the Andes. Given their location and cultural make-up, the Yanesha make for an ideal case study for investigating language and population dynamics across the Andes-Amazonia divide. In this study, we analyze data from high and mid-altitude Yanesha villages, both Y chromosome (17 STRs and 16 SNPs diagnostic for assigning haplogroups) and mtDNA data (control region sequences and 3 SNPs and one INDEL diagnostic for assigning haplogroups). We uncover sex-biased genetic trends that probably arose in different stages: first, a male-biased gene flow from Andean regions, genetically consistent with highland Quechua-speakers and probably dating back to Inca expansion; and second, traces of European contact consistent with Y chromosome lineages from Italy and Tyrol, in line with historically documented migrations. Most research in the history, archaeology and linguistics of South America has long been characterized by perceptions of a sharp divide between the Andes and Amazonia; our results serve as a clear case-study confirming demographic flows across that 'divide'.

Unraveling the complex maternal history of Southern African Khoisan populations.

The Khoisan populations of southern Africa are known to harbor some of the deepest-rooting lineages of human mtDNA; however, their relationships are as yet poorly understood. Here, we report the results of analyses of complete mtDNA genome sequences from nearly 700 individuals representing 26 populations of southern Africa who speak diverse Khoisan and Bantu languages. Our data reveal a multilayered history of the indigenous populations of southern Africa, who are likely to be the result of admixture of different genetic substrates, such as resident forager populations and pre-Bantu pastoralists from East Africa. We find high levels of genetic differentiation of the Khoisan populations, which can be explained by the effect of drift together with a partial uxorilocal/multilocal residence pattern. Furthermore, there is evidence of extensive contact, not only between geographically proximate groups, but also across wider areas. The results of this contact, which may have played a role in the diffusion of common cultural and linguistic features, are especially evident in the Khoisan populations of the central Kalahari.

Global musical diversity is largely independent of linguistic and genetic histories.

Music is a universal yet diverse cultural trait transmitted between generations. The extent to which global musical diversity traces cultural and demographic history, however, is unresolved. Using a global musical dataset of 5242 songs from 719 societies, we identify five axes of musical diversity and show that music contains geographical and historical structures analogous to linguistic and genetic diversity. After creating a matched dataset of musical, genetic, and linguistic data spanning 121 societies containing 981 songs, 1296 individual genetic profiles, and 121 languages, we show that global musical similarities are only weakly and inconsistently related to linguistic or genetic histories, with some regional exceptions such as within Southeast Asia and sub-Saharan Africa. Our results suggest that global musical traditions are largely distinct from some non-musical aspects of human history.

Contrasting maternal and paternal histories in the linguistic context of Burkina Faso.

Burkina Faso is located in the heart of West Africa and is a representative of the local structured patterns of human variability. Here, different cultures and languages are found in a geographic contiguity, as a result of several waves of migration and the succession of long- and short-term empires. However, historical documentation for this area is only partial, focusing predominantly on the recent empires, and linguistic surveys lack the power to fully elucidate the social context of the contact-induced changes. In this paper, we report Y-chromosomal data and complete mtDNA genome sequences for ten populations from Burkina Faso whose languages belong to two very distantly related branches of the Niger-Congo phylum, the Gur and Mande language families. In addition, two further populations, the Mande-speaking Mandenka from Senegal and the Yoruba from Nigeria, were included for regional comparison. We focus on the different historical trajectories undergone by the maternal and paternal lineages. Our results reveal a striking structure in the paternal line, which matches the linguistic affiliation of the ethnolinguistic groups, in contrast to the near-complete homogeneity of the populations in the maternal line. However, while the ancient structure along the linguistic lines is apparent in the Y-chromosomal haplogroup affiliation, this has clearly been overlain by more recent migrations, as shown by significant correlations between the genetic distances based on Y chromosome short tandem repeats and geographic distances between the populations, as well as by the patterns of shared haplotypes. Using the complete mtDNA sequences, we are able to reconstruct population size variation in the past, showing a strong sign of expansion in the concomitance with the Holocene Climate Optimum approximately 12,000-10,000 years ago, which has been suggested as the cause of the spread of the Niger-Congo phylum in the area. However, subsequent climatic fluctuations do not appear to have had an impact on the demography of the inhabitants of West Africa, probably reflecting the adaptive advantages of cultural innovations, such as pastoralism and agriculture.

Bridging the gap: returning genetic results to indigenous communities in Latin America.

In response to inequality in access to genomics research, efforts are underway to include underrepresented minorities, but explicit (and enforcing) guidelines are mostly targeted toward the Global North. In this work, we elaborate on the need to return scientific results to indigenous communities, reporting the actions we have taken in a recent genomic study with Mapuche communities in Chile. Our approach acknowledged the social dynamics perpetuating colonial hierarchies. We framed genetic results to empower indigenous knowledge and communities' history and identities. A fundamental step in our strategy has been sharing the results with the communities before publishing the scientific paper, which allowed us to incorporate community perspectives. We faced the challenge of translating genetic concepts like admixture, emphasizing the distinction between identity and biology. To reach a broad and diverse audience, we disseminated the study results to single community members, cultural representatives, and high schools, highlighting the importance of the history of the region before the European contact. To facilitate results dissemination, we prepared didactic material and a report in Spanish written in non-specialized language, targeting a wider Latin American readership. This work illustrates the benefits of discussing scientific findings with indigenous communities, demonstrating that a collaborative and culturally sensitive approach fosters knowledge sharing and community empowerment and challenges power dynamics in genetic research. Bridging the gap between academia and indigenous communities promotes equity and inclusion in scientific endeavors.