About

Abigail Bigham is an Associate Professor of Anthropology at UCLA and the Principal Investigator of the Bigham Lab for Anthropological Genomics. She received her Bachelor of Arts in Anthropology from the University of Arizona and completed her PhD under the mentorship of Mark Shriver at Penn State University. Prior to joining UCLA, she was a postdoctoral researcher with Mike Bamshad at the University of Washington and held a faculty position at the University of Michigan. Professor Bigham's research group focuses on exploring human genomic adaptation, investigating how human populations have evolved genetically in response to various environmental pressures.

Research topics

• Biology
• Genetics
• Physiology
• Internal medicine
• Medicine
• Evolutionary biology

Selected publications

• Rapid adaptive increase of amylase gene copy number in Indigenous Andeans

  Nature Communications · 2026-05-05

  articleOpen access

  The salivary amylase gene AMY1 exhibits remarkable copy number variation linked to dietary shifts in human evolution. While global studies highlight its structural complexity and association with starch-rich diets, localized selection patterns remain underexplored. Here, we analyze AMY1 copy number in 3,723 individuals from 85 populations, revealing that Indigenous Peruvian Andean populations possess the highest AMY1 copy number globally. A genome-wide analysis shows significantly higher amylase copy numbers in Peruvian Andean genomes compared to closely related populations. Further, we identify positive selection (selection coefficient of 0.0124, log likelihood ratio of 11.1543) at the nucleotide level on a haplotype harboring at least five haploid AMY1 copies, with a Peruvian Andean-specific expansion dated to around 10,000 years ago, coinciding with potato domestication in the region. Using ultra-long-read sequencing, we demonstrate that previously described recombination-based mutational mechanisms drive the formation of high-copy AMY1 haplotypes observed in Andean population. Our study provides a framework for investigating structurally complex loci and their role in human dietary adaptation.

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• High-altitude hypoxia alters the visual control of standing balance in lowlanders and Tibetan highlanders

  Journal of Neurophysiology · 2026-05-19

  articleOpen access

  High-altitude hypoxia affects both visual function and postural control, yet the influence of optic-flow perturbations on standing balance under hypoxic stress remains unclear. Tibetan highlanders (TH) exhibit adaptations to chronic hypoxia, but whether their visually-driven postural responses differ from those of lowlanders (LL) has not been investigated. We examined how high-altitude exposure and acclimatization influence static and dynamic visual contributions to balance by delivering sinusoidal optic-flow perturbations in virtual reality at low altitude (1,400 m) and after incremental ascent to high altitude (4,300 m) in acclimatizing LL (n=15) and TH (n=14). Anteroposterior center of pressure (AP CoP) velocity and mean power frequency (MPF) were measured during three visual-field conditions (full-, central-, peripheral-vision) and two optic-flow velocities (peak 1m/s and 8m/s at 0.25 Hz). At high altitude, both groups showed attenuated responses to optic flow compared to 1,400 m, reflected by reduced AP CoP velocity and lower MPF across visual-field conditions, consistent with reduced responsiveness to dynamic visual-motion cues under high altitude hypoxia. In contrast, during eyes-open quiet stance (no VR), TH but not LL exhibited increased AP CoP velocity and MPF at 4,300 m, and no altitude effect was observed with eyes-closed in either group. This finding indicates that TH adopt a visually-dependent postural strategy at altitude, whereas LL show minimal changes in static visual balance control but reduced responsiveness to fast dynamic motion. Together, these findings demonstrate that high-altitude hypoxia disrupts dynamic visual processing for balance control in both groups, while revealing group differences in the use of static visual cues during quiet stance.

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• Hemoglobin mass and plasma volume responses are not different between lowlanders and Tibetan highlanders during early acclimatization to 4300 m

  European Journal of Applied Physiology · 2026-02-25

  article
  PublisherDOI

• Reply to Kleinsasser and Burtscher

  Journal of Applied Physiology · 2026-05-01

  articleOpen access
  PublisherDOI

• Incremental ascent to 4300 m does not alter standing balance in lowlanders or Tibetan highlanders

  European Journal of Applied Physiology · 2025-04-11 · 1 citations

  article
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• Advances in Understanding Adaptive Hemoglobin Concentration at High Altitude

  American Journal of Human Biology · 2025-07-01 · 5 citations

  articleOpen accessSenior authorCorresponding

  Today, more than 81 million people globally live at altitudes ≥ 2,500 m (Tremblay and Ainslie 2021), which corresponds to less than 73% of the oxygen present at sea level, dropping exponentially downwards with increasing elevation. This reduced atmospheric oxygen content, known as high-altitude hypoxia, presents a pronounced physiological challenge to human health, well-being, and reproduction. Nevertheless, there are three global regions where humans have lived in the hypoxic conditions of high altitude for millennia. They include the Andean Altiplano of South America, the Himalayan Plateau of East/Central Asia, and the Semien Plateau of Ethiopia. For decades, biological anthropologists, physiologists, and others have studied human adaptation to hypoxia among the high-altitude populations from these regions (Beall 1982; Frisancho 1969). This work has highlighted that each of these groups has developed unique physiological, genetic, and potentially epigenetic adaptations to life in low oxygen conditions (Alkorta-Aranburu et al. 2012; Beall et al. 2010; Bigham et al. 2010; Childebayeva et al. 2021). One phenotype that has been of particular interest in high-altitude evolutionary studies is hemoglobin. Hemoglobin (Hb) is the iron-containing protein found in red blood cells (RBC) responsible for oxygen transport. It carries oxygen from the lungs to the various tissues in the body. Hb concentration is a measure of the amount of hemoglobin protein in red blood cells. At high elevation, atmospheric oxygen is limited, thus reducing arterial oxygen content. High-altitude sojourners overcome this reduction by increasing the amount of circulating Hb, initially through reductions in plasma volume and Hb-O2 affinity, and later through increases in red cell volume (Siebenmann et al. 2015). Among high-altitude-adapted populations, we see distinct hematological adaptations to hypoxia both between and in comparison to high-altitude sojourners. Tibetans display a relatively low erythropoietic response and attendant low Hb concentration (Adams and Strang 1975; Beall and Goldstein 1987; Beall and Reichsman 1984). Andeans exhibit elevated concentrations with some individuals presenting with polycythemia, or the increase of hematocrit and/or Hb (Beall et al. 1990, 1998). Hematocrit is related to Hb concentration and measures the percentage of whole blood composed of red blood cells. High-altitude Ethiopians of mainly Amharic ancestry show similar Hb concentrations compared to low-altitude US residents (Beall et al. 2002), but high-altitude Amhara and Oromo exhibit elevated Hb levels compared to their low-altitude (< 1500 masl) counterparts (Scheinfeldt et al. 2012; Alkorta-Aranburu et al. 2012), with Oromo displaying twice the elevation in Hb level compared to Amhara (Alkorta-Aranburu et al. 2012). Collectively, this physiological evidence demonstrates that modifications to Hb concentration play an important role in the biological response to hypoxia. A cohort of genome-wide investigations published in 2010 demonstrated that Andeans and Tibetans have adapted by natural selection to high-altitude hypoxia (Beall et al. 2010; Bigham et al. 2010; Simonson et al. 2010; Yi et al. 2010), and, among Tibetans, that adaptive genetic variation contributed to their blunted Hb phenotype. In particular, two genes central to the hypoxia inducible factor (HIF) pathway, an evolutionarily ancient transcriptional regulatory pathway for the cellular response to hypoxia (Semenza 2012), showed signatures of positive selection and possessed variation that was associated with Hb concentration: EPAS1 (also known as HIF2A) and EGLN1 (also known as PHD2). These findings provided strong support for the hypothesis that hypoxia has acted as a selective agent on HIF genes to influence Hb concentration. Genome-wide data from Andeans also showed evidence of natural selection at EGLN1 (Bigham et al. 2010) and EPAS1 (Foll et al. 2014) but associations with phenotype were not explored at that time. In 2013, we and others published “Andean and Tibetan patterns of adaptation to high-altitude” in the American Journal of Human Biology. In this article, we tested for EGLN1 and EPAS1 SNP associations with Hb concentration in Andeans, identifying no significant genotype–phenotype relationships. These findings suggested that the two genes with variation associated with Hb concentration among Tibetans did not contribute to the Andean Hb phenotype. We were careful to emphasize that Hb concentration could indeed have a genetic basis among Andeans and importantly, yet to be identified genetic variants in EGLN1 and/or EPAS1 could contribute. We recommended continued investigation into the genetic contributions to Andean Hb concentration. Since our 2013 publication, much has been learned about the genetic basis of Hb concentration among Andeans, Tibetans, and, to a lesser degree, highland Ethiopians. In this commentary, we discuss the advances in our understanding of the genetic basis of altitude-adaptive Hb concentration, the strides made in characterizing the functional consequence of altitude-adaptive variation on Hb phenotypes, and the integration of epigenetics into Hb studies. Hb plays a central role in acclimatization, as it is one of the main mechanisms by which the body physiologically adjusts to lower oxygen partial pressure (Jourdanet 1875; Monge and León-Velarde 1991; Viault 1890). At high elevation, reduced environmental oxygen diminishes available oxygen along the oxygen transport chain, physiologically translating to reduced blood oxygen content and diminished tissue oxygenation. The reduction in oxygen upon acute exposure to hypoxia (Figure 1) sets in motion a series of physiological changes, including a hematopoietic response wherein Hb concentration rises over a period of several weeks. This occurs through a cascade of events rooted in oxygen sensing and signaling by the kidney. Upon immediate exposure to high elevation, the kidney detects lowered blood oxygen content. The renal glycoprotein hormone erythropoietin (EPO) then stimulates erythropoiesis in the bone marrow, resulting in increased red blood cell production that compensates for the lowered arterial oxygen content (Knaupp et al. 1992). Activated by the HIF pathway, plasma EPO levels rise rapidly and peak 1–2 days after initial hypoxic exposure (Haase 2010), eventually decreasing as hematocrit increases over a period of a few weeks. For lowland sojourners to high elevation, this leads to an increase in Hb concentration over a period of 1–2 weeks of sustained hypoxia exposure (Childebayeva, Harman, et al. 2019; D'Alessandro et al. 2016). This increased production of erythrocytes promotes greater oxygen-carrying capability that helps overcome the lower ambient oxygen tension and is part of the acclimatization process to high elevation. Hb concentration is a highly polygenic phenotype. Although sometimes elusive in its genomic underpinnings, it has emerged as an extremely useful example of how natural selection can act across diverse, population-specific variation to shape high-altitude-adaptive phenotypes. Investigations seeking to understand the genetic basis of Hb concentration among the three long-term, high-altitude populations have highlighted distinct genetic adaptations within each population and have revealed a breadth of potentially Hb-associated genes. These include HIF-pathway genes such as EPAS1 and EGLN1, as well as genes that participate in other biological pathways including HMOX2, PDE1B, NOS2, and NFKB1 (Amaru et al. 2022; Beall et al. 2010; Scheinfeldt et al. 2012; Yang et al. 2017; Yi et al. 2010). EPAS1 and EGLN1 are among the few genes that show signals of selection across populations, and for which there exists evidence that naturally selected variation underlies Hb-adaptive phenotypes. EPAS1 encodes for the HIF-2α protein and, together with its paralogue HIF-1α, comprises the α-subunit (HIF-α) of the constitutively expressed heterodimeric HIF transcription factor responsible for oxygen sensing. EGLN1 plays a key role in the regulation of HIF-α. It encodes for the PHD2 enzymatic protein, which together with PHD1 and PHD3, regulates HIF-α. Under normoxia, HIF-α is hydroxylated by PHD, targeting it for proteasomal degradation by the ubiquitin-proteasome pathway (Kaelin Jr. and Ratcliffe 2008). Under hypoxia, HIF-α is stabilized through arrested posttranslational modification by PHD, leading to the upregulation of target genes involved in oxygen homeostasis, including the erythropoietin-encoding gene EPO that controls Hb concentration (Lappin and Lee 2019). The evidence for Hb association for EPAS1 is compelling and has been replicated across studies, whereas the EGLN1 evidence of association with Hb concentration is weaker, underlying the complex polygenic nature of Hb response that is different by population. The most compelling evidence of genetic variation contributing to the Tibetan pattern of Hb adaptation is for EPAS1. Early work identified EPAS1 genotypes and a haplotype that have been repeatedly associated with the low Hb concentration observed among Tibetan and Tibetan-derived populations (Beall et al. 2010; Bhandari et al. 2017; Yang et al. 2017; Yi et al. 2010; Ye et al. 2024). Adaptive Tibetan EPAS1 variation is non-coding, with over 30 variants identified to date, and the dominant Tibetan haplotype has an estimated frequency of 72% (Huerta-Sánchez et al. 2014; Peng et al. 2011). This haplotype has been attributed to Denisovan introgression (Huerta-Sánchez et al. 2014), indicating an important role for adaptive archaic introgression in shaping this phenotype. Evidence suggests that the Tibetan EPAS1 allele results in transcriptional downregulation of the protein product or decreased splicing and could be a loss-of-function allele. First, EPAS1 adaptive variation is associated with a blunted hemopoietic response as opposed to an augmented response (Beall et al. 2010; Yi et al. 2010). Second, Tibetan EPAS1 homozygotes display a lowered plasma EPO response to hypoxia in comparison to Tibetans who are homozygous for the lowland allele (Petousi et al. 2014). Third, Tibetan EPAS1 mRNA levels from multiple cell types are lower than levels measured among closely related Han Chinese (Peng et al. 2017; Petousi et al. 2014; Xin et al. 2020). Fourth, Tibetan EPAS1 SNV reporter gene assays across multiple cell types and transcriptomic analysis of differential expression in iPSCs show a lowered EPAS1 transcriptional response in hypoxia for Tibetan adaptive alleles (Gray et al. 2022, 2025). However, every one of the at least 30 Tibetan EPAS1 variants is noncoding, making identification and functional characterization of the causal variant(s) challenging. Negative associations with Hb concentration also have been identified for EGLN1 variants by some studies (Lorenzo et al. 2014; Simonson et al. 2010), but not all (Wuren et al. 2014; Yang et al. 2017; Jeong et al. 2018). Whereas others have detected weak associations with sex-specific effects (Xiang et al. 2013). It is noteworthy that fewer studies have replicated EGLN1 associations with Hb concentration compared to the number of studies that have replicated this association for EPAS1. The discrepancy between EGLN1 findings likely results from differences in study populations (geographic location and level of admixture), range of Hb levels including some studies with Hb concentration in the anemic range, and total number of study participants. Considering the HIF pathway's role in regulating physiology beyond Hb concentration, natural selection on EGLN1 variation may have been driven by additional altitude-adaptive phenotypes and is supported by mounting functional evidence (D. Song et al. 2020). Two nonsynonymous coding variants, rs12097901 (C127S) and rs186996510 (D4E), found to be in strong linkage disequilibrium, are enriched in the Tibetan population (Lorenzo et al. 2014; Petousi et al. 2014). Some have suggested that the Tibetan D4E/C127S allele is a gain-of-function allele, observing increased oxygen binding in interaction experiments of recombinant proteins (Lorenzo et al. 2014). However, in vitro functional work exploring the effect of the Tibetan D4E/C127S haplotype demonstrated that this allele is defective in its interaction with p23, a cochaperone of the HSP90 pathway involved in HIF-α hydroxylation (Song et al. 2014). This results in impaired down-regulation of the HIF pathway and suggests that the Tibetan allele is a loss-of-function hypomorphic allele. Loss-of-function is further supported by knock-in mouse lines wherein mice bearing the Tibetan allele have an augmented hypoxic ventilatory response (Song et al. 2020). Of importance, this same study showed that mice bearing the Tibetan allele did not show any effect of hypoxia on Hb compared to wild-type mice (Song et al. 2020). Interestingly, a gene–gene interaction study suggested that Tibetan-specific variation in EGLN1 may act in concert with the presence of a Tibetan-specific EPAS1 haplotype to lower Hb concentration (Tashi et al. 2017). Together, the full suite of EPAS1 and EGLN1 data that EPAS1 variation is the main of the Tibetan low with variation in EGLN1 likely other or its The evidence for EPAS1 role in shaping the Tibetan Hb phenotype and to a lesser EGLN1 associations with Hb concentration not the of additional genomic contributing to this phenotype. For genetic variation in a with lowered Hb concentrations et al. 2010), a Tibetan in has been found to have a sex-specific association with lowered Hb et al. 2016). However, others have found no evidence of polygenic selection among Tibetans after for the effects of EPAS1 on Hb concentration et al. 2018). Together, continued beyond EPAS1 and EGLN1 to understand the genetic of the Tibetan adaptive phenotype is compelling evolutionary studies of altitude adaptation it the of exploring polygenic selection to more the evolutionary of adaptation to high altitude and Hb adaptation Among Andeans, to genetic variation in EPAS1 and EGLN1 contributing to Andean Hb concentration. studies that variants associated with this phenotype among Tibetans did not show patterns of adaptation among Andeans, did with Andean Hb concentration (Bigham et al. et al. 2019). This gene work was in the for studies on understanding the role of adaptive genetic variation in shaping Andean studies have further explored the hypothesis that EGLN1 and EPAS1 variation contribute to Hb variation among et al. demonstrated that EGLN1 haplotype variation in and associated with elevated Hb concentration. These data support to the that elevated Andean Hb concentration is an adaptive for hypoxia and the hypothesis that natural selection has in Andeans to increase Hb concentration over evolutionary time. However, this study EGLN1 EPAS1 an for which natural or a selective that is in its by selection analysis on alleles with has been detected among Andean from and et al. 2017; et al. et al. 2024). This was not found to be associated with Andean Hb concentration in a cohort of high-altitude with Hb concentration of mice et al. the data from this study that the SNV associated with increased of and may contribute to Andean from through impaired interaction with Together, the human and mouse data that the Andean allele is a partial loss-of-function allele. In et al. identified an association for with decreased hematocrit among but not support for this association from human kidney cell work wherein expression of genes in hypoxia was lower for cells with one of the Andean allele compared to wild-type cells. the this association with may be to the of individuals with or a high concentration of red blood with the adaptive allele to Hb concentrations in the of the The discrepancy between the et al. and et al. findings may be a of the range of Hb concentrations among the study with the et al. study including individuals with studies be to the effect of EPAS1 on Andean phenotypes. we not yet how or to natural selection may be on Hb concentrations among One hypothesis suggests that elevated concentrations are driven by acclimatization to hypoxia, and this response can be in the exposure to high-altitude hypoxia may to and selection may be to this response among Andeans, thus resulting in is observed among natural selection may be to shape an Hb concentration that between and This for increased blood oxygen but to the of increased blood and diminished blood Today, there are two main groups who have lived for at high elevation in the Semien of the Amhara and Amhara are estimated to have lived at high elevation for the whereas the Oromo to the within the (Alkorta-Aranburu et al. 2012). The two groups display distinct Hb phenotypes, with Amhara a blunted hemopoietic response to high-altitude hypoxia, but Oromo presenting with elevated Hb concentration et al. 2017). to Tibetan and Andean populations, there is a of the genomic basis of Hb concentration among have identified a range of Hb or genes that may be important Hb adaptive phenotypes among both Oromo and Amhara and among the Amhara (Huerta-Sánchez et al. 2013). and have been to the protein, as has been to decreased protein can target for Among a in a gene is associated with Hb level (Alkorta-Aranburu et al. 2012). In evidence for weak association with Hb concentration has been identified for variants in genes that show evidence of selection and for others that not (Alkorta-Aranburu et al. 2012; Scheinfeldt et al. 2012). associations for EGLN1 with Hb level have been identified to Human Hb concentration is known to be a highly polygenic et al. et al. et al. 2020). it is likely that natural selection is to shape high-altitude Hb concentration in an polygenic natural selection can act to complex adaptive more rapidly than can be by selective and this of genetic adaptation is likely more than selective et al. et al. et al. et al. 2010). polygenic such as Hb concentration may be by of variants unique to each underlying genomic and population This is with the of Hb-associated genes across such as EPAS1 and EGLN1 may phenotypes in distinct However, polygenic selection is the of effect over a of genes. Nevertheless, genome-wide investigations of Hb concentration have supported a of polygenic selection by associations for an of genomic Among Andeans, variants in the genes EGLN1, PDE1B, and have association with Hb concentration (Amaru et al. 2022; et al. 2020). For Tibetans, genetic variation in EGLN1, and may contribute to lowered Hb concentration (Beall et al. 2010; Simonson et al. 2010; Yang et al. Yi et al. 2010). of other genes significant signals of such as and could further on the range of genomic and pathways that contribute to this adaptive as genome-wide selection have revealed patterns of adaptation with population-specific adaptive variation across the genome-wide association studies further of how Hb concentration is studies and, in some to gene expression that not to the and 2012; and such as and the is the most to environmental et al. epigenetic have been to play a role in in the of life that may influence and and 2011). In the of high hypoxia exposure in and the of life may to the body for life in low oxygen Although epigenetic modifications have been to contribute to high-altitude adaptation it is mainly within the that epigenetic has been studied in this environmental (Childebayeva, et al. 2019). Some of the most compelling epigenetic findings to from studies among in have been identified in Andeans with both and to high altitude compared to Andeans and at low elevation et al. et al. 2019). This suggests of exposure to hypoxia that an Early work with Ethiopians identified no significant differences and low-altitude Oromo and but this was likely to low (Alkorta-Aranburu et al. 2012). among high-altitude Tibetans, and Andeans a role for epigenetic modification in shaping hemopoietic to high-altitude hypoxia. In the of individuals to high-altitude hypoxia an increase in of has been to increased Hb concentration levels (Childebayeva, Harman, et al. 2019). is a gene that is for and in et al. 2017; et al. significant association between EPAS1 and Hb concentration was identified in the same study (Childebayeva, Harman, et al. 2019). In Tibetans from high altitude levels in the regions of and have been identified in high-altitude compared to the controls et al. 2024). Among Andeans, lower levels at in the with the EPAS1 have been found in individuals at high with the of at high elevation associated with levels (Childebayeva, et al. 2019). on these same we identified an association between EPAS1 and Hb levels that Andean from both high and low altitude for of and (Figure occurs within groups with as a with associated with lower In this lower of the in the the EPAS1 is associated with Hb a of This the effect of hypoxia on EPAS1 which in Hb our of an association between lower EPAS1 and the altitude of in the (Childebayeva, et al. we also identified a significant association between EPAS1 and and EPAS1 et al. 2021). to the that genetic variation plays a role in the variation for EPAS1 (Childebayeva, et al. in EGLN1 have been to the levels of the et al. Together, these findings a complex between environmental genetic epigenetic and the resulting phenotype (Figure an of Hb concentration is for the body in hypoxia, as this phenotype has the for hypoxic conditions but also contributing high-altitude elevated Hb concentrations blood oxygen and tissue but elevated Hb concentrations may the of oxygen across the The increased blood by an elevated Hb concentration can in reduced and blood 2021). by high Hb can in and to increased blood et al. 2018). is a key of a that can after an period of at high altitude and that is by polycythemia, and blood Among high-altitude adapted populations, Andeans display the of at to among Tibetans of among and no evidence to exists for among Ethiopians et al. genes such as and have been associated with the erythropoietic response that and high-altitude among Andean populations et al. et al. Song et al. et al. 2017; et al. 2013). some investigations have identified and genes that show signals of including and et al. et al. 2019; et al. 2013). Although these genes have been identified in association with polycythemia, it is likely that also may Hb concentrations of this in Andeans who exhibit increased levels with epigenetic modifications could at least to a degree, the of the of and be explored in of beyond in our understanding of the genetic basis for altitude-adaptive Hb phenotypes, in the has identified genetic variation associated with additional altitude-adaptive with for human These genes and phenotypes but are not EGLN1 variation on or work among Andeans et al. and variation on et al. and variation on measured as number of and number of live et al. 2018). In the more than the of “Andean and Tibetan patterns of adaptation to high-altitude” in the American Journal of Human a understanding of the underlying of high-altitude Hb adaptation has among Tibetans has been with several studies characterizing adaptive Tibetan EPAS1 and EGLN1 their on protein This work has revealed in part how genetic into altitude-adaptive phenotypes. Among Andeans, strides in understanding the genetic basis of adaptive Hb variation have suggested that polygenic natural selection may be to Hb concentration in this and that the HIF genes EGLN1 and EPAS1 may indeed contribute to the Andean Hb phenotype. For several including but not EGLN1, have emerged as of natural selection that may be involved in shaping Hb in this of the In to in understanding the genetic basis of Hb concentration, epigenetics has emerged as a for high-altitude adaptation an effect on Hb, including evidence that EPAS1 helps shape Hb concentration. The to which epigenetic modifications are involved an and further In the the continued integration of evolutionary and functional in the study of human adaptation to high elevation to into the mechanisms adaptive hemopoietic it as a for understanding the functional basis of naturally selected genetic variation and and and and We all the individuals who have in high-altitude across the We to and Lee for that have to of the in this The have to The no of not to this as no were or the

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• Adaptive Increase of Amylase Gene Copy Number in Peruvians Driven by Potato-rich Diets

  Research Square · 2025-03-24

  preprintOpen accessSenior author
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• Large artery and cerebral pulsatile hemodynamics during high-altitude sojourn

  Journal of Applied Physiology · 2025-10-18

  articleOpen access

  We observed differential changes in aortic versus carotid stiffness, consistent reductions in characteristic impedance and cerebral pulsatility, and increased mean hydraulic energy in the carotid and MCA with ascent from 1,400 to 4,300 m over 6 days, with modest sex-specific responses. These data suggest there may be modest sex differences in cerebrovascular hemodynamic mechanisms driving reductions in cerebral pulsatility with ascent to high altitude that require further investigation.

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• Vestibular-evoked balance responses are blunted in lowlanders and Tibetan highlanders with ascent to 4300 m

  Applied Physiology Nutrition and Metabolism · 2025-01-01

  article

  Hypoxia influences postural control and vestibular function. However, the vestibular control of standing balance at high altitude is poorly understood. Furthermore, Tibetan highlanders are physiologically adapted to high altitude, but it is unclear whether vestibular-driven signals for balance within this population acclimate differently than lowlanders with ascent. This study investigated vestibular-evoked balance responses in unacclimatized lowlanders and Tibetan highlanders at low altitude (1400 m) and after 6 or 7 days of incremental ascent to high altitude (4300 m). Twenty-eight participants (15 lowlanders, 8 F, 7 M; 13 Tibetan highlanders, 7 F, 6 M) stood on a force plate facing forward with their eyes closed and underwent 90-s stochastic electrical vestibular stimulation trials at a peak-to-peak amplitude of ±2 or ±4 mA. Vestibular-evoked balance responses were quantified using cumulant density and coherence (0–5 and 5–10 Hz) between electrical vestibular stimulation and mediolateral forces. With ±2 mA stimulation, the peak-to-peak amplitude of vestibular-evoked balance responses decreased at high compared to low altitude for both groups ( P = 0.003). With ±4 mA stimulation, only lowlanders showed a reduction in peak-to-peak amplitude at high altitude ( P = 0.03), and their responses were smaller than Tibetan highlanders at high altitude ( P = 0.046). For frequency-domain outcomes, lowlanders exhibited a smaller 0–5 Hz coherence area at high compared to low altitude with ±2 mA stimulation ( P = 0.002), whereas Tibetan highlanders showed no change. No differences in coherence area were observed in either group with ±4 mA stimulation. These findings indicate that while the vestibular control of balance is blunted at high altitude for lowlanders and highlanders, the altitude effect is greater in lowlanders.

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• No altitude required: differential ventilatory and blood acid-base homeostasis between unacclimatized lowlanders and Tibetan highlanders at 1,400 m

  Journal of Applied Physiology · 2025-09-18 · 3 citations

  articleOpen access

  Understanding the role of ancestry in the regulation of ventilatory and renal homeostasis is key to interpreting high-altitude acclimatization and adaptation. We compared unacclimatized lowlanders (LL) and Tibetan highlanders (TH; Sherpa) at 1,400 m. TH had significantly lower Pco 2 and [HCO 3 − ], suggesting a distinct respiratory and blood acid-base set point. These results highlight intrinsic respiratory and renal integration in TH, revealing population-level physiological differences independent of hypoxic stress, likely shaped by developmental or genetic adaptation.

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Recent grants

• Investigating Targets of Natural Selection for Hypoxic Adaptation at High Altitudes

  NSF · $408k · 2016–2019

Frequent coauthors

• Tom D. Brutsaert

  Syracuse University

  37 shared

• Melisa Kiyamu

  Universidad Peruana Cayetano Heredia

  22 shared

• Lorna G. Moore

  21 shared

• Michael J. Bamshad

  Brotman Baty Institute

  20 shared

• Fabiola Lèon‐Velarde

  20 shared

• Mark D. Shriver

  Pennsylvania State University

  19 shared

• Maria C. Rivera

  19 shared

• Ainash Childebayeva

  Max Planck Institute for Evolutionary Anthropology

  17 shared

Labs

• UCLA Bigham Lab for Anthropological GenomicsPI