Biology subjects

Hawks, J.

Publications and source records attributed to Hawks, J..

7 recordsLinked to original sources

bioRxiv2026

Sub-second Extracellular Impedance Measurement of Epithelial Cell Monolayers using Step Excitations and Time-domain Analysis

Extracellular electrochemical impedance spectroscopy (EIS) is emerging as a powerful technique in in vitro epithelial research, offering quantitative insights into barrier integrity, morphology, and apical-basolateral polarity noninvasively through metrics such as transepithelial electrical resistance (TER/TEER), transepithelial capacitance (TEC), and membrane ratio (), respectively. However, due to the broad range of frequencies probed, EIS typically requires tens of seconds per measurement, limiting its ability to capture more rapid biological phenomena. We present Time-domain Epithelial Impedance Measurement (TEIM), a method for sub-second extracellular impedance measurements of epithelial cell monolayers based on step (Heaviside function) current excitation and time-domain analysis of the voltage transients, without the need for Fourier transforms. We experimentally demonstrate TEIM measuring TER, TEC, , and model-derived impedance spectrum at [~]0.3 s sampling rate, which represents a 100- fold improvement in time resolution compared with traditional EIS. The accuracy and precision of TEIM were benchmarked against EIS on both electrical circuits and epithelial cell monolayers of immortalized Human Bronchial Epithelial (16HBE) and Human Colorectal Adenocarcinoma (Caco-2) (n = 3 for each), and average percent errors for TER, TEC, and ranged from 0.17-3.55%, 1.13-8.96%, and 0.59-26.35%, respectively. Application of TEIM to monitor Caco-2 responses to saponin, a quick-acting pore-forming detergent, revealed smoothly gated double-exponential transient TER and TEC dynamics that were too rapid to be adequately captured previously using EIS. Overall, TEIM enables electrophysiology studies of rapid changes in epithelial cell culture models and possibly more complex in vitro models, holding promise for future applications in areas such as disease modeling, therapeutic development, and beyond.

bioengineering↗

bioRxiv2026

Genetic Basis of Social Structure in the Pastoral Nomads of Central Eurasia

Although the social structure of Central Eurasian pastoral nomads has been described as fluid and ad hoc by historians and anthropologists, its potential genetic basis remains poorly understood. To evaluate whether kinship based social organization has biological foundations, we surveyed Kazak populations in Jetisuu, Kazakstan, for genomic diversity with special reference to their kinship structure. We generated genome-wide SNP data ([~]750K) using GenoChip microarrays for 80 individuals from four Kazak clans in Jetisuu and 10 Kazaks from other regions. Our results reveal substantial concordance between genetic and genealogical data, with [~]64% of Jetisuu Kazaks sharing the same Y-chromosome haplotype, indicating they have a common paternal ancestry aligning with clan genealogies. By contrast, maternal lineages show remarkable heterogeneity, thereby reflecting female exogamy. Despite this sex-biased admixture pattern, autosomal SNPs reveal no pronounced population structure in Kazaks, suggesting genetic homogenization through ancient admixture followed by continuous gene flow between Kazak populations. Notably, Jetisuu Kazaks exhibit significantly reduced levels of runs of homozygosity (ROH) compared to their sedentary neighbors such as Turkmens, Tajiks, Uyghurs, and Uzbeks. This genomic signature likely results from clan exogamy, which functions as a biological mechanism to prevent inbreeding and maintain genetic diversity. Our findings demonstrate that nomadic social organization represents a sophisticated example of gene-culture co-evolution, where cultural practices have systematically shaped genetic patterns over centuries. These data provide new insights into historical pastoral nomadic societies and offer a nuanced perspective on anthropological debates about kinship authenticity in Central Eurasian nomads.

genetics↗

bioRxiv2025

Genomes of the Golden Horde Elites and their Implications for the Rulers of the Mongol Empire

The Golden Horde, the northwestern extension of the Mongol Empire that was ruled by the eldest son of Genghis Khan (also spelled Chinggis Khan) and his descendants, played an important role in the history of Central Eurasia and eastern Europe. For this reason, the genetic profiles of Genghis Khan and his descendants are of keen academic and public interest. His Y-chromosome has been hypothesized to belong to haplogroup C3* (C2a1a3-F1918) but this has yet to be substantiated. To explore the genetic ancestry of Genghis Khan, we analyzed four archaeological individuals from the Golden Horde, including three males and one female, who were buried in separate medieval elite mausoleums in the Ulitau region of Kazakstan. One of the males is believed to be Joshi (Juchi), the eldest son of Genghis Khan. We generated genomic data from these archaeological individuals and found that the three males were paternally related, sharing the Y-chromosome haplogroup C3*, consistent with the hypothesized signature haplotype of Genghis Khan. In addition, we confirm that the Golden Horde elites derived most of their genomes from Ancient Northeast Asians (ANA) while having an additional ancestral component from either Ancient North Eurasians (ANE) or a Berel Scythian related population. Furthermore, we were able to identify their medieval relatives in the Mongolian Plateau through constructing an Identity by Descent (IBD) network.

genomics↗

bioRxiv2023

Evidence for deliberate burial of the dead by Homo naledi

In this study we describe new results of excavations in the Dinaledi Subsystem of the Rising Star cave system, South Africa. In two areas within the Hill Antechamber and the Dinaledi Chamber this work uncovered concentrations of abundant Homo naledi fossils including articulated, matrix-supported skeletal regions consistent with rapid covering by sediment prior to the decomposition of soft tissue. We additionally re-examine the spatial positioning of skeletal material and associated sediments within the Puzzle Box area, from which abundant H. naledi remains representing a minimum of six individuals were recovered in 2013 and 2014. Multiple lines of evidence exclude the hypothesis that skeletal remains from these three areas come from bodies that decomposed on the floor of the chamber or within a shallow depression prior to burial by sediments. The spatial positioning of skeletal material, the topography of the subsystem, and observations on sediments within and surrounding features exclude the hypothesis that rapid burial by sediment was a result of gravity-driven slumping or spontaneous movement of sediments. We present a minimal hypothesis of hominin cultural burial and test the evidence from all three areas, finding that this hypothesis is most compatible with the pattern of evidence. These results suggest that mortuary behavior including cultural burial was part of the repertoire of Homo naledi.

paleontology↗

bioRxiv2023

241,000 to 335,000 Years Old Rock Engravings Made by Homo naledi in the Rising Star Cave system, South Africa.

The production of painted, etched or engraved designs on cave walls or other surfaces is recognized as a major cognitive step in human evolution. Such intentional designs, which are widely interpreted as signifying, recording, and transmitting information in a durable manner were once considered exclusive to Late Pleistocene Homo sapiens. Here we present observations of what appear to be engraved abstract patterns and shapes within the Dinaledi Subsystem of the Rising Star cave system in South Africa, incised into the dolomitic limestone walls of the cave. The markings described here are found on a pillar in the Hill Antechamber that extends into the natural fissure corridor that links the two chambers and we associate them with H. naledi. They include deeply impressed lines, cross-hatchings, percussion marks, and other geometric shapes on flat wall surfaces and in and around existing cracks and grooves in the dolomitic limestone walls, found in one specific location of the Dinaledi Subsystem. Remains of multiple Homo naledi are found in this part of the cave system and evidence mortuary behaviour appears in both the Dinaledi Chamber and adjacent Hill Antechamber dated to between 241 and 335 ka (Dirks et al., 2017; Robbins et al., 2021, Berger et al, 2025).

evolutionary biology↗

bioRxiv2023

Burials and engravings in a small-brained hominin, Homo naledi, from the late Pleistocene: contexts and evolutionary implications

Explorations in the Dinaledi Subsystem of the Rising Star cave system have yielded some of the earliest evidence of a mortuary practice in hominins. Because the evidence is attributable to the small-brained Homo naledi, these analyses call into question several assumptions about behavioral and cognitive evolution in Pleistocene hominins. The evidence from the Dinaledi Subsystem, and at other locations across the Rising Star cave system may widen the phylogenetic breadth of mortuary, and possibly funerary, behaviors. These discoveries may also associate the creation of meaning making and increased behavioral complexity with a small-brained hominin species, challenging certain assertions about the role of encephalization and cognition in hominin and human evolution. We suggest that the hominin socio-cognitive niche is more diverse than previously thought. If true, technological, meaning-making activities, and cognitive advances in human evolution are not associated solely with the evolution of larger brained members of the genus Homo. One-Sentence SummaryEvidence for complex behaviors associated with a small-brained hominin suggest that large brains are not solely responsible for the manifestation of human-like behavioral complexity.

evolutionary biology↗

bioRxiv2017

Introgression Makes Waves In Inferred Histories Of Effective Population Size

Human populations have a complex history of introgression and of changing population size. Human genetic variation has been affected by both these processes, so that inference of past population size depends upon the pattern of gene flow and introgression among past populations. One remarkable aspect of human population history as inferred from genetics is a consistent \"wave\" of larger effective population size, prior to the bottlenecks and expansions of the last 100,000 years. Here I carry out a series of simulations to investigate how introgression and gene flow from genetically divergent ancestral populations affect the inference of ancestral effective population size. Both introgression and gene flow from an extinct, genetically divergent population consistently produce a wave in the history of inferred effective population size. The time and amplitude of the wave reflect the time of origin of the genetically divergent ancestral populations and the strength of introgression or gene flow. These results demonstrate that even small fractions of introgression or gene flow from ancient populations may have large effects on the inference of effective population size.

genomics↗