-
Cell Jul 2023Comparative studies of great apes provide a window into our evolutionary past, but the extent and identity of cellular differences that emerged during hominin evolution... (Comparative Study)
Comparative Study
Comparative studies of great apes provide a window into our evolutionary past, but the extent and identity of cellular differences that emerged during hominin evolution remain largely unexplored. We established a comparative loss-of-function approach to evaluate whether human cells exhibit distinct genetic dependencies. By performing genome-wide CRISPR interference screens in human and chimpanzee pluripotent stem cells, we identified 75 genes with species-specific effects on cellular proliferation. These genes comprised coherent processes, including cell-cycle progression and lysosomal signaling, which we determined to be human-derived by comparison with orangutan cells. Human-specific robustness to CDK2 and CCNE1 depletion persisted in neural progenitor cells and cerebral organoids, supporting the G1-phase length hypothesis as a potential evolutionary mechanism in human brain expansion. Our findings demonstrate that evolutionary changes in human cells reshaped the landscape of essential genes and establish a platform for systematically uncovering latent cellular and molecular differences between species.
Topics: Animals; Humans; Hominidae; Neural Stem Cells; Pan troglodytes; Pluripotent Stem Cells; Stem Cells
PubMed: 37343560
DOI: 10.1016/j.cell.2023.05.043 -
Animal Cognition Sep 2023Object interactions play an important role in human communication but the extent to which nonhuman primates incorporate objects in their social interactions remains...
Object interactions play an important role in human communication but the extent to which nonhuman primates incorporate objects in their social interactions remains unknown. To better understand the evolution of object use, this study explored how objects are used in social interactions in semi-wild chimpanzees (Pan troglodytes). We used an observational approach focusing on naturally occurring object actions where we examined their use and tested whether the production of object actions was influenced by the recipients' visual attention as well as by colony membership. The results show that chimpanzees adjusted both the type of object used, and the modality of object actions to match the visual attention of the recipient, as well as colony differences in the use of targeted object actions. These results provide empirical evidence highlighting that chimpanzees use objects in diverse ways to communicate with conspecifics and that their use may be shaped by social factors, contributing to our understanding of the evolution of human nonverbal communication, language, and tool use.
Topics: Animals; Animal Communication; Language; Nonverbal Communication; Pan troglodytes
PubMed: 37314595
DOI: 10.1007/s10071-023-01792-z -
European Journal of Human Genetics :... Jun 2024There have been reports of examples of exclusive yin yang haplotypes, differing at every locus, but there has been no systematic search for them. Unphased whole genome...
There have been reports of examples of exclusive yin yang haplotypes, differing at every locus, but there has been no systematic search for them. Unphased whole genome sequence data for 2504 unrelated 1000 Genomes subjects was searched for chains of SNPs having global minor allele frequency (MAF) > =0.1 made up of at least 20 SNPs in complete linkage disequilibrium with each other and with no pair being separated by more than 9 other SNPs. The global distribution of these haplotypes was investigated, along with their ancestral origins and associations with genes and phenotypes. A number of previously unrecognised repeats were noted, flagged by all or most subjects being called as heterozygotes, and these were discarded. There were 5114 exclusive yin yang haplotypes each consisting of on average 34.8 SNPs, each spanning on average 15.7 kb and cumulatively covering 80 Mb. Although for some haplotypes the MAF varied markedly between populations the average global fixation index was similar to that for SNPs elsewhere in the genome and there was no evidence of enrichment for genes or gene ontologies. For all but 92 haplotypes there were partial forms present in the chimpanzee and/or Neanderthal genome, indicating that they had been formed in a gradual process but that intermediate haplotypes were now absent from modern humans. Exclusive yin yang haplotypes cover over 2% of the human genome. The mechanisms accounting for their formation and preservation are unclear. They may serve as useful markers of the dispersal of chromosomal regions through human history.
Topics: Humans; Haplotypes; Polymorphism, Single Nucleotide; Genome, Human; Yin-Yang; Animals; Linkage Disequilibrium; Gene Frequency; Pan troglodytes
PubMed: 37308599
DOI: 10.1038/s41431-023-01399-5 -
Behavior Research Methods Mar 2024Cardiac measures such as heart rate measurements are important indicators of both physiological and psychological states. However, despite their extraordinary potential,...
Cardiac measures such as heart rate measurements are important indicators of both physiological and psychological states. However, despite their extraordinary potential, their use is restricted in comparative psychology because traditionally cardiac measures involved the attachment of sensors to the participant's body, which, in the case of undomesticated animals such as nonhuman primates, is usually only possible during anesthesia or after extensive training. Here, we validate and apply a camera-based system that enables contact-free detection of animals' heart rates. The system automatically detects and estimates the cardiac signals from cyclic change in the hue of the facial area of a chimpanzee. In Study 1, we recorded the heart rate of chimpanzees using the new technology, while simultaneously measuring heart rate using classic PPG (photoplethysmography) finger sensors. We found that both methods were in good agreement. In Study 2, we applied our new method to measure chimpanzees' heart rate in response to seeing different types of video scenes (groupmates in an agonistic interaction, conspecific strangers feeding, nature videos, etc.). Heart rates changed during video presentation, depending on the video content: Agonistic interactions and conspecific strangers feeding lead to accelerated heart rate relative to baseline, indicating increased emotional arousal. Nature videos lead to decelerated heart rate relative to baseline, indicating a relaxing effect or heightened attention caused by these stimuli. Our results show that the new contact-free technology can reliably assess the heart rate of unrestrained chimpanzees, and most likely other primates. Furthermore, our technique opens up new avenues of research within comparative psychology and facilitates the health management of captive individuals.
Topics: Animals; Emotions; Heart Rate; Pan troglodytes; Photoplethysmography; Primates
PubMed: 37249898
DOI: 10.3758/s13428-023-02136-y -
Journal of Anatomy Sep 2023Computational musculoskeletal modeling represents a valuable approach to examining biological systems in physical anthropology. Probabilistic modeling builds on...
Computational musculoskeletal modeling represents a valuable approach to examining biological systems in physical anthropology. Probabilistic modeling builds on computational musculoskeletal models by associating mathematical distributions of specific musculoskeletal features within known ranges of biological variability with functional outcomes. The purpose of this study was to determine if overlap in rotator cuff muscle force predictions would occur between species during the performance of an evolutionarily relevant horizontal bimanual arm suspension task. This necessitated creating novel probabilistic models of the human and chimpanzee glenohumeral joint through augmentation of previously published deterministic models. Glenohumeral musculoskeletal features of anthropological interest were probabilistically modeled to produce distributions of predicted human and chimpanzee rotator cuff muscle force that were representative of the specific anatomical manipulations. Musculoskeletal features modeled probabilistically included rotator cuff origins and deltoid insertion, glenoid inclination, and joint stability. Predicted human rotator cuff muscle force distributions were mostly limited to alternating between infraspinatus and teres minor, with both 100% and 0% muscle force predicted for both muscles. The chimpanzee model predicted low-to-moderate muscle force across all rotator cuff muscles. Rotator cuff muscle force predictions were most sensitive to changes of muscle origins and insertions. Results indicate that functional rotator cuff overlap is unlikely between chimpanzees and humans without greater modifications of the glenohumeral musculoskeletal phenotypes. The results also highlight the low efficacy of the human upper extremity in overhead, weight-bearing tasks, and propensity for rotator cuff injury.
Topics: Humans; Animals; Rotator Cuff; Pan troglodytes; Shoulder Joint; Rotator Cuff Injuries; Scapula; Biomechanical Phenomena
PubMed: 37186281
DOI: 10.1111/joa.13882