File:Did Archaic Hominins and Modern Humans Diverge in Circadian Biology?.jpg

English: "Did the sharing of functionally diverged alleles from archaic hominins influence human circadian biology? (A) AMHs and archaic hominins evolved separately at different latitudes for hundreds of thousands of years. The ancestors of modern Eurasian humans left Africa approximately 70 ka and admixed with archaics, likely in southwestern Asia. The shaded range in Eurasia represents the approximate Neanderthal range. The dot in Asia represents the location of the sequenced Denisovan individual in the Altai Mountains; the full range of Denisovans is currently unknown. Silhouettes from phylopic.org. (B) After the split between the human and archaic lineages, each group accumulated variation and evolved in their respective environments for approximately 700 ka. We first test for evidence for divergent circadian evolution during this time. Humans acquired introgressed alleles from Neanderthals and from Denisovans around 60 and 45 ka, respectively. These alleles experienced strong selective pressures; however, ∼40% of the genome retains archaic ancestry in some modern populations. The second question we explore is whether introgression made contributions to human circadian biology. (C) The core circadian clock machinery is composed of several transcription factors (ovals) that dimerize and interact with E-box enhancer elements and each other to create a negative feedback loop. We defined a set of 246 circadian genes through a combination of literature search, expert knowledge, and existing annotations (supplementary table S1 and fig. S1, Supplementary Material online; Materials and Methods). Lines with arrows represent activation, and lines with bars represent suppression." "Following divergence ∼700 ka (Nielsen et al. 2017; Gómez-Robles 2019), archaic hominins and AMH were geographically isolated, resulting in the accumulation of lineage-specific genetic variation and phenotypes (fig. 1). In the next several sections, we evaluate the genomic evidence for divergence in circadian biology between archaic hominin and modern human genomes."