| 1. |
- Ekström, Axel G., et al.
(author)
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Reverse engineering great ape vocal tract configurations with implications for evolving speech biomechanics
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Other publication (other academic/artistic)abstract
- Great ape call production may inform research on the evolution of speech but remains poorly understood. The vowel-like qualities of long-distance vocalizations of nonhuman great apes are seemingly both acoustically and perceptually comparable to human close back vowel [u]. However, nonhuman great ape vocal tract morphology, including the species-typical tongue and lack of an expanded pharynx, preclude comparable articulation. Here, we explore possible vocal tract configurations underlying chimpanzee (Pan troglodytes) pant hoots, gorilla (Gorilla gorilla) hoots , and orangutan (Pongo abelii) long calls. We present the result of computer simulations of acoustic tube vocal tract models based on MRI great ape articulator data and behavior. Predicted first and second formant simulation data were compared against data collected from adult male chimpanzees, silverback male gorillas, and flanged male orangutans in the wild. We explored the explanatory value of four sets of models corresponding to (i) uniform tubes, (ii) narrowed lip passage, (iii) narrowed and extremely protruded lip passage, and (iv) a “retracted model”, with dorsal oral tract constriction achieved via tongue retraction, combined with a narrowed lip passage. Our results show that great ape hoot data are most consistent with an articulatory model assuming dorsal oral tract stricture through tongue retraction (the only model to achieve a fit for the second formant). Our work indicates articulatory configurations employed in great ape call production may exist in continuity with speech production, without being identical to those observed in modern humans.
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| 2. |
- Staedele, Veronika, et al.
(author)
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The complex Y-chromosomal history of gorillas
- 2022
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In: American Journal of Primatology. - : John Wiley & Sons. - 0275-2565 .- 1098-2345. ; 84:3
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Journal article (peer-reviewed)abstract
- Studies of the evolutionary relationships among gorilla populations using autosomal and mitochondrial sequences suggest that male-mediated gene flow may have been important in the past, but data on the Y-chromosomal relationships among the gorilla subspecies are limited. Here, we genotyped blood and noninvasively collected fecal samples from 12 captives and 257 wild male gorillas of known origin representing all four subspecies (Gorilla gorilla gorilla, G. g. diehli, G. beringei beringei, and G. b. graueri) at 10 Y-linked microsatellite loci resulting in 102 unique Y-haplotypes for 224 individuals. We found that western lowland gorilla (G. g. gorilla) haplotypes were consistently more diverse than any other subspecies for all measures of diversity and comprised several genetically distinct groups. However, these did not correspond to geographical proximity and some closely related haplotypes were found several hundred kilometers apart. Similarly, our broad sampling of eastern gorillas revealed that mountain (G. b. beringei) and Grauer's (G. b. graueri) gorilla Y-chromosomal haplotypes did not form distinct clusters. These observations suggest structure in the ancestral population with subsequent mixing of differentiated haplotypes by male dispersal for western lowland gorillas, and postisolation migration or incomplete lineage sorting due to short divergence times for eastern gorillas.
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