apiths had chimp-like cochlear morphology
Cochlear morphology of Indonesian Homo erectus from Sangiran
Alessandro Urcioli cs 2022 JHE 165,103163
doi org/10.1016/j.jhevol.2022.103163
H.erectus s.l. is key for deciphering the origin & subsequent evolution of genus Homo,
but its characterization is hindered by multiple variants in mainland & insular Asia: divergent chrono-geographic evol.trends, genetic isolation & interbreeding with other human spp.
Previous research has shown:
cochlear morphology embeds taxonomic & phylogenetic infm, that may help infer the phylogenetic relationships among hominin spp.
Here we describe the cochlear morphology of 2 Indonesian H.erectus: Sangiran-2 & -4,
we compare it with australopiths, Mid-to-Late-Pleist.humans & extant Hs (linear measurements & principal components & canonical variates analyses, performed on shape ratios).
Results:
1) H.erectus displays a mosaic morphology, cons.x the more basal position of H.erectus:
- plesiomorphic (apith-like) features (chimp-like round cochlear cross-section, low cochlear thickness),
- derived characters of later humans (voluminous & long cochlea, possibly related to hearing abilities).
2) We show substantial variation between Sangiran-2 & -4:
- in the length & radius of the first turn,
- cross-sectional shape,
but (cf the small size of the available sample):
-- do such differences merely reflect intra-specific variation among +-coeval H.erectus individuals?
-- or do they result from greater age differences between them than currently considered?
3) Most characters found in later humans were already present in Indonesian H.erectus, except Hn:
neandertals display an autapomorphic condition vs other Homo spp.
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