Further analyses of the structural organization of Homo luzonensis teeth: Evolutionary implications
Clément Zanolli cs 2022 J.hum.Evol.163:103124
doi 10.1016/j.jhevol.2021.103124
(Callao Archaeological Project: Going Deep in Time)

H.luzonensis has recently been described based on a set of dental & postcranial elements found at Callao Cave (N-Luzon, Philippines, at least 50–67 ka).
7 post-canine maxillary teeth are attributed to this taxon:
- 5 of them belong to the same individual (CCH6), and represent the holotype of H. luzonensis,
- the isolated upper premolar CCH8 & the upper 3rd molar CCH9 are paratypes.

-The teeth are characterized by their small dimensions ass.x primitive features, as also found in H.floresiensis (another hominin having evolved in an insular environment of SE.Asia).
-Postcranial bones of the hands & feet of H. luzonensis & floresiensis show Homo habilis–like or australopith-like features,
-Cranial & dental morphology is more consistent with the Asian H.erectus morphology.
Due to this mosaic morphology, the origin & phylogenetic relationships of both H. luzonensis & floresiensis are still debated:
- does H. luzonensis derive from H.erectus?
- or from an earlier small-brained hominin?

We analyzed the µCT-scans of the teeth:
we investigated external & internal tooth structure, using morphometric methods:
- crown outline shape,
- tooth crown tissue proportions,
- enamel-dentine junction shape,
- pulp morphology.

H.luzonensis external crown morphology aligns more with H.erectus than with H.habilis-rudolfensis.
The internal structural organization of H.luzonensis teeth exhibits more affinities with H.erectus & floresiensis than with neanderthals & modern humans.

Our results suggest:
both H.floresiensis & luzonensis likely
- evolved from some H.erectus groups that dispersed in the various islands of this region,
- became isolated until endemic speciation events occurred at least twice during the Pleistocene in insular environments.

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