Palau is fast becoming an anthropological paradise. In addition to being one of the places Margaret Mead did fieldwork, we now have news that a large collection of skeletons have been found. Currently, the fragmentary remains of 25 individuals have been excavated, but others remain to be freed from their calcium carbonate matrix:
Let’s start at the beginning. The find is being published in PLoS One. The material was found in two caves (Ucheliungs and Omedokel) which are not, apparently habitation areas. Material in the first cave dates, via AMS, to 1420-2890 years BP, while material from the second cave dates to 1410-2300 years BP. The skeletal material is, apparently, the result of secondary deposition rather than primary burials. The intriguing part is the size of the skeletal material. For example, a left os coxa (belonging to a female) is similar in size to AL-288-1 (Lucy), several others (males) are similar in size to the LB1 os coxa. Measurements of the acetabulum (the socket where the head of the femur articulates with the pelvis) allowed body mass to be estimated (28.7 kg for the female, 43.2 kg for one male). Measurements on the femur, tibia, and talus provided similar body size estimates. Several were also similar in size to LB1. The authors summarize this section by noting:
More than 61 measurable postcranial elements recovered from the two caves also indicate body sizes at the lower extreme of recent human variation and in some cases the range of smallbodied australopithecines. These include tali that approach closely the size of the talus of the small bodied australopithecine ”Little Foot” from South Africa (Figure 6), supporting the hypothesis that small body size was the norm in the earlier populations preserved in the cave.
If you are jumping to some conclusions right about now, like “hey, didn’t someone float the idea that Homo floresiensis evolved from australopithecines” you should probably stop.
Earlier in the paper the authors describe a number of traits autapomorphic for Homo sapiens. These traits include a maxillary canine fossa, mandibular mental trigone, bossing on the frontal and parietal among others.
On the other hand, the new finds do share some traits with the Flores finds. Among them are reduction of the craniofacial area, megodontia, some had suprorbital tori, weakly developed or absent mental fossae and mental tuburcles, and rotated or missing teeth. Brain size is larger than in LB1, but is within range of Homo erectus and at the lower end of H. sapiens
So, we have an intriguing mix of morphology. What do the authors make of it? After cautioning that the traits linking H. erectus, H. floresiensis, and the Palau population could be homoplasies (early in the paper) the authors make an excellent point when they observe that small bodied populations that do not share all the traits considered taxonomically significant in the LB1 material can not support the validity of the H. floresiensis taxon. They conclude the paper by saying:
Based on the evidence from Palau, we hypothesize that reduction in the size of the face and chin, large dental size and other features noted here may in some cases be correlates of extreme body size reduction in H. sapiens. These features when seen in Flores may be best explained as correlates of small body size in an island adaptation, regardless of taxonomic affinity. Under any circumstances the Palauan sample supports at least the possibility that the Flores hominins are simply an island adapted population of H. sapiens, perhaps with some individuals expressing congenital abnormalities.
Which prompts me to ask if anyone has ever considered what a population of H. erectus that had been subject to island dwarfing would look like. Most of the debate that I am aware of, and someone please correct me if I’m wrong, uses H. sapiens as a starting point.