Wednesday, April 10, 2019

Another Hobbit Species In Southeast Asia

When I saw the headline, I figured it was an old report of the discovery of very archaic diminutive hominins on the island of Flores. But, I was wrong. The skeletal evidence is patchy, but this new discovery in the Philippines is from the same time period, in a similar habitat, in the same general region of the world as the hobbits of Flores (Homo floresiensis) from 60,000 years ago and seems rather similar. 
In a cave in the Philippines, scientists have discovered a new branch of the human family tree. 
At least 50,000 years ago, an extinct human species lived on what is now the island of Luzon, researchers reported on Wednesday. It’s possible that Homo luzonensis, as they’re calling the species, stoodless than three feet tall.
From the New York Times.

First impressions are that both the hobbits of the Philippines and the hobbits of Flores, are branches of a hominin species from Africa more archaic than Homo erectus such as Homo habilis.

They were still in the Philippines and Flores, in all probability, when modern humans at the dawn of the Upper Paleolithic era were finally colonizing Papua New Guinea and Australia by sea, and were having hybrid offspring with a branch of Denisovans (possibly from two separate populations both distinct from the Siberian ones from whom we have ancient DNA) who didn't admix with modern humans anywhere else at any other time. And did the Toba eruption somehow facilitate that expansion of modern humans (perhaps clearing an ecology space of Homo erectus in their path, or temporarily taming the jungle en route to which they were ill adapted).

The Denisovans, however, were probably not Homo floresiensis or Homo luzonensis or Homo erectus. Instead, they were a less basil species of the genus Homo more closely related to Neanderthals and probably just as intelligent. Also, Homo floresiensis and Homo luzonensis are probably not Homo erectus. 

Did they arrive with Homo erectus? Did they arrive with the Denisovans? Or were they an earlier first, pre-Homo erectus Out of Africa wave for our genus who were already in Southeast Asia and maybe East Asia as well, when Homo erectus, the Denivosans, and more than one wave of modern humans arrived after them? Are archaic skeletal remains in China really Denisovans? Did a meteor strike about 800,000 years ago in Southeast Asia, around the time of the earliest evidence of each of them in Southeast Asia, have something to do with their migration (e.g. freeing up previously occupied ecological space)?

The latter hypothesis seems to make more sense. Why would Homo erectus or the Denisovans bring them with them otherwise? 

The more plausible theory is that they were the first wave of hominins out of Africa, and were wiped out by later arriving Homo erectus everywhere west of the Wallace line which Homo erectus never managed to cross.

More from John Hawks:
D├ętroit and colleagues studied the details of the bones and teeth. Together, they represent a mash of features that are confusingly reminiscent of a huge range of other hominins, and together make for something new and hard to classify. The molars, for example, are small compared to every other known species, while the adjacent premolars, bizarrely, are not so small. The molar crowns have a simple, humanlike pattern, but the premolars bear resemblance to the larger teeth more typical in older species, including H. floresiensis and some early specimens of Homo erectus. Some premolars have three roots, as sometimes found in H. erectus and more distant human relatives. The toe and finger bones also seem different from modern humans: One finger bone is curved, and the toe doesn’t seem to have been able to bend upward at the ball of the foot as much as ours. In some ways, these bones resemble hominins that lived more than 2 million years ago, such as Lucy’s species, Australopithecus afarensis. No other known species shares the whole set of features found at Callao.


neo said...

does the article explain why it is called Homo luzonensis and not just Homo floresiensis in phillipines?

"The more plausible theory is that they were the first wave of hominins out of Africa,"

Australopithecus perhaps?

Homo floresiensis brain size and body size matches up well with Australopithecus

andrew said...

There isn't enough material in either case to confirm that it is the same species.

DDeden said...

Recall the two Narmada River Homo/Hominins of pygmy size, claimed to predate Mt Toba, and Tam Pa Ling cave tiny cranium in Laos. John Hawks has a good article in Sapiens.

Tom Bridgeland said...

The odd teeth and bones suggest they may be mixing samples of different species.