A new early human fossil has been reported, recovered from the seabed near Taiwan. We are calling it Penghu 1.
Simply put, it is the lower right jaw of a hominid (hominine) that most resembles either a form of Homo erectus or Archaic Homo sapiens (kin to, but not, Neanderthal). Teeth are fairly useful for categorizing hominids into groups that can be thought of as species. This hominid does not look like modern humans (teeth are way too big and the enamel is not right). It does not look like African Homo ergaster or Asian Homo erectus. It does not look like Neanderthal or so called Denisovan. It looks most like Hexian, a middle pleistocene hominid (about a half million years old) from China, but not exactly. But close. Hexian, for it’s part, looks like earlier Homo erectus but changed over time to be distinctly different from other contemporary (late) Homo erectus from East Asia.
I’ll provide more information about the fossil below, but since the paper that reports it is available on line you might as well go read the original. Rather, I’d like to say a couple of things about the possible significance of this find.
First, this is probably a new species, though it could end up getting lumped with Hexian. But, the new fossil probably dates to the last interglacial (120,000 years go) or later. I’m guessing later if its presence on the sea floor indicates that the original possessor of the mandible lived during times of lower sea level. (I suppose this could be an individual that died and floated down a river. Or fell out of a boat!?!?!?)
Let’s assume for a moment that Penghu 1 is a new species, in the sense that we see Neanderthals, Denisovans, and various variants of Homo erectus or Archaic homo as different species (we’ll put aside species-population differences and arguments for now). If so there is one obvious very significant (provisional) conclusion that could be advanced, and a second less obvious (and more provissional).
The obvious significance is that Penghu is yet another indicator that multiple different hominids lived on the Earth at the same time after the rise of Homo erectus. We see lots of different hominids, mainly called Australopithecus, in Africa prior to about two million years ago, which is interesting but also known for some time now. But for a long time it looked like there was not too much diversity in the fossil record after that, though we’ve always seen some. Over the last couple of decades, though, the evidence for Pleistocene diversity in Eurasia appears to have grown, with Homo floresiensis and Hexian in the east, Denisova Cave in the middle, and the hominid from the Republic of Georgia in the west. The idea of a high level of diversity is not new, but it is a relatively recent concept and is growing. (I’ll also mention that finding a new hominid on the sea floor underscores the problem we have that so many of the great places for early humans to live are inundated!)
The less obvious and much more conjectural significance is in the shift of diversity from one region of the world to another. Prior to about 2.0 million years go, we see great diversity in hominids in Africa (where, for the most part, most of the hominids lived). Over time, African diversity dwindles as modern humans, or a hominid just precedent to modern humans, seems to have more or less taken over and replaced their contemporaries. Archaic hominids, however, which had already spread into Eurasia, continued the diversification earlier hominids had achieved, and this diversity was manifest in the absence of those pesky moderns.
Putting this another way, one could say that hominids, including pre- and post-Homo forms, have as one of their characteristics a propensity to diversity. This is true of many (but not all) primates. It may have to do with ecological and social/cultural characteristics of the various species, or perhaps basic demography. Adherence to ecological zones that are patchy and spread apart would encourage more speciation than might occur if populations were more connected or continuous. Related (or alternatively, depending) great increases and decreases of population size, causing separation of subgroups, might enhance this. At the same time, evolutionary stasis is repressed; separate groups change fast enough to be noted by us on time scales of several thousand years.
In contrast, modern or near-modern humans seem not to have had this propensity.
The most obvious explanation for this difference is, it seems to me, the degree of cultural buffering found in modern humans being much higher than in these other hominids.
OK, enough of the wild speculation. Here is the abstract from the paper:
Recent studies of an increasing number of hominin fossils highlight regional and chronological diversities of archaic Homo in the Pleistocene of eastern Asia. However, such a realization is still based on limited geographical occurrences mainly from Indonesia, China and Russian Altai. Here we describe a newly discovered archaic Homo mandible from Taiwan (Penghu 1), which further increases the diversity of Pleistocene Asian hominins. Penghu 1 revealed an unexpectedly late survival (younger than 450 but most likely 190–10 thousand years ago) of robust, apparently primitive dentognathic morphology in the periphery of the continent, which is unknown among the penecontemporaneous fossil records from other regions of Asia except for the mid-Middle Pleistocene Homo from Hexian, Eastern China. Such patterns of geographic trait distribution cannot be simply explained by clinal geographic variation of Homo erectus between northern China and Java, and suggests survival of multiple evolutionary lineages among archaic hominins before the arrival of modern humans in the region.
The citation and link:
Chun-Hsiang Chang, Yousuke Kaifu, Masanaru Takai, Reiko T. Kono, Rainer Grün, Shuji Matsu’ura, Les Kinsley & Liang-Kong Lin. The first archaic Homo from Taiwan. Nature Communications. 27 January 2015.
And above the post is a picture of the fossil.