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The Sahul is the Australia-New Guinea continent, which is exposed during glacial maximums. If one were to take a satellite photograph of the Sahul during an ice age, you’d see more or less a complete island in the picture, one that spans from New Guinea to Australia and Tasmania. Kind of like the one to your right. Understanding the peopling of the Sahul is critical to understand human migrations and the peopling of Australia.

In the late ’70’s to the late ’80’s, most archaeologists thought that the Sahul was occupied by Late Pleistocene humans, somewhere around 45,000 years ago. A bit of a shake-up spurred about the exact timing of the occupation when older sites like the Devil’s Lair, Lake Mungo, Nauwalabila, Malakunanja, and Huon Peninsula were discovered.

Predictably, two camps emerged. One camp asserted that the Sahul was peopled around 60,000 years ago. The other camp held on the later date, contesting that their dates are based upon more reliable dating techniques, such as radiocarbon, luminescence, and uranium-thorium dating methods. They also contest that 45,000 year old artifacts better resemble the Out of Africa “package” that is represented elsewhere.

A new paper in the Journal of Human Evolution looks at the archaeological “package” from the earlier sites. The authors of the paper compare this archaeological record to the record of other Middle Stone Age sites in Africa, Europe, and Asia. Similar to genes, the displacement of artifacts occurs when new technologies and cultures influence existing ones. It can happen under different tempos — there can be a slow, gradual change of material culture or there can be rapid and punctual changes. There can even a mix of the two. In places like Europe, we see rather fast changes, as pre-existing populations like Neandertals were replaced by humans during the Middle to Upper Paleolithic transition.

To see whether or not the Sahul represents a slower change, Phillip Habgooda and Natalie Franklin have looked at the archaeological record of the Sahul. They’ve published their findings under the title, “The revolution that didn’t arrive: A review of Pleistocene Sahul.” I figure you can extract the main conclusion from this concise title. But I won’t stop there because Habgooda and Franklin have written up a rather thorough study. They specifically timed the rate of change in exchange networks, mining & quarrying, beads, ochre, art, burials, shellfish middens, grindstones, modified bone, and new lithic techniques.

For the section on exchange networks, they review the archaeological record of 20 sites. The trade of exotic materials for symbolic reasons, especially over long-distances, is understood to be a relatively modern behavioral trait. 40,000 years ago, the people who occupied the Sahul were moving shells and other materials long distances — in some cases 300 kilometers and in other cases to places like the little islands in the Bismarck Sea, which is north of Papau New Guinea.

Related to trade networks, mining and quarrying, also represents a modern trait as people specifically sought out certain rocks to fashion into tools and adornments. The record for mining emerges at a much more recent date: around 24,000 years ago. Take note of the discontinuity between these dates, because a rapid displacement of the Sahul should share similar dates among the different parts of the package looked at.

I shouldn’t really need to define why we consider personal adornments like beads, as modern. And in the Sahul, they are seen as 42,000 years ago. But other pieces of adornments, such as this limestone plaque from the Devil’s Lair appear only as early as 25,000 years ago. The role of ochre in art, rituals, and personal hygiene is also looked at. Similar to bead usage, ochre usage is seen as early as 42,000 years ago but not in an artistic and elaborate burial context until 2,000 years later. Complex rock art and symbolic burials are traits of modern humans and for them to not sync up with ochre usage and adornments make me wonder what was going on?

In general, resource exploitation is a modern human trait and by looking at the composition of middens and the number and specialization of grindstones, we can get an idea about when people started to change their lifestyles. In the Sahul, this didn’t start happening until around 30,000 years ago. Again, remember some other modern human traits are seen as early as 42,000 years ago but economic intensification didn’t happen until much later. Furthermore, modified bone tools, a hallmark of modern human behavior, is seen around 22,000 years ago but compound stone tools like adzes are seen as early as 40,000 years ago!

Clearly, this paper shows that the Sahul was gradually influenced by the modern human expansions out of Africa. Parts of the modern human package appear at different sites, separated spatially and temporally. The authors provide us with this poignant summary as well as an image depicting their results,

“Following initial colonization of the continent, terrestrial fauna are the dominant resources exploited, but freshwater shell middens are apparent around the palaeoriver and lake systems of southeast Australia. Long-distance transport and/or exchange networks are evident, as is collection and use of ochre for ritual behaviour (burial) and rock painting. Stone assemblages are dominated by retouched and unretouched flakes, but waisted hatchets are found in Papua New Guinea at this time. By 30,000 years BP, an expansion in resource exploitation may be signified by evidence of marine exploitation on islands off the northern coast of Sahul, the (possible) appearance of grindstones, and the intensive exploitation of macropods in southwest Tasmania. Flake-based stone tool assemblages are augmented by the introduction of ground stone hatchets in northern Australia and small thumbnail scrapers in southwest Tasmania. Personal ornaments in the form of shell beads are also present in northwestern Australia at this time. By 20–18,000 years BP the variety of personal ornaments has expanded to include bone beads, pendants, and notational pieces. Although there is evidence of painting of some form by 40,000 years BP, identifiable art does not appear until around 20,000 years BP. Flint mining is evident at this time, and the flake-based stone tool assemblages are supplemented with bone points made on macropod long bones in the southeast of the continent.”

Modern human behavioral traits in the archaeological record of the Sahul, emerged over a 30,000 year period, even though modern humans clearly had an early influence. The authors consider one possibility may have been that there was not a rapid colonization of the Sahul. I’ve thought about this some and think that differences in population densities and impact of new technologies, i.e. adoption rates amongst ‘stubborn’ populations affect rates of cultural change. Hell, look how long it has taken people to switch from Windows to Macs. ;-) Somethings may not have been useful to early peoples and may have not been taken up as readily, and adopted later under different pressures and considerations. What we can figure out is that what we consider the “package” is not necessarily and all or none indicator of modern human existance.

If you’re interested in understanding the peopling of the Greater Australia area, and wanna know more about Sahul sites, I recommend reading this paper. I got a bit annoyed by the over-usage of “package.” I know even though I used the phrase in similar manner — without directly defining it. But if you mentally replace it with other synonyms that work for you, the paper is much more digestible and chock full of information about the archaeology of early Austrialia, Papau New Guinea and adjacent areas.

    P HABGOOD, N FRANKLIN (2008). The revolution that didn’t arrive: A review of Pleistocene Sahul Journal of Human Evolution, 55 (2), 187-222 DOI: 10.1016/j.jhevol.2007.11.006