Day of Archaeology 2016

Well, it has been a little quiet around here lately. I’ve been busily working on pulling my thesis together, teaching, and getting a couple of small publications out (updates on those soon!), and the months have just slipped by in a blink. I’ll be back here soon with some new archaeoecology posts, but in the meantime, here’s my post from Day of Archaeology 2016!

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“Day of (Zoo)Archaeology” was originally posted on DayofArchaeology.com

Hello from Perth, Western Australia! My name is Carly and I’m a zooarchaeologist, which means that I work with animal remains (usually bones) to explore how people and animals interacted in the past. Right now, I’m in the late stages of my PhD research. I’ve been working on my PhD for almost 3 years, and I’m planning to submit my thesis in February. Last year when I wrote my Day of Archaeology post I was in Sydney, preparing charcoal samples for radiocarbon dating. This year, I’m writing the part of my thesis that puts those dates into context, allowing me to analyse and interpret my data.

Sorting through excavated material in the lab

A chuditch (sometimes called a “native cat”) might end up in a site as food, but they’re also predators! Working out how they ended up in the assemblage – and what other bones they might have contributed – is something I need to think about. Image source: Wikimedia Commons, licensed under Creative Commons Attribution-Share Alike 3.0 Unported.

Because I’m working from home today, I won’t have a chance to get into the lab, but on a normal day I usually try to get in a few hours of lab work. Most of the data collection required for my thesis is now complete, but I still have to finish identifying animal remains from a small portion of my assemblage. The main site I’m working on is a large limestone cave located a few hours drive north of Perth. This cave was periodically used for shelter by Aboriginal people over tens of thousands of years, but it was also used by carnivores like the thylacine, dingo, chuditch (an Australian “native cat”), and owls. This history of site use means that the bones I look at include animals from the size of a grey kangaroo to small native mice! With this information I can look at how Aboriginal people selected and used certain animals for food, what the environment was like, and how that changed through time.

The skull of a thylacine from the museum’s reference collection

Identifying animals requires a lot of time spent learning about the animals and their anatomy, and comparing specimens to reference collections held by my university and the Western Australian Museum. I’ve been very fortunate to have generous supervisors and mentors who have spent many long hours with me in the field, the lab, and at the museum, sharing their knowledge. Faunal identification skills are not something that can be learned just by reading books: the best way to learn is to hold the bones in your hands, and to learn from an expert.

Some animals are easier to identify than others (like these fragments of bettong jaws)… which is why access to good reference collections is important!

Having worked through most of the assemblages now, I have a pretty good feel for the animals that were present in my sites, and how they are connected to people’s use of the sites, environmental changes, and each other. Now, I’m starting to analyse the data and look for patterns or things that stand out. I’m also writing up results, and in a month I’ll be in Europe presenting some of these results at two conferences. That’s where today’s tasks come in!

Thesis writing (in fact, any writing) can be a long, drawn out process filled with draft after draft and plenty of revisions, so I try to mix my day up a little. Today I’ll be writing, creating some tables and graphs showing the distribution of different animal species through time, and drafting a conference paper. I might even do some mapping if I get time… conference presentations need high quality maps! While I love the challenge of the field and lab-work side of archaeology, the writing and analytical side of the job requires almost as many diverse skills. But I have to admit, after a few days of office work, I do love to get back into those bones!

Just some of the reference materials used to identify kangaroo and wallaby teeth!

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Of course, I highly recommend you go over to the Day of Archaeology website and have a browse through the wide range of blog posts contributed by archaeologists all over the world. There’s everything from digital archaeology, to commercial cultural resource management, to people refitting and identifying finds, and so much more. The Day of Archaeology project has been running for a few years now, and provides a fabulous showcase of the variety found in archaeological work. Here are a few of my favourite posts from 2016:

This post by Elizabeth Moore, on “Crowdsourcing Science”. I love her idea of creating an “identification kit” to help students and volunteers sort the overwhelming amounts of material we excavate.

Erik De’Scathebury has shared a great post on what it means to be an archaeologist working with a disability, and what we can do to make the field more accessible. His post is really important, and I recommend you read it!

And another of my favourites has to be this post by Kimberlee Moran, on how forensic archaeology is not quite how it’s shown on TV.

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Crowdfunded Caving: Recent PhD fieldwork

Earlier this year, my supervisors and I were discussing ways to raise money for a small field trip to excavate a second site as part of my PhD research. We had all-but exhausted the available funding during my first phase of fieldwork, at a site that had produced a far richer and more complex archaeological record than we had expected. How could we raise the funds needed for second phase of fieldwork to provide a comparative sample?

One of my supervisors, Joe, suggested crowdfunding, and the idea for our crowdfunding campaign was born. Thanks to the generosity of family, friends, and strangers, we were able to fund a five-day field trip to excavate a cave slightly north of last year’s site. A total of 73 people backed our campaign, and I’m immensely grateful to each and every person who donated, shared, and supported us. A little over a week ago, I was finally able to conduct the fieldwork. A few details of the trip were shared on twitter via a great hashtag started by Gilbert Price and Julien Louys: #LiveFromTheDig (if palaeontology and fieldwork is your thing, I recommend you check it out!). But for those of you who aren’t on twitter or who want a little more detail, I thought I’d share some of our experiences here.

The first stage of fieldwork: getting to site. I’m lucky to do fieldwork only a half-day drive from Perth, which meant we could drive directly to site on that first day.

I find fieldwork incredibly fun, challenging, and exciting. And that’s not just the excavating: one of my favourite moments on any field trip is the moment when you leave suburbia and start to drive out of the city!

On this field trip, I was fortunate to have the help of Joe, Alexander Baynes (a palaeontologist based at the Western Australian Museum), Alex’s former student Cassia and an archaeology student I’d previously taught, Dan. Our small team was rounded out by two Amangu Traditional Owners, Reg and Thomas, who provided us with important insight into the cultural and environmental aspects of the area. Both men hold a lot of knowledge about the area, and it was great to be out on Country with them, talking about the plants, animals, water sources, and the ways that the landscape and communities have changed through time.

A 40 minute drive through kwongan shrubland to site – the track was a bit rough, but the views were delightful!

Getting to site was half of the battle, but one of the interesting (and challenging) aspects of this phase of fieldwork was that we were attempting to find a site with little/no human contribution. What that meant, therefore, was that we needed to try and find a site that was accessible enough to do our excavation, but was not accessible enough that people would have regularly visited and camped there in the past. Obviously, this was going to cause some challenges in the form of our own access to the site! The cave we chose ended up being a great compromise:

Cave site “E24″… doesn’t look like much more than a crack in the ground from this angle…

… but from the inside, it’s a completely different story!

As you might be able to see from these photos, the entrance to the cave is steep, rocky, and reasonably difficult to negotiate. Unlike the cave we excavated last year, the entrance has very few flat, open areas that would make it suitable for human occupation: much of that front area is dominated by impressive cave formations and rockfall. The cave is also very dark. The light you see in the foreground of the photograph above is mostly a trick of exposure: the place from which I took the photo is dark enough that torches are necessary.

Bones of small animals (mostly rodents) on the surface showed that the ledge above had probably been used as an owl roost (Image courtesy of Joe Dortch)

We set up our excavation square in the area we thought would most likely give us a good comparison to the  previous site: at the edge of the light area, beneath a ledge that appeared to have been used as an owl roost. Our location was also chosen as we wanted to be sure of the level of human contribution to the site: if people had been using the site regularly, we wanted to know, and this location appeared to be the easiest thoroughfare with which to access the rest of the cave.

A quartz flake – the only direct evidence for Aboriginal activity at the site.

As we started digging, it became clear that we were recovering a small but consistent assemblage of small animal remains, mostly rats, mice, small dasyurids, bandicoots and juvenile bettongs. These animals are all typically eaten by owls, and it seems clear that owls were indeed the main contributors to the assemblage. Charcoal fragments were also scattered through the deposit (whether resulting from hearths or bushfires, I don’t yet know), but only one stone artefact was identified during the excavation: a beautiful quartz flake found on day 3. Compared to the rich archaeological assemblage found at the previous site, this might suggest that while people occasionally visited the site, use of the cave for shelter and as a camp site was not common.

Sieving the deposit to recover bone, charcoal, artefacts, and other material. We were collecting some of the bone for DNA sampling, hence the gloves and mask!

One of the difficult aspects of archaeological and palaeontological excavation is that we have no real way of knowing what we’ll find until we dig! You can ‘read’ the site and the soil well, but it’s only through excavation that you’ll learn exactly what is buried beneath the surface. Our excavation at E24 provided us with a great collection of small mammal fauna with which to compare the material from the site excavated in 2014, and I’m looking forward to getting stuck into the sorting and analysis early next year.

So there you have it: a brief overview of the fieldwork you and others helped to fund! The generous donations helped to feed, transport, and house all seven of us through the week, and we’ve got enough left to pay for a few radiocarbon dates to date the deposit (a critical part of the research). I’ll leave you with one of my favourite images from the trip, which shows half of the excavation team in action:

The excavation team in action.

Thanks to everyone who supported this research. Stay tuned for more updates as we analyse the excavated material!

The course of PhD fieldwork never did run smooth, and my track record for needing to buy replacement tyres remains intact. Why is it always the expensive ones that I stake?

Blurred Lines: When natural and cultural landscapes collide

“The natural landscape is being subjected to transformation at the hands of man [sic*], the last and for us the most important morphologic factor. By his cultures, he makes use of the natural forms, in many cases alters them, in some destroys them.” – Carl O. Sauer (1925).

Along the coastlines of northern Australia – hidden in mangroves, rising up from flat coastal plains, and lining narrow tidal creeks – mounds of shell reach up to 12 metres in height. The landscape is peppered with these distinctive relics of cultural activities. But beyond providing a tangible, conspicuous link to the past, how do these shell mounds influence the surrounding cultural and physical landscape?

When archaeologists or anthropologists use the term “cultural landscape”, what we are referring to is the space in which human groups – past or present – operated, and the relics of cultural practices on the natural landscape. As the quote from Sauer notes, humans have a transformative effect on the environment, modifying the natural condition of an area by their presence. These effects are many and varied, and are visible in most landscapes across the globe.

A shell mound from Weipa, photographed in 1958. Image via National Archives of Australia.

Landscape modification takes many different forms, and has many different impacts on people and ecosystems. In coastal landscapes, for example, shell mounds and middens range from sparse shell scatters resulting from a single meal, to huge hillocks that show continual, prolonged use by large groups of people. The impacts of these sites and associated cultural activities are just as varied.

Gumbaloo gathering shellfish at low tide, Liverpool River, Arnhem Land, Northern Territory, 1952 Axel Poignant. Image via National Library of Australia

Shell mounds and middens are evidence of the collection and use of marine or freshwater shellfish. While many people exploit shellfish, it is hunter-gatherers who are most commonly associated with the creation of these landscape features. Shell middens and mounds form when people discard shellfish remains, often creating large mounds that incorporate other waste materials such as seeds, animal bones and broken tools. They are evidence of people’s use of these coastal margins: the foods they ate, the environments they favoured, and sometimes even the time of year they were there. But one of the characteristics that makes these sites so valuable – the robust nature of marine shell – also makes them distinctive features of the coastal landscape.

Baja California (shown in red). Image via Wikimedia Commons.

If we look at shell mound sites in North America, we can begin to understand how people’s movement of resources – such as marine shell – from one place to another can directly influence the physical landscape. In a recent paper, a Californian/Texan research team investigated the relationships between aragonitic shell middens and plant biodiversity in the Baja California Peninsula. These shell middens are the material remains of the exploitation of marine shellfish from the rocky headlands and sandy beaches some 3000-5000 years ago. This research shows the extent to which the simple activity of collecting (and then discarding) shellfish has modified the local ecosystems which incorporate these remnant midden complexes.

Along the Baja Peninsula, high, steady winter rainfall has leached calcium from the discarded shells over several thousand years, altering the chemical properties of the soil around the middens. The study’s authors tested the hypothesis that this altered soil chemistry affected the plants that grew on and around the midden sites. By assessing the vegetation growing on the middens on the low-lying floodplain, they were able to identify stark differences in plant diversity between the naturally saline, high-sodium soils of the surrounding floodplain, and the aragonite-laden soils of the middens.

As the study’s authors note: “deposited during the Holocene, the shells have been weathered, and new anthropogenic soils have formed that show unique soil signatures and plant communities.” These new soils are the indirect result of human activity – certainly the creators of the middens didn’t intend for these soils to form, and in fact, the soils haven’t formed in similar sites further inland where rainfall is far lower. But the result of the collection and mass discard of marine shells by late Holocene people living in the Baja Peninsula, combined with the steady, winter-wet climatic conditions, has created a unique environment where plants have been able to colonise and thrive in areas in which they would not otherwise have succeeded.

Shell mound covered in vegetation, Cape York Peninsula. Image via Mick Morrison, used under Creative Commons.

Did the same process happen in Australia? Whether or not the slow breakdown of shells fundamentally altered soil in coastal landscapes like Weipa, on the Cape York Peninsula, shell mounds do have other attributes that have altered the ‘natural’ landscape. Middens and mounds might be primarily made up of discarded shell, but they also contain other discarded items, including seeds and pits from plants. In Cape York, research indicates that many shell mounds are the sites of ‘gardens’ or ‘orchards’ created over time as people have brought fruits and other plants into the site and discarded the scraps. Similarly, the mounds can act as ‘islands’ which contain ideal growing conditions for some plants in an otherwise inhospitable landscape. Some researchers have argued that the creation and curation of these orchards and gardens was a form of cultural manipulation of plant resources, a process they called ‘domiculture’.

Does this mean people were intentionally bringing these plants into the shell mound sites to create these orchards? The evidence is far from conclusive. However, there was certainly an ecological consequence of people’s actions, even just on a very local scale. Physical geography was altered by the accumulation of shell, which may also have altered soil geochemistry. People brought plants from other parts of the landscape, and discarded scraps, including seeds and nuts, in the midden piles. Some of these germinated, creating patches of plant resources that may not have otherwise been present in that location. And people likely benefitted from the development of these orchards, as plant foods then became available for collection and use closer to other important resources.

So does what does this all mean for the traditional dichotomy of the natural vs. the cultural landscape? One of humanity’s defining characteristics is our ability to exploit, alter, and permanently change the natural world. The result is a blurring of the lines between nature and culture. How widespread and influential have these cultural alterations been on natural landscapes? That remains to be seen, but it is increasingly clear that interpretations of small scale hunter-gatherer societies as leaving no lasting environmental footprint are naive at best. Shell mounds are only the tip of the iceberg!

References and Further Reading:

Moore, J.D. 1999, ‘Archaeology in the Forgotten Peninsula: Prehistoric Settlement and Subsistence Strategies in Northern Baja California’, Journal of California and Great Basin Anthropology, vol. 21(1): 17-44.

Morrison, M. 2014, ‘From scatter to mound: A new developmental model for shell mound sites at Weipa’, Queensland Archaeological Research, vol. 16: 165-184.

Vanderplank, S.E., Mata, S. and Ezcurra, E. 2014, ‘Biodiversity and Archeological Conservation Connected: Aragonite Shell Middens Increase Plant Diversity’, BioScience, vol. 64(3):202-209.

To read more about Michael Morrison’s research into the Weipa shell mounds, visit his blog.

*As a staunch advocate for the use of gender inclusive language, I do consider it necessary to note that Sauer’s statement uses ‘man’ where we would now use ‘humankind’. It may seem innocuous, but in archaeology, particularly in pre-historic archaeology, it leads to a phenomenon of invisible women. I could go on, but perhaps that’s something for a future post!

Radiocarbon dating: the science that helps archaeologists ‘time travel’ | Day of Archaeology

Each July, archaeologists around the world contribute to an excellent online project, the Day of Archaeology, via blogs and social media. The project is run by a group of dedicated volunteers who aim to provide a snapshot of the many different activities that archaeologists are engaged in, including fieldwork, community outreach, research, teaching. This year, the Day of Archaeology fell on my last day of my visit to ANSTO, where I was learning how to prepare charcoal samples for radiocarbon analysis. I’ve reposted the content here, but please click through on the link at the bottom of the page and check out some of the other fantastic Day of Archaeology posts.

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One of the things I love most about archaeology is the variety of work. I’m currently working on my PhD, which means that a “typical” week could see me in the lab, on fieldwork, writing, teaching, at a conference or workshop, or meeting with people to chat about research. This week, I’m at the Australian Nuclear Science and Technology Organisation (ANSTO) in Sydney, learning to prepare charcoal samples for radiocarbon analysis. The ‘Day of Archaeology’ actually falls on my last day/travel home to Western Australia, so rather than focus on one day I thought I’d share what I’ve been doing for the past week.

Sadly for Superman, radiocarbon dating is only useful for samples that are less than ~50,000 years old. Photo credit: radio-carbon testing via photopin (license)

Accurate dates are very important for archaeological research. Scientific dating of excavated material, using techniques like radiocarbon analysis and optically stimulated luminescence (OSL), provides a time frame with which to assess the archaeological record. But most archaeologists are not chemists or physicists, so we often collect and send our samples to specialist laboratories, and then wait weeks or months before we receive an email with results of the analysis with limited understanding of what goes on in the meantime. Sometimes these samples are sent off accompanied by a whispered prayer to the universe: ‘please let them arrive safely, be large enough, and be uncontaminated!’

I’ve collected and sent many samples for analysis before, but this week I was fortunate enough to travel to ANSTO to meet their researchers and learn how charcoal samples are prepared and pre-treated for analysis. This opportunity is courtesy of an AINSE research grant, and means that I’ve been able to work on samples I collected during my fieldwork last year.

ANSTO uses an isotope analysis technique called “Accelerator Mass Spectrometry”, or AMS, for radiocarbon analysis, which involves firing a sample of carbon through a particle accelerator to measure carbon isotope ratios. This method can be used to get accurate ages from very small samples (as small as 10 mg); very useful for archaeologists as we really don’t like destroying our samples!

Charcoal samples that were collected in the field, and then packaged ready for submission to the radiocarbon laboratory.

Before a sample can be analysed, it needs to go through a series of pre-treatments to remove contaminants, and combustion to prepare it for analysis in the mass spectrometer. The charcoal is converted into carbon dioxide, before going through a series of processes to extract contaminants (like nitrogen). The carbon dioxide gas is then heated (with hydrogen gas and an iron catalyst to remove the oxygen) to produce graphite – solid carbon – before it is finally ready to be sent through one of ANSTO’s particle accelerators (check out this videoto see more about the particle accelerator, or this one for a more detailed explanation of what goes on inside it).

Sample being cleaned of excess sediment and cut into small pieces for chemical pre-treatment.

So this week, I’ve been dealing with the first half of this process: sample pre-treatment and combustion. It’s a fairly straightforward process – even for a non-chemistry-minded person such as myself – similar to following a recipe (albeit one that involves sterile facilities and acids!). Pre-treatment involves scraping the outside off the charcoal sample, then treating it with acid, then an alkali solution, and then acid again. The sample is then dried and repackaged into small glass vials before being combusted at around 900°C.

Samples sat in first acid wash

So that’s been my work for this week: travel to a facility on the other side of the country, and a week in a small, sterile lab learning a new skill. Who says archaeology isn’t glamorous? As I post this, I’m packing up and getting ready to head back to the airport to fly home. It’s been a fun, challenging week as I’ve tried to wrap my head around the chemistry and physics involved in the process.

As for my samples? I won’t know how old they are for another few weeks. But having now seen them through the stages of collection, preparation and pre-treatment, I’ll be keeping a close eye on my email inbox for the results!

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Many thanks to the staff at ANSTO’s Institute for Environmental Research for their efforts in teaching me about these processes. Any errors are mine.

This post was first published on 24 July 2015, here: Radiocarbon dating: the science that helps archaeologists ‘time travel’ | Day of Archaeology.

Archaeoecology in Southwestern Australia Part 2: What could you possibly learn from a quokka?

I’m excited to introduce a guest post today, written by Dr Joe Dortch. Joe’s research has explored megafaunal extinctions, the preservation of ancient DNA in archaeological bone, and human-environmental relationships. His PhD research investigated environmental changes and human occupation in WA’s southwestern forests. Joe is also one of my PhD supervisors, and is the other half of the crowdfunding team behind “How nature and nurture created biodiversity in south-western Australia“.

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In my first post for Archaeoecology I’d like to show what the remains of quokkas (Setonix brachyurus) can tell an archaeologist. It’s based on their ecology, and their place in ethnography – the records of cultural practices.

Quokkas – now famous for their reputations as the world’s happiest animals – were also a favoured prey animal by Aboriginal people in southwestern Australia. [Image source]

Despite their abundance on waterless and sunny Rottnest Island, where quokkas have few predators, what they really like is thick vegetation around watercourses. Their home is their castle, as it’s difficult for a dingo or human predator to travel through a thicket. Add fire, however, and the threat from humans changes dramatically. When their home is on fire, they will reach their maximum speed of a stately 12 km/hour and keep going in the opposite direction from the fire. Quokkas prefer habitat that has been long unburnt – so much so that they stay in one locality for most of their lives, provided it stays unburnt, and only the youngest members of the clan will migrate if the population increases to bursting point.

What do these observations have to do with archaeology? It seems obvious that Aboriginal hunters could have easily used fire to hunt quokkas. Put some good quokka catchers and dowak throwers on one side of a thicket, get someone else to light up the other side, and boom, plenty of food for everyone. However, it takes 10 years to build up suitable quokka habitat. That means looking after a resource before it was harvested. More crucially, as Sylvia Hallam argued recently, the responsibility of management implies some form of ownership.

Karri forest around a cave site is great quokka habitat. Image: Joe Dortch.

In Noongar country of the early 1800s, when a few British colonists were keenly observing Noongar practices, you couldn’t just burn anyone’s quokka thicket. You could only burn your own – or if you did want to burn someone else’s, the owner had to be present. Noongars of south-western Australia even had a word for burning on someone’s patch without permission – quippel.

One fine summer day in 1831, Nakinah, estate owner on the north side of King George Sound, asked the commander of the Albany garrison, Captain Collet Barker, for the loan of a boat to take him and several other young men to Bald Head and burn for “wallaby” – in a few days. When Barker asked why not go now, Nakinah said, we must wait for the owner, Coolbun, who is away, or it’s quippel – stealing. The men, including Coolbun, did get their wallaby, and quokkas, several days later.

This story points to another thing about hunting quokkas (and wallabys). When it was time to burn them out, people would have needed to organize a firing (and catching) party. That means at times of year when it was difficult to get a lot of people together, it was also best not to worry about burning. In south-western Australia, that season is winter. For various reasons, winter was a good time to travel in small groups across the small creeks in the hinterland. It was also too wet to keep bush-fires going. Instead, it was the time of year to hunt solitary big game, like kangaroo, and make do with what grew. Come summer, people gathered to transact business, go fishing, and burn patches that were ready.

All very well, but what about the archaeology? How do we know whether people who lived thousands of years ago did the same thing as those who lived just 200 years ago? We don’t know for sure, but after digging through layers of campfires and other traces of occupation, as well as other layers that don’t have evidence for occupation, we have worked out whether the abundance of quokka bones (and bones of other species) correlates with evidence for past Aboriginal occupation. In short, we have a fair idea of whether a species was a likely food item at certain sites over time. It turns out that three cave sites in the south-west corner of Western Australia have abundant quokka bones – but those bones don’t correlate with human occupation. They probably got there thanks to other predators, like dingoes. People could have hunted them still – just not at the season that those sites were occupied. It’s an interesting point that each of those sites is rich in emu eggshell – emu eggs are best harvested when fresh, in winter and spring.

A 13,000 yr old campfire bed – rich in animal bones, but not so much quokka. Image: Joe Dortch.

As result, we can say that quokka hunting was not the main pre-occupation at the season when people used those three caves. We can also say that people mainly used those caves in winter, and must have been somewhere else in summer. We don’t know for sure where that is, but coastal sites seem like a good bet, since Noongars often headed to the coast in summer. A fourth cave near Margaret River could provide an answer, but we’re still crunching the numbers.

The hunt is on for that good quokka site! And there’s still one big question – what do they taste like?

I acknowledge the help of many traditional owners of south-western Australia with this topic.

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Further reading:

Barker, C., 1992. In: Mulvaney, John, Green, Neville (Eds.), Commandant of Solitude: the Journals of Captain Collet Barker 1828-1831. Melbourne University Press, Melbourne.

Dortch, J., J. Balme and J. Ogilvie 2012 Aboriginal responses to late Quaternary environmental change in a Mediterranean-type region: Zooarchaeological evidence from southwestern Australia. Quaternary International 264:121-134.

Hallam, S. 2002 Peopled landscapes in southwestern Australia in the early 1800s: Aboriginal burning off in the light of Western Australian historical documents. Early Days 12(2):177-191.

Hayward, M., de Tores, P.J., Augee, M.L., Fox, B.J. and P.B. Banks 2004 Home range and movements of the quokka Setonix brachyurus (Macropodidae: Marsupialia), and its impact on the viability of the meta-population on the Australian mainland.
Journal of Zoology 263:219-228.

Archaeoecology in Southwestern Australia Part 1: What can animal bones tell us about Aboriginal land management practices?

This post is the first in a series I’ll be posting this week, discussing some of the key aspects of my PhD research. This series corresponds with the final week of our crowdfunding campaign, which will help us understand how the Amangu and Yued people manipulated landscapes and ecosystems of the northern Swan Coastal Plain and Lesueur sandplains. Please share this campaign (here: How nature and nurture created biodiversity in south-western Australia) with your friends and colleagues, and help send us back to the field this year!

In recent months, it has become something of a ritual aspect of any social gathering. I meet someone new, or start to chat with a friend I’ve not seen in a while, and the topic of my PhD research inevitably arises. As anyone who’s ever pursued a PhD can tell you, attempts to explain your research are often met by a complicated combination of facial expressions. The raising of eyebrows in surprise. A polite smile. The faintly perplexed glazing-over of eyes. But in my experience, these initial responses are often quickly followed by a single, important question:

“How can you learn about past Aboriginal land management practices by looking at animal bones?”

It’s a great question, and like many great questions, it doesn’t have a simple answer.

Historic records show that Aboriginal people across Australia modified the landscape and ecology to change the availability of plants and animals. But while that gives us a bit of an understanding of cultural landscapes and practices in the 18th and 19th centuries, it doesn’t tell us anything about how (or when) these activities began, or how they have changed through space and time. Did ‘fire-stick farming’ serve the same purpose in the tropical north as it did in the cool, wet forests of the southwest? Was vegetation managed in the same way in southwestern and southeastern Australia? How did past environments change when more or fewer Aboriginal groups lived in an area? And what does this variation mean for our understanding of “traditional land management practices”, or how we employ them in modern land management?

One of the more difficult aspects of this research is developing a way to identify Aboriginal impacts on landscapes and ecosystems. In lieu of a time machine, archaeologists and palaeontologists typically use “proxy data“: things that we can observe in the archaeological or palaeontological record, which we can then use to infer events, activities and systems that are not directly observable. Proxy records can be anything from charcoal (used to look at fire frequency and intensity), pollen (changes in plant species distribution, which can indicate environmental and cultural changes), to sediment and soil (environmental and depositional processes), and much more. Animal remains, including bones and teeth, eggshell, horns and antlers, shells, and fish otoliths, are some of the more commonly used proxy records. They tell us about past environments, diets, and the relationships we have with other species.

During excavation, sediment is sieved and the sieve remnants collected. The material being sorted here includes bones, teeth, fragments of eggshell and charcoal.

But how can animal remains tell us about the ways in which people have influenced the ecosystems in which they live? The most widespread and significant cultural land management practice employed by Aboriginal peoples across Australia was probably the use of fire to clear vegetation: it opened up landscapes, changed the distribution of communities in different fire succession stages, and impacted on plants and animals that required specific habitat niches to survive.

Animals like quokkas, kangaroos, possums and bandicoots all formed an important part of the diets of people living in southwestern Australia. By managing vegetation, it was possible for Aboriginal people to manipulate animal populations. Kangaroos are attracted to areas with fresh, young growth. Brushtail possums need nesting hollows (usually created by fire), as well as the flowers and shoots of trees like Eucalyptus. Quokkas live in dense thickets and woodland, and seem to prefer a combination of vegetation that has been recently burnt (in the last 10 years) and long unburnt (at least 10 years post-fire). When these animals appear in the archaeological or palaeontological record, we can be reasonable sure that they were living nearby. By understanding their specific habitat niches and needs, we can reconstruct the surrounding environments and begin to infer the ways in which natural and cultural systems might have influenced the availability of these habitats.

Animals like the Western Grey Kangaroo are often drawn to the fresh young growth that sprouts after fire [Image credit: David Burton, Flickr]

My PhD research tests the hypothesis that Aboriginal people maintained or increased food resource diversity and availability over time, as management practices (like burning) intended to stabilise resource accessibility created a mosaic of interconnected communities in different fire succession stages. This modification of ‘natural’ communities would likely have been associated with cultural changes, particularly those linked to the transfer of Traditional Ecological Knowledge, seasonal patterns of mobility and changes in the structure of cultural groups.

One of the ways we can look for this is by exploring changes in biodiversity over time (particularly the period of initial European colonisation and post-European changes to floral and faunal diversity), testing the hypothesis that management of the landscape by Aboriginal people resulted in changes to resource structures and availability. Biodiversity that is high and stable (or increasing) through time would support this interpretation, particularly if it is accompanied by archaeological evidence of cultural changes, indicating a link between changes in biodiversity and patterns of cultural resource management.

The first panel of Ensign Robert Dale’s panorama of King George Sound shows an Aboriginal camp in the foreground, with fires burning in the dense vegetation that surrounds the cleared lands occupied by Europeans. [Image via National Library of Australia]

Research like this has been undertaken in other parts of the world (like this study in the Quiroste Valley, California), demonstrating the potential to shed light on the processes behind the development of cultural landscapes, and how people responded to major transition events like climatic changes. By combining the macro (ecosystem/landscape biodiversity) and micro (individual species, which I will talk about in the next post) scales of analysis, together with the archaeological record, we can begin to look at how plant and animal communities responded to environmental and cultural activity.

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We need your help!

We’re so close to reaching our funding goal. Learn more about our project, and how you can help, here.

Did people on WA’s Mid West coast stop eating shellfish 3000 years ago?

Wide, parabolic bays like this stretch between rocky headlands in the southern end of the study area. View south from North Head towards Jurien Bay.

Looking out over the glittering turquoise bays and limestone ledges of Western Australia’s ‘Coral Coast’, it can be easy to forget that the coastline we see today only began to resemble its modern form about 6,000 years ago. Marine gastropods like turban snails, abalone, and limpets established themselves in littoral ecosystems, producing a rich range of food sources that were readily accessible to Aboriginal people wading through the intertidal zone. For several thousand years, people on the Mid West coast exploited these resources, leaving evidence in the form of middens: culturally-derived scatters of shell, bone and stone tools. But around 3,000 years ago, midden formation appears to have stopped abruptly. Why?

In a paper published this week in Australian Archaeology, Bob Sheppard, Joe Dortch and I report the findings of the investigation of two new midden sites on the Mid West coast: the first at Oakajee River, north of Geraldton, and the second at North Head, near Jurien Bay. Radiocarbon dating shows that these sites are between 4,500 and 5,600 years old, with both middens apparently forming over a very short period of time. Possibly best described as small, shallow shell scatters, the Oakajee and North Head middens are typical of midden sites in the Mid West. They add to a growing body of evidence which suggests that through the mid-Holocene, Aboriginal people living along the coast engaged in consistent (though small-scale) exploitation of coastal ecosystems, including littoral and estuarine resources.

Some of the shells from an eroded section of the North Head midden, including turban snails, chitons, abalone, and limpets.

The sites also add to the evidence of regular use of littoral resources prior to 3,000 years ago, when an environmental or cultural change apparently resulted in these resources became far less economically important. Research carried out in the 1980s indicated that the decline in intertidal foraging could have been related to changes in marine and estuarine coastal formation processes that changed the availability of many mollusc species. Changes to the highly productive hind-dune lagoons occurring together with these processes would have altered the ways in which Aboriginal groups used the coastal fringe. As a result, fish and terrestrial species became the primary focus of coastal economies in the region, with molluscs only exploited in very small quantities (Dortch 1997; Hallam 1987).

Interestingly, geomorphological research (which looks at the formation and evolution of surface landforms and landscapes, including coastlines) suggests that the Mid West coastline may have experienced increased storm activity in the mid- to late Holocene. This storm activity would have included higher energy waves and storm surges, and is supported by evidence of a period of increased erosion of coastal sand dunes around 3,000 to 2,000 years ago. Could this have been the driving factor behind this regional change?

Map of the lower Mid West, showing the locations of all dated archaeological shell middens. Image source.

It seems likely that increased storm and erosional activity could have trigged changes to the environmentally sensitive littoral and estuarine ecosystems. Certainly, there is good reason to think that changing coastal conditions made these resources less reliable, and that this may have altered the way that Aboriginal people were using coastal and inland landscapes. For parts of the coastal plain further south (towards Perth), Hallam argued that it was the coastal woodland, riverine and wetland communities that were the cornerstone of the mid- to late Holocene economy. But what about the coastal plain north of Jurien Bay, which is dotted with salt lakes instead of freshwater wetlands, and is covered in more arid-adapted kwongan and woodland vegetation?

As part of my PhD research, I’m interested in seeing how inland resources – including animals like kangaroos, small mammals, and emus – were being used at that time. Was there a corresponding change in food sources in other sites across the coastal plain, as marine resources became less important?

You can help with this research!

To understand the ways in which Aboriginal people living in the Mid West and Swan coastal plains dealt with changes like this, we’re currently investigating several sites further inland. Limestone caves like those found near Jurien Bay and Leeman contain well-preserved archaeological and palaeontological evidence that can help us understand Aboriginal cultural practices and environmental conditions. We are currently raising funds to do fieldwork later this year, and every donation (be it $5 or $500) will help get us closer to understanding the complex relationships between Aboriginal people and the plants and animals of coastal plains. Please visit our fundraising page to learn more about this research.

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This post is based on research published in Australian Archaeology, vol. 80:

Monks, C., Sheppard, B. and J. Dortch 2015 ‘Mid-Holocene exploitation of marine molluscs in the lower Mid West, Western Australia’, Australian Archaeology, vol. 80, pp 99-103.

Digging deep for biodiversity conservation

There’s an ancient limestone spine that runs along Australia’s southwestern coastline. Formed by sand dunes that have compacted and lithified over time, the Tamala limestone formation is covered by forest, woodland thickets, and low coastal shrubland known as kwongan. Caves scar the spine from its northern tip all the way south to Augusta in Western Australia’s far southwest. Most aren’t easily accessed by people: they are fissures in the ground that open into dark, deep tunnels and caverns. But in some places, erosion has opened cave entrances until they are large enough to walk into. Many West Australians are familiar with the ‘show caves’ of the Augusta-Margaret River region, but fewer know of the smaller, more secluded caves that pockmark the coastal plain north of Perth.

Caves provide shelter to people and animals, making them ideal places to look for evidence of past activity.

Caves are archaeological and palaeontological time capsules. As well as being protected from the harsher environmental conditions of the surrounding sandplains, the caves collect a record of human activity, combined with activity from animals like owls, dingos, and extinct predators the thylacine (Tasmanian tiger).

The 2014 field team in action. Photo: Joe Dortch.

In late 2014, I worked with a team of Amangu elders, undergraduate university students, volunteers, and cavers to investigate some caves a few hours north of Perth. Archaeological excavations often feel like a gamble: you can plan and survey a site to your heart’s content, but it’s only when you start to dig that you’ll know what is hidden in the ground. In this case, we had placed our bets on two particular locations within the cave that looked most promising. We aimed to excavate small samples of material; to collect animal bones, evidence of hearth fires lit by Aboriginal people, and stone tools that might tell us about who used these caves and why. Luckily for us our bets paid well. Moments after scraping back the top layer of sediment we found our first stone tool: a small flake of white quartz.

Over two weeks, we excavated almost four tonnes of sand, ash, bone, rubble, emu eggshell, and artefacts from two small pits. We collected samples of bone and sediment to test for ancient DNA, and spoke to the elders about how Amangu people used the plants and animals of the coastal plain. We collected charcoal for radiocarbon dating, and surveyed the area around the cave to record the plants that currently grow there. We also recorded some evidence of historic activity: a couple of pieces of broken glass, an old farrier’s file, and graffiti scratched into the limestone wall.

The base of a glass bottle, showing breaks that are consistent with knapping. Photo: Ian McCann.

Our plan had been to excavate a second cave nearby – one that wasn’t easily accessed by people but would give us an insight into the past environments. This would give us a ‘control’ with which to compare the findings from the first excavation, and would help us separate human activity from that of dingos, owls and other predators. But because our first site was so rich in animal bone and cultural material, that excavation consumed all of our available time. Archaeological evidence from this part of the southwest coastal plain is rare, so we dedicated our time and resources to maximising our archaeological results. Now, we need help to fund a return trip.

How does archaeological research help us preserve biodiversity?

Research like this has benefits not only for understanding Aboriginal cultural practices, but also understanding past ecosystems. Since European arrival, plants and animals across Australia have become endangered and extinct at an astonishing rate. The combination of introduced predators, destruction of habitat, and changes to fire regimes has devastated ecosystems. Palaeoecological evidence allows us to reconstruct past environments and examine environmental trends. Archaeological evidence helps us to understand Aboriginal use of landscapes, plants and animals. When we examine these two strands of evidence together, we can begin to understand the influences of Aboriginal activity on the environment. This helps us to identify the consequences of Aboriginal burning on the plant and animal communities, and whether certain species (such as kangaroos, possums, quandong trees, or yams) were being deliberately managed. Importantly for modern conservation efforts, this information can help to highlight management strategies that might benefit endangered species.

You can help us

We’re seeking financial support to get us back in the field this year and cover lab costs associated with dating changes in environmental conditions and cultural practices. This will help us create a framework for investigating how environments and Aboriginal cultural practices changed through time, and will mean that we can identify the impacts of these changes on the associated ecosystems.

For more details about our crowdfunding campaign, visit our page on Chuffed.org: How nature and nurture created biodiversity in south-western Australia. We think that this research is interesting and important. We’d love your support.

An introduction

In 1975, Western Australian archaeologist Sylvia Hallam published Fire and Hearth: an excellent overview of the historical and archaeological evidence of Aboriginal use of fire to modify and manipulate the environment in southwestern Australia. Hallam’s argument boiled down to one simple, but important statement:

“The land the English settled was not as God made it. It was as the Aborigines made it.”

Most non-Indigenous people to whom I’ve spoken hold the belief that at the time of European arrival, Aboriginal Australia was made up of scattered groups of nomadic hunters and gatherers; people who left almost no ‘ecological footprint’ and managed to survive in the harsh, sometimes hostile Australian environment. But how true is that assumption? Many Australians have heard of ‘firestick farming‘, a term coined by Rhys Jones to describe the deliberate, systematic use of fire by Aboriginal people to create landscape-scale changes in plant and animal communities. Recently, Bill Gammage’s The Biggest Estate on Earth has rekindled public discussion about the extent to which Aboriginal activities impacted on Australia’s landscape and ecosystems.

Joseph Lycett’s 1817 painting shows Aboriginal men using fire to burn vegetation and flush out kangaroos [Image source]

The ways in which ecosystems operate are complex. But when we consider the roles of humans in these systems, we introduce a group of actors who have their own agendas, perceptions, and behavioural practices – like ‘firestick farming’, or planting and tending gardens. My PhD research examines the ways in which these cultural aspects influence (and are influenced by) environments. Using archaeological and palaeoecological evidence, this research explores the nature and extent of Aboriginal resource management and manipulation in the coastal plain north of Perth.

This blog is where I’ll share my research and field experiences. If you have any questions or suggestions, I’d love to hear from you!