First and Last: Dating People and Extinct Animals in Australia

By Gillespie, Richard | Australian Aboriginal Studies, Spring 2004 | Go to article overview
Save to active project

First and Last: Dating People and Extinct Animals in Australia

Gillespie, Richard, Australian Aboriginal Studies

Thirty years ago, a radiocarbon date of 'more than forty thousand years' from Lake Mungo became both a slogan for Indigenous pride and a challenging focus for archaeological science. It wasn't much of a date (and consequently never published) but everyone wanted to know for how much more than 40 000 years people had been living in Australia. New developments in numerical dating techniques are now providing answers to that question, and there is similar progress in the understanding of climate change, landscape evolution and extinction of the Late Pleistocene megafauna. This update is based on a review (Gillespie 2002) of the oldest archaeological sites from the Late Pleistocene continent of Australia, when Tasmania and New Guinea were connected to the mainland by land-bridges (Figure 1).


It should be remembered that dating laboratories do not actually measure the age of samples. Quite a lot of the work they do is analytical chemistry, measuring the concentrations of elements and isotopes that give rise to a time-varying signal in some component of a sample. Specialists in the numerical dating techniques use the analytical methods that they consider to be appropriate, and this primary data is converted into age-estimates via mathematical procedures. As the technology for both analytical chemistry and measurement of the signal of interest improves, providing higher precision on smaller samples, best practice for any given laboratory will also change--if they can afford the regular upgrades.

Developments in numerical dating methods

Radiocarbon analysis has been the dominant method for estimating the age of Holocene and Late Pleistocene archaeological and geological sites for more than 50 years. Three aspects of the radiocarbon method continue to tax practitioners and are of concern to archaeologists and others who rely on radiocarbon results: maximum possible age, contamination, and calibration. That famous result from John Mulvaney's Mungo excavation could not be distinguished from laboratory 'background' measurements. In the early 1970s, background for the ANU laboratory (and the similar University of Sydney laboratory) was about 40 000 BP, so nothing older than that limit could be determined. Improvements in sample processing and measuring equipment have now shifted the background for many laboratories to 45 000 BP and the best can manage 55 000 BP or more, so radiocarbon age-estimations greater than 40 000 BP certainly now are possible.

Most readers are familiar with 'contamination' of radiocarbon samples, usually by materials younger than the true sample age. Much improved chemical decontamination procedures have been made possible by the small-sample capability of accelerator mass spectrometry (AMS) systems. One example is the change from routine acid/base/acid (ABA) chemistry to acid/base/wet oxidation (ABOX) methods for the removal of humic acids from charcoal. Radiocarbon measurements on microfauna and flora, such as foraminifera and pollen, and specific molecules such as single amino acids are also possible. These procedures give more reliable results because the identity of samples being dated is more accurately known and contamination can be reduced to insignificant levels.

Radiocarbon analysis of annual tree rings shows deviations from the exactly known tree-ring age, so the idea of 'calibration' was developed whereby radiocarbon years are converted to calendar years. The data currently accepted by the radiocarbon community (known as INTCAL04) extends to 26 000 calendar years ago, but a consensus calibration curve back to 50 000 years should be available within two or three years (Bard et al. 2004). Calibration of radiocarbon age-estimates is necessary for comparison with other dating methods which yield dates in calendar years.

Thermoluminescence (TL) dating was developed for ceramics and still works well for that application because it relies on heating in antiquity to reset the TL signal to zero, but results for sediments that were never heated have been mixed.

The rest of this article is only available to active members of Questia

Sign up now for a free, 1-day trial and receive full access to:

  • Questia's entire collection
  • Automatic bibliography creation
  • More helpful research tools like notes, citations, and highlights
  • Ad-free environment

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
Loading One moment ...
Project items
Cite this article

Cited article

Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited article

First and Last: Dating People and Extinct Animals in Australia


Text size Smaller Larger
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

While we understand printed pages are helpful to our users, this limitation is necessary to help protect our publishers' copyrighted material and prevent its unlawful distribution. We are sorry for any inconvenience.
Full screen

matching results for page

Cited passage

Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.

Are you sure you want to delete this highlight?