SAEDNEWS: This article provides a brief introduction to how archaeologists determine the age of ancient artifacts and objects, explaining common dating methods in archaeology in simple, accessible terms.
You have probably seen in newspapers, documentaries, or museum visits that the age of various ancient artifacts is often provided. Naturally, many people wonder how archaeologists can determine the age of objects that are sometimes thousands of years old. In general, the role of archaeologists is to identify and study past cultures through the material remains they left behind, using careful study and interpretation of these artifacts.
Relative Dating
Relative dating is a method of estimating the age of artifacts based on archaeological knowledge and findings. Unlike absolute dating, which relies on precise laboratory testing, archaeologists interpret the age of objects by comparing them to previously collected data and known examples.
Absolute Dating
Absolute dating is another key method in archaeology for determining the age of artifacts and remains. Using scientific and precise tests, archaeologists can estimate the exact age of objects. Perhaps the most well-known method in this category is carbon-14 dating.
Absolute dating methods are essential for understanding the history and origin of artifacts. Broadly, archaeology relies on two main dating approaches: relative dating and absolute dating. Here is a brief explanation of each.
Absolute Dating Methods
Absolute dating uses scientific techniques to determine the precise age of discovered objects. Carbon-14 dating, the most famous method, applies only to organic materials—those that were once part of living organisms—and cannot be used for inorganic objects.
Carbon exists in different isotopes, one of which is carbon-14. At altitudes of 6 to 15 kilometers in the Earth’s atmosphere, cosmic rays collide with atmospheric particles, producing high-energy neutrons. When these neutrons have energies between 0.4 and 1.6 million electron volts, they can interact with nitrogen atoms to create carbon-14.
All living organisms—including plants, animals, and humans—contain carbon. While alive, the proportion of carbon-14 remains relatively constant. After death, carbon-14 begins to decay into nitrogen-14 through beta decay, releasing energy. This decay follows a known half-life of 5,730 years, with a margin of error of 40 years. By measuring the initial and current amount of carbon-14 in an artifact, scientists can accurately calculate its age.
Other absolute dating methods include:
Archaeomagnetic dating: Used on fired clay or ceramics, this method measures the orientation of magnetic particles that align with the Earth’s magnetic field during firing.
Dendrochronology: Studying tree ring patterns to determine age.
Amino acid racemization: Determining age based on changes in amino acid structures over time.
Potassium-argon and argon-argon dating: Radiometric methods used mainly for fossils and human remains, based on the decay of potassium-40 to argon-40.
Lead analysis: Dating based on lead oxidation.
Thermoluminescence: Dating objects based on electrons trapped in materials heated over time; when heated, these electrons are released as light, revealing the object’s age.
Relative Dating Methods
Relative dating estimates the age of artifacts by examining their style, construction techniques, decorations, and even colors, in comparison with known artifacts from previous studies.
For example, archaeologists encountering a ceramic vessel can often estimate its age by comparing it with hundreds of known pottery examples from various historical periods. This method also applies to stone and metal tools. In prehistoric archaeology, the use of stone tools varies by period: the Paleolithic (Old, Middle, New), Mesolithic, and Neolithic periods each exhibit distinct tools, from hand-held stone axes to microliths and eventually composite tools mounted on wooden or bone handles. Finding a microlith in a site, for example, indicates a Mesolithic context.
Written evidence and inscriptions are also critical for relative dating. Coins, texts, or inscriptions provide clues about the historical period of a layer. The style of writing, script type, content, or symbols on a coin can all indicate the approximate age of the artifact.
Stratigraphy
Another effective method is stratigraphy—the study of soil layers (strata) at archaeological sites. Excavations are often divided into squares, with careful mapping of each trench. Archaeologists dig from the uppermost layer down to undisturbed soil. Distinct layers reveal a chronological sequence of cultural deposits, allowing researchers to estimate the relative age of artifacts. Knowledge from other sciences, such as geology, can also support relative dating techniques.
This combination of absolute and relative dating methods enables archaeologists to reconstruct past civilizations with remarkable accuracy, providing insights into human history and cultural development over millennia.
