Reviewing the principles of dating
Let’s take a few moments to remind ourselves of some of the important principles of dating that you investigated last week.
There were quite a few principles to consider. We’ve summarised them here so that you don’t need to go back over the material. We’ve also added a few challenges to start you thinking about their application this week.
Stratigraphy: The layers of geological materials that are deposited over time, with the lower layers containing the older material, and the upper layers containing the younger materials. But what happens when the layer in which the fossil is discovered has been eroded or washed away?
Context: The location and conditions in which the fossil was discovered. This includes the stratigraphy and associated artifacts and sediments. But what happens when a fossil was discovered decades ago and its context has not been preserved for us to study?
Taphonomy: The study of how human remains turn into fossils, how the fossil has been modified by subsequent effects or processes, and how the sites in which they were discovered were formed. But what happens if we don’t know the history of the fossil, or the site has been disturbed by subsequent human activity, such as construction or mining?
Morphology: The study of the physical attributes of a skull to arrive at a ‘biological chronology’. We try to identify older from younger species from attributes such as the size, shape and thickness of the skull, the brow ridge, the teeth and so on. But what happens if the skull is of a shape or size that doesn’t seem to fit our chronology?
Direct dating and indirect dating: Direct dating is the dating of the fossil itself. Indirect dating is the dating of the artifacts or materials associated with the fossils and is an important method of confirming (or challenging) direct dating methods. But what happens if we can no longer access these artifacts or materials?
Relative dating and numerical dating: Relative dating is the dating of a fossil in relationship to another fossil or artifact. For example, “Fossil A is older than Artifact B”. Numerical dating is a method of arriving at a chronological estimate. For example, “Fossil A is 170,000 to 192,000 years old.” But what happens when the dating or sequence does not fit our understanding of human evolution?
We also looked at the challenges of the dating methods and why we always report errors with our dates. Here’s Mathieu on why we report errors:
This is an additional video, hosted on YouTube.
What do think of Mathieu’s comments on reporting errors?
Please select the comments link and post your thoughts.
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