Homework 3: Dating the Distant Past

Homework 3:
Dating the Distant Past INSTRUCTIONS
Background

Just about everyone has heard of radiocarbon dating. It’s frequently mentioned in documentaries, news stories, and media articles about the past. As a result, most folks think that radiocarbon dating is the primary (if not the only) method scientists use to determine how old something is. This is because few people understand how it actually works. Did you know it can only be used to date organic (meaning formerly alive) materials like bones, seeds, wood, leaves, seashells, teeth, and such? You can’t use it to date rocks (never alive!) or even fossils (which used to be alive but have been chemically changed to rock or minerals over many, many years). And did you know that that you can’t use it to date anything that’s more than about 50,000 years old? That rules out most of human history since our species and our earlier human ancestors have been around for millions of years.

This isn’t to say that radiocarbon dating isn’t a useful tool—it most certainly is! In fact, it’s the primary dating method I use in my work in the Caribbean. It works great for me because all of my sites are less than 1200 years old and are full of organic materials like bones and wood charcoal. But if I studied early Neanderthals who lived in Europe 125,000 years ago, or Australopithecus who lived in Ethiopia 3,000,000 years ago, well, it wouldn’t work at all! In that case I’d need to use a different dating method—a different tool.

Like all tools, dating methods are designed to do a certain thing in a certain way in a certain context. You already understand this concept. When you do laundry you put your clothes in the washing machine, not the microwave. If you play basketball you shoot at a hoop, not a soccer goal. And you wouldn’t pound a nail into the wall with a pair of tweezers any more than you’d try to remove a splinter from your finger with a claw hammer. Every day of your life you use tools, and you select them based on the task at hand because each tool has a specific purpose for which it was designed! Methods of dating the past are the same way. There are literally DOZENS of chronometric dating methods (tools) at science’s disposal, and we can almost always find at least one in our “tool box” that works. It all depends on the circumstances and what we’re trying to accomplish.
Learning Outcomes
The following course Learning Outcomes are assessed by Homework 3:
Learning Outcome KA1: Characterize a scientific theory as a product of objective evidence and scientific methods.

Learning Outcome KA4: Employ scientific principles, techniques, or concepts to identify, explain, or address challenges facing society.

Learning Outcome IE3: Understand how to collect, evaluate, or interpret data to draw conclusions.

STEP 1: Go back to Module 6 and re-read the “Dating Methods” section of Chapter 7, on pages 248-256 (you can stop at “Environmental Reconstruction”). This section will give you the background you need to answer the homework questions.

STEP 2: Answer the five questions below. Each question requires enough detail to fill a short paragraph (80-100 words) to answer completely. Cut and paste the questions from here and into Word, and then work on your answers there.

YOUR ANSWERS MUST BE TYPED AND SUBMITTED IN A WORD FILE! Turnitin.com must run on your file, so PDFs, Apple pages, and/or a picture of the answers you scrawled on a bar napkin at 3 am WILL NOT BE ACCEPTED and there will be no “re-dos” if you didn’t read and follow these simple directions the first time.

1. (KA4) How does knowledge from the scientific disciplines of chemistry and physics help anthropologists determine the age of the things they study? Make sure to give two specific and distinct examples. (5 points)

2. (KA1) Say you discover a nice ceramic cooking pot in an archaeological site you are excavating. Your previous research has shown that pots like this were used to boil wild grains into a kind of porridge, and the outside of the pot has so much soot and scorching on it that you know it must have been placed over a hot fire. If you wanted to know how long ago the pot was last used by the people who made it, which chronometric dating method would be appropriate, and why? (5 points)

3. (KA1) Say the chronometric dating method you used to date the cooking pot in Question 2 above revealed that it was last used about 1,400 years ago. With that in mind, how might you use stratigraphy and the Law of Superposition to obtain a relative date for the animal bones you found in the layer of dirt above the pot, and the arrowhead you found in the layer of dirt beneath it? (5 points)

4. (IE3) Why would it be useful to use Potassium-argon (K-Ar) dating to determine the age of a human skeleton that is millions of years old and was recovered from a site in a volcanic region of Africa? Why would it NOT be useful to use Potassium-argon (K-Ar) dating to determine the age of a human skeleton that is hundreds of years old and was recovered from a site near Orlando? Which chronometric dating method(s) might be better for determining the age of the Orlando material, and why? (5 points)

5. (KA4) In your own words, explain why it is important that people today know WHEN important human events happened in the past. (5 points)

Last Completed Projects