Radioactive dating

Amid sediment in an oxbow of the ever-changing curves of the Red River, a well-preserved collection of items has been found. Among the items is a leather belt and buckle, reminiscent of the ones worn by those who traversed the Northwest transporting furs during the great North American fur trade of the 1700s. Could this belt have belonged to those fur traders, whose travels helped explore and settle Western Canada?

In the late 1940s, Willard Libby, using his knowledge of radioactive decay, labored to develop a method to calculate the age of once-living organisms—creatures that contained carbon, or what is called organic ma­terial. This method, known as radiocarbon dating or carbon-14 (14C) dating, uses the rate at which 14C radioactively decays to determine the age of artifacts.

Understanding how radioactive dating works is im­portant to Christians. One reason to learn about radio­active dating is to see what it teaches us about God and His work in the creation. When learning about such a topic, we again are impressed with the wisdom of God displayed in His marvelous creation, which is so intri­cately woven together. In addition, we see God’s orderly and sovereign governance of the creation.

But in the age in which we live, it is also important for us to understand radioactive dating as this technique is used to estimate the age of the earth. Modern scien­tists, using radioactive-dating techniques, estimate the earth to be approximately 4.5 billion years old. But by faith we believe the teaching of the Bible, that the earth is young—some 6,000 years old. Using such a tech­nique, modern scientists assume an age of the earth that is in contradiction with the testimony of Holy Scripture. We repudiate such a position. But what do we make of radioactive dating? Is the technique itself flawed? What do we make of using the technique to estimate the age of “artifacts”?

Radioactive carbon

Carbon exists in the creation in various forms. The most abundant form of carbon (98.9%) is comprised of 6 protons, 6 neutrons, and 6 electrons, known as 12C. This form has a stable combination of protons and neutrons. Another form of carbon is comprised of 6 protons, 8 neutrons, and 6 electrons, known as 14C.

Because the ratio of 6 protons and 8 neutrons is an unstable ratio, 14C is radioactive. The unstable (radioactive) 14C nucleus becomes stable by undergoing a spontaneous transformation in which a neutron is converted to a proton, releasing a form of radiation called a beta particle. The final result is that 14C, in the process of becoming stable, loses a neutron and gains a proton, transforming into a nitrogen atom (14N, 7 neutrons and 7 protons). Without the generation of any new 14C, the supply of 14C in the creation would slowly diminish over time.

But in God’s sovereign government of the creation new 14C supplies are generated. In our upper atmo­sphere, nitrogen atoms (14N), are being converted into new supplies of 14C atoms. By this mechanism, which we call deposition, God provides a new supply of 14C to be regularly generated in our atmosphere. The balance between deposition and radioactive decay is such that a relatively constant amount of 14C is present in our atmo­sphere at all times.

Constant 14C levels in living organisms

Most of the 14C found in our atmosphere is found in combination with oxygen atoms to form carbon dioxide (CO2), which in this case contains a radioactive carbon atom (note that because only a small fraction—about one in a trillion, or 1 ppt—of all carbon is of the 14C form, there is only a small amount of radioactive carbon dioxide in the atmosphere). Plants take in carbon dioxide (including radioactive versions of it) during the process of photosynthesis. Because the relative amount of 14C in our atmosphere remains constant, the amount of radioactive CO2 similarly remains constant. In the process of photosynthesis, the plant constructs different forms of sugar, which is, in turn, used by the plant itself to make its own leaves and stalk, as well as its fruit. While the 14C incorporated into the plant by photosynthesis undergoes radioactive decay, thus decreasing the amount of 14C in the plant, fresh supplies of 14C are daily taken in by the plant during the photosynthesis process. Therefore, living plants, like grass for example, will maintain a level of 14C that reflects the constant amount of this form of carbon in the atmosphere.

But that is not where this cycle of 14C incorpora­tion ends. A cow eats the grass that contains a constant level of 14C. The forms of sugar in the grass fibers are decom­posed by the cow during its digestive processes. The 14C that was part of the sugar molecules in the grass is freed to be used in the cow to make other carbon-based molecules (important ones such as DNA molecules, protein molecules, and fat molecules), which eventually become parts of the cow’s muscles, bone, and other bodily tissues and organs. Thus, the cow itself, by virtue of eating the grass that contained some radioactive carbon particles, now has radioactive carbon within it. The 14C in the cow’s body parts will, of course, radioactively decay over time; but because the cow will eat more grass that contains 14C particles, the cow will, during its life, maintain a constant level of 14C that matches that of the grass and atmospheric CO2—as will all other living organisms, since all are connected to the process of photosynthesis in some way and, there­fore, receive fresh supplies of 14C on a regular basis.

One might wonder if the rate of intake of 14C in par­ticular organisms might differ, so that the abundance of 14C might differ from organism to organism. As far as we can measure, living organisms contain a constant level of 14C—a level that corresponds with the gener­al percent abundancies found throughout creation (1 ppt—part per trillion). While a tree has much more mass than a human, both organisms contain the same relative amount of 14C; that is, 1 part 14C per trillion atoms of 12C. And since all living organisms contain that same relative amount of 14C (1 ppt), they also emit a specific level of beta radiation, relative to their size.

Radioactive dating

It should be apparent that dead organisms cannot absorb new sources of 14C because dead organisms do not take in any new 14C-based compounds. It should also, then, be apparent that dead organisms will over time have an increasingly lower amount of 14C present in them due to the ongoing radioactive decay of this form of carbon. And therefore, dead organisms will, over time, emit less and less radiation.

And with that knowledge we can begin to under­stand how one might try to estimate the age of a dead (once-living) organism. Assuming that the rate of 14C decay remains constant over time, one could, on the ba­sis of the percentage of 14C atoms yet remaining in the specimen, back-calculate to determine when the specimen was yet alive.

Let us consider the hypothetical historical example with which we began the article.

With modern instruments and techniques (mass spectrometry), the composition of the leather belt found along the Red River can be determined. By comparing the ratio of 14C to 12C of the dead organism (from which the leather belt was made) to the ratio of 14C to 12C in liv­ing organisms, the scientists can calculate how long ago it was that the dead organism had been alive. In living organisms this ratio is constant. In dead organisms the ratio decreases slowly at a constant rate. On the basis of this process, the scientist can determine how long ago the animal from which the leather belt was made lived. Perhaps the results of that study would indicate that the leather belt would have been made approximately 250 years ago—dating the belt to the late 1700s—providing support to the hypothesis that the belt perhaps belonged to some fur trader who had passed through the area.

Praise to the Creator!

By faith we believe that God created all things out of nothing and with a purpose—“giving unto every creature its being, shape, form, and several offices to serve its Creator” (Belgic Confession, Art. 12). All things have not only been created, but also are wisely and sovereignly upheld by our almighty God—for the purpose that they bring glory and honor to the One who created and upholds them. “Praise the Lord from the earth, ye dragons, and all deeps: fire, and hail; snow, and vapor; stormy wind fulfilling his word: mountains, and all hills; fruitful trees, and all cedars: beasts, and all cattle; creeping things, and flying fowl…” (Ps. 148:7-10). All creatures shout the praises of God as they reveal the great wisdom and power of our God.

As God’s covenant children, we ought to praise God for the beauty, order, and intricacy found in all of the creation—including radioactive elements. Radioactive decay truly is an amazing process. As we have seen, unstable 14C atoms slowly transform into more sta­ble atoms over time, while, at the same time, in God’s amazing government of the creation, new 14C is formed at such a rate to replace the radioactively decaying 14C—thus maintaining a remarkably constant level of 14C in living organisms. May these unique details fill us with awe of our Creator and serve as a reminder to us to walk daily throughout the creation meditating on the mighty works of God that surround us—the Queen Anne’s Lace along the road; the brilliant planet (Venus) in the western sky; the peach trees in the local orchard; the frost-crystal designs on the window; the spider web in the corner of the barn; the nectar-sucking bumble­bee; or the many wonders of our own human body.

When, by the gracious work of the Spirit, we live and walk out of faith, we render praise to God for such won­drous works! Pausing from all our busyness and consid­ering God’s handiwork, we are humbled at our creaturely finiteness and awed by God’s infinite greatness. So finite are we that we find it difficult to comprehend even one simple process in a creation filled with seemingly in­finite, interrelated processes. We hear the words of God: “Hearken unto this, O Job: stand still, and consider the wondrous works of God” (Job 37:14). Stand still and consider, for example, the amazing way in which unsta­ble 14C atoms become stable. Stand still and consider the marvelous details of how 14C decays and is also generated to maintain a constant balance! What a marvelous, al­mighty, all-wise, and sovereign God we serve! And this God is our God! He who so marvelously directs even the tiny particles of the creation is directing every aspect of our lives, preparing us for our home in heaven. All glory and praise be to Him! “And blessed be his glorious name for ever: and let the whole earth be filled with his glory; Amen, and Amen” (Ps 72:19).

And thus, with a view to honoring the almighty Cre­ator God, we will return, in a future article, the Lord willing, to the value and appropriateness of radioactive decay as a tool to date artifacts and to determine the age of the earth.