Dating Fossil Age

AtomsDating fossils using radioisotopes is a modern method for estimating a fossil’s age. However, a recent Public Broadcasting Service (PBS) program illustrates why questioning any age-dating theory based solely on radioisotopes is warranted.

The case in point, a “1.8 million-year-old skull,” the PBS reported, “may revise [our] understanding of human evolution.” While the fossilized skull was dated to 1.8 million years old using radiocarbon dating, it was discovered in a medieval village in the former Soviet Republic of Georgia.

Understanding Earth’s history is important for understanding life’s foundations. However, the methods used and the conclusions drawn over the centuries have generated mixed results and reactions. The age difference between the 1.8-million-year-old skull and the ninth-century village is a classic example of this tension.

From philosophers to nuclear physicists, the history of methods for dating the Earth spans a range of speculation and science. Importantly, life is contingent on its environment.

Records of our interest in a natural history of Earth’s biosphere date back to the fourth century B.C. Since then, radically different methods and views have emerged and then disappeared.

B.C. Dating

The Greek philosopher Aristotle, in the fourth century B.C., reasoned that Earth’s existence extends from eternity past and continues into an infinite future. He also regarded motion and matter as metaphysically eternal, holding that a beginning arising from nothing was impossible.

Aristotle’s assumptions effectively removed all time limits, making the concept of a beginning impossible. However, modern science accepts the concept of the beginning of time as one of its most secure foundations. Aristotle’s concept of life emerging before Earth’s timeframe, now defies modern empirical logic.

Moses’ Genesis, a thirteenth-century B.C. account, is recognized as the most enduring source of time, asserting a finite beginning of time. However, this narrative was not available in Greek during Aristotle’s lifetime, and it was not translated into Greek until the third century B.C.

In the first century, the Roman philosopher Titus Lucretius Carus, intellectual heir to the Greek atomists, inverted Aristotle’s logic of eternity. Using empirical-historical reasoning, Lucretius argued that the Earth is relatively young, since there were no records before the Trojan War. Since then, empirical evidence has upended Lucretius’ argument.

Since radiometric dating did not emerge until late in the nineteenth century, understandings of Earth’s biospheric history were based on historical records and inference.

Early A.D. Dating

Pre-Darwin Era

In 1654 Archbishop James Ussher estimated the origin of the Earth at 4004 B.C. primarily framed by genealogies in Genesis. Usher also synchronized genealogies with the reign of Near East Kings, classical historical sources, and astronomical markers, specifically Johannes Kepler’s Tabulae Rudolphinae (1627). 

Select editions the King James Bible often included Usher’s dating synthesis inserted in the margins. Usher emerged as a pivotal pre‑scientific Earth age figure by pioneering the synchronization of textual and historical reasoning. However, Ussher’s dates remain controversial since genealogies throughout the Bible are not routinely comprehensive.

John Herschel (1792–1871), an English mathematician, astronomer, and chemist, found reasons for “many thousand millions of years.” Since Darwin was intent on understanding Earth’s history, he arranged to meet with Herschel when the HMS Beagle ported in Cape Town, South Africa, in 1836.

Herschel is credited with introducing the Julian day system in astronomy. Geologically, Herschel aligned with Charles Lyle’s timeframes of Earth’s history.

English geologist Charles Lyle (1797–1875) in the Principles of Geology (1830–33) advanced, that to understand Earth’s history, “the present is the key to the past.” A theory known as the uniformitarianism. Therefore, no sudden climatic changes have ever occurred, including the global flooding event mentioned throughout the biblical texts.

While on the 5-year voyage on the HMS Beagle, Darwin read Lyle’s three volumes of the Principles of Geology. Eventually, as he looked “through Lyell’s eyes,” Darwin synthesized the geological spheres of Lyell’s influence with his theory of natural selection.

Despite friendship collegiality, Lyell eventually, and only reluctantly, gave small credence to Darwin’s theory of natural selection.

Darwin Era

However, Lyell’s reluctance was overshadowed by Irish physicist William Thomson Kelvin‘s (1824–1907) critique. Based on thermodynamic principles and calculations of Earth’s cooling, Kelvin publically challenged the concepts of time in uniformitarianism and natural selection. Darwin had explained in The Origin of Species –

“We may continue the process [natural selection] by similar steps for any length of time.”

While viewing the Earth’s age as longer than Ussher’s estimate, Darwin’s “any length of time” concept drew increasing criticism. The late nineteenth-century discovery of radioactivity, however, was soon to disintegrate the time assumptions drawn by Lyell, Darwin, and Kelvin.

Origins of Radiometric Dating

Henri Becuerel The discovery of radioactivity in 1896 by Henri Becquerel (pictured left), a French physicist and chemist, revolutionized the dating of fossils, rocks, and minerals. Atoms in fossils, rocks, and minerals throughout the universe were found to contain radioactivity, which is slowly emitted over time. This process is known as radioactive decay.

In just the following decade, in 1907, Yale University professor Bertram Boltwood (pictured right) was the first to show that the rate of radioactive decay can be used to estimate the time span.Bertram Boltwood Since its formation, the Boltwood method has been credited with introducing the first uranium-lead dating technique to determine the age of geological samples.

Radioactive “parent atoms” decay into stable “daughter atoms” over time. Parent and daughter atoms are also known as parent and daughter isotopes. By measuring the number of remaining unstable radioactive atoms and comparing it to the number of stable daughter atoms, the estimated age of the material can be calculated.

Decay Chain

This decay process from a parent to a daughter isotope is known as the decay chain or the radioactive cascade. For example,  Uranium (atomic number 92) decays into thorium (atomic number 90). This decay chain process releases energy.

Isotopes decay spontaneously. The time it takes for a single parent atom to decay to an atom of its daughter isotope, however, varies widely. According to WIKIPEDIA – 

“One of the properties of an isotope is its half-life, the time by which half of an initial number of identical parent radioisotopes have decayed to their daughters… Half-lives have been determined in laboratories for many radioisotopes (or radionuclides). These can range from nearly instantaneous (less than 10−21 seconds) to more than 1019 years.”

Carbon Dating Facts

    • Carbon dating is a widely used method applied to establish the age of organic material, such as things that were once living.
    • Dating methods measure elements that decay over time, not time itself.
    • Live organisms absorb C-14, but once an organism dies, absorption stops.
    • Living things have carbon in them in various forms. The dating method uses the fact that a particular isotope of carbon, C-14, with an atomic mass of 14, is radioactive and decays at a well-known rate.
    • The most abundant isotope of carbon in the atmosphere is carbon-12, or a carbon atom whose atomic mass is 12.
    • A very small amount of carbon-14 is also present. The ratio of carbon-12 to carbon-14 in the atmosphere is almost static and is known.
    • Plants get their carbon through the process of photosynthesis, while animals get it mainly through food.
    • Because plants and animals get their carbon from the atmosphere, they, too, acquire carbon-12 and carbon-14 isotopes in roughly the same proportion as is available in the atmosphere.
    • But when they die, the interactions with the atmosphere stop. There is no further intake of carbon (and no outgo either, because metabolism stops).
    • Now, carbon-12 is stable and does not decay, while carbon-14 is radioactive. Carbon-14 reduces to one-half of itself in about 5,730 years. This is what is known as its ‘half-life’.
    • Radiocarbon dating is only effective on fossils younger than 50,000 years.
    • So, after a plant or animal dies, the ratio of carbon-12 to carbon-14 in the body, or its remains, begins to change.
    • This change can be measured and can be used to deduce the approximate time when the organism died.
    • Carbon dating cannot be applied to determine the age of non-living materials, like rocks.

Calculation Assumptions

EugeneDetermining a radiometric age requires applying a range of assumptions. Radiometric dating is not absolute; it is a calculated age estimate. To calculate the date, the investigator selects from a range of assumptions, including the isotope’s extremely variable half-life. As the executive director of the National Center for Science Education (NCSE), Eugenie Scott explains in her book entitled Evolution vs. Creationism, from a professor of physics at the Massachusetts Institute of Technology (MIT), Philip Morrison –

“If certain assumptions are made about it [radiometric dating], then it can yield a date which could be called the apparent age. Whether or not the apparent age is the true age depends completely on the validity of the assumptions.”

Measuring element concentration is empirical; however, scientists can only make assumptions about element stability, half-life, and the original concentration at the start. Scott continues quoting Morrison –

“Since there is no way in which these assumptions can be tested, there is no sure way (except by divine revelation) of knowing the true age of any geological formation.”

In recognizing these limitations, “the highly speculative nature of all methods of geochronometry [radiometric dating] becomes apparent,” Scott continues, “one realizes that not one of the above assumptions is valid! None are provable, or testable, or even reasonable.”

These assumptions include –

    • Atmospheric radiation concentrations have been constant, despite known bursts of cosmic radiation and Earth’s core. “If the level of atmospheric 14C were constant, this would be easy. However, it has fluctuated significantly throughout history.” (PhysOrg, Proceedings on the Royal Society)
    • Production of parent isotopes has been constant since the origin of the specimen.
    • The ratio and concentrations of the isotope in the sample since the origin of the specimen are known.
    • Decay rates are constant since the origin of the specimen
    • Radiation exposure has not occurred since the origin of the specimen
    • No daughter (stable) elements existed in the specimen before the origin of the specimen
    • Use of scientifically validated radioisotope decay rates
    • Isotope concentration changes only stem from the decay process

The first assumption, “atmospheric radiation concentrations have been constant,” is now known not to be true. “The amount of carbon-14 in the atmosphere fluctuates through time; it’s not a constant baseline,” Julie Hoggarth of Baylor University explains for PHYS.ORG in the paper “Scientists develop a statistical fix for archaeology’s dating problem.”

Solar flares, also known as solar storms, produce radiation across the electromagnetic spectrum, though at varying intensities. While not as intense as visible light on Earth, they can be very bright at particular spectral lines, producing bremsstrahlung in X-rays and synchrotron radiation. The first solar flares were observed by Richard Carrington and Richard Hodgson independently on 1 September 1859.

Experimental Science

Different radiometric dating methods vary in the timescale over which they are accurate. “We must remember that the past is not open to the normal processes of experimental science,” Scott continues –

“A scientist cannot do experiments on events that happened in the past… Scientists do not measure the age of rocks; they measure isotope concentrations… [and] the age is calculated using assumptions about the past that cannot be proven.”

Calculations require that neither the parent nuclide nor the daughter product can enter or leave the material after its formation.

Correlation Testing

To test for alteration or contamination, different methods and minerals from different locations should be used. Strong correlations indicate a more reliable dating estimate; weak correlations cast doubt on it. As Scott points out –

“If the dating methods are an objective and reliable means of determining ages, they should agree [correlate].

Using different methods and minerals, more often than not, do not correlate. According to Scott –

“With radiometric dating, the different techniques often give different results.”

Scott lists the following factors why radiometric dating, even using the best methods and technology, may never be scientifically valid –

    • No one has ever measured decay rates directly
    • If assumed decay rates are in the range of billions of years, it is impossible to determine the actual decay rate from measurements over only a few decades
    • Decay rates are poorly known
    • Decay rates are affected by the physical environment – including the effects of Earth’s mantle.
    • Original parent element concentration is not known, and no method exists to measure the original concentration
    • The original daughter decay product concentration is not known, and no method exists to measure the original concentration

More recently, a “blip” of the radioactive isotope Beryllium-10, found deep beneath the Pacific Ocean in 2025, is evidence of previously unknown recent radioactive exposure. The global effect on other radioactive isotopes is unknown.

Therefore, the untestable assumptions required to calculate a radiometric date render the date a speculation, yet to be validated through falsification testing.

Global Flood and Plate Tectonic Events

The fossils found today result globally from the massive global flooding and plate tectonic events documented by Moses in Genesis chapters 7 and 8.

“In the six hundredth year of Noah’s life, on the seventeenth day of the second month—on that day all the springs of the great deep burst forth, and the floodgates of the heavens were opened. 12 And rain fell on the earth forty days and forty nights.” Genesis 7:11.

“Now the springs of the deep and the floodgates of the heavens had been closed, and the rain had stopped falling from the sky. Genesis 8:2.

Evidence indicates that plants and animals were alive when they were buried nearly instantly.

Dating Fossil Tips

While the estimated age of a fossil can be obtained through radiometric dating, the accuracy depends heavily on assumptions and testing methods.

Without knowing the assumptions, testing method, and correlation assessment, any estimated date, published or otherwise, should not be considered a scientifically valid age.

DNA Stability Over Millions of Years?

Recent reports speculate that fossilized DNA is millions of years old. Science writer Ewen Callaway for the journal Nature in 2021 wrote the article “Million-year-old mammoth genomes shatter the record for oldest ancient DNA. Permafrost-preserved teeth, up to 1.6 million years old, identify a new kind of mammoth in Siberia.”

However, how the dating is incongruent with findings by others, Karishma Matange, James M. Tuck & Albert J. Keung published “DNA stability: a central design consideration for DNA data storage systems” in Nature Communications (2021). In laboratory testing, the paper reported –

“Eighty percent of the encapsulated DNA was recovered while only 0.05% of the unprotected dried DNA survived. Grass and colleagues estimated that encapsulation in silica particles could maintain DNA for 20–90 years at room temperature.”

Given the limited physical stability properties of DNA, dating methods using DNA in preserved specimens that yield dates thousands of years or more require further scientific validation.

 

Dating Fossils is a subcategory of the Fossil Record.

 

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Subcategories of the Fossil Record include –

 

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Darwin Then and Now is an educational resource on the intersection of evolution and science, highlighting the ongoing challenges to the theory of evolution.

 

 

Move On

Explore how to understand twenty-first-century concepts of evolution further using the following links –

    • The Understanding Evolution category showcases how varying historical study approaches to evolution have led to varying conclusions. Subcategories include –
      • Studying Evolution explains how key evolution terms and concepts have changed since the 1958 publication of The Origin of Species.
      • What is Science explains Charles Darwin’s approach to science and how modern science approaches can be applied for different investigative purposes.
      • Evolution and Science (current page) features study articles on how scientific evidence influences the current understanding of evolution.
      • Theory and Consensus feature articles on the historical timelines of the theory and Natural Selection.
    • The Biography of Charles Darwin category showcases relevant aspects of his life.
    • The Glossary defines terms used in studying the theory of biological evolution.

 

 

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