The Age of the Earth, Humans, and Dating Methods - What is a Day?
Central to the theory of evolution and creationism is the age of things. The age of rocks. The age of fossilized living things. The age of humans. If there was a Noah flood, when did it occur? How old things are helps formulate the idea of how things came about and are related. This article will discuss chronography, the science of dating things, and will attempt to harmonize religious revelations and scientific data on the age of the earth, life, and human kind.
This is a long article. If you don’t have the time and patience to read through it all, skip to the summary and take your “Credo Score”.
The Science
Chronography - Science employs many techniques to tell how old something is. There are two main types of dating: Relative and Absolute. Relative dating uses successive layers of rock, or stria, to understand how artifacts have changed over time (based on detailed sequencing items such as a pottery or axes). Absolute dating attempts to use various methods to date something directly, for instance radioactive, magnetic, reflectance, or tree ring dating.
Everyone has heard of radioactive carbon dating. However, C-14 dating is limited to only young (typically <20-50 thousand years) living things. It relies on the principle that all living organisms contain traces of radioactive carbon from the atmosphere. When cosmic rays reach earth's upper atmosphere, they react with nitrogen (N-14) to form the radioactive isotope carbon-14, which is present everywhere in the environment. Living organisms absorb this C-14 into their tissue. Once they die, the absorption stops, and the carbon-14 begins very slowly to change into other atoms at a predictable rate.
Carbon 14 Generation and Decay Cycle 1
M(t)=M0e-kt
where M(t) = mass at t,
M0 = initial mass (t=0),
k = decay constant (half life, 5,700 yrs. for C-14).
Carbon dating does have some reasonable problems. One of these involves the complications of measuring only trace amounts of C-14. For each half-life that passes, half of the most recent quantity of the element remains. For instance, after 10 half-lives have elapsed (57,000 years), there is less than 0.001 M0 left. Because each living organism only contains trace amounts of C-14 to begin with (of all carbon atoms, only about one-trillionth are C-14), after 10 half-lives elapse, the remaining amount of C-14 is so small that it is not only difficult to measure accurately, but it is difficult to ensure that the C-14 measured actually remains from the organism of interest, and was not somehow contributed from another source. So any organism deemed older than that needs to be dated in another manner, typically using other radioactive isotopes that have considerably longer half-lives. In fact, most scientists consider anything over 20,000 years, or so, for C-14 dating to be unreliable for most situations.
Because radiocarbon dating depends on naturally occurring radioactive decay, its accuracy depends on the decay not being altered by natural or unnatural causes. If the historical cosmic ray reaction varies it could greatly affect the results. For instance in the 1940s, the Manhattan Project resulted in humankind’s development of synthetic nuclear energy and weapons; subsequent nuclear testing and accidents have released radiation into the atmosphere that makes the accuracy of C-14 dating more suspect for organisms that die after 1940. Other environments can affect the trace C-14 in a decaying organism. For example water can dilute the trace amount of C-14. The level of effect of water on a particular sample varies significantly, depending on the body of water, and more locally on depths, upwelling currents, and freshwater discharges. Also, fluctuations in the earth’s magnetic field can affect the cosmic ray interaction with the atmosphere, thus changing the amount of C-14 in the ambient environment.
A rearrangement of the decay equation gives:
t = [Ln (Mt/M0) / -0.693] x h
where t = the age of the sample,
Ln = the natural logarithm
Mt/M0 = the ratio of remaining C-14,
h = the half life (5,700 years for C-14).
So if a sample has 25% remaining C-14, the sample would be:
t = [Ln (0.25) / -0.693] x 5,700 = 11,402 years old
To show how sensitive the measurement of C-14 can be, suppose that the ratio Mt/M0 varied by +/-10%. This would give an error of about +/-7% in age.
To help correct C-14 dating, it is correlated with dendrochronology, which simply counts and matches tree rings, resulting in a more accurate and precise absolute date.
Rocks - Rocks are dated similarly, by radioactive means. Igneous and Metamorphic rocks that contain zircon crystals usually use Uranium - Lead (U-Pb) radioactive dating. Uranium (either 238 or 235) that is incorporated into zircon decays to lead (206 or 207, respectively) at their own respective fixed rates. These rocks are formed by pressure and heat. Once zircon cools below a certain temperature, called the “closure temperature”, the decay rate is “locked in”. For U-Pb the closure temperature is about 900C. The uranium decay from 238U to 206Pb, has a half-life of 4.47 billion years and the actinium decay from 235U to 207Pb, has a half-life of 710 million years.
Zircon is very chemically inert and resistant to weathering. However, zircon crystals with prolonged and complicated histories can contain zones of dramatically different ages (usually with the oldest zone forming the core, and the youngest zone forming the rim of the crystal).
Fossils - Fossils pose a special problem for dating. They generally do not contain C-14, having been washed away long ago. Also, the sandstone in which they are usually embedded cannot be dated by radioactive means. Sandstone particles are composed of material from various sources and will yield nonsensical readings. Therefore, fossils are dated by relative means. Rock layers above, below, or even sometimes “like striae" on the other side of the earth are used.
Human bodies do not remain without special treatment much past a few hundred years, depending on the environmental conditions. Even the skeletal remains are gone by then. Human bodies rapidly decompose with moisture, bacteria, and even insects. Mummies are preserved through drying, chemically treatment, and then sealing the body. The oldest Egyptian mummies are around 3,000 BC. However, the oldest mummies are from the Chinchorro civilization in Chile and tip the chronograph to over 5,000-7,000 BC 2. Even Otzi, the “iceman”, the peat mummies in Europe 3, the Tarim mummies in China, and Lady Dai are all less than 10,000 years old.
Fossils are formed when the body is quickly encased in either sediment or volcanic ash and minerals replace the cells. Fossil encasement then needs to be subjected to pressure, heat, and minerals that seep into the remaining organic parts. Even then the soft tissue rapidly decays with bacterial action leaving slower decaying materials. Most fossils are made from bone or harder materials. All existing bodily remains over 10,000 years are preserved in fossils. If fossilized the remains can last indefinitely.
Age of the Earth - The age of the earth (through rocks) is measured by absolute dating techniques. It is fairly assured that the age of the earth (and solar system) is some 4.5 billion years old. Even moon rocks and meteorites have been dated using the same radiometric techniques and have been found to be the same age. Each of these rocks have all been subjected to different “rock cycles” and environments and still tell the same story. The evidence weighs heavily that we live on an old earth planet.
Left, A piece of the Henbury iron meteorite, which was found in Australia.
Right, A moon rock from the Apollo 14 mission.
Age of Plants and Animals - Here’s where things start to be more subjective. Plants and animals need to be dated using relative means, by studying their fossilized remains. Unfortunately fossils fall within a dating gap between C-14 and other dating methods (K-Ar, U-Pb, etc.) that render absolute dating methods as unreliable. Also, since they are usually found in sedimentary rock, direct radioactive dating methods of the “host” material are useless. Instead, paleontologists largely depend on the location of fossils in a stria to date them. This is called biostratigraphy, or the study of layers above and or below the fossil that can be dated using absolute means (usually U-Pb and K-Ar). Standard tables of layer dates are published and used in this process.
Determining age by biostratigraphy can be hard to determine and very debatable. Anything that disturbs stria can throw off fossil dating. Nature has been shaping the Earth for billions of years through both slow, steady processes and sudden, violent events like the following:
Tectonics (Orogeny): The movement of Earth's plates can tilt, fold, or completely flip rock layers upside down. This is why you can find sea shell fossils at the top of the Himalayan Mountains.
Erosion and Weathering: Wind, water, and ice wear away existing strata. This creates "unconformities"—gaps in the geological record where millions of years of history are simply missing.
Volcanism: Eruptions deposit new layers of ash (tephra) and lava instantly, creating distinct markers that cover vast distances.
Sea-Level Fluctuations (Eustasy): As glaciers melt or grow, oceans rise and fall. This shifts where sand (beach) and mud (deep ocean) are deposited, changing the "recipe" of the rock layers.
Asteroid Impacts: Rare but massive events that can vaporize rock and spread a thin layer of rare elements (like Iridium) globally in a single day.
These changes in nature cause certain Biostratigraphic errors in dating fossils. Other errors come from not knowing the migration and historical information of different species. Assumptions need to be made about the global changes to the earth and why certain fossils are found in different layers. Some of the major errors are listed in the table below.
In establishing the age of fossils, paleontologists try to look at the whole story to piece together when species occurred. In doing so they use many inputs from different disciplines, such as geology, chemistry, astronomy, botany, physics, etc. For much of 150 years, since Darwin published his “Origin of Species” theory, paleontologists used his story line to try to place fossils into a timeline. However, as new data comes forward the story line is being challenged and is changing. The table below shows sample fossils with the traditional paleontologists best guess ages. These extend from the oldest Precambrian (half a billion years ago) to the most recent Cenozoic / Pleistocene period (4,000 years ago).
Generally fossils are greater than 10,000 years old, but included in the table is a rare Mammoth “fossil” that was found in frozen soil. This is called cryofossilization. This is recent enough to be in the realm of possibility for DNA to be extracted from this specimen.
Note that all of the fossils were found in a medium that could not be dated directly. As you can imagine, there are big debates among scientists on the accuracy of these dates. A tug of war has ensued between evolution and creation scientists. Some claim that this has affected the dating decisions; evolutionists trying to show a slow evolutionary flow, while creationists hold to explosive species with large gaps and inconsistencies.
Age of Humans - So now we get to the important part, and, the most debatable. What do scientists say about the age of humans? Firstly, we need to define “human”. More and more scientists will point out a huge age gap exists between the Neanderthal, Denisovan, and Homo Sapiens from the rest of the fossils. They posit that the later groups belong to Hominids and all the rest are just old apes (see chart below).
Geologist, Dr. Casey Luskin, coauthor of science and human origins states, “Hominid fossils generally fall into one of two main categories, and that is human-like fossils and ape-like fossils and there is a large distinct gap between those two groups.” He goes on further to state that Lucy, Ardi, Australopithecus Sediba, Homo Naledi, and Ida were mis-typed as hominids instead of apes. In fact, because of the excitement to find missing links, some fudging has occurred to make fossils fit into the Human family. Lucy and Arti for instance had crushed pelvic bones. During the reconstruction the hips were shaped so that they could stand erect. 4
Consequently, many now believe that “humans” came onto the scene recently and are not at all linked to apes. There may be fossil evidence of old apes that are even a few million years old, but human fossils are more and more being considered distinct and less than 60,000 years old. The search still continues for missing links.
Dating hominid fossils is uniquely challenging compared to dating dinosaurs or ancient plants. Because humans and our ancestors appeared very recently in geological time, we fall into a "dating gap" where neither long-term radioactive clocks nor short-term ones work well. Here are the primary technical and geological hurdles scientists face:
The "Carbon-14" Limit - Radiocarbon dating is the most famous method, but it is useless for most hominids. Because of C-14 half-life, after 50,000 years, there isn't enough left to measure accurately. Since most significant hominid evolution (like Homo erectus or early Australopithecus) happened between 100,000 and 4 million years ago, they are "too old" for Carbon dating.
The Lack of Volcanic Ash (The "Tuff" Problem) - To get an exact age for a fossil older than 50,000 years, geologists usually use Potassium-Argon (K-Ar) or Argon-Argon (Ar-Ar) dating. However, these methods don't date the bone itself; they date volcanic ash layers (tuffs) above and below the fossil. If a hominid died in a region without active volcanoes (like many parts of South Africa), there are no ash layers to act as "time brackets." Consequently, scientists must rely on less precise methods, like the "relative dating" of animal teeth found nearby.
Cave Context (The "South African Puzzle") - Many famous hominid fossils (like Homo Naledi or "Little Foot") are found in deep cave systems. Caves are nightmares for geochronology for several reasons:
Stratigraphic Scrambling: In a cave, older layers can be washed away by internal floods, and younger fossils can fall into deep crevices, making them appear older than they are (stratigraphic leaking).
Reworking: Bones can be moved by scavengers or water multiple times before they finally mineralize, detaching them from their original time-marker layer.
The "Hominid Gap" (0.5 to 1.5 Million Years) - There is a specific window in time that is notoriously difficult to date:
Too Old for: Carbon-14 and Luminescence.
Too Young for: Standard Potassium-Argon (which is more accurate for things older than 2 million years).
Scientists often have to use Paleomagnetism—checking the magnetic orientation of the soil to see if it matches known "flips" in Earth's magnetic field—but this only gives a general range and is prone to error.
Contamination and Diagenesis - Because hominid bones are "young" (in geological terms), they are often not fully petrified. They are porous and can easily absorb minerals from groundwater.
Uranium-Series Dating: This method measures how uranium leaches into a tooth or bone. However, if groundwater moves in and out of the bone over thousands of years, the "clock" is reset or skewed, leading to wildly incorrect ages.
The Religion
What can we discover about the age of things from the scriptures or revealed prophets? It turns out depending on how you interpret things, not very much.
What’s a Day? - People referring to Genesis in the bible for the age of the earth and living things have little to go on. Young earth creationists (YEC) either believe that each day in Genesis 1 & 2 is a literal 24 hour period, or that each day is 1,000 years (combining Genesis with 2 Peter 3:8, “...that with the Lord one day is as a thousand years, and a thousand years as one day.”).
The Hebrew word for “day” is “yowm”, meaning to be hot, as in the warm hours of the day, sunrise to sunset. However, it can mean a 24 hour day, an age, or period of time. Those believing in the literal translation of a “day” being 24 hours must reconcile Genesis 1:5 where, “God called the light day, and darkness night”, a period of 12 hours; Genesis 8, “the evening and the morning were the second day”, typical 24 hours; and Genesis 2:4, “in the day that the Lord God made the earth and the heavens”, longer period of time incorporating several days.
Also, those believing that Genesis gives a literal account of the creation must give an explanation of Genesis 2:4-5, that says that God made the earth and heavens, and every plant of the field before it was in the earth. What does that mean? Harmonizing this with Abraham 5:3-5 seems to indicate that the Genesis 1 account is not the telestial physical creation, but rather planning, or some other pre-earthly creation going on. Maybe a spiritual creation? Maybe a terrestrial creation? (see article, “Moses Walked on Lava”)
If “day” in the scriptures means a “longer period of time”, then the account in Genesis could be consistent with both the beliefs of Old earth creationist (OEC) and evolution scientists. Indeed, the earth, plants, and animals were formed over the period of 4.5 billion years, either with or without divine intervention.
What a Fall - Genesis 2 seems to give a gap between the creation of the earth and heavens, and the arrival of man (Adam and Eve). The approximate date of this event according to the bible is calculated by adding up the ages between the patriarchs given in the biblical lineages, and arriving at 6,200 to 7,300 years ago, depending on whether you use the Masoretic or Septuagint text.
This chronology can be supported by both a YEC and an OEC. An OEC can accept an earth 4.5 billion years old with plants and animals appearing according to the paleontological timeline, and still believe that human life was introduced 6-10,000 years ago.
How this happened is debated among the creationists. Some believe that Adam (and Eve) were made from the elements of this earth by God, and life was either breathed into him, or his spirit was placed within his body giving him life. Others believe that Adam was placed on this earth from an existence alien to this earth and by his choice was changed to the elements of this earth (hence the term “fall”). In doing so he no longer had the ability to stay in the presence of God. Either way, according to the scriptures our human family is somewhere less than 10,000 years old.
Summary
There are some challenges in reconciling scientific dates of the earth, plant and animal life, and the emergence of the human family with religious writings. Depending on your interpretation of the Bible, dates just don’t jive. Probably the biggest problem is with the timeline of Adam and Eve. There are valid interpretations of the bible that can be reconciled with the earth being 4.5 billion years old, with plants and animals appearing one-half billion years ago (Cambrian explosion), but the biblical timeline has Adam present on the earth less than 10,000 years ago and human fossils being dated 40X older. Was there a catastrophic event that disrupted the fossil record? Did plate tectonics, flood water erosion, or solar flares affect the dating? With genetics (see article “My Momma was a Mutant”) and demographic evidence (see article “My 130th Great Grandpa”), scientists are re-evaluating their dating assumptions.
To wind this article up, let’s see how you score for your “Credo Code” for your age beliefs. Below is a legend for assigning yourself a 4 digit code, much like a psychology temperament score.
Simply look at each column topic and for each row (code “A”, “B”, and “C”) distribute numbers 1-7 under “σ” (for the strength of your conviction). Each column should add up to “7”. This will force you to not sit on the fence and decide in favor of either “A”, “B”, or “C” for each topic. The highest number for each column should give you a four letter code (AABB in the example). The sum along each row should indicate the strength of which way you’re leaning, whether a “Traditional Scientist”, "Old Earth Creationist” (OEC), or a “Young Earth Creationist” (YEC). The example leans toward an OEC. What are you?
Dasari S and Widory D (2022) Radiocarbon (14C) Analysis of Carbonaceous Aerosols: Revisiting the Existing Analytical Techniques for Isolation of Black Carbon. Front. Environ. Sci. 10:907467. doi: 10.3389/fenvs.2022.907467
Arriaza, Bernardo T. (1995). “Beyond Death: The Chinchorro Mummies of Ancient Chile.” Washington: Smithsonian Institution.
K. Brøste, K. Fischer-Møller (1943). Geologisk Datering af Koelbjerg-Skelettet (in Danish).
https://www.youtube.com/watch?v=Bhnb2Y66gXc
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