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Can we determine a person's age by dating methods or other means?

Can we determine a person's age by dating methods or other means?


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There are many sports restricted to players of a certain age (e.g. 16 and under, 18 and under, etc.) What if a person is older and fakes his birth certificate to say that he is younger? Is there any way to expose this person?

Can we determine such a person's age by radiocarbon dating methods or other means?


No, one can't confirm age by carbon dating. That doesn't mean we can't make a decent guess by other methods.

There is an interesting case of a 33 year old Texas woman who enrolled in 10th grade in Texas. She said she had no transcripts because she had been homeschooled. She looked like a teenager and acted like a one too. She even fooled her new 23 year old boyfriend. So it happens. It also happened in the Little Leagues World Series, if I remember correctly. A twenty-something guy passed himself off as a 14 year old. He was a star (for a while).

In children and adolescents, the combination of a dental exam, dental films and bone X-rays can narrow a one's biological age well. Once the bones are done growing in length, that avenue is closed.

After that, someone might have to provide a tooth. Chemical analysis of tooth dentin, such as aspartic acid racemization, has shown reproducible and fairly precise results.

Global levels of carbon-14 (14C) have been carefully recorded over time. In one 2010 study, forty-four teeth from 41 individuals (one per individual) were analyzed using aspartic acid racemization analysis of tooth crown dentin or radiocarbon analysis of enamel. Teeth from individuals with dates of birth ranging from 1936 through 1994 (aged 13-70 years) were analyzed, and where the date of birth was known, yielded a 14C-based date of birth estimation accuracy of 1.3 years (S.D. = 0.9 years). In one case, a date of birth was determined to be 1948.4. In another, it was determined to be 1988.

[T]en of these were split and subjected to both radiocarbon and racemization analysis. Combined analysis showed that the two methods correlated well (R2 = 0.66, p < 0.05). Radiocarbon analysis showed an excellent precision with an overall absolute error of 1.0 ± 0.6 years. Aspartic acid racemization also showed a good precision with an overall absolute error of 5.4 ± 4.2 years. Whereas radiocarbon analysis gives an estimated year of birth, racemization analysis indicates the chronological age of the individual at the time of (tooth extraction).

During the course of aging, l-forms of amino acids are transformed by racemization to the d-forms.

[T]he extent of racemization of amino acids may be used to estimate the age of various tissues. Of all stable amino acids, aspartic acid has one of the fastest racemization rates and is therefore the amino acid most commonly used for age estimation… [T]eeth are the tissue of choice for age estimation analysis.

Both methods have strengths and limitations.

The radiocarbon birth dating method can tell the birth date of the person regardless of the time of (extraction). However, the time window for this analysis is limited to subjects born after the early 1940s because the calculations are based on the measurement of bomb pulse-derived 14C.

Clearly this wouldn't be of too much use in people trying to pass themselves off as teens.

Some studies of aspartic acid racemization report accuracies of age ±3 years. The radiocarbon and racemization can further narrow it down.

Why did Charity Johnson pretend to be a teenager for 20 years?
Age Estimation in Forensic Sciences APPLICATION OF COMBINED ASPARTIC ACID RACEMIZATION AND RADIOCARBON ANALYSIS
Strategy for the estimation of chronological age using the aspartic acid racemization method with special reference to coefficient of correlation between D/L ratios and ages


To grab this opportunity to sum up the comments for the C-14 dating method, including those of of @MattDMo and @canadier: Theoretically spoken - Yes we can! But only after (1) killing the person and (2) waiting a few hundred years. As carbon keeps on being recycled in a living carbon-based organism, it has to be dead first. Secondly, because the margin or error is about 80 years, mainly due to the relatively long half-life of C14 (5730 years) and the variability in the C14 dating method (see wiki on C14 dating) one should wait, ideally between 1k and 1000k years. But given the error margin a few hundred years may suffice to get a rough idea. So to sum up - practically this test, although it is objective and free of subjectivity and robust to false pretenses, makes no sense as (a) a human life is about the same a the error margin of the test and (b) the competitor cannot participate in the contest after his or her life has being taken.

I am not aware of any biologoical methods to objectively measure age.


How do scientists figure out how old things are?

The ability to precisely date, or identify the age of an object, can teach us when Earth formed, help reveal past climates and tell us how early humans lived. So how do scientists do it?

Radiocarbon dating is the most common method by far, according to experts. This method involves measuring quantities of carbon-14, a radioactive carbon isotope — or version of an atom with a different number of neutrons. Carbon-14 is ubiquitous in the environment. After it forms high up in the atmosphere, plants breathe it in and animals breathe it out, said Thomas Higham, an archaeologist and radiocarbon dating specialist at the University of Oxford in England.

"Everything that's alive takes it up," Higham told Live Science.

While the most common form of carbon has six neutrons, carbon-14 has two extra. That makes the isotope heavier and much less stable than the most common carbon form. So after thousands of years, carbon-14 eventually breaks down. One of its neutrons splits into a proton and an electron. While the electron escapes, the proton remains part of the atom. With one less neutron and one more proton, the isotope decays into nitrogen.

When living things die, they stop taking in carbon-14 and the amount that's left in their body starts the slow process of radioactive decay. Scientists know how long it takes for half of a given quantity of carbon-14 to decay — a length of time called a half-life. That allows them to measure the age of an organic piece of matter — whether that's an animal skin or skeleton, ash or a tree ring — by measuring the ratio of carbon-14 to carbon-12 left in it and comparing that quantity to the carbon-14 half-life.

The half-life of carbon-14 is 5,730 years, making it ideal for scientists who want to study the last 50,000 years of history. "That covers basically the really interesting part of human history," Higham said, "the origins of agriculture, the development of civilizations: All these things happened in the radiocarbon period."

However, objects older than that have lost more than 99% of their carbon-14, leaving too little to detect, said Brendan Culleton, an assistant research professor in the Radiocarbon Laboratory at Pennsylvania State University. For older objects, scientists don't use carbon-14 as a measure of age. Instead, they often look to radioactive isotopes of other elements present in the environment.

For the world's oldest objects, uranium-thorium-lead dating is the most useful method. "We use it to date the Earth," Higham said. While radiocarbon dating is useful only for materials that were once alive, scientists can use uranium-thorium-lead dating to measure the age of objects such as rocks. In this method, scientists measure the quantity of a variety of different radioactive isotopes, all of which decay into stable forms of lead. These separate chains of decay begin with the breakdown of uranium-238, uranium-235 and thorium-232.

"Uranium and thorium are such large isotopes, they're bursting at the seams. They're always unstable," said Tammy Rittenour, a geologist at Utah State University. These "parent isotopes'' each break down in a different cascade of radioisotopes before they wind up as lead. Each of these isotopes has a different half-life, ranging from days to billions of years, according to the Environmental Protection Agency. Just like radiocarbon dating, scientists calculate the ratios between these isotopes, comparing them with their respective half-lives. Using this method, scientists were able to date the oldest rock ever discovered, a 4.4 billion-year-old zircon crystal found in Australia.

Finally, another dating method tells scientists not how old an object is, but when it was last exposed to heat or sunlight. This method, called luminescence dating, is favored by geo-scientists studying changes in landscapes over the last million years — they can use it to discover when a glacier formed or retreated, depositing rocks over a valley or when a flood dumped sediment over a river-basin, Rittenour told Live Science

When the minerals in these rocks and sediments are buried, they become exposed to the radiation emitted by the sediments around them. This radiation kicks electrons out of their atoms. Some of the electrons fall back down into the atoms, but others get stuck in holes or other defects in the otherwise dense network of atoms around them. It takes second exposure to heat or sunlight to knock these electrons back to their original positions. That's exactly what scientists do. They expose a sample to light, and as the electrons fall back into the atoms, they emit heat and light, or a luminescent signal.

"The longer that object is buried, the more radiation it's been exposed to," Rittenour said. In essence, long-buried objects exposed to a lot of radiation will have a tremendous amount of electrons knocked out of place, which together will emit a bright light as they return to their atoms, she said. Therefore, the amount of luminescent signal tells scientists how long the object was buried.

Dating objects isn't just important for understanding the age of the world and how ancient humans lived. Forensic scientists use it to solve crimes, from murder to art forgery. Radiocarbon dating can tell us for how long a fine wine or whiskey has been aged, and thus whether it has been faked, Higham said. "There's a whole range of different applications."


Relative Dating Vs. Absolute Dating

Relative Dating

➤ It determines if an object/event is younger or older than another object/event from history.
➤ Relative dating is qualitative.
➤ This technique helps determine the relative age of the remains.
➤ It is less specific than absolute dating.
➤ Relative dating is comparatively less expensive and time-efficient.
➤ It works best for sedimentary rocks having layered arrangement of sediments.

The following are the major methods of relative dating.

Stratigraphy: The oldest dating method which studies the successive placement of layers. It is based on the concept that the lowest layer is the oldest and the topmost layer is the youngest.

Biostratigraphy: An extended version of stratigraphy where the faunal deposits are used to establish dating. Faunal deposits include remains and fossils of dead animals.

Cross dating: This method compares the age of remains or fossils found in a layer with the ones found in other layers. The comparison helps establish the relative age of these remains.

Fluorine dating: Bones from fossils absorb fluorine from the groundwater. The amount of fluorine absorbed indicates how long the fossil has been buried in the sediments.

Absolute Dating

➤ It determines the age of a rock/object using radiometric techniques.
➤ Absolute dating is quantitative.
➤ This technique helps determine the exact age of the remains.
➤ It is more specific than relative dating.
➤ Absolute dating is expensive and time-consuming.
➤ It works best for igneous and metamorphic rocks.

The following are the major methods of relative dating.

Radiometric dating: This technique solely depends on the traces of radioactive isotopes found in fossils. The rate of decay of these elements helps determine their age, and in turn the age of the rocks.

Amino acid dating: Physical structure of living beings depends on the protein content in their bodies. The changes in this content help determine the relative age of these fossils.

Dendrochronology: Each tree has growth rings in its trunk. This technique dates the time period during which these rings were formed.

Thermoluminescence: It determines the period during which certain object was last subjected to heat. It is based on the concept that heated objects absorb light, and emit electrons. The emissions are measured to compute the age.

Differentiation Using a Venn Diagram

A Venn diagram depicts both dating methods as two individual sets. The area of intersection of both sets depicts the functions common to both. Take a look at the diagram to understand their common functions.

When we observe the intersection in this diagram depicting these two dating techniques, we can conclude that they both have two things in common:

1.Provide an idea of the sequence in which events have occurred.
2.Determine the age of fossils, rocks, or ancient monuments.

Although absolute dating methods determine the accurate age compared to the relative methods, both are good in their own ways.

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Other factors affecting carbon dating

The amount of cosmic rays penetrating the Earth's atmosphere affects the amount of 14 C produced and therefore dating the system. The amount of cosmic rays reaching the Earth varies with the sun's activity, and with the Earth's passage through magnetic clouds as the solar system travels around the Milky Way galaxy.

The strength of the Earth's magnetic field affects the amount of cosmic rays entering the atmosphere. A stronger magnetic field deflects more cosmic rays away from the Earth. Overall, the energy of the Earth's magnetic field has been decreasing,[5] so more 14 C is being produced now than in the past. This will make old things look older than they really are.

Also, the Genesis flood would have greatly upset the carbon balance. The flood buried a huge amount of carbon, which became coal, oil, etc., lowering the total 12 C in the biosphere (including the atmosphere—plants regrowing after the flood absorb CO2, which is not replaced by the decay of the buried vegetation). Total 14 C is also proportionately lowered at this time, but whereas no terrestrial process generates any more 12 C, 14 C is continually being produced, and at a rate which does not depend on carbon levels (it comes from nitrogen). Therefore, the 14 C/ 12 C ratio in plants/animals/the atmosphere before the flood had to be lower than what it is now.

Unless this effect (which is additional to the magnetic field issue just discussed) were corrected for, carbon dating of fossils formed in the flood would give ages much older than the true ages.

Creationist researchers have suggested that dates of 35,000 - 45,000 years should be re-calibrated to the biblical date of the flood.[6] Such a re-calibration makes sense of anomalous data from carbon dating—for example, very discordant “dates” for different parts of a frozen musk ox carcass from Alaska and an inordinately slow rate of accumulation of ground sloth dung pellets in the older layers of a cave where the layers were carbon dated.[7]

Also, volcanoes emit much CO2 depleted in 14 C. Since the flood was accompanied by much volcanism (see Noah's Flood…, How did animals get from the Ark to isolated places?, and What About Continental Drift?), fossils formed in the early post-flood period would give radiocarbon ages older than they really are.

In summary, the carbon-14 method, when corrected for the effects of the flood, can give useful results, but needs to be applied carefully. It does not give dates of millions of years and when corrected properly fits well with the biblical flood.


FAQ - Radioactive Age-Dating

In nature, all elements have atoms with varying numbers of neutrons in their nucleus. These differing atoms are called isotopes and they are represented by the sum of protons and neutrons in the nucleus. Let's look at a simple case, carbon. Carbon has 6 protons in its nucleus, but the number of neutrons its nucleus can host range from 6 to 8. We thus have three different isotopes of carbon: Carbon-12 with 6 protons and 6 neutrons in the nucleus, Carbon-13 with 6 protons and 7 neutrons in the nucleus, Carbon-14 with 6 protons and 8 neutrons in the nucleus. Both carbon-12 and carbon-13 are stable, but carbon-14 is unstable, which means that there are too many neutrons in the nucleus. Carbon-14 is also known as radiocarbon. As a result, carbon-14 decays by changing one proton into a neutron and becoming a different element, nitrogen-14 (with 7 protons and 7 neutrons in the nucleus). The isotope originating from the decay (nitrogen-14 in the case of radiocarbon) is called the daughter, while the original radioactive isotope (like carbon-14) is called the parent. The amount of time it takes for an unstable isotope to decay is determined statistically by looking at how long it takes for a large number of the same radioactive isotopes to decay to half its original amount. This time is known as the half-life of the radioactive isotope.

Once the half life of an isotope and its decay path are known, it is possible to use the radioactive decay for dating the substance (rock) it belongs to, by measuring the amount of parent and daughter contained in the sample. An important point is that we must have an idea of how much of the daughter isotope was in the sample before the decay started.


An Ice Cream Definition of Half-Life

Imagine that you enjoy a certain kind of ice cream flavored with chocolate chips. You have a sneaky, but not especially clever, roommate who doesn't like the ice cream itself, but cannot resist picking out eating the chips – and in an effort to avoid detection, he replaces each one he consumes with a raisin.

He is afraid to do this with all of the chocolate chips, so instead, each day, he swipes half of the number of remaining chocolate chips and puts raisins in their place, never quite completing his diabolical transformation of your dessert, but getting closer and closer.

Say a second friend who is aware of this arrangement visits and notices that your carton of ice cream contains 70 raisins and 10 chocolate chips. She declares, "I guess you went shopping about three days ago." How does she know this?

It's simple: You must have started with a total of 80 chips, because you now have 70 + 10 = 80 total additives to your ice cream. Because your roommate eats half of the chips on any given day, and not a fixed number, the carton must have held 20 chips the day before, 40 the day before that, and 80 the day before that.

Calculations involving radioactive isotopes are more formal but follow the same basic principle: If you know the half-life of the radioactive element and can measure how much of each isotope is present, you can figure out the age of the fossil, rock or other entity it comes from.


New Forensic Method Can Determine a Person’s Age from Blood Left at a Crime Scene

Forensic scientists have a new tool to help them reconstruct the identities of persons at the scene of crime, at least the kind of crime scene where things got physical. Dutch researchers have devised a method for estimating the age of a suspect or missing person by simply examining blood collected from the scene, even if that blood isn’t particularly fresh.

The test isn’t perfect that is, it has a margin of error of nine years in either direction. But in cases where police are trying to build a profile of an unknown person, the test can narrow the possibilities down to a generational cohort spanning about two decades. Previous attempts to do so have proved inaccurate, but this attempt at deriving a phenotypic human trait from DNA information is at least as accurate, if not more so, than other profiling methods like a similar means of determining eye color from DNA.

The science turns on a certain molecular process tied to the T cells in blood. The ability of T cells to recognize foreign threats depends upon the diversity of receptors that match up with characteristics found in the invaders. That diversity is achieved by a rearrangement of the T cells’ DNA over time, a process that produces distinguishable circular DNA molecules as a byproduct. Those molecules decline constantly in number over time in correlation with the person’s age.

By counting up the number of these circular DNA molecules in a sample and comparing it to the quantity of another reference gene that remains constant throughout a person’s lifetime (as a reference that compensates for the varying amount of DNA in a given sample), forensics experts can deduce, with reasonable accuracy, the age of the blood’s owner.

The method won’t be used like DNA matching that links a suspect definitively to the scene of a crime, but in situations where authorities have no leads regarding the identity of a wanted or missing person, it should help police build a more accurate profile of who it is they are looking for.


Difference Between Relative and Absolute Dating

Dating is a technique used in archeology to ascertain the age of artifacts, fossils and other items considered to be valuable by archeologists. There are many methods employed by these scientists, interested in the old, to get to know the age of items. It is possible to tell the number of years ago a particular rock or archeological site had been formed. Two broad categories of classification methods are relative dating and absolute dating. Though using similar methods, these two techniques differ in certain ways that will be discussed in this article.

As the name implies, relative dating can tell which of the two artifacts is older. This is a method that does not find the age in years but is an effective technique to compare the ages of two or more artifacts, rocks or even sites. It implies that relative dating cannot say conclusively about the true age of an artifact. Absolute dating, on the other hand is capable of telling the exact age of an item using carbon dating and many other techniques that were not there in earlier times.

Relative dating makes use of the common sense principle that in a deposition of layers. A layer that is higher is of later age than a layer that is lower in order. This means that the oldest are the strata that are lying at the bottom. However, age of deposition does not mean the age of artifacts found in that layer. Artifacts found in a layer can be compared with other items found in layers of similar age and placed in order. However, archeologists still require further information to find out the items that are oldest and those that are youngest in the order.

It is left for absolute dating to come up with the precise age of an artifact. This type of dating employs many dating techniques like atomic clocks, carbon dating, annual cycle methods, and trapped electron method. Dendrochronology is another of the popular method of finding the exact age through growth and patterns of thick and thin ring formation in fossil trees. It is clear then that absolute dating is based upon physical and chemical properties of artifacts that provide a clue regarding the true age. This is possible because properties of rock formations are closely associated with the age of the artifacts found trapped within them.

The most popular method of radio dating is radio carbon dating which is possible because of the presence of C-14, an unstable isotope of carbon. C-14 has a half life of 5730 years which means that only half of the original amount is left in the fossil after 5730 years while half of the remaining amount is left after another 5730 years. This gives away the true age of the fossil that contains C-14 that starts decaying after the death of the human being or animal.

Relative Dating vs. Absolute Dating

• Dating techniques are used in archeology to ascertain the age of old artifacts and a broad classification of these methods bifurcates them in relative dating and absolute dating

• Relative dating comes to a conclusion based upon the study of layer formation of rocks. Upper most layers are considered the youngest while the lowermost deposition is considered as oldest.

• Relative dating does not tell the exact age, it can only compare items as younger and older.

• Absolute dating techniques can tell the exact age of an artifact by employing various techniques, the most popular being C-14 dating.


How Carbon-14 Dating Works

­You probably have seen or read news stories about fascinating ancient artifacts. At an ar­chaeological dig, a piece of wooden tool is unearthed and the archaeologist finds it to be 5,000 years old. A child mummy is found high in the Andes and the archaeologist says the child lived more than 2,000 years ago. How do scientists know how old an object or human remains are? What methods do they use and how do these methods work? In this article, we will examine the methods by which scientists use radioactivity to determine the age of objects, most notably carbon-14 dating.

Carbon-14 dating is a way of determining the age of certain archeological artifacts of a biological origin up to about 50,000 years old. It is used in dating things such as bone, cloth, wood and plant fibers that were created in the relatively recent past by human activities.

Co­smic rays enter the earth's atmosphere in large numbers every day. For example, every person is hit by about half a million cosmic rays every hour. It is not uncommon for a cosmic ray to collide with an atom in the atmosphere, creating a secondary cosmic ray in the form of an energetic neutron, and for these energetic neutrons to collide with nitrogen atoms. When the neutron collides, a nitrogen-14 (seven protons, seven neutrons) atom turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons). Carbon-14 is radioactive, with a half-life of about 5,700 years.

For more information on cosmic rays and half-life, as well as the process of radioactive decay, see How Nuclear Radiation Works.

Carbon-14 in Living Things

­The carbon-14 atoms that cosmic rays create combine with oxygen to form carbon dioxide, which plants absorb naturally and incorporate into plant fibers by photosynthesis. Animals and people eat plants and take in carbon-14 as well. The ratio of normal carbon (carbon-12) to carbon-14 in the air and in all living things at any given time is nearly constant. Maybe one in a trillion carbon atoms are carbon-14. The carbon-14 atoms are always decaying, but they are being replaced by new carbon-14 atoms at a constant rate. At this moment, your body has a certain percentage of carbon-14 atoms in it, and all living plants and animals have the same percentage.

­As soon as a living organism dies, it stops taking in new carbon. The ratio of carbon-12 to carbon-14 at the moment of death is the same as every other living thing, but the carbon-14 decays and is not replaced. The carbon-14 decays with its half-life of 5,700 years, while the amount of carbon-12 remains constant in the sample. By looking at the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing fairly precisely.

A formula to calculate how old a sample is by carbon-14 dating is:

T = [ ln (Nf/No) / (-0.693) ] x t1/2

t = [ ln (Nf/No) / (-0.693) ] x t1/2

where ln is the natural logarithm, Nf/No is the percent of carbon-14 in the sample compared to the amount in living tissue, and t1/2 is the half-life of carbon-14 (5,700 years).

So, if you had a fossil that had 10 percent carbon-14 compared to a living sample, then that fossil would be:

t = [ ln (0.10) / (-0.693) ] x 5,700 years

t = [ (-2.303) / (-0.693) ] x 5,700 years

T = 18,940 years old

Because the half-life of carbon-14 is 5,700 years, it is only reliable for dating objects up to about 60,000 years old. However, the principle of carbon-14 dating applies to other isotopes as well. Potassium-40 is another radioactive element naturally found in your body and has a half-life of 1.3 billion years. Other useful radioisotopes for radioactive dating include Uranium -235 (half-life = 704 million years), Uranium -238 (half-life = 4.5 billion years), Thorium-232 (half-life = 14 billion years) and Rubidium-87 (half-life = 49 billion years).

The use of various radioisotopes allows the dating of biological and geological samples with a high degree of accuracy. However, radioisotope dating may not work so well in the future. Anything that dies after the 1940s, when Nuclear bombs, nuclear reactors and open-air nuclear tests started changing things, will be harder to date precisely.


Is carbon dating a reliable method for determining the age of things?

Carbon dating, or radiocarbon dating, like any other laboratory testing technique, can be extremely reliable, so long as all of the variables involved are controlled and understood. Several factors affect radiocarbon test results, not all of which are easy to control objectively. For this reason, it’s preferable to date objects using multiple methods, rather than relying on one single test. Carbon dating is reliable within certain parameters but certainly not infallible.

When testing an object using radiocarbon dating, several factors have to be considered:

First, carbon dating only works on matter that was once alive, and it only determines the approximate date of death for that sample. For example, a steel spearhead cannot be carbon dated, so archaeologists might perform testing on the wooden shaft it was attached to. This provides good information, but it only indicates how long ago that piece of wood was cut from a living tree. Radiocarbon dating can’t tell the difference between wood that was cut and immediately used for the spear, and wood that was cut years before being re-used for that purpose. Nor can it tell if a much older spearhead was attached to a brand-new shaft.

Most archaeological items can’t be directly carbon dated, so their dating is based on testing done on nearby objects or materials. This makes the results subject to the researchers’ assumptions about those objects. If the spear head is dated using animal bones nearby, the accuracy of the results is entirely dependent on the assumed link between the spear head and the animal. This is perhaps the greatest point of potential error, as assumptions about dating can lead to circular reasoning, or choosing confirming results, rather than accepting a “wrong” date.

Second, radiocarbon dating becomes more difficult, and less accurate, as the sample gets older. The bodies of living things generally have concentrations of the isotope carbon-14, also known as radiocarbon, identical to concentrations in the atmosphere. When an organism dies, it stops taking in new carbon-14, and whatever is inside gradually decays into other elements. Carbon-14 normally makes up about 1 trillionth (1/1,000,000,000,000) of the earth’s atmosphere. So even brand-new samples contain incredibly tiny quantities of radiocarbon.

Eventually, the amount of carbon-14 remaining is so small that it’s all but undetectable. Tiny variations within a particular sample become significant enough to skew results to the point of absurdity. Carbon dating therefore relies on enrichment and enhancement techniques to make smaller quantities easier to detect, but such enhancement can also skew the test results. Normal errors in the test become magnified. As a result, carbon dating is only plausible for objects less than about 40,000 years old.

The other major factor affecting the results of carbon dating is gauging the original proportion of carbon-14 itself. Carbon dating is based on the loss of carbon-14, so, even if the present amount in a specimen can be detected accurately, we must still know how much carbon-14 the organism started with. Scientists must assume how much carbon-14 was in the organism when it died. Complicating matters is the fact that Earth’s carbon-14 concentrations change drastically based on various factors. As samples get older, errors are magnified, and assumptions can render carbon dating all but useless.

For example, variations in greenhouse effects and solar radiation change how much carbon-14 a living organism is exposed to, which drastically changes the “starting point” from which a radiocarbon dating test is based. Likewise, different living things absorb or reject carbon-14 at different rates. Two plants that died at the same moment, but which naturally contained different levels of radiocarbon, could be dated to drastically different times. Modern effects such as fossil fuel burning and nuclear testing have also changed atmospheric carbon-14 levels and in turn change the “starting point” for a radiocarbon test. All in all, setting the parameters of the carbon-14 test is more of an art than a science.

Contamination and repeatability are also factors that have to be considered with carbon dating. A tiny amount of carbon contamination will greatly skew test results, so sample preparation is critical. Even then, a large proportion of radiocarbon dating tests return inconsistent, or even incoherent, results, even for tests done on the same sample. The explanation given for these outliers is usually “contamination.” Inconsistent results are another reason why multiple samples, multiples tests, and various parallel methods are used to date objects.

Due to all these factors, it’s common for carbon dating results of a particular sample, or even a group of samples, to be rejected for the sole reason that they don’t align with the “expected” results. That’s not unusual in science, so far as it goes, but the relationship between assumptions and interpretations must be kept in mind. At best, it needs to be acknowledged. At worst, it can make carbon dating circular and self-confirming, though there are other means of dating that can reduce this risk.

In short, carbon dating is as useful as any other technique, so long as it’s done properly and the results are objectively interpreted. It is not, however, an inherently error-free or black-and-white method for dating objects.



Comments:

  1. Kazirisar

    Of course. It was with me too. Let's discuss this issue.

  2. Clustfeinad

    You were mistaken, it is obvious.

  3. Saville

    In my opinion it is obvious. You did not try to look in google.com?



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