Researchers can now determine when a human was born by looking into the eyes of the dead

Jan 30, 2008

Using the radiocarbon dating method and special proteins in the lens of the eye, researchers at the University of Copenhagen and Aarhus can now establish, with relatively high precision, when a person was born. This provides a useful tool for forensic scientists who can use it to establish the date of birth of an unidentified body and could also have further consequences for health science research. The findings are published in the online, open-access journal PLoS ONE on January 30.

The lens of the eye is made up of transparent proteins called crystallins. These are packed so tightly together and in such a particular way, that they behave like crystals, allowing light to pass through the lens of the eye so that we can see. From conception and up until a human being is 1-2 years of age, the cells in the lens build these crystalline proteins. Once this organic construction work is done, however, the lens crystallins remain essentially unchanged for the rest of our lives. This is a fact that researchers can now put to good use.

A minute quantity of Carbon (C-12) in the carbon-dioxide content of the atmosphere contains two extra neutrons and is therefore called Carbon-14 (C-14). This isotope is radioactive, but decays so slowly and harmlessly into nitrogen, that this small carbon element, which occurs quite naturally in nature, is in no way harmful to humans, plants or animals.

At the same time, carbon is one of the principal organic elements, and constantly moves in and out of the food chain. The same is true for the tiny quantity of C-14 in the atmosphere. As long as an organism is part of the food chain, the amount of C-14 in its cells will remain constant and stay at the same level as the C-14 atmospheric content. When the organism dies, however, the quantity of C-14 will slowly but surely drop over the course of thousands of years, while it transforms into nitrogen. This is they key to the Carbon 14 method known as radiocarbon dating, which scientists use to date up to 60, 000 year old biological, archaeological finds.

From the end of World War II and up until about 1960, the superpowers of the Cold War era, conducted nuclear tests, detonating bombs into the atmosphere. These detonations have affected the content of radioactive trace materials in the air and created what scientists refer to as the C-14 bomb pulse. From the first nuclear detonation and, until the ban on nuclear testing was evoked, the quantity of C-14 in the atmosphere doubled. Since 1960, it has only slowly decreased to natural levels.

This sudden curve has left an impression in the food chain and therefore also in the lens crystallins of the eyes, which have absorbed the increased carbon content through food stuffs. Since the crystallins remain unchanged once they have been created, they reflect the content of C-14 present in the atmosphere at the time of their creation. An event occurring shortly after birth. Using a large nuclear accelerator, physicists at Aarhus University can now determine the amount of C-14 in as little as one milligram of lens tissue and thereby calculate the year of birth.

Associate Professor Niels Lynnerup from the Department of Forensic Sciences developed the forensic method, together with the Department of Eye Pathology and the Department of Physics and Astronomy at Arhus University, Denmark.

Professor Lynnerup explains that the technique can have several other applications: “As has been pointed out by other researchers, we think that the carbon dating of proteins and other molecules in the human body can also be used to study when certain kinds of tissue are generated and regenerated,” he explains. “This could, for example, be applied to cancer tissue and cancer cells. Calculating the amount of C-14 in these tissues could perhaps tell us when the cancerous tissues formed, and this could further the understanding of cancer.”

Citation: Lynnerup N, Kjeldsen H, Heegaard S, Jacobsen C, Heinemeier J (2008) Radiocarbon Dating of the Human Eye Lens Crystallines Reveal Proteins without Carbon Turnover throughout Life. PLoS ONE 3(1): e1529. doi:10.1371/journal.pone.0001529 (www.plosone.org/doi/pone.0001529)

Source: Public Library of Science

Explore further: Art of Science 2014: Princeton launches online galleries of prize-winning images and video

add to favorites email to friend print save as pdf

Related Stories

Kingston, Jamaica hybrid project to harness sun and wind

10 hours ago

A hybrid energy project in Kingston, Jamaica, aims to satisfy the need for money-saving renewable energy. U.S.-based WindStream Technologies recently announced the wind solar hybrid installation commissioned ...

Archaeologists excavate NY Colonial battleground

10 hours ago

Archaeologists are excavating an 18th-century battleground in upstate New York that was the site of a desperate stand by Colonial American troops, the flashpoint of an infamous massacre and the location of the era's largest ...

Google eyes Chrome on Windows laptop battery drain

17 hours ago

Google Chrome on Microsoft Windows has been said to have a problem for some time but this week comes news that Google will give it the attention others think the problem quite deserves. Namely, Google is to ...

Security contest techies say they hacked Tesla Model S

19 hours ago

The good news: Tomorrow's cars are computers on wheels. The bad news: Tomorrow's cars are computers on wheels. Ma Jie, writing in Bloomberg News, reported this week that the Tesla Model S sedan was the target ...

Water problems lead to riots, deaths in South Africa

21 hours ago

Three babies who died from drinking tap water contaminated by sewage have become a tragic symbol of South Africa's struggle to cope with a flood of people into cities designed under apartheid to cater to ...

Recommended for you

How to win a Tour de France sprint

Jul 22, 2014

The final dash to the line in a Tour de France sprint finish may appear to the bystander to be a mess of bodies trying to cram into the width of a road, but there is a high degree of strategy involved. It ...

Bible museum planned for US capital

Jul 18, 2014

The devout Christian family that upended a part of President Barack Obama's health care law aims to open a Bible museum in Washington in 2017, a spokesperson for the project said Friday.

User comments : 0