When Did Neanderthals Disappear? - Chromatography Checks the Dates

Knowing when the Neanderthals disappeared from Eurasia is a hotly contested subject. It is one of the key questions in palaeoanthropology and the answer determines how much interaction there could have been between Neanderthals and Homo sapiens in Europe. Knowing the accurate date an event happened is key to fully understanding relationships between our ancestors.

A recent paper - Reevaluating the timing of Neanderthal disappearance in Northwest Europe - published in the Proceedings of the National Academy of Sciences reports on work carried out by scientists from Belgium, Germany, and the UK. They used chromatography to put a more accurate date on when Neanderthals disappeared from Europe. And the results suggest they left earlier than scientists originally thought.

Carbon dating Neanderthals

Neanderthal remains from a site known as Spy Cave in Belgium had been dated as approximately 24000 years old. This would have made them amongst the latest surviving Neanderthals in Europe. Knowing when Neanderthals, our closest human relative, disappeared helps us along the path to know more about their nature and what they were capable of doing. This could in turn help us to understand why they died out and H sapiens prospered.

Plants and animals absorb carbon while they are alive. Some of that carbon is radioactive carbon-14. When plants and animals die, they stop absorbing carbon and hence carbon-14. Analysing the amount of carbon-14 in a fossil or remains allows us to determine the age of the object. What the multinational team did was to go beyond normal radiocarbon dating.

Chromatography separates the amino acids

It has been suspected that the remains were contaminated by glues from museum work or even from the burial environment. Bovine DNA was detected on the remains which could come from glues used in museum work. So, the team developed a new method that still relies on carbon-14 dating but refines how the sample is prepared. They used liquid chromatography to separate and extract a single amino acid from collagen in the Neanderthal remains. The analysis of biomolecules using chromatography is discussed in the article, Fast Analysis of Biomolecules by Using Smaller and Innovative Particles.

Using the new advanced method, the team were able to reliably date the remains without the contaminants that had plagued previous carbon dating attempts. The results suggest that the Neanderthals disappeared from the region approximately 44200-40600 years ago, much earlier than previously thought. Lead author Dr Thibaut Devièse said

The new chemistry methods we have applied in the case of the Spy and other Belgian sites provide the only means by which we can decontaminate these key Neanderthal bones for dating and check that contaminants have been fully removed. This gives us confidence in the new ages we obtained for these important specimens.

The work also highlights the need to use robust pre-treatment methods when analysing samples to minimise the potential contamination and thus biasing the dates to more recent ages.