London Student Issue 7 - Futures DNA Neanderthal

London Student Issue 7 - futures DNA neanderthal

The humans are coming! Words to this effect must have struck fear into the heart of every Neanderthal that heard them 30, 000 years ago, just before they became extinct at our hands. Yes, it seems that causing the extinction of endangered species, far from being a recent development, is something we humans have been doing since our evolutionary birth.

Research published in the prestigious scientific journal, Cell, earlier this year lends considerable weight to the ‘displacement model’ of human-Neanderthal relationships. In other words we wiped them out. Neanderthal man lived peacefully in Europe and Western Asia for at least 100, 000 years. There is evidence of their having an advanced culture and they were definitely bigger than us, about 30% larger all round than modern man.

Around 30, 000 years ago along came humans. Travelling from northern Africa we encountered Neanderthal men, our physical superiors, and annihilated them. It seems that our greater intelligence and a more war-like nature must have won the day. It has been suggested in the past that Neanderthals were either our ancestors or had contributed genes to modern humans (by interbreeding). If either of these theories are true then modern humans and Neanderthal man would share some common DNA. Ancient DNA from a Neanderthal bone, found in Germany in 1856, was extracted and studied to try and shed some light on these theories.

The work, detailed in Cell, relied on the latest techniques of ancient DNA extraction. Ancient materials such as the Neanderthal bone contain only minuscule amounts of DNA. For this DNA to be analysed it is necessary that the amount be amplified. Essential for this amplification is the Polymerase Chain Reaction (PCR). PCR relies on the ability of the enzyme DNA Polymerase to recognise DNA and duplicate it millions of times over. Using this technique the scientists analysed Neanderthal DNA and found no significant similarity when compared to that of modern humans. So Neanderthals must have been a separate species, contributing http://www.londonstudent.org.uk/7issue/futures/neanderthal.htm (1 of 2)1/29/2006 10:47:43 AM London Student Issue 7 - futures DNA neanderthal no genes to humans during their extinction. Thomas Lindahl, an expert in the field from the Imperial Cancer Research Fund, has described this work with Neanderthal DNA as, “arguably the greatest achievement so far in the field of ancient DNA research”.

However, there is bad news for dinosaur fans. The work with Neanderthal DNA is now thought to represent a cut-off point of around 30, 000 years. DNA is unrecoverable in material older than this. We all witnessed the ‘Jurrasic Park’ hype concerning the extraction of DNA from dinosaur blood found within ancient insects encased in amber. Research this year has shown that amber is a very poor substance for storing DNA. Air can freely diffuse into amber, oxidising any DNA inside. Oxidised DNA cannot be recognised by DNA polymerase so PCR, essential if any DNA is to be recovered, is impossible. Amazingly, until this year nobody had tried to recover DNA from young insects recently preserved in solidified pine resin, called copal. Pine resin solidifies into copal in a few months, then takes roughly four million years to convert into amber. If DNA cannot be recovered form insects preserved in copal then there is no way it could be recovered from insects in amber. Alas, it was shown to be impossible to recover any DNA from insects preserved in copal. It would seem the ‘Jurrassic Park’ method of ancient DNA recovery is as dead as the dinosaurs it sought to resurrect.

Darren Nesbeth

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