пятница, 19 июля 2019 г.

A new look at the Gibraltar Neanderthals

Modern DNA sequencing techniques are allowing us to discover more about some iconic Neanderthal skulls than ever before.

A new look at the Gibraltar Neanderthals
The adult female Neanderthal cranium discovered at Forbes Quarry, Gibraltar
[Credit: Natural History Museum]

Two skulls from Gibraltar were among the first Neanderthal remains ever found, and have since become some of the best-studied human fossils in the world.

One was found at Forbes’ Quarry in 1848, and one at a site called Devil’s Tower in 1926.

Despite their fame, there are many remaining uncertainties about the two partial skulls, including their geological age and their relationship to other European Neanderthals.

It was long thought that little DNA analysis could be done on the two skulls, since they had been preserved in unfavourable conditions for many years, and because present-day human DNA has contaminated them.

But ancient DNA has finally been extracted from these fossils, in a collaboration led by the Natural History Museum in London and the Max Planck Institute for Evolutionary Anthropology in Leipzig,

We now know the sex of both the individuals as well as details about how one of them could be linked to Neanderthal relatives beyond Gibraltar.

The Forbes’ Quarry Neanderthal

The Forbes’ Quarry skull (pictured above) was the first adult Neanderthal ever discovered, and it is one of the most precious specimens in the Museum collections. It is also known as Gibraltar 1.

A new look at the Gibraltar Neanderthals
A three-quarter view of the Forbes’ Quarry Neanderthal, which is held in the Museum collection
[Credit: Natural History Museum]

It was found in the northern end of the Rock of Gibraltar in 1848, and presented to the Gibraltar Scientific Society by Lieutenant Edmund Flint on 3 March of that year.  This was eight years before the Neanderthal type specimen was discovered in the Neander Valley in Germany.

The skull came to Britain in 1864, where Charles Darwin recorded that he examined it, and it was donated to the Royal College of Surgeons in London four years later. It was transferred to the Natural History Museum in the 1950s.

The Museum’s Prof Chris Stringer, an expert on human evolution, says, ‘It has long been recognised as one of the most important Neanderthal fossils, the first one showing the typical Neanderthal facial shape, dominated by a projecting midface and nose.’

The Devil’s Tower child

Further Neanderthal discoveries were made nearby in the 1910s and 1920s. The Devil’s Tower specimen (also known as Gibraltar 2 and pictured above) is part of a Neanderthal child’s skull. It was found in 1926 by a team led by the archaeologist Dorothy Garrod.

A new look at the Gibraltar Neanderthals
The Devil’s Tower child skull [Credit: Guérin Nicolas/WikiCommons]

The Devil’s Tower site is at a rock shelter not far from Forbes’ Quarry where the skull was recovered alongside animal remains and stone tools.

The Neanderthal remains consist of parts of the jaws and parts of the braincase, and its teeth show that the child was probably about four or five years old when they died.

In 1928 the Trustees of the Percy Sladen Fund presented the remains to the Museum.

Modern DNA techniques

Studying ancient human remains can be difficult because they are easily contaminated by modern human DNA.

A new look at the Gibraltar Neanderthals
The Devils Tower Neanderthal child fossil in pieces
[Credit: Natural History Museum]

To investigate DNA preservation in these Neanderthal remains, Lukas Bokelmann and his colleagues at the Max Planck Institute for Evolutionary Anthropology analysed bone powder from the base of each of the skulls.

They used a preparation method that reduces modern contamination before sequencing, to isolate the Neanderthal DNA.

Analyses confirmed that the Devil’s Tower child was male, and the Forbes’ Quarry adult was female. The researchers also found that the adult was genetically more similar to earlier (60,000- to 120,000-year-old) Neanderthals in Europe and western Asia than to younger Neanderthal remains from Spain.

So although Gibraltar is often considered as one of the last refugia of the Neanderthals, the Forbes’ Quarry fossil appears from its DNA to be an earlier example.

Prof Stringer adds, ‘These results show that it’s now possible to analyse DNA in highly contaminated fossils from relatively warm climates.

‘It holds out promise for the recovery of comparably ancient DNA from regions such as North Africa, the Middle East and China.’

The findings are published in the Proceedings of the National Academy of Sciences.

Author: Katie Pavid | Source: Natural History Museum [July 16, 2019]



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