Was it the more highly developed Homo sapiens that spelled the end for Neanderthal man? Did he die out because he could not find enough meat to satisfy his extreme 5,000-calorie a day hunger? Or was it simply the cold that caused the extinction of our massive cousins? New techniques applied by UWA scientists suggest that it was not the freezing temperatures of the last glaciation in Central Europe that killed off the species we know as Neanderthals.
Research Assistant Professor Grzegorz (Greg) Skrzypek has used stable oxygen isotope biogeochemistry to find out just how cold it was during the last warm phases of the Pleistocene, about 115-74,000 and 59-41,000 years ago.
A paper setting out his findings, co-authored with Dr Pauline Grierson, director of UWA ’s West Australian Biogeochemistry Centre, and archaeologist Dr Andrzej Wisniewski from the University of Wroclaw, Poland, has attracted a lot of interest in Europe, following its publication earlier this year in the Quaternary Science Reviews.
Dr Skrzypek analysed scraps of animal bones found in a huge excavation site in Poland, near the borders with Germany and the Czech Republic. The site is 800 square metres in area and up to four metres deep and archaeologists have been working it for about 10 years, salvaging about 2,000 pieces of bone and 3,000 prehistoric stone artefacts including tools made of flint.
“We know the bones were found near a Neanderthal camp, and they are the dining scraps of Palaeolithic hunters,” Dr Skrzypek said. “We know the Neanderthals had to work hard to hunt and kill enough animals to feed their massive bodies. They needed more than two kilos of fresh meat every day, about 5,000 calories.
“We chose teeth and bone fragments from horses, bison and mammoths from the site to bring back to UWA to analyse. Bones are made of phosphate, calcium carbonate and collagen. The phosphate stable oxygen isotope composition in teeth reflects the isotope composition of the water the animal drank, and so its geographic location,” he said.
“From the stable isotope composition of the water, we can also tell what the temperatures would have been around the time the animal lived.”
Dr Skrzypek and his team estimated that the average temperature before the Neanderthals became extinct was 6.3-6.8°C, compared with the average at the site now, which is around 9°C. While cooler than present day, the temperatures for Neanderthals were substantially warmer during interglacial periods than previously thought. Other archaeological evidence also shows that, during the interglacial periods, the Neanderthal population was not ecologically stressed.
“We don’t know exactly why the Neanderthals became extinct,” he said. “Perhaps climate conditions were much worse during the last glaciations, around 30,000 years ago, and they were living at an ecological threshold and couldn’t get enough food to maintain their huge bodies.
“It is also likely there was interaction with modern Homo sapiens, who were also migrating north from Africa. They were more technologically advanced and their bodies were more efficient in a cold climate so the Neanderthals may have been overpowered by them.”
However, according to other studies it seems there was some reproductive interaction with Homo sapiens before the Neanderthals died out. Dr Skrzypek said that especially blond blue-eyed people of European descent were likely to have between one and four per cent of Neanderthal genes.
Whatever the reason or reasons, the Neanderthals did not live beyond the last glaciation of Central Europe around 30,000 years ago.
Dr Skrzypek, Dr Grierson and other colleagues are now employing stable isotope techniques for various studies including assessment of evaporation rates from water holes in the Pilbara, tracing climate changes based on peat and tree-rings isotope composition.
“By using stable isotopes, we can tell a lot about environmental changes over time,” he said.
from UWANews 18 April 11 pg 6-7