In 2010, current genetic evidence suggests interbreeding took place with Homo sapiens sapiens (anatomically modern humans) between roughly 80,000 to 50,000 years ago in the Middle East, resulting in Caucasians and Asians having between 1% and 6% more Neanderthal DNA than indigenous sub-Saharan Africans. Specimens with combined Cro-Magnon and Neanderthal traits have also been found in Spain as recently as 40,000 BC suggesting long term and widespread intermingling of "anachronistic races" throughout history.
Neanderthal cranial capacity is thought to have been as large as that of Homo sapiens, in some cases larger, ranging from 1,500 cm3 to 1,650 cm3 (modern human 1,425-1,450 cm3). In 2008, a group of scientists created a study using three-dimensional computer-assisted reconstructions of Neanderthal infants based on fossils found in Russia and Syria, showing that they had brains as large as modern humans' at birth and larger than modern humans' as adults. On average, the height of Neanderthals was comparable to contemporaneous Homo sapiens. Neanderthal males stood about 165–168 cm (65–66 in), and were heavily built with robust bone structure. They were much stronger than Homo sapiens, having particularly strong arms and hands.
The Neanderthal is named after the Neanderthal valley, which is situated about 12 km (7.5 mi) east of Düsseldorf, Germany. The valley itself was named after the theologian Joachim Neander, who lived nearby in Düsseldorf in the late 17th century. The fossil discovered in the Neandertal in 1856, Neanderthal 1, was known as the "Neanderthal skull" or "Neanderthal cranium" in anthropological literature, and the individual reconstructed on the basis of the skull was occasionally called the "Neanderthal man."
Early Neanderthals lived in the Last Glacial age for a span of about 100,000 years. Because of the damaging effects the glacial period had on the Neanderthal sites, not much is known about the early species. Countries where their remains are known include most of Europe south of the line of glaciation, roughly along the 50th parallel north, including most of Western Europe, including the south coast of Great Britain, Central Europe and the Balkans, some sites in the Ukraine and in western Russia and outside of Europe in the Zagros Mountains and in the Levant.
Neanderthal fossils have to date not been found in Africa, but there have been finds rather close to Africa, both at Gibraltar and in the Levant. At some Levantine sites, Neanderthal remains in fact date after the same sites were vacated by Homo sapiens. Mammal fossils of the same time period show that cold-adapted animals were present alongside these Neanderthals in this region of the Eastern Mediterranean. This implies Neanderthals were better adapted biologically to cold weather than modern Homo sapiens and at times displaced modern Homo sapiens (Cro-Magnon) in parts of the Middle East when the climate got cold enough. Cro-Magnon appears to have been the only human type in the Nile River Valley during these periods, and Neanderthals are not known to have ever lived southwest of modern Israel.