Remains of Homo neanderthalensis have been found at sites throughout Europe, as well as in western Asia. Fossils assigned to this species are also found as far east as Uzbekistan in Central Asia. The sites from which this species is known, which are predominantly cave sites, date from roughly 400,000 years ago for the earliest genetic evidence and 200,000 for fossil evidence to as late as roughly 40,000 years ago. H. neanderthalensis displays many unique features, including features in the skull and postcranial skeleton (skeleton minus skull), which are related to their adaptation to hunting large game in cold environments. Homo neanderthalensis also had sophisticated stone tool technologies designed to hunt large mammals at close range. This species is important to human evolution because it was contemporary with Homo sapiens and is therefore crucial to our understanding of the origin of our species.
Many of the unique features possessed by H. neanderthalensis are found in the skull. As with Homo erectus, the general shape of the H. neanderthalensis skull is long and low with large brow ridges. Unlike those of H. erectus, however, the brow ridges of H. neanderthalensis form individual arches above each eye orbit (the evolutionary significance of heavy brow ridges, called supra orbital tori, is not certain; scientists are confident they did not act as a visor against the sun, did not contribute to the structural strength of the cranium, and were not needed as eye protection. Some researchers suggest they may have been part of a mate recognition system). In this way, the H. neanderthalensis skull resembles that of Homo heidelbergensis. The H. neanderthalensis skull is quite large, with brain sizes averaging over 1400 cubic centimeters (cc) in volume. Indeed, the brains of H. neanderthalensis were bigger than those of H. sapiens; when judged in relation to body size (see below), however, the brain of H. neanderthalensis is slightly smaller than that of H. sapiens.
The middle and lower parts of the face are positioned far forward relative to the braincase (a condition called “midfacial prognathism”), giving the zygomatics (cheek bones) a “swept back” appearance. The nasal aperture (hole for the nose) in H. neanderthalensis is large, especially when compared to those of H. sapiens. Because the widest point of the cranium (skull minus lower jaw) is across the middle of the braincase, the skull of H. neanderthalensis is oval-shaped when viewed from behind (the so-called “en bombe” shape). The braincase also exhibits unique features not found in other hominin species—e.g., occipital buns (thickened, projecting areas at the back of the skull) and suprainiac fossae (small depressions at the back of the skull, just above the occipital bun). The mandibles (lower jaws) are also large and bear molar teeth with “taurodontism,” a trait defined by large pulp chambers (the area below the enamel in which nerves and blood vessels reside).
The Neandertal postcranial skeleton also exhibits unique features. The entire postcranial skeleton is very heavily-built with thick bones. Individuals were short compared to modern humans; their bodies were also wider, with wider shoulders, rib cages, and hips. The limb bones were short, and the distal segments of the limbs (the bones of the forearm and lower leg) were particularly short. These features of the postcranial skeleton are similar to those seen in other mammals that live in cold environments. That is, the skeleton is short and wide to minimize surface area (thereby minimizing heat loss) while maintaining the same mass.
The fossil record of H. neanderthalensis is large, and this extensive record has allowed scientists to make interesting inferences about the lifestyle of this species using evidence gleaned from the skeleton. For example, the postcranial skeletons contain many healed fractures, particularly in the limb bones. Researchers suggest that these fractures are related to hunting dangerous prey at close range, although the fractures have not been directly linked to hunting behaviors.
Neandertal individuals were adept large game hunters, and this fact is reflected by the archaeological remains associated with them. They employed a technique for making stone tools called “prepared-core” or “Levallois” technique. This technique involves removing flakes from a core (source rock) in order to produce a flake (a chip of stone removed from a core) of a desired shape. In particular, chips of stone are removed around the perimeter of the core. A large flake is then removed from the “prepared” core; the shape of this flake is determined by how the original chips are from the core. The flake is then sharpened (and resharpened) by removing small flakes on the edges (a technique called “retouching”). In addition to points, this technique was also used to create other tools—particularly, many different kinds of scrapers. However, Neandertals also made nonprepared core tools. Specifically, many late Neandertal sites contain lithic assemblages (the entire collection of stone artifacts from an archaeological site) that were not made using the prepared-core technique and thus more closely resemble Acheulean tools. Distances between the sites where stone tools have been discovered and the location of the source of the raw material used to make the tools—often used as a proxy of the size of the range of hominin species—is greater in H. neanderthalensis than in Homo erectus, but less than that of H. sapiens. This evidence suggests that the ranges of Neandertal populations were intermediate between those of H. erectus and H. sapiens.
Members of H. neanderthalensis possessed important adaptations for dealing with the cold environments in which they lived. For example, Neandertal cave sites often contain hearths, and it is likely that individuals of this species used animal hides to insulate themselves from cold temperatures. H. neanderthalensis also produced stone tools that closely resemble those made by contemporary Homo sapiens in Europe. Although some scholars argue these tools reflect independent innovations, other scientists believe that these tools are evidence that Neandertals were copying the tools made by H. sapiens. This position is corroborated by the fact that these tools are normally found at H. neanderthalensis sites, which were close to and contemporary with H. sapiens sites. In addition, these tools are almost always produced using the same techniques used by H. neanderthalensis to make other tools. In other words, the evidence suggests that Neandertals made these H. sapiens-like tools using the same techniques they used to make tools prior to the arrival of H. sapiens. Thus, it seems more likely that these tools are the result of H. neanderthalensis copying the end-products of H. sapiens stone tool technology, rather than an independent invention.
Consensus regarding the evolutionary relationships between H. neanderthalensis and other hominin species has not been reached. This controversy largely involves the relationship of this taxon and H. sapiens. This issue is dealt with in greater detail elsewhere (read more on Homo sapiens), but the current, general consensus is that H. neanderthalensis was a separate species from H. sapiens and that, although some interbreeding may have occurred, H. neanderthalensis did not make a lasting genetic contribution to H. sapiens; although this belief may be changing.