Overview:

Neanderthals (the ‘th’ pronounced as ‘t’) are our closest extinct human relative. Some defining features of their skulls include the large middle part of the face, angled cheek bones, and a huge nose for humidifying and warming cold, dry air. Their bodies were shorter and stockier than ours, another adaptation to living in cold environments. But their brains were just as large as ours and often larger - proportional to their brawnier bodies.

Neanderthals made and used a diverse set of sophisticated tools, controlled fire, lived in shelters, made and wore clothing, were skilled hunters of large animals and also ate plant foods, and occasionally made symbolic or ornamental objects. There is evidence that Neanderthals deliberately buried their dead and occasionally even marked their graves with offerings, such as flowers. No other primates, and no earlier human species, had ever practiced this sophisticated and symbolic behavior.

DNA has been recovered from more than a dozen Neanderthal fossils, all from Europe; the Neanderthal Genome Project is one of the exciting new areas of human origins research.

History of Discovery:

Neanderthal 1 was the first specimen to be recognized as an early human fossil. When it was discovered in 1856 in Germany, scientists had never seen a specimen like it: the oval shaped skull with a low, receding forehead and distinct browridges, the thick, strong bones. In 1864, it became the first fossil hominin species to be named. Geologist William King suggested the name Homo neanderthalensis (Johanson and Edgar, 2006), after these fossils found in the Feldhofer Cave of the Neander Valley in Germany (tal—a modern form of thal—means “valley” in German). Several years after Neanderthal 1 was discovered, scientists realized that prior fossil discoveries—in 1829 at Engis, Belgium, and in 1848 at Forbes Quarry, Gibraltar—were also Neanderthals. Even though they weren’t recognized at the time, these two earlier discoveries were actually the first early human fossils ever found.

How They Survived:

Compared to early humans living in tropical Africa, with more abundant edible plant foods available year-round, the number of plant foods Neanderthals could eat would have dropped significantly during the winter of colder climates, forcing Neanderthals to exploit other food options like meat more heavily. There is evidence that Neanderthals were specialized seasonal hunters, eating animals were available at the time (i.e. reindeer in the winter and red deer in the summer). Scientists have clear evidence of Neanderthal hunting from uncovering sharp wooden spears and large numbers of big game animal remains were hunted and butchered by Neanderthals. There is also evidence from Gibraltar that when they lived in coastal areas, they exploited marine resources such as mollusks, seals, dolphins and fish. Isotopic chemical analyses of Neanderthal bones also tell scientists the average Neanderthal’s diet consisted of a lot of meat. Scientists have also found plaque on the remains of molar teeth containing starch grains—concrete evidence that Neanderthals ate plants.

The Mousterian stone tool industry of Neanderthals is characterized by sophisticated flake tools that were detached from a prepared stone core. This innovative technique allowed flakes of predetermined shape to be removed and fashioned into tools from a single suitable stone. This technology differs from earlier ‘core tool’ traditions, such as the Acheulean tradition of Homo erectus. Acheulean tools worked from a suitable stone that was chipped down to tool form by the removal of flakes off the surface.

Neanderthals used tools for activities like hunting and sewing. Left-right arm asymmetry indicates that they hunted with thrusting (rather than throwing) spears that allowed them to kill large animals from a safe distance. Neanderthal bones have a high frequency of fractures, which (along with their distribution) are similar to injuries among professional rodeo riders who regularly interact with large, dangerous animals. Scientists have also recovered scrapers and awls (larger stone or bone versions of the sewing needle that modern humans use today) associated with animal bones at Neanderthal sites. A Neanderthal would probably have used a scraper to first clean the animal hide, and then used an awl to poke holes in it, and finally use strips of animal tissue to lace together a loose-fitting garment. Neanderthals were the first early humans to wear clothing, but it is only with modern humans that scientists find evidence of the manufacture and use of bone sewing needles to sew together tighter fitting clothing.

Neanderthals also controlled fire, lived in shelters, and occasionally made symbolic or ornamental objects. There is evidence that Neanderthals deliberately buried their dead and occasionally even marked their graves with offerings, such as flowers. No other primates, and no earlier human species, had ever practiced this sophisticated and symbolic behavior. This may be one of the reasons that the Neanderthal fossil record is so rich compared to some earlier human species; being buried greatly increases the chance of becoming a fossil!

Evolutionary Tree Information:

Both fossil and genetic evidence indicate that Neanderthals and modern humans (Homo sapiens) evolved from a common ancestor between 700,000 and 300,000 years ago. Neanderthals and modern humans belong to the same genus (Homo) and inhabited the same geographic areas in western Asia for 30,000–50,000 years; genetic evidence indicate while they interbred with non-African modern humans, they ultimately became distinct branches of the human family tree (separate species).

In fact, Neanderthals and modern humans may have had little direct interaction for tens of thousands of years until during one very cold period when modern humans spread into Europe. Their presence may have prevented Neanderthals from expanding back into areas they once favored and served as a catalyst for the Neanderthal’s impending extinction. Over just a few thousand years after modern humans moved into Europe, Neanderthal numbers dwindled to the point of extinction. All traces of Neanderthals disappeared by about 40,000 years ago. The most recently dated Neanderthal fossils come from small areas of western Europe and the Near east, which was likely where the last population of this early human species existed.

Questions:

We don’t know everything about our early ancestors. But scientists are constantly in the field and the laboratory, excavating new areas and conducting analyses with groundbreaking technology, continually filling in some of the gaps about our understanding of human evolution. 

Below are some of the still unanswered questions about H. neanderthalensis that may be better answered with future discoveries: 

1. Will more studies of Neanderthal DNA help us identify what is unique about the modern human genome compared with our closest extinct relatives, the Neanderthals?
2. Is there a close correlation between climate change and the extinction of the Neanderthals, or was competition with modern humans the most important factor?
3. What was the relative contribution of animal and plant sources to the average Neanderthal's diet?
4. Were Neanderthals routinely symbolic (e.g. making ornamental or decorative objects, burying the dead), or did this just occur in specific populations? If the latter is the case, why did those populations exhibit these behaviors? 
5. What was the relationship between Neanderthals and the "Denisovans", a population of early humans known mainly from DNA, which overlapped with Neanderthals in time and space in Asia?

References:

First paper:

King, W., 1864. The reputed fossil man of the Neanderthal.  Quarterly Review of Science 1, 88-97.

Other recommended readings:

Trinkhaus, E., 1985. Pathology and the posture of the La Chappelle-aux-Saints Neanderthal. American Journal of Physical Anthropology 67, 19-41.

Trinkaus, E., Shipman, P., 1993. The Neanderthals: Changing the Image of Mankind. Knopf: New York.

Berger, T., Trinkaus, E., 1995. Patterns of trauma among the Neandertals. Journal of Archaeological Science 22, 841-852.

Schmitt, D., Churchill, S., 2003. Experimental evidence concerning spear use in Neandertals and early modern humans. Journal of Archaeological Science 30, 103-114.

Delson, E., Harvati, K., 2006. Return of the last Neanderthal. Nature 443, 762-763.

Lalueza-Fox, C., Römpler, H., Caramelli, D., Stäubert, C., Catalano, G., Hughes, D., Rohland, N., Pilli, E., Longo, L., Condemi, S., de la Rasilla, M., Fortea, J., Rosas, A., Stoneking, M., Schöneberg, T., Bertranpetit, J., Hofreiter, M., 2007. A Melanocortin 1 Receptor Allele Suggests Varying Pigmentation Among Neanderthals. Science 318, 1453-1455.

Stringer, C.B., Finlayson, J.C., Barton, R.N.E,  Fernández-Jalvo, Y., Cáceres, I., Sabin, R.C., Rhodes, E.J., Currant, A.P., Rodríguez-Vidal, J., Giles-Pacheco, F., Riquelme-Cantal, J.A., 2008. Neanderthal exploitation of marine mammals in Gibraltar. Proceedings of the National Academy of Sciences USA 105, 14319–14324.

Shipman, P., 2008. Separating "us" from "them": Neanderthal and modern human behavior. Proceedings of the National Academy of Sciences USA 105, 14241-14242.