2010, a Good Year for Neandertals

A few posts back, we wrote on the publication in Science of DNA evidence that Neandertals (or Neanderthals) interbred with modern humans and that non-Africans have a bit of Neandertal DNA in them.

This raised my curiosity about our cave-dwelling ancestors and led me to read a very interesting survey of the history of paleoanthropology (i.e., the study of ancient humans) called The Neandertals:  Changing the Image of Mankind by Erik Trinkaus and Pat Shipman.  These authors make it quite clear that there has been plenty of back-and-forth among scholars over the relationship between modern humans (Homo sapiens) and Homo neanderthalensis, dating back to the first discovery of a Neandertal skull cap and other bones in a cave in Germany’s Neander Valley in 1856.

For example, during the last couple of decades, and bolstered by DNA evidence, the so-called “out of Africa hypothesis” advocating total replacement of Neandertals by modern humans has gained sway.  But this theory is opposed by another theory called multiregionalism, which emphasizes continuity through gene flow, i.e., interbreeding.

The recent finding of DNA evidence that Neandertals interbred with sapiens indicates at minimum that total replacement is unfounded and that the “out of Africa” hypothesis will need some modification, since Neandertals are unknown outside Europe and Western and Central Asia.

But as I learned from Trinkhaus and Shipman, the originator of the “out of Africa” theory, a German named Günter Bräuer, argued as early as the 1970s, based upon his study of late archaic hominids in Africa,

that modern Homo sapiens had arisen initially in Africa and migrated outward to populate the rest of the world.  Humans . . . moved northward into Europe and westward across the continent, until they encountered and hybridized with Neandertals. . . .  Consequently, he [Bräuer] believed that Neandertals were not replaced entirely by modern humans, for they had left some genetic contribution to future generations.  [emphasis added]

Nearly four decades ago Bräuer thus seems to have anticipated a theoretical position that fits quite well with the recent finding of interbreeding made by the Max Planck Institute, as they map the Neandertal genome.

But this isn’t the only recent finding of great import about Neandertals.  Earlier this year, archaeologists working in Southeastern Spain led by João Zilhão published evidence that Neandertals used painted seashells decoratively and symbolically.  It had previously been believed that Neandertals adopted body ornamentation from Cro-Magnons (the first anatomically modern humans), who are believed to have begun having contact with Neandertals about 40,000 years ago, but Zilhão’s team found a paint-decorated shell dated to 50,000 years ago, as many as 10,000 years before Cro-Magnons would have arrived in Europe.  This suggests that Neandertals had a capability for symbolic thought that was not previously understood.

Zilhão also believes he now has dating evidence for “evolutionarily significant admixture” between Neandertals and modern humans, what is known as the “Ebro Frontier” model which suggests widespread interbreeding of the two in Iberia before Neandertals died out there about 37,000 years ago, based largely upon the anatomical features of a four year-old child (known as the Lapedo Child) unearthed at the Lagar Velho, Portugal, and estimated to be about 24,000 years old, which exhibits “a mosaic” of Neandertal and modern features.  Remains found at the Isreali sites of Skhul and Qafzeh in the 1930s are also believed to be anatomically modern humans with some Neandertal features.

So, one might say it has been a rather good year for Neandertals, as it seems they’re looking more human with just about each new discovery these days.

Nonetheless, as Trinkaus and Shipman describe in their book, we’ve been through this before.  In the early twentieth century, for example, most paleoanthropologists thought of Neandertals as another species entirely different from Homo sapiens.  By the 1960s, however, they had been rehabilitated and humanized as “the first flower children” by an archaeologist who studied Neandertal remains at an Iraqi site called Shanidar, only to once again be cast into otherness by the “out of Africa” hypothesis and its advocates, such as Chris Stringer, ca. 1990, supported by strong mitochondrial DNA evidence indicating a fairly recent African origin for modern humans — until of course the discovery of interbreeding with Neandertals published in May.

But no doubt the pendulum will swing back again.

At any rate, if you’d like to read more about human evolution, try some of the books from this previous post.