Were Neanderthals a sub-species of modern humans? New research says no

Disappearance of Neanderthals likely the result of competition from Homo sapiens, and not from poor adaptation to cold

In an extensive, multi-institution study led by SUNY Downstate Medical Center, researchers have identified new evidence supporting the growing belief that Neanderthals were a distinct species separate from modern humans (Homo sapiens), and not a subspecies of modern humans.

The study looked at the entire nasal complex of Neanderthals and involved researchers with diverse academic backgrounds. Supported by funding from the National Science Foundation and the National Institutes of Health, the research also indicates that the Neanderthal nasal complex was not adaptively inferior to that of modern humans, and that the Neanderthals' extinction was likely due to competition from modern humans and not an inability of the Neanderthal nose to process a colder and drier climate.

Samuel Márquez, PhD, associate professor and co-discipline director of gross anatomy in SUNY Downstate's Department of Cell Biology, and his team of specialists published their findings on the Neanderthal nasal complex in the November issue of The Anatomical Record, which is part of a special issue on The Vertebrate Nose: Evolution, Structure, and Function (now online).

They argue that studies of the Neanderthal nose, which have spanned over a century and a half, have been approaching this anatomical enigma from the wrong perspective. Previous work has compared Neanderthal nasal dimensions to modern human populations such as the Inuit and modern Europeans, whose nasal complexes are adapted to cold and temperate climates.

However, the current study joins a growing body of evidence that the upper respiratory tracts of this extinct group functioned via a different set of rules as a result of a separate evolutionary history and overall cranial bauplan (bodyplan), resulting in a mosaic of features not found among any population of Homo sapiens. Thus Dr. Márquez and his team of paleoanthropologists, comparative anatomists, and an otolaryngologist have contributed to the understanding of two of the most controversial topics in paleoanthropology - were Neanderthals a different species from modern humans and which aspects of their cranial morphology evolved as adaptations to cold stress.

"The strategy was to have a comprehensive examination of the nasal region of diverse modern human population groups and then compare the data with the fossil evidence. We used traditional morphometrics, geometric morphometric methodology based on 3D coordinate data, and CT imaging," Dr. Márquez explained.

Anthony S. Pagano, PhD, anatomy instructor at NYU Langone Medical Center, a co-author, traveled to many European museums carrying a microscribe digitizer, the instrument used to collect 3D coordinate data from the fossils studied in this work, as spatial information may be missed using traditional morphometric methods. "We interpreted our findings using the different strengths of the team members," Dr. Márquez said, "so that we can have a 'feel' for where these Neanderthals may lie along the modern human spectrum."

Co-author William Lawson, MD, DDS, vice-chair and the Eugen Grabscheid research professor of otolaryngology and director of the Paleorhinology Laboratory of the Icahn School of Medicine at Mount Sinai, notes that the external nasal aperture of the Neanderthals approximates some modern human populations but that their midfacial prognathism (protrusion of the midface) is startlingly different. That difference is one of a number of Neanderthal nasal traits suggesting an evolutionary development distinct from that of modern humans. Dr. Lawson's conclusion is predicated upon nearly four decades of clinical practice, in which he has seen over 7,000 patients representing a rich diversity of human nasal anatomy.
Distinguished Professor Jeffrey T. Laitman, PhD, also of the Icahn School of Medicine and director of the Center for Anatomy and Functional Morphology, and Eric Delson, PhD, director of the New York Consortium in Evolutionary Primatology or NYCEP, are also co-authors and are seasoned paleoanthropologists, each approaching their fifth decade of studying Neanderthals. Dr. Delson has published on various aspects of human evolution since the early 1970's.

Dr. Laitman states that this article is a significant contribution to the question of Neanderthal cold adaptation in the nasal region, especially in its identification of a different mosaic of features than those of cold-adapted modern humans. Dr. Laitman's body of work has shown that there are clear differences in the vocal tract proportions of these fossil humans when compared to modern humans. This current contribution has now identified potentially species-level differences in nasal structure and function.

Dr. Laitman said, "The strength of this new research lies in its taking the totality of the Neanderthal nasal complex into account, rather than looking at a single feature. By looking at the complete morphological pattern, we can conclude that Neanderthals are our close relatives, but they are not us."

Ian Tattersall, PhD, emeritus curator of the Division of Anthropology at the American Museum of Natural History, an expert on Neanderthal anatomy and functional morphology who did not participate in this study, stated, "Márquez and colleagues have carried out a most provocative and intriguing investigation of a very significant complex in the Neanderthal skull that has all too frequently been overlooked." Dr. Tattersall hopes that "with luck, this research will stimulate future research demonstrating once and for all that Homo neanderthalensis deserves a distinctive identity of its own."

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The article in The Anatomical Record is entitled, "The Nasal Complex of Neanderthals: An Entry Portal to their Place in Human Ancestry." It is available online at: http://onlinelibrary.wiley.com/doi/10.1002/ar.23040/full.

SURPRISING EUROPEAN ANCESTORS

Left:The Stuttgart skull, from a 7,000-year-old skeleton found in Germany among artifacts from the first widespread farming culture of central Europe. Right: Blue eyes and dark skin, that's how the European hunter-gatherer appeared 7,000 years ago. Artist depiction based on La Braña 1, whose remains were recovered at La Braña-Arintero site in León, Spain. Courtesy of the Consejo Superior de Investigaciones Cientificas

What if you researched your family's genealogy, and a mysterious stranger turned out to be an ancestor?

That's the surprising feeling had by a team of scientists who peered back into Europe's murky prehistoric past thousands of years ago. With sophisticated genetic tools, supercomputing simulations and modeling, they traced the origins of modern Europeans to three distinct populations.

The international research team published their September 2014 results in the journal Nature.

XSEDE, the Extreme Science and Engineering Discovery Environment, provided the computational resources used in the study. It's a single virtual system that scientists use to interactively share computing resources, data and expertise.

Genomic analysis code ran on Stampede, the nearly 10 petaflop Dell/Intel Linux supercomputer at the Texas Advanced Computing Center (TACC). The research was funded in part by the National Cancer Institute of the National Institutes of Health.

The 8,000 year-old skull discovered in Loschbour, Luxembourg provided DNA evidence for the study of European ancestry. Scientists really only have a handful of ancient remains well-preserved enough for their genomes to be sequenced. The remains studied were found at the caves of Loschbour, La Braña, Stuttgart, a ritual site at Motala, and at Mal'ta.

"The main finding was that modern Europeans seem to be a mixture of three different ancestral populations," said study co-author Joshua Schraiber, a National Science Foundation Postdoctoral fellow at the University of Washington. 

Schraiber said these results surprised him because the prevailing view among scientists held that only two distinct groups mixed between 7,000 and 8,000 years ago in Europe, as humans first started to adopt agriculture.

Hunter-gatherers with olive skin and mainly blue-eyes first expanded upon the continent about 12,000 years ago, moving north with the retreat of glaciers at the end of the last Ice Age. Later, early European farmers from the Near East migrated west and mixed with the hunter-gatherers. Genetic evidence revealed these farmers had light-colored skin and brown eyes.

The third mystery group that emerged from the data is ancient northern Eurasians.  "People from the Siberia area is how I conceptualize it. We don't know too much anthropologically about who these people are. But the genetic evidence is relatively strong, because we do have ancient DNA from an individual that's very closely related to that population, too," Schraiber said.

"Having access to the TACC was really essential for me because at some point I was using a hundred gigabytes of RAM to do something."

Joshua Schraiber, National Science Foundation Postdoctoral fellow, University of Washington

That individual is a three-year-old-boy whose remains were found near Lake Baikal in Siberia at a site called Mal'ta. Scientists determined his arm bone to be 24,000 years old. They then sequenced his genome, making it thesecond oldest one yet sequenced of a modern human.  Interestingly enough, in late 2013 scientists used the Mal'ta genome to find that about one-third of Native American ancestry originated through gene flow from these ancient North Eurasians.

"I think there was a little bit of luck in this," Schraiber said, referring to the Mal'ta genome. "We knew the models weren't fitting. But we didn't know what was wrong. Luckily, this new ancient DNA had come out."

What scientists did was take the genomes from these ancient humans and compare them to those from 2,345 modern-day Europeans.  "I used the POPRES data set, which had been used before to ask similar questions just looking at modern Europeans," Schraiber said. "And then I used a piece of software called Beagle, which was written by Brian Browning and Sharon Browning at the University of Washington, which computationally detects these regions of identity by descent."

The heavy demand on CPU time and RAM caused a bottleneck in the analysis. "Having access to the Stampede supercomputer at TACC was essential for me because at some point I was using a hundred gigabytes of RAM to do something. It took days, even spreading it across multiple processors. It takes a lot of effort to do this identity by descent detection," Schraiber said.

Working on the hunch that the Mal'ta genome might fill in some missing blanks that the modeling pointed out, Schraiber saw a lot more identity by descent between the ancient individuals and modern individuals than he expected. "It made us happy in a lot of ways to find that these are people who share ancestors with modern Europeans." 

Schraiber looks to East Asia and Africa as the next hot spots to study human history as scientists push forward to discover and analyze new sources of ancient DNA.

"Using archeological evidence tells you a lot. Modern DNA tells you a lot. But it's by combining the two and getting ancient DNA, which is anthropological evidence and genetic evidence at the same time, you're able to unravel these things. You're able to find complexity that you just didn't know was there before," he said.

Population boom, droughts contributed to collapse of ancient Assyrian Empire

There’s more to the decline of the once mighty ancient Assyrian Empire than just civil wars and political unrest. Archaeological, historical, and paleoclimatic evidence suggests that climatic factors and population growth might also have come into play. This is theopinion of Adam Schneider of the University of California-San Diego in the US, and Selim Adalı of the Research Center for Anatolian Civilizations in Turkey, published in Springer’s journal Climatic Change.

In the 9th century BC, the Assyrian Empire of northern Iraq relentlessly started to expand into most of the ancient Near East. It reached its height in the early 7th century BC, becoming the largest of its kind in the Near East up to that time. The Assyrian Empire’s subsequent quick decline by the end of the 7th century has puzzled scholars ever since. Most ascribe it to civil wars, political unrest, and the destruction of the Assyrian capital, Nineveh, by a coalition of Babylonian and Median forces in 612 BC. Nevertheless, it has remained a mystery why the Assyrian state, the military superpower of the age, succumbed so suddenly and so quickly.

Schneider and Adalı argue that factors such as population growth and droughts also contributed to the Assyrian downfall. Recently published paleoclimate data show that conditions in the Near East became more arid during the latter half of the 7th century BC. During this time, the region also experienced significant population growth when people from conquered lands were forcibly resettled there. The authors contend that this substantially reduced the state’s ability to withstand a severe drought such as the one that hit the Near East in 657 BC. They also note that within five years of this drought, the political and economic stability of the Assyrian state had eroded, resulting in a series of civil wars that fatally weakened it.

“What we are proposing is that these demographic and climatic factors played an indirect but significant role in the demise of the Assyrian Empire,” says Schneider.

Schneider and Adalı further draw parallels between the collapse of the Assyrian Empire and some of the potential economic and political consequences of climate change in the same area today. They point out, for instance, that the onset of severe drought which, followed by violent unrest in Syria and Iraq during the late 7th century BC, bears a striking resemblance to the severe drought and subsequent contemporary political conflict in Syria and northern Iraq today. On a more global scale, they conclude, modern societies can take note of what happened when short-term economic and political policies were prioritized rather than ones that support long-term economic security and risk mitigation.

“The Assyrians can be ‘excused’ to some extent for focusing on short-term economic or political goals which increased their risk of being negatively impacted by climate change, given their technological capacity and their level of scientific understanding about how the natural world worked,” adds Selim Adalı. “We, however, have no such excuses, and we also possess the additional benefit of hindsight. This allows us to piece together from the past what can go wrong if we choose not to enact policies that promote longer-term sustainability.“

Reference: Schneider, A.W. & Adalı, S.F. (2014). “No harvest was reaped”: demographic and climatic factors in the decline of the Neo-Assyrian Empire. Climatic Change. DOI 10.1007/s10584-014-1269-y

Ancient DNA, recovered from one of the earliest known Europeans, now provides unique insights into the history of the continent

DNA recovered from a 36,000 year old fossil skeleton found in Russia shows early divergence of Eurasians once they had left Africa, and the deep shared ancestry of Europeans.

The new study, carried out by an international team of researchers, also reveals when Neanderthals and early modern humans out of Africa interbred - around 54,000 years ago, before the modern human population began to differentiate.

The study was led by the Centre for GeoGenetics at the University of Copenhagen, in collaboration with scientists from several institutions, including Cambridge, UC Berkeley, Griffith, Texas A&M, California San Francisco, and the Peter the Great Museum of Anthropology and Ethnography (Kunstkamera) RAS.

Early European history

Ancient DNA, recovered from one of the earliest known Europeans, now provides unique insights into the history of the continent. The complete genome of an individual who died more than 36,000 years ago at the site of Kostenki 14 (also known as Markina Gora) in westernmost Russia was recovered and sequenced. The Kostenki 14 genome shows that once people had dispersed beyond the African homeland into Eurasia, they separated early - before 36,000 years ago - into at least three populations whose descendants would develop the unique features that reflect the core of the diversity of non-African peoples.

Ancient genomes show the European meta-population

Since then, despite major fluctuations in climate, one of these groups - Palaeolithic Europeans - persisted as a population, ebbing and flowing by moments of contraction and expansion, but persisting intertwined until the arrival of farmers from the Middle East in the last 8,000 years, with whom they mixed extensively. Lundbeck Foundation Professor Eske Willerslev, leader of the research team, says:

"What we can see from Kostenki and other ancient genomes is that for 30,000 years there was a single meta-population in Europe. These Palaeolithic hunter-gatherer groups split up, mixed, dispersed and changed, and through ancient genomes we can trace the genetic thread of their shared ancestry".
Across time the distribution changed, sometimes spreading far to the east, sometimes probably more fragmented, but surviving continuously. Martin Sikora and Ludovic Orlando from the Centre for GeoGenetics in Copenhagen add:

"For example, the genome reveals that the people from Kostenki contributed genes to the ancestors of the boy from Mal'ta, who lived in Siberia 26,000 years ago, and whose descendants spread as far as Europe and the Americas.

Marta Mirazón Lahr and Robert Foley from the University of Cambridge's Leverhulme Centre for Human Evolutionary Studies say:

"It is not just a question of who they were, but what it tells us about how they lived. That there was continuity from the earliest Upper Palaeolithic to the Mesolithic, across a major glaciation, is a great insight into the evolutionary processes underlying human success."

It was only when farmers from the Near East arrived about 8,000 years ago, that the structure of the European population changed significantly.

A 54,000 year old encounter

The genome of the man from Kostenki held other secrets as well. One of these is that, like all people of Eurasia today, his genome included a small percentage of Neanderthal genes. This confirms earlier findings which showed that early in the human colonisation of Eurasia there was an isolated admixture event with the Neanderthals. But being that much closer in age to the event, the Kostenki genome throws new light on this. Professor Rasmus Nielsen from the University of California at Berkeley explains:

"Kostenki 14 actually has a slightly higher percentage of Neanderthal genes than ever observed before, and the genetic fragments that the man from Kostenki inherited from a Neanderthal ancestor are larger, not yet broken by the thousands of natural recombination events that have occurred since. This allowed us to estimate the time of human-Neanderthal admixture to 54,000 years ago".

Early European-Asian split

But that is not all. A portion of the Kostenki genome was not passed on to Palaeolithic Europe, but is instead found in the population from the Middle East who brought farming and a lighter skin colour to Europe 30,000 years later.

Andaine Seguin-Orlando and Thorfinn Korneliussen from the Centre for GeoGenetics in Copenhagen say:
"This unique element of the Kostenki genome confirms the presence of a yet unmapped major population lineage in Eurasia. That population separated early on from the ancestors of other Eurasians, both Europeans and eastern Asians".

Identifying the fossil and archaeological remains that map the evolutionary history and adaptations of this population is now a major challenge. Professor Eske Willerslev ends:

"Ancient genomes add a time and space stamp to our genetic history. Recovering the whole genome, rather than just small fragments as happened in the past, adds the power of genomics. This reveals the complex web of population relationships in the past, generating for the first time a firm framework with which to explore how humans responded to climate change, encounters with other populations, and the dynamic landscapes of the ice age".