The Neanderthals

An evolutionary chart from the National Geographic magazine (from the same article below) shows ancestral modern human and Neanderthal populations beginning to significantly diverge in 700,000 BC. Before that, the common ancestor of both modern humans and Neanderthals may have been Homo Heidelbergensis - though some anthropologists consider it a European species ancestral to the Neanderthals alone. Over the next 330,000 years interbreeding continues to lessen between the two diverging species and ceases altogether around 370,000 BC where the genetic trunklines by now greatly diverged in lineage from one another.  Dating to 195,000 BC the earliest known anatomically modern human fossil is discovered in Africa and then in Europe at 40,000 BC, thus giving evidence of the migration north by homo sapiens into the frozen ice lands of the Neanderthal. By 28,000 BC the last remaining Neanderthals have died out (or have been killed by homo sapiens) as is later explained.

Importantly, I thought to recite such an article as we continue examining the Evolutionary Theory of human development from both an archaeological-scientific viewpoint, as well as that of a biblical- theological viewpoint. And in so doing show just how far "modern Evangelical Creationism" differs from that of the earthen fossil and geological records uncovered in archaeological digs and genome projects during this past decade. Importantly, these discoveries bear directly upon the Genesis story of Adam and Eve, whether they are specific homo sapiens as named, or as collective representative populational figures for our race of men (as earlier discussed in several of RJS's opening articles - cf. "Faith and Science" categories in this blog).

To that end, I wish to recite the proposed scientific view of the homo sapien story through the eyes of the Neanderthal's gradual extinction (or extermination) as shown by fossil records, geographic digs and genome studies. In so doing, it is meant to better enlighten Christians to the necessity of expanding their understanding of the early biblical texts through a greater refinement of theologic examinations, suppositions, and theories. For if the Genesis story is untrue, than essentially human sin, comparisons of Christ to the figure of Adam, the groaning of creation until the time of eschatological redemption, and other important theological / biblical doctrines would make no sense and would have to be regulated to that of myth and fiction. Which I cannot argue.

And so, it is my suspicion that God enlighten ancient mankind found within the biblical records (specifically Genesis 1-11) to the degree that ancient man's "technology" and "worldview" was capable of understanding and explaining it (that is, God spoke to the ancients in such a way as to not confound their comprehension of His revelation). Thus, God utilized the ancient comprehension of that revelatory time without apologizing for stooping to ancient man's then current mythical understandings and worldviews. Thus, as seen within Genesis, it's ancient creation stories and creation metaphors are used to describe what neither the ancients (nor I suspect even modern man today) could clearly comprehend in describing the creation of the heavens and earth, day and night, light and dark, oceans and land, fishes and animals, man and woman, and the Sabbath Day of Rest.

Pointedly, God's revelation of creation in its theological implications still remains the same, but the "how" of explanation has become more refined as mankind has progress over the millenias. So then, rather than thinking of the ancient Genesis stories as "inaccurate" I would rather think of them as "incomprehensible" in their mythic retelling. But if described through today's modern physics and sciences I would suspect that it would be an even more difficult task to narrate unless science is abandoned and poetry is again used like it was in the ancient creation story of Genesis telling us of a loving God who created the worlds and mankind before sin destroyed its orders.

For if scientific explanation is sought we will loose the simplicity inherent in the mythic recounts of Genesis so espoused replacing its creation story with an even more "inscrutable" retelling through today's scientific languages and mathematical, linguistic paradoxes. Too, a thousand years from now, that scientific retelling will be dated and inaccurate. And thus we should not purport today's "evolutionary quests" across cosmological, geological, and anthropological studies as "anti-biblical" but rather read them as expanded testimonies to previously understood biblical records (by us moderns as well as by the ancients).

I suppose this then would put me in the "theistic-evolutionary" camp as an "evolutionary creationist," - although I still think of myself as a "creationist" but one who has necessarily refined and expanded his biblical understanding from a "paleo-creatinism" to a "(post)modern-creationism"; marking my theological understanding as different from that of earlier theologians who were less informed by their societies and civilization in previous decades and centuries before me. A good motto may then be, "As man grows in his sciences so must our theology grow."

And yet, as one exploring the theistic/evolutionary side of Christianity, I still must hold to the historical figures of Adam and Eve in a theologic sense, both as individuals and as representatives of mankind in the creation story of Genesis. For this bears upon the doctrine of original sin and its transmission to all mankind through the historical fall of two individuals. And not merely the Fall by a representative tribe or a representative species of mankind; for those communal/corporate examples are readily seen in the Tower of Babel, in Noah's story, in the Patriarchal covenants, and in Israel's Exodus, to mention a few within the biblical record as communal/corporate historical instances rather than as individual instances. Now perhaps we may have to relent to the re-examined Genesis records and allow for an historical representation rather than for  personal, individual transgression of sin in the Garden of Eden by two individuals, as many are now proposing. But for me, my bias is towards two individuals rather than to a corporate representatives from a group of people who have fallen and committed the human race to sin.

With that said, given the earth's fossil records, man's long genomic heritage, our current scientific studies in earth, rock, sky and sea - all have lent evidence to an ancient earth and an even more ancient cosmology. These are not "apparent-age" manifestations by God so as to mislead us, but mediated processes that have historically occurred according to what we're discovering in science through these past 100 years and more of inquiry and examination.

And so, "Yes," God uses evolution to bring the worlds and life into being. But "No," evolution is not a Christian's replacement of God for a God-less society. "Yes," evolution may tell us of our origins, but it also may speak to us of an ever present God mediating creation's continual birth as He gives life to man, and restores order redemptively to all.

Consequently, I intend to explore all areas around both the scientific and hermeneutical/theological nuances of these facts as they are currently understood. It will be an exploratory study that will be held in academic/scholastic tension - but one that I do not mind unwinding slowly while holding both sides up in equal parts to investigation. Thus, any and all pertinent discussions on evolutionary creationism must be examined whether we have answers or not. The questions in-and-of themselves are just as valuable to us. And so we will proceed, beginning here with a species antecedent to homo sapiens we call the Neanderthals. And in later documents we will discuss "Adam and Eve," "sin and redemption," "The Fall," "New Heavens and New Earth." These remain theological truths based upon past and future historical precedences and promise.

R.E. Slater
July 4, 2011

ps - forgive me for this extremely long blog article... but rather than split it up I wish to leave it wholly intact. If you must, please bookmark this article and read it in "sputters and spurts" and "parts and pieces." Thanks.

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Last of the Neanderthals

http://ngm.nationalgeographic.com/2008/10/neanderthals/hall-text.html

Eurasia was theirs alone for 200,000 years.

Then the newcomers arrived.

By Stephen S. Hall

Published: October 2008

Reconstruction by Kennis & Kennis/Photograph by Joe McNally

For the first time, a Neanderthal female peers from the past in a reconstruction

informed by both fossil anatomy and ancient DNA. At least some of her kind

carried a gene for red hair and pale skin.

Neanderthals, an intelligent and resilient human species, lived in Eurasia for some 200,000 years. Then about 28,000 years ago the last of them died. No one knows exactly what led to their extinction, but it was probably a combination of factors, including climate change and the arrival of modern humans in the region, around 45,000 years ago.

Since Neanderthals and modern humans overlapped for some 15,000 years, many wonder if they ever interbred. It's possible. But DNA studies show that Neanderthals were indeed a separate species, and no trace of Neanderthal DNA has been found in humans today. Yet Neanderthals had some genes that are similar to those in humans but evolved separately. Studying DNA MC1R, indicating that some Neanderthals would have had red hair, pale skin, and possibly freckles, though the gene is unlike the one in red-haired people today. Scientists also found that Neanderthals had a gene that's necessary for speech and language, FOXP2, though this one is identical to the gene in modern humans. No one knows if they could speak like us, but they at least had the genetic capacity for speech.

Rothberg, one of the scientists involved in the mapping. "Neanderthal [genome] is going to open the box. It's not going to answer the question, but it's going to tell where to look to understand all of those higher cognitive functions."

Bibliography

National Geographic (October 2008), 34-59.

Green, Richard, and others. "Analysis of One Million Base Pairs of Neanderthal DNA." Nature (November 16, 2006).

Lalueza-Fox, Carles, and others. "Neandertal Evolutionary Genetics; Mitochondrial DNA Data From the Iberian Peninsula." Molecular Biology and Evolution (February 2, 2005).

Moulson, Gier. "Neanderthal Genome Project Launches." MSNBC, July 20, 2006.

Noonan, James, and others. "Sequencing and Analysis of Neanderthal Genomic DNA." Science (November 17, 2006).

Featured Article

In March of 1994 some spelunkers exploring an extensive cave system in northern Spain poked their lights into a small side gallery and noticed two human mandibles jutting out of the sandy soil. The cave, called El Sidrón, lay in the midst of a remote upland forest of chestnut and oak trees in the province of Asturias, just south of the Bay of Biscay. Suspecting that the jawbones might date back as far as the Spanish Civil War, when Republican partisans used El Sidrón to hide from Franco's soldiers, the cavers immediately notified the local Guardia Civil.

But when police investigators inspected the gallery, they discovered the remains of a much larger—and, it would turn out, much older—tragedy.

Within days, law enforcement officials had shoveled out some 140 bones, and a local judge ordered the remains sent to the national forensic pathology institute in Madrid. By the time scientists finished their analysis (it took the better part of six years), Spain had its earliest cold case. The bones from El Sidrón were not Republican soldiers, but the fossilized remains of a group of Neanderthals who lived, and perhaps died violently, approximately 43,000 years ago. The locale places them at one of the most important geographical intersections of prehistory, and the date puts them squarely at the center of one of the most enduring mysteries in all of human evolution.

With their large brains and enormous strength, Neanderthals seemed equipped

to face any obstacle. But as the climate changed and a new kind of human

appeared on the landscape, their dwindling numbers sought refuge in the

highlands. The heights of northern Spain suggest the demanding environment

that confronted many Neanderthals late in their reign. The model grips a spear

to signify that females may have hunted with males.

The Neanderthals, our closest prehistoric relatives, dominated Eurasia for the better part of 200,000 years. During that time, they poked their famously large and protruding noses into every corner of Europe, and beyond—south along the Mediterranean from the Strait of Gibraltar to Greece and Iraq, north to Russia, as far west as Britain, and almost to Mongolia in the east. Scientists estimate that even at the height of the Neanderthal occupation of western Europe, their total number probably never exceeded 15,000. Yet they managed to endure, even when a cooling climate turned much of their territory into something like northern Scandi-navia today—a frigid, barren tundra, its bleak horizon broken by a few scraggly trees and just enough lichen to keep the reindeer happy.

By the time of the tragedy at El Sidrón, however, the Neanderthals were on the run, seemingly pinned down in Iberia, pockets of central Europe, and along the southern Mediterranean by a deteriorating climate, and further squeezed by the westward spread of anatomically modern humans as they emerged from Africa into the Middle East and beyond. Within another 15,000 years or so, the Neanderthals were gone forever, leaving behind a few bones and a lot of questions. Were they a clever and perseverant breed of survivors, much like us, or a cognitively challenged dead end? What happened during that period, roughly 45,000 to 30,000 years ago, when the Neanderthals shared some parts of the Eurasian landscape with those modern human migrants from Africa? Why did one kind of human being survive, and the other disappear?

On a damp, fog-shrouded morning in September 2007, I stood before the entrance to El Sidrón with Antonio Rosas of the National Museum of Natural Sciences in Madrid, who heads the paleoanthropological investigation. One of his colleagues handed me a flashlight, and I gingerly lowered myself into the black hole. As my eyes adjusted to the interior, I began to make out the fantastic contours of a karstic cave. An underground river had hollowed out a deep vein of sandstone, leaving behind a limestone cavern extending hundreds of yards, with side galleries spidering out to at least 12 entrances. Ten minutes into the cave, I arrived at the Galería del Osario—the "tunnel of bones." Since 2000, some 1,500 bone fragments have been unearthed from this side gallery, representing the remains of at least nine Neanderthals—five young adults, two adolescents, a child of about eight, and a three-year-old toddler. All showed signs of nutritional stress in their teeth—not unusual in young Neanderthals late in their time on Earth. But a deeper desperation is etched in their bones. Rosas picked up a recently unearthed fragment of a skull and another of a long bone of an arm, both with jagged edges.

"These fractures were—clop—made by humans," Rosas said, imitating the blow of a stone tool. "It means these fellows went after the brains and into long bones for the marrow."

Suited up to avoid contaminating her find, researcher Araceli Soto Flórez

bags a Neanderthal bone from El Sidrón cave in Spain. Fossils uncovered

here have yielded faint traces of ancient DNA. Genetic analysis provides

evidence for red hair, and perhaps a capacity for speech.

In addition to the fractures, cut marks left on the bones by stone tools clearly indicate that the individuals were cannibalized. Whoever ate their flesh, and for whatever reason—starvation? ritual?—the subsequent fate of their remains bestowed upon them a distinct and marvelous kind of immortality. Shortly after the nine individuals died—possibly within days—the ground below them suddenly collapsed, leaving little time for hyenas and other scavengers to scatter the remains. A slurry of bones, sediment, and rocks tumbled 60 feet into a hollow limestone chamber below, much as mud fills the inside walls of a house during a flood.

There, buffered by sand and clay, preserved by the cave's constant temperature, and sequestered in their jewel cases of mineralized bone, a few precious molecules of the Neanderthals' genetic code survived, awaiting a time in the distant future when they could be plucked out, pieced together, and examined for clues to how these people lived, and why they vanished.

The first clue that our kind of human was not the first to inhabit Europe turned up a century and a half ago, about eight miles east of Düsseldorf, Germany. In August 1856 laborers quarrying limestone from a cave in the Neander Valley dug out a beetle-browed skullcap and some thick limb bones. Right from the start, the Neanderthals were saddled with an enduring cultural stereotype as dim-witted, brutish cavemen. The size and shape of the fossils does suggest a short, stout fireplug of a physique (males averaged about five feet, five inches tall and about 185 pounds), with massive muscles and a flaring rib cage presumably encasing capacious lungs. Steven E. Churchill, a paleoanthropologist at Duke University, has calculated that to support his body mass in a cold climate, a typical Neanderthal male would have needed up to 5,000 calories daily, or approaching what a bicyclist burns each day in the Tour de France. Yet behind its bulging browridges, a Neanderthal's low-domed skull housed a brain with a volume slightly larger on average than our own today. And while their tools and weapons were more primitive than those of the modern humans who supplanted them in Europe, they were no less sophisticated than the implements made by their modern human contemporaries living in Africa and the Middle East.

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One of the longest and most heated controversies in human evolution rages around the genetic relationship between Neanderthals and their European successors. Did the modern humans sweeping out of Africa beginning some 60,000 years ago completely replace the Neanderthals, or did they interbreed with them? In 1997 the latter hypothesis was dealt a powerful blow by geneticist Svante Pääbo—then at the University of Munich—who used an arm bone from the original Neanderthal man to deliver it. Pääbo and his colleagues were able to extract a tiny 378-letter snippet of mitochondrial DNA (a kind of short genetic appendix to the main text in each cell) from the 40,000-year-old specimen. When they read out the letters of the code, they found that the specimen's DNA differed from living humans to a degree suggesting that the Neanderthal and modern human lineages had begun to diverge long before the modern human migration out of Africa. Thus the two represent separate geographic and evolutionary branches splitting from a common ancestor. "North of the Mediterranean, this lineage became Neanderthals," said Chris Stringer, research leader on human origins at the Natural History Museum in London, "and south of the Mediterranean, it became us." If there was any interbreeding when they encountered each other later, it was too rare to leave a trace of Neanderthal mitochondrial DNA in the cells of living people.

Taking DNA from a 38,000-year-old leg bone fragment found in
Croatia, scientists are spelling out the complete Neanderthal genetic code.

Results from the DNA sample suggest that Neanderthals and modern
humans are separate species, but do not rule out some interbreeding.

Pääbo's genetic bombshell seemed to confirm that Neanderthals were a separate species—but it does nothing to solve the mystery of why they vanished, and our species survived.

One obvious possibility is that modern humans were simply more clever, more sophisticated, more "human." Until recently, archaeologists pointed to a "great leap forward" around 40,000 years ago in Europe, when the Neanderthals' relatively humdrum stone tool industry—called Mousterian, after the site of Le Moustier in southwestern France—gave way to the more varied stone and bone tool kits, body ornaments, and other signs of symbolic expression associated with the appearance of modern humans. Some scientists, such as Stanford University anthropologist Richard Klein, still argue for some dramatic genetic change in the brain—possibly associated with a development in language—that propelled early modern humans to cultural dominance at the expense of their beetle-browed forebears.

But the evidence in the ground is not so cut and dried. In 1979 archaeologists discovered a late Neanderthal skeleton at Saint-Césaire in southwestern France surrounded not with typical Mousterian implements, but with a surprisingly modern repertoire of tools. In 1996 Jean-Jacques Hublin of the Max Planck Institute in Leipzig and Fred Spoor of University College London identified a Neanderthal bone in another French cave, near Arcy-sur-Cure, in a layer of sediment also containing ornamental objects previously associated only with modern humans, such as pierced animal teeth and ivory rings. Some scientists, such as British paleoanthropologist Paul Mellars, dismiss such modern "accessorizing" of a fundamentally archaic lifestyle as an "improbable coincidence"—a last gasp of imitative behavior by Neanderthals before the inventive newcomers out of Africa replaced them. But more recently, Francesco d'Errico of the University of Bordeaux and Marie Soressi, also at the Max Planck Institute in Leipzig, analyzed hundreds of crayon-like blocks of manganese dioxide from a French cave called Pech de l'Azé, where Neanderthals lived well before modern humans arrived in Europe. D'Errico and Soressi argue that the Neanderthals used the black pigment for body decoration, demonstrating that they were fully capable of achieving "behavioral modernity" all on their own.

"At the time of the biological transition," says Erik Trinkaus, a paleoanthropologist at Washington University in St. Louis, "the basic behavior [of the two groups] is pretty much the same, and any differences are likely to have been subtle." Trinkaus believes they indeed may have mated occasionally. He sees evidence of admixture between Neanderthals and modern humans in certain fossils, such as a 24,500-year-old skeleton of a young child discovered at the Portuguese site of Lagar Velho, and a 32,000-year-old skull from a cave called Muierii in Romania. "There were very few people on the landscape, and you need to find a mate and reproduce," says Trinkaus. "Why not? Humans are not known to be choosy. Sex happens."

It may have happened, other researchers say, but not often, and not in a way that left behind any evidence. Katerina Harvati, another researcher at the Max Planck Institute in Leipzig, has used detailed 3-D measurements of Neanderthal and early modern human fossils to predict exactly what hybrids between the two would have looked like. None of the fossils examined so far matches her predictions.

The disagreement between Trinkaus and Harvati is hardly the first time that two respected paleoanthropologists have looked at the same set of bones and come up with mutually contradictory interpretations. Pondering—and debating—the meaning of fossil anatomy will always play a role in understanding Neanderthals. But now there are other ways to bring them back to life.

Two days after my first descent into El Sidrón cave, Araceli Soto Flórez, a graduate student at the University of Oviedo, came across a fresh Neanderthal bone, probably a fragment of a femur. All digging immediately ceased, and most of the crew evacuated the chamber. Soto Flórez then squeezed herself into a sterile jumpsuit, gloves, booties, and plastic face mask. Under the watchful eyes of Antonio Rosas and molecular biologist Carles Lalueza-Fox, she delicately extracted the bone from the soil, placed it in a sterile plastic bag, and deposited the bag in a chest of ice. After a brief stop in a hotel freezer in nearby Villamayo, the leg bone eventually arrived at Lalueza-Fox's laboratory at the Institute of Evolutionary Biology in Barcelona. His interest was not in the anatomy of the leg or anything it might reveal about Neanderthal locomotion. All he wanted from it was its DNA.

Prehistoric cannibalism has been very good for modern-day molecular biology. Scraping flesh from a bone also removes the DNA of microorganisms that might otherwise contaminate the sample. The bones of El Sidrón have not yielded the most DNA of any Neanderthal fossil—that honor belongs to a specimen from Croatia, also cannibalized—but so far they have revealed the most compelling insights into Neanderthal appearance and behavior. In October 2007 Lalueza-Fox, Holger Römpler of the University of Leipzig, and their colleagues announced that they had isolated a pigmentation gene from the DNA of an individual at El Sidrón (as well as another Neanderthal fossil from Italy). The particular form of the gene, called MC1R, indicated that at least some Neanderthals would have had red hair, pale skin, and, possibly, freckles. The gene is unlike that of red-haired people today, however—suggesting that Neanderthals and modern humans developed the trait independently, perhaps under similar pressures in northern latitudes to evolve fair skin to let in more sunlight for the manufacture of vitamin D. Just a few weeks earlier, Svante Pääbo, who now heads the genetics laboratory at the Max Planck Institute in Leipzig, Lalueza-Fox, and their colleagues had announced an even more astonishing find: Two El Sidrón individuals appeared to share, with modern humans, a version of a gene called FOXP2 that contributes to speech and language ability, acting not only in the brain but also on the nerves that control facial muscles. Whether Neanderthals were capable of sophisticated language abilities or a more primitive form of vocal communication (singing, for example) still remains unclear, but the new genetic findings suggest they possessed some of the same vocalizing hardware as modern humans.

All this from a group of ill-fated Neanderthals buried in a cave collapse, soon after they were consumed by their own kind.

"So maybe it's a good thing to eat your conspecifics," says Pääbo.

A tall, cheerful Swede, Pääbo is the main engine behind a breathtaking scientific tour de force: the attempt, expected to be completed next month, to read out not just single Neanderthal genes, but the entire three-billion-letter sequence of the Neanderthal genome. Traces of DNA in fossils are vanishingly faint, and because Neanderthal DNA is ever so close to that of living people, one of the biggest hurdles in sequencing it is the ever present threat of contamination by modern human DNA—especially by the scientists handling the specimens. The precautions taken in excavating at El Sidrón are now becoming standard practice at other Neanderthal sites. Most of the DNA for Pääbo's genome project, however, has come from the Croatian specimen, a 38,000-year-old fragment of leg bone found almost 30 years ago in the Vindija cave. Originally deemed unimportant, it sat in a drawer in Zagreb, largely untouched and thus uncontaminated, for most of its museum life.

Now it is the equivalent of a gold mine for prehistoric human DNA, albeit an extremely difficult mine to work. After the DNA is extracted in a sterile laboratory in the basement of the Max Planck Institute, it is shipped overnight to Branford, Connecticut, where collaborators at 454 Life Sciences have invented machines that can rapidly decipher the sequence of DNA's chemical letters. The vast majority of those letters spell out bacterial contaminants or other non-Neanderthal genetic information. But in the fall of 2006, Pääbo and his colleagues announced they had deciphered approximately one million letters of Neanderthal DNA. (At the same time, a second group, headed by Edward Rubin at the Department of Energy Joint Genome Institute in Walnut Creek, California, used DNA provided by Pääbo to read out snippets of genetic code using a different approach.) By last year, dogged by claims that their work had serious contamination problems, the Leipzig group claimed to have improved accuracy and identified about 70 million letters of DNA—roughly 2 percent of the total.

"We know that the human and chimpanzee sequences are 98.7 percent the same, and Neanderthals are much closer to us than chimps," said Ed Green, head of biomathematics in Pääbo's group in Leipzig, "so the reality is that for most of the sequence, there's no difference between Neanderthals and [modern] humans." But the differences—less than a half percent of the sequence—are enough to confirm that the two lineages had begun to diverge around 700,000 years ago. The Leipzig group also managed to extract mitochondrial DNA from two fossils of uncertain origin that had been excavated in Uzbekistan and southern Siberia; both had a uniquely Neanderthal genetic signature. While the Uzbekistan specimen, a young boy, had long been considered a Neanderthal, the Siberian specimen was a huge surprise, extending the known Neanderthal range some 1,200 miles east of their European stronghold.

So, while the new genetic evidence appears to confirm that Neanderthals were a separate species from us, it also suggests that they may have possessed human language and were successful over a far larger sweep of Eurasia than previously thought. Which brings us back to the same hauntingly persistent question that has shadowed them from the beginning: Why did they disappear?

To coax a Neanderthal fossil to reveal its secrets, you can measure it with calipers, probe it with a CT scan, or try to capture the ghost of its genetic code. Or if you happen to have at your disposal a type of particle accelerator called a synchrotron, you can put it in a lead-lined room and blast it with a 50,000-volt x-ray beam, without disturbing so much as a single molecule.

Over a sleep-deprived week in October 2007, a team of scientists gathered at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, for an unprecedented "convention of jawbones." The goal was to explore a crucial question in the life history of the Neanderthals: Did they reach maturity at an earlier age than their modern human counterparts? If so, it might have implications for their brain development, which in turn might help explain why they disappeared. The place to look for answers was deep inside the structure of Neanderthal teeth.

"When I was young, I thought that teeth were not so useful in assessing recent human evolution, but now I think they are the most important thing," said Jean-Jacques Hublin, who had accompanied his Max Planck Institute colleague Tanya Smith to Grenoble.

Along with Paul Tafforeau of the ESRF, Hublin and Smith were squeezed into a computer-filled hutch at the facility—one of the three largest synchrotrons in the world, with a storage ring for energized electrons half a mile in circumference—watching on a video monitor as the x-ray beam zipped through the right upper canine of an adolescent Neanderthal from the site of Le Moustier in southwestern France, creating arguably the most detailed dental x-ray in human history. Meanwhile, a dream team of other fossils sat on a shelf nearby, awaiting their turn in the synchrotron's spotlight: two jawbones of Neanderthal juveniles recovered in Krapina, Croatia, dating back 130,000 to 120,000 years; the so-called La Quina skull from a Neanderthal youth, discovered in France and dating from between 75,000 to 40,000 years ago; and two striking 90,000-year-old modern human specimens, teeth intact, found in a rock shelter called Qafzeh in Israel.

When teeth are imaged at high resolution, they reveal a complex, three-dimensional hatch of daily and longer periodic growth lines, like tree rings, along with stress lines that encode key moments in an individual's life history. The trauma of birth etches a sharp neonatal stress line on the enamel; the time of weaning and episodes of nutritional deprivation or other environmental stresses similarly leave distinct marks on developing teeth. "Teeth preserve a continuous, permanent record of growth, from before birth until they finish growing at the end of adolescence," Smith explained. Human beings take longer to reach puberty than chimpanzees, our nearest living relatives—which means more time spent learning and developing within the context of the social group. Early hominin species that lived on the savanna in Africa millions of years ago matured fast, more like chimps. So when in evolution did the longer modern pattern begin?

To address this question, Smith, Tafforeau, and colleagues had previously used the synchrotron to demonstrate that an early modern human child from a site called Jebel Irhoud in Morocco (dated to around 160,000 years ago) showed the modern human life history pattern. In contrast, the "growth rings" in the 100,000-year-old tooth of a young Neanderthal discovered in the Scladina cave in Belgium indicated that the child was eight years old when it died and appeared to be on track to reach puberty several years sooner than the average for modern humans. Another research team, using a single Neanderthal tooth, had found no such difference between its growth pattern and that of living humans. But while a full analysis from the "jawbone convention" would take time, preliminary results, Smith said, were "consistent with what we see in Scladina."

"This would certainly affect Neanderthal social organization, mating strategy, and parenting behavior," says Hublin. "Imagine a society where individuals start to reproduce four years earlier than in modern humans. It's a very different society. It could also mean the Neanderthals' cognitive abilities may have been different from modern humans'."

Neanderthal society may have differed in another way crucial to group survival: what archaeologists call cultural buffering. A buffer is something in a group's behavior—a technology, a form of social organization, a cultural tradition—that hedges its bets in the high-stakes game of natural selection. It's like having a small cache of extra chips at your elbow in a poker game, so you don't have to fold your hand quite as soon. For example, Mary Stiner and Steven Kuhn of the University of Arizona argue that early modern humans emerged from Africa with the buffer of an economically efficient approach to hunting and gathering that resulted in a more diverse diet. While men chased after large animals, women and children foraged for small game and plant foods. Stiner and Kuhn maintain that Neanderthals did not enjoy the benefits of such a marked division of labor. From southern Israel to northern Germany, the archaeological record shows that Neanderthals instead relied almost entirely on hunting big and medium-size mammals like horses, deer, bison, and wild cattle. No doubt they were eating some vegetable material and even shellfish near the Mediterranean, but the lack of milling stones or other evidence for processing plant foods suggests to Stiner and Kuhn that to a Neanderthal vegetables were supplementary foods, "more like salads, snacks, and desserts than energy-rich staple foods."

Their bodies' relentless demand for calories, especially in higher latitudes and during colder interludes, probably forced Neanderthal women and children to join in the hunt—a "rough and dangerous business," write Stiner and Kuhn, judging by the many healed fractures evident on Neanderthal upper limbs and skulls. The modern human bands that arrived on the landscape toward the end of the Neanderthals' time had other options.

"By diversifying diet and having personnel who [did different tasks], you have a formula for spreading risk, and that is ultimately good news for pregnant women and for kids," Stiner told me. "So if one thing falls through, there's something else." A Neanderthal woman would have been powerful and resilient. But without such cultural buffering, she and her young would have been at a disadvantage.

Of all possible cultural buffers, perhaps the most important was the cushion of society itself. According to Erik Trinkaus, a Neanderthal social unit would have been about the size of an extended family. But in early modern human sites in Europe, Trinkaus said, "we start getting sites that represent larger populations." Simply living in a larger group has biological as well as social repercussions. Larger groups inevitably demand more social interactions, which goads the brain into greater activity during childhood and adolescence, creates pressure to increase the sophistication of language, and indirectly increases the average life span of group members. Longevity, in turn, increases intergenerational transmission of knowledge and creates what Chris Stringer calls a "culture of innovation"—the passage of practical survival skills and toolmaking technology from one generation to the next, and later between one group and another.

Whatever the suite of cultural buffers, they may well have provided an extra, albeit thin, layer of insulation against the harsh climatic stresses that Stringer argues peaked right around the time the Neanderthals vanished. Ice core data suggest that from about 30,000 years ago until the last glacial maximum about 18,000 years ago, the Earth's climate fluctuated wildly, sometimes within the space of decades. A few more people in the social unit, with a few more skills, might have given modern humans an edge when conditions turned harsh. "Not a vast edge," Stringer said. "Neanderthals were obviously well adapted to a colder climate. But with the superimposition of these extreme changes in climate on the competition with modern humans, I think that made the difference."

Which leaves the final, delicate—and, as Jean-Jacques Hublin likes to say, politically incorrect—question that has bedeviled Neanderthal studies since the Out of Africa theory became generally accepted: Was the replacement by modern humans attenuated and peaceful, the Pleistocene version of kissing cousins, or was it relatively swift and hostile?

"Most Neanderthals and modern humans probably lived most of their lives without seeing each other," he said, carefully choosing his words. "The way I imagine it is that occasionally in these border areas, some of these guys would see each other at a distance…but I think the most likely thing is that they excluded each other from the landscape. Not just avoided, but excluded. We know from recent research on hunter-gatherers that they are much less peaceful than generally believed."

"Sometimes I just turn out the lights in here and think what it must have been like for them."

Evolutionary biologist Clive Finlayson, of the Gibraltar Museum, was standing in the vestibule of Gorham's Cave, a magnificent tabernacle of limestone opening to the sea on the Rock of Gibraltar. Inside, fantastic excretions of flowstone drooled from the ceiling of the massive nave. The stratigraphy in the cave is pocked with evidence of Neanderthal occupation going back 125,000 years, including stone spearpoints and scrapers, charred pine nuts, and the remains of ancient hearths. Two years ago, Finlayson and his colleagues used radiocarbon dating to determine that the embers in some of those fireplaces died out only 28,000 years ago—the last known trace of Neanderthals on Earth. (Other hearths in the cave may be as young as 24,000 years old, but their dating is controversial.)

From pollen and animal remains, Finlayson has reconstructed what the environment was like from 50,000 to 30,000 years ago. Back then, a narrow coastal shelf surrounded Gibraltar, the Mediterranean two or three miles distant. The landscape was scrub savanna scented with rosemary and thyme, its rolling sand dunes interrupted by the occasional cork oak and stone pine, with wild asparagus growing in the coastal flats. Prehistoric vultures, some with nine-foot wingspans, nested high up in the cliff face, scanning the dunes for meals. Finlayson imagines the Neanderthals watching the birds circle and descend, then racing them for food. Their diet was certainly more varied than the typical Neanderthal dependence on terrestrial game. His research team has found rabbit bones, tortoise shells, and mussels in the cave, along with dolphin bones and a seal skeleton with cut marks. "Except for rice, you've almost got a Mousterian paella!" Finlayson joked.

But then things changed. When the coldest fingers of the Ice Age finally reached southern Iberia in a series of abrupt fluctuations between 30,000 and 23,000 years ago, the landscape was transformed into a semiarid steppe. On this more open playing field, perhaps the tall, gracile modern humans moving into the region with projectile spears gained the advantage over the stumpy, muscle-bound Neanderthals. But Finlayson argues that it was not so much the arrival of modern humans as the dramatic shifts in climate that pushed the Iberian Neanderthals to the brink. "A three-year period of intense cold, or a landslide, when you're down to ten people, could be enough," he said. "Once you reach a certain level, you're the living dead."

The larger point may be that the demise of the Neanderthals is not a sprawling yet coherent paleoanthropological novel; rather, it is a collection of related, but unique, short stories of extinction. "Why did the Neanderthals disappear in Mongolia?" Stringer asked. "Why did they disappear in Israel? Why did they disappear in Italy, in Gibraltar, in Britain? Well, the answer could be different in different places, because it probably happened at different times. So we're talking about a large range, and a disappearance and retreat at different times, with pockets of Neanderthals no doubt surviving in different places at different times. Gibraltar is certainly one of their last outposts. It could be the last, but we don't know for sure."

Whatever happened, the denouement of all these stories had a signatory in Gorham's Cave. In a deep recess of the cavern, not far from that last Neanderthal hearth, Finlayson's team recently discovered several red handprints on the wall, a sign that modern humans had arrived in Gibraltar. Preliminary analysis of the pigments dates the handprints between 20,300 and 19,500 years ago. "It's like they were saying, Hey, it's a new world now," said Finlayson.

**********

All Non-Africans Part Neanderthal,

Genetics Confirm

http://news.discovery.com/human/genetics-neanderthal-110718.html

A museum reconstruction of a Neanderthal/credit: iStockPhoto

Analysis by Jennifer Viegas
Mon Jul 18, 2011 10:25 AM ET

If your heritage is non-African, you are part Neanderthal, according to a new study in the July issue of Molecular Biology and Evolution. Discovery News has been reporting on human/Neanderthal interbreeding for some time now, so this latest research confirms earlier findings.

Damian Labuda of the University of Montreal's Department of Pediatrics and the CHU Sainte-Justine Research Center conducted the study with his colleagues. They determined some of the human X chromosome originates from Neanderthals, but only in people of non-African heritage.

"This confirms recent findings suggesting that the two populations interbred," Labuda was quoted as saying in a press release. His team believes most, if not all, of the interbreeding took place in the Middle East, while modern humans were migrating out of Africa and spreading to other regions.

The ancestors of Neanderthals left Africa about 400,000 to 800,000 years ago. They evolved over the millennia mostly in what are now France, Spain, Germany and Russia. They went extinct, or were simply absorbed into the modern human population, about 30,000 years ago.

Neanderthals possessed the gene for language and had sophisticated music, art and tool craftsmanship skills, so they must have not been all that unattractive to modern humans at the time.

"In addition, because our methods were totally independent of Neanderthal material, we can also conclude that previous results were not influenced by contaminating artifacts," Labuda said.

This work goes back to nearly a decade ago, when Labuda and his colleagues identified a piece of DNA, called a haplotype, in the human X chromosome that seemed different. They questioned its origins.

Fast forward to 2010, when the Neanderthal genome was sequenced. The researchers could then compare the haplotype to the Neanderthal genome as well as to the DNA of existing humans. The scientists found that the sequence was present in people across all continents, except for sub-Saharan Africa, and including Australia.

"There is little doubt that this haplotype is present because of mating with our ancestors and Neanderthals," said Nick Patterson of the Broad Institute of MIT and Harvard University. Patterson did not participate in the latest research. He added, "This is a very nice result, and further analysis may help determine more details."

David Reich, a Harvard Medical School geneticist, added, "Dr. Labuda and his colleagues were the first to identify a genetic variation in non-Africans that was likely to have come from an archaic population. This was done entirely without the Neanderthal genome sequence, but in light of the Neanderthal sequence, it is now clear that they were absolutely right!"

The modern human/Neanderthal combo likely benefitted our species, enabling it to survive in harsh, cold regions that Neanderthals previously had adapted to.

"Variability is very important for long-term survival of a species," Labuda concluded. "Every addition to the genome can be enriching."