A battle between unknowns

I recently got into a discussion with a history-buff friend about the unfortunate fact that everything we know about history is incomplete -- and generally speaking, the further back in time you go, the more incomplete it is.  She referenced human remains like Tollund Man, the Lady of Caviglione, and the Egtved Girl, all European burials that have been extensively studied.  Tollund Man is the most recent (estimated at around 400 B.C.E.) and the Lady of Caviglione by far the oldest (at around 24,000 years ago), but all three share an aura of mystery regarding who they were, raising questions we almost certainly will never have answers to.  There's evidence Tollund Man was the victim of a sacrifice, but by whom, and toward what end, is unknown.  And about the circumstances of the other two, we know next to nothing.

Compound this with the fact that for every body that has survived, at least in skeletal form, literally millions more have crumbled into dust and are completely gone.  Most of our history is, and will always remain, lost.

The reason this comes up is the excavation in the Tollense Valley of Germany of the site of an ancient battlefield, dating to around 1250 B.C.E.  It was discovered in 1996 when an amateur archaeologist was walking along the edge of the Tollense River and saw something protruding from the bank.  It turned out to be a human bone -- and since that time, over 12,500 bones and 300 bronze arrowheads have been recovered from the area.  It appears to have been the site of one of the oldest known battles in Europe.  Some of the finds were downright gruesome:

The skull of one of the battle's casualties -- with the arrowhead that killed him still embedded in his cranium [Image credit: Volker Minkus]

What is most curious about the site is not that a bunch of people fought and killed each other -- after all, humans have been doing that pretty much forever -- but that an analysis of the arrowheads shows that the battle was between two groups, one of which had traveled there from hundreds of kilometers away.  The Tollense River Valley is in Mecklenburg-Western Pomerania, and about half the arrowheads are of a design known to occur in archaeological sites from that area; but the other half are clearly of a different make, matching designs from much farther south, in Bavaria and Moravia.

"This suggests that at least a part of the fighters or even a complete battle faction involved in Tollense Valley derive from a very distant region," said Leif Inselmann, of the Free University of Berlin, who co-authored the paper on the study, which appeared this week in the journal Archaeology.

Who they were, and what brought them northward and into conflict with the residents there, are unknown, although there are some speculative possibilities.

"A causeway that crossed the Tollense River, constructed about five hundred years before the battle, is thought to have been the starting point of the conflict," said study co-author Thomas Terberger, of the University of Göttingen.  "The causeway was probably part of an important trade route.  Control of this bottleneck situation could well have been an important reason for the conflict...  This new information has considerably changed the image of the Bronze Age, which was not as peaceful as believed before.  The thirteenth century B.C.E. saw changes of burial rites, symbols and material culture.  I consider the conflict as a sign that this major transformation process of Bronze Age society was accompanied by violent conflicts.  Tollense is probably only the tip of the iceberg."

The fact is, though, the rest of that iceberg is likely to remain forever underwater.  Who the people were that fought and died in the now peaceful river valley in northern Germany is very likely going to stay a mystery, as will the reason that drove some of them to make the long trip from the forests of Bavaria.  It behooves us amateur students of history to remember not only the old adage that "history is written by the victors," but that the vast majority of history is completely forgotten by both sides -- what we don't know about our own past far outweighs what we do know.

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Paleobling

We are hardly the only animal species that sports adornments, but most of the others -- bright colors, flashy feathers, ornate fins, and so on -- are created by genes and produced by the animal's own body.  We're one of the only ones who fashion those adornments out of other objects.

It's a curious thing when you think about it.  Virtually everyone wears clothes even when there's no particular necessity for purposes of protection or warmth; and a great many of us don such accessories as ties, scarves, hats, necklaces, bracelets, and rings.  The significance of these objects is largely culturally-determined (e.g. in western society a guy wearing a tie is a professional, someone with a ring on the fourth left finger is probably married, and so on).  Some have ritual meanings (clothing or jewelry that marks you as belonging to a particular religion, for example).  Others are simply for the purpose of increasing attractiveness to one's preferred gender.

But the odd fact remains that in the animal world, such items are almost entirely confined to the human species.

However such practices got started, what's certain is that they go back a long way.  A study that came out in Nature this week, by a team led by Jack Baker of the University of Bordeaux, has shown that not only does jewelry-making and wearing go back at least 34,000 years, the jewelry styles of prehistoric Europe belong to nine discernibly different styles -- suggesting that beads, necklaces, and the like may have been used as markers for belonging to particular cultures.

A few of the shells, beads, teeth, and other trinkets used in the Baker et al. study

The study was comprehensive, analyzing artifacts from Paviland, Wales east to Kostenki, Russia, and covering a period of nearly ten thousand years.  "We've shown that you can have two [distinct] genetic groups of people who actually share a culture," Baker said.  "In the East, for example, they were very, very much more focused on ivory, on teeth, on stone.  But on the other side of the Alps, people would have adorned themselves with really flamboyant colors: reds, pinks, blues, really vibrant colors.  If you were to see one person from each group, you could say, ‘He's from the East, and he's from the West,’ at a quick glance."

The intricacy and complexity of a particular adornment, Baker said, were probably reflective of wealth or social status -- just as they are today.

Interestingly, there was no particularly good correlation between the genetic relatedness of two groups and the similarity in their jewelry.  As Baker put it, "This study has shown really nicely that genetics does not equal culture."

Given its ubiquity -- there are very few cultures that don't wear some sort of jewelry -- you have to wonder how it got started.  Who was the first early human who thought, "Hey, I could string this shell on a piece of leather and hang it around my neck"?  Why would that thought have occurred to him/her?

And how did the other early humans react?  I picture them looking at their necklace-wearing friend and saying something like the Gary Larson/The Far Side line, "Hey!  Look what Zog do!"

It's interesting to try to consider it from the standpoint of an alien scientist studying anthropology.  How would you answer the question, "Why are you wearing that bracelet?"  Okay, you think it looks good, but why?

I'm not sure I have an answer to that.

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Rehabilitating our cousins

The Neanderthals have gotten an undeservedly bad reputation.

"Neanderthal" has become an insult for someone perceived as dumb, crude, vulgar, lacking in any sort of refinement.  This perception wasn't helped any by Jean Auel's Clan of the Cave Bear and its sequels, where the "Clan" (the Neanderthals) are primitive, ugly, brutal people (personified by the violent and cruel Broud), contrasted to the beautiful, heroic, sophisticated Cro Magnons (such as virile, handsome, blue-eyed Jondalar, who is portrayed basically as a prehistoric Liam Hemsworth, only sexier).  The truth is way more complex than that; they certainly weren't unintelligent, and in fact, the most recent Neanderthals had an average brain size larger than a modern human's.  (I'm aware that brain size doesn't necessarily correlate with higher intelligence, but the depiction of them as tiny-brained primitives is almost certainly false.)

They had culture; the Mousterian tool complex, with its beautifully fluted stone arrowhead points, was Neanderthal in origin.  They were builders, weavers, jewelry-makers, and knew the use of medicinal plants.  There's evidence that they made music -- the Divje Babe flute, from 43,000 years ago, was made by Neanderthals from a bear femur, was probably made by Neanderthals.  The structure of the Neanderthal hyoid bone, and the presence of the FoxP2 gene, strongly suggests that they had the capacity for language, although cognitive scientist Philip Lieberman suggests that their mouth morphology would have made it difficult or impossible to articulate nasal sounds and the phonemes /a/, /i/, /u/, /ɔ/, /g/, and /k/, so any language they had probably wasn't as rich phonetically as ours are.  (Although that, too, is an overgeneralization; as I pointed out in a post only a month ago, the phonemic inventory of modern languages varies all over the place, with some only having a dozen or so distinct sounds.)

Another thing that people tend to get wrong is that the Neanderthals were displaced by modern Homo sapiens, and eventually driven to extinction, because we were smarter, faster, and more sophisticated.  Which is not only false, it carries that hint of self-congratulation that should be an immediate tipoff that there's more to it.  It's undeniable that our Neanderthal cousins did diminish and eventually disappear something on the order of forty thousand years ago, but what caused it is uncertain at best.  Other hypotheses regarding why they declined are climatic shifts, disease, and loss of food sources... and, most interestingly, that they interbred with, and were eventually subsumed by, modern humans.  Genetic analysis shows that a great many of us -- including most people of European ancestry -- contain genetic markers indicating Neanderthal ancestry.  Current estimates are that western Europeans have the highest percentage of Neanderthal DNA (at around four percent), while some groups, most notably sub-Saharan Africans, have almost none.

My own DNA apparently has 284 distinct Neanderthal markers, putting me in the sixtieth percentile.  So at least I'm above average in something.

[Image licensed under the Creative Commons Neanderthal-Museum, Mettmann, Homo sapiens neanderthalensis-Mr. N, CC BY-SA 4.0]

What brings this up is some new research indicating that the overlap between Neanderthals and anatomically modern humans may have lasted longer than we thought, and completely upends the picture of hordes of highly-advanced humans (led, of course, by Liam Hemsworth) sweeping over and destroying the primitive knuckle-dragging Neanderthal cave-dwellers.  Archaeologists working in the cave complex Grotte Mandrin, in the Rhône Valley of France, came upon a child's tooth and some stone tools (both of a distinctly modern sort), that date from 54,000 years ago -- a good twelve thousand years earlier than previous estimates.

"It wasn't an overnight takeover by modern humans," said Chris Stringer, of the Natural History Museum of London, who co-authored the paper.  "Sometimes Neanderthals had the advantage, sometimes modern humans had the advantage, so it was more finely balanced...  We have this ebb and flow.  The modern humans appear briefly, then there's a gap where maybe the climate just finished them off and then the Neanderthals come back again..  [W]e don't know the full story yet.  But with more data and with more DNA, more discoveries, we will get closer to the truth about what really happened at the end of the Neanderthal era."

Human history (and prehistory) are a lot more complex than you'd think on first glance, and it bears keeping in mind that usually when we build up a picture of something that happened in the past, we're working on (very) incomplete data filled in with guesses and surmises.  If a time machine is ever invented, and we can go back and look for ourselves, I think we'd be astonished at how much we missed -- or got flat wrong.

It reminds me of the famous quote by H. L. Mencken -- "For every problem, there is an answer that is clear, simple... and wrong."

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People made fun of Donald Rumsfeld for his statement that there are "known unknowns" -- things we know we don't know -- but a far larger number of "unknown unknowns," which are all the things we aren't even aware that we don't know.

While he certainly could have phrased it a little more clearly, and understand that I'm not in any way defending Donald Rumsfeld's other actions and statements, he certainly was right in this case.  It's profoundly humbling to find out how much we don't know, even about subjects about which we consider ourselves experts.  One of the most important things we need to do is to keep in mind not only that we might have things wrong, and that additional evidence may completely overturn what we thought we knew -- and more, that there are some things so far out of our ken that we may not even know they exist.

These ideas -- the perimeter of human knowledge, and the importance of being able to learn, relearn, change directions, and accept new information -- are the topic of psychologist Adam Grant's book Think Again: The Power of Knowing What You Don't Know.  In it, he explores not only how we are all riding around with blinders on, but how to take steps toward removing them, starting with not surrounding yourself with an echo chamber of like-minded people who might not even recognize that they have things wrong.  We should hold our own beliefs up to the light of scrutiny.  As Grant puts it, we should approach issues like scientists looking for the truth, not like a campaigning politician trying to convince an audience.

It's a book that challenges us to move past our stance of "clearly I'm right about this" to the more reasoned approach of "let me see if the evidence supports this."  In this era of media spin, fake news, and propaganda, it's a critical message -- and Think Again should be on everyone's to-read list.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

The climatic teeter-totter

I remember how blown away I was when I first saw British science historian James Burke's documentary After the Warming, shortly after its release in 1991.  Its intent was ambitious, to say the least; to trace the effects of climate on humanity, from prehistory up to and beyond the point where (in Burke's words) "the climate stopped doing things to us, and we started doing things to it."

What struck me most is something that at this point is much more widely known; that the periodic warming and cooling had dramatic effects on sea level.  Up during warm periods, down during cold ones, enough to open and close land passages from one place to the other.  The most famous is the "Bering Land Bridge" between what are now Siberia and Alaska, but similar pathways existed across what are now the English Channel and the Gulf of Carpentaria (between Australia and New Guinea).

It shouldn't have been surprising, science geek that I am, but I'd honestly never thought that much about it.  The idea that climatic shifts affected history in such a profound way was an eye-opener.  Take, for example, the Little Ice Age, that started in the mid-fourteenth century and continued into the eighteenth, which had dramatic effects on the climate of northern Europe.  Prior to this, it'd been warm enough that shipping lanes to places like Iceland, Greenland, and Svalbard were open all year long; very quickly, they became impassible ice in the winter, and plagued by devastating storms in the summer.  All of this shut down what had been a thriving avenue for commerce and colonization.  The Icelanders survived okay; but the Greenlanders weren't so lucky.  All of the Viking era Greenland settlements were frozen out by 1400.

The idea was such a poignant one to me -- thinking about what it would be like to be one of the last settlers left alive, knowing you were stranded -- that it inspired me to write a poem called "Greenland Colony 1375," which is not only one of the very few poems I've ever written, but is the only piece of writing I've ever won a prize for -- second place in the 1999 Writers' Journal national poetry contest, an honor that still kid of blows me away when I think about it.

The reason all this comes up is a new study that appeared this week in Proceedings of the National Academy of Science suggesting that major impacts on the human species have been happening for a lot longer than even Burke's documentary covered.  A climatic teeter-totter called the "Wake Circulation" caused a back-and-forth swing of wet and dry from the east to the west part of the African continent, much as the monsoons do on a yearly basis.

But this oscillation has a period of 100,000 years.

That's enough time for an entire ecosystem to form.  Then when the climate changes, what were great adaptations for that habitat suddenly aren't any more, and either you move or you die.  But one other possibility is to live in an ecotone -- the transitional area between two climatic regions.  Since the rainfall didn't disappear from the continent as a whole, just shifted from one side to the other, the ecotone regions didn't move much.  The organisms that made it through the climate shifts tended to be ones that lived in ecotones.

Guess where humanity evolved?

"This alternation between dry and wet periods appeared to have governed the dispersion and evolution of vegetation as well as mammals in eastern and western Africa," said Stefanie Kaboth-Bahr of the University of Potsdam, who led the study.  "The resultant environmental patchwork was likely to have been a critical component of human evolution and early demography as well."

[Image licensed under the Creative Commons Bjørn Christian Tørrissen, Serengeti-African-Elephants, CC BY-SA 3.0]

"We see the archaeological signatures of early members of our species all across Africa," said Eleanor Scerri, of the Max Planck Institute, who co-authored the study.  "Innovations come and go and are often re-invented, suggesting that our deep population history saw a constant saw-tooth like pattern of local population growth and collapse.  Ecotonal regions may have provided areas for longer term population continuity, ensuring that the larger human population kept going, even if local populations often went extinct."

So we may owe our success -- and possibly even our existence -- to our evolving in an ecological borderland, and surviving while other, more specialized, species became extinct when their biome's climate shifted.  

All of this, of course, makes me wonder what the long-term outcome of our current idiotic, la-la-la-la-not-listening climate policy will be.  Will our long-standing flexibility save us -- or will we be, like the tragic last settlers in Greenland, done in by our own short-sightedness?

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Astronomer Michio Kaku has a new book out, and he's tackled a doozy of a topic.

One of the thorniest problems in physics over the last hundred years, one which has stymied some of the greatest minds humanity has ever produced, is the quest for finding a Grand Unified Theory.  There are four fundamental forces in nature that we know about; the strong and weak nuclear forces, electromagnetism, and gravity.  The first three can now be modeled by a single set of equations -- called the electroweak theory -- but gravity has staunchly resisted incorporation.

The problem is, the other three forces can be explained by quantum effects, while gravity seems to have little to no effect on the realm of the very small -- and likewise, quantum effects have virtually no impact on the large scales where gravity rules.  Trying to combine the two results in self-contradictions and impossibilities, and even models that seem to eliminate some of the problems -- such as the highly-publicized string theory -- face their own sent of deep issues, such as generating so many possible solutions that an experimental test is practically impossible.

Kaku's new book, The God Equation: The Quest for a Theory of Everything describes the history and current status of this seemingly intractable problem, and does so with his characteristic flair and humor.  If you're interesting in finding out about the cutting edge of physic lies, in terms that an intelligent layperson can understand, you'll really enjoy Kaku's book -- and come away with a deeper appreciation for how weird the universe actually is.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Imaging behavior

When I first started teaching biology -- thirty-four years ago, which kind of seems impossible to me -- I always prefaced any discussion of fossils and extinct animals by emphasizing what fossils don't tell us.

"All the kids' books about prehistoric animals," I told my classes, "illustrate what the living animals looked like by making inferences based on current species.  A hundred years ago, the paleontologists thought of the dinosaurs as being big lizards; in fact, the word dinosaur comes from the Greek words for 'terrible lizard.'  Since that time we've discovered their relationship to birds, and it seems like there were a number of species covered with feathers, not scales.  The truth is, we have extraordinarily limited information about what the dinosaurs looked like from the outside, and almost nothing in the way of knowledge about their behavior.  Fossils just don't give us that information."

Well, I was wrong.

Maybe not in general; your average triceratops thigh bone doesn't tell you anything about the color of the animal it came from.  But paleontologists are getting better and better at figuring out amazing detail about the appearance and behavior of prehistoric animals using nothing but the preserved bones, and some astonishingly sensitive equipment to study them with.

Take the recent study of a wonderfully well-preserved skull of Thecodontosaurus, which lived about 205 million years ago and was an earlier cousin of such behemoths as Brachiosaurus and Diplodocus.  Thecodontosaurus itself wasn't that big -- about 1.5 meters tip-to-tail -- and little was known about its appearance and behavior, even such broad-brush features as whether it was bipedal or quadrupedal.

We now have some much better data to work from, thanks to a paper that appeared in the Zoological Journal of the Linnean Society last week.  A team made up of Antonio Ballell, J. Logan King, Emily Rayfield, and Michael Benton (of the University of Bristol) and James Neenan (of Oxford Univeristy) did a phenomenally detailed study of the skull, which was itself found near Bristol.  Using a combination of CT scans and imaging software, they reconstructed what the animal's brain -- long since decayed away -- looked like.

And from that, to determine how it behaved while it was alive.

"Even though the actual brain is long gone, the software allows us to recreate brain and inner ear shape via the dimensions of the cavities left behind," study lead author Antonio Ballell said, in a press release in Phys.org.  "The braincase of Thecodontosaurus is beautifully preserved so we compared it to other dinosaurs, identifying common features and some that are specific to Thecodontosaurus.  Its brain cast even showed the detail of the floccular lobes, located at the back of the brain, which are important for balance.  Their large size indicate it was bipedal.  This structure is also associated with the control of balance and eye and neck movements, suggesting Thecodontosaurus was relatively agile and could keep a stable gaze while moving fast...  This could also mean Thecodontosaurus could occasionally catch prey, although its tooth morphology suggests plants were the main component of its diet.  It's possible it adopted omnivorous habits."

Amazingly, all this was done without removing the skull from the rock that encased it, a process that often damages fine structures even if the researchers are as careful as possible while extracting it.  The CT scanner was able to see not only inside the rock but inside the skull itself, distinguishing the fossil from the sedimentary rock outside and inside, and the imaging software helped to clarify minuscule details of the interior of the brain case -- and thus details of the brain it once enclosed.

Study co-author Michael Benton said, "It's great to see how new technologies are allowing us to find out even more about how this little dinosaur lived more than 200 million years ago."

Thinking about prehistory has been a positive fascination of mine since I was a kid, and I remember how disappointed I was to find out that all the stripy and spotted and colorful pictures in my dinosaur books were "artists' renditions" -- i.e., made up and very probably wrong.  We're still not there with color, yet, although a single feather from Eocoracias, a kingfisher-relative that lived 47 million years ago, was so well-preserved that scientists were able to make a shrewd guess that it was blue in color, like many of its modern relatives.

We still have a long way to go, and it's likely that the ravages of time have erased the vast majority of the information that could clue us in on prehistoric animal behavior and appearance.  The fact that we can ascertain anything is itself remarkable.  And I'd wager that if we ever do time-travel back to the distant past, we'd be in for some serious surprises at how different everyone looked than the way we'd always pictured them.

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If you, like me, never quite got over the obsession with dinosaurs we had as children, there's a new book you really need to read.

In The Rise and Fall of the Dinosaurs: A New History of a Lost World, author Stephen Brusatte describes in brilliantly vivid language the most current knowledge of these impressive animals who for almost two hundred million years were the dominant life forms on Earth.  The huge, lumbering T. rexes and stegosauruses that we usually think of are only the most obvious members of a group that had more diversity than mammals do today; there were not only terrestrial dinosaurs of pretty much every size and shape, there were aerial ones from the tiny Sordes pilosus (wingspan of only a half a meter) to the impossibly huge Quetzalcoatlus, with a ten-meter wingspan and a mass of two hundred kilograms.  There were aquatic dinosaurs, arboreal dinosaurs, carnivores and herbivores, ones with feathers and scales and something very like hair, ones with teeth as big as your hand and others with no teeth at all.

Brusatte is a rising star in the field of paleontology, and writes with the clear confidence of someone who not only is an expert but has tremendous passion and enthusiasm.  If you're looking for a book for a dinosaur-loving friend -- or maybe you're the dino aficionado -- this one is a must-read.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

A window into the distant past

I love a good mystery, and mysteries abound regarding human prehistory.

Of course, that's kind of self-evident, given that it's pre-history.  Anything we know is based on inference, from looking at artifacts and other traces left behind for us to find.  And like fossils, we have to keep in mind that what we're seeing is a small percentage -- no one knows how small -- of what was originally out there.  (One of my biology professors said that trying to reconstruct the Tree of Life from the existing fossil record is analogous to reconstructing the entire History of Art from a dozen paintings or sculptures chosen at random from the tens of thousands that have been created by humanity.  This was before the use of genetic evidence for determining phylogeny, so the situation has improved -- but we're still working from inference and very incomplete evidence.)

So that's pretty much where we are with our knowledge of human prehistory.  Which is why when there are eye-opening new discoveries in that field, it always makes me sit up and take notice.

Today we're going to look at three new archeological finds that have given us a new lens into our distant ancestors' lives, and all of which were published in the last week.

First, some new artifacts from Scotland have provided information about one of the least-known European cultures -- the Picts.

The Picts were a collection of (probably) Celtic-speaking tribes that inhabited Scotland prior to its invasion first by the Irish Dál Riata and then by the Vikings.  We know next to nothing about them or their culture.  Even the name of the group isn't native to them -- it comes from the Latin pictus ("painted"), from their habit of going into battle naked, covered with paint.

Which, I have to admit, is pretty damn badass.

But we don't know much else about them, because they left no written records at all.  We assume they spoke a Celtic language, but don't really know for sure; and any suggestion of root words in Gaelic that may have come from Pictish are guesses (such as the claim that place names starting with Pit-, Lhan-, and Aber- come from Pictish words).

So any artifacts that are unequivocally Pictish in origin are pretty amazing.  Like the ones discovered earlier this year by Anne MacInnes of the North of Scotland Archaeological Society.

The face of the stone in the photograph not only has designs and a pretty cool-looking mythical beast, it has an inscription -- in Latin letters -- that may well be a Latin transliteration of the Pictish language.  Which makes it a rarity indeed.

"The two massive beasts that flank and surmount the cross are quite unlike anything found on any other Pictish stone," said John Borland, of Historic Environment Scotland and the Pictish Arts Society.  "These two unique creatures serve to remind us that Pictish sculptors had a remarkable capacity for creativity and individuality.  Careful assessment of this remarkable monument will be able to tell us much about the production of Pictish sculpture that we could never have guessed at."


Then, there's the discovery that was made near the Tollense River, on the Baltic coast of Germany, that indicates the existence of mercenary soldiers -- three thousand years ago.

On a historic -- well, prehistoric -- battleground, a team from the Lower Saxony State Agency for Cultural Heritage discovered, alongside skeletal remains showing war-related injuries, a toolkit brought in by one of the soldiers.  It contains a chisel, a knife, an awl, and a small sword, along with fasteners that seem to indicate its origin in southern Germany -- a distance of about five hundred miles.

"It was a surprise to find a battlefield site.  It was a second surprise to see a battlefield site of this dimension with so many warriors involved, and now it's a big surprise that we are dealing with a conflict of a European scale," says Thomas Terberger, co-author of the study.  "We had before speculated that some of these people might have come from the south.  Now we have, from our point of view, a quite convincing indication that people from southern Central Europe were involved in this conflict."

Suggesting that the man who carried the bag may have been a mercenary, although that is (of course) an inference.  So right around the time King David ruled the Israelites, there were professional soldiers waging war upon either other in northern Europe.

Last, we have a study showing that the Greek islands have been occupied for longer than we'd realized...

... a lot longer.

When most people in North America and Western Europe think of an "old civilization," they come up with Greece, Rome, Egypt, Sumer, China, India, the Inca, the Mayans...  but all of those (venerable and fascinating though they are) only date back a few thousand years.  The Great Pyramid at Giza, for example, was built around 3,500 years ago -- which seems like a lot.

But this new discovery shows that the island of Naxos was inhabited by our ancestors (and/or near relatives) two hundred thousand years ago.

At that point, they weren't exactly human, or at least not what we usually consider to be modern humanity.  These inhabitants of Naxos were Neanderthals, and had crossed into what is now an island during a time when the sea level was considerably lower because a lot of the water was locked up in glacial ice.

"Until now, the earliest known location on Naxos was the Cave of Zas, dated to 7,000 years ago," said project director Tristan Carter, an anthropologist at Ontario’s McMaster University.  "We have extended the history of the island by 193,000 years...  It was believed widely that hominin dispersals were restricted to terrestrial routes until the later Pleistocene, but recent discoveries are requiring scholars to revisit these hypotheses."

The word "Neanderthal" has, in common parlance, become synonymous with "uncultured cave man," and that characterization misses the mark by a mile.  They had culture -- they buried their dead, apparently made music, and may have even had spoken language (DNA studies show that they had the FOX-P2 gene, which is one of the genetic underpinnings of language in humans).  They made artifacts not only of utility but of great beauty:

A Neanderthal Acheulean hand-axe from about 50,000 years ago

Some of the archaeologists associated with the Naxos study even think the Neanderthal inhabitants of the island may not have walked there when the sea level was low -- they may actually have arrived there by boat.

Pretty smart folks, the Neanderthals.

It's also uncertain that they actually represent a different species from us.  Most of us carry Neanderthal genetic markers -- apparently I have three-hundred-odd of them, making me in the sixtieth percentile, cave-man-wise -- so there was definitely interbreeding between them and modern humans.  So they might be more correctly considered a subspecies -- although, as I've mentioned before, the concept of species is one of the wonkiest definitions in biology, and all attempts to refine it have resulted in more exceptions and contradictions than ever.

So probably best just to say that they're part of the family.

In any case, we've got three papers in one week that give us some very impressive new data on prehistory.  Until we invent time travel, this kind of evidence is about all we can rely on to create a picture of what life was like back then.  Which, even with the new information, leaves lots of room for refinement -- and imagination.

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In keeping with Monday's post, this week's Skeptophilia book recommendation is about one of the most enigmatic figures in mathematics; the Indian prodigy Srinivasa Ramanujan.  Ramanujan was remarkable not only for his adeptness in handling numbers, but for his insight; one of his most famous moments was the discovery of "taxicab numbers" (I'll leave you to read the book to find out why they're called that), which are numbers that are expressible as the sum of two cubes, two different ways.

For example, 1,729 is the sum of 1 cubed and 12 cubed; it's also the sum of 9 cubed and 10 cubed.

What's fascinating about Ramanujan is that when he discovered this, it just leapt out at him.  He looked at 1,729 and immediately recognized that it had this odd property.  When he shared it with a friend, he was kind of amazed that the friend didn't jump to the same realization.

"How did you know that?" the friend asked.

Ramanujan shrugged.  "It was obvious."

The Man Who Knew Infinity by Robert Kanigel is the story of Ramanujan, whose life ended from tuberculosis at the young age of 32.  It's a brilliant, intriguing, and deeply perplexing book, looking at the mind of a savant -- someone who is so much better than most of us at a particular subject that it's hard even to conceive.  But Kanigel doesn't just hold up Ramanujan as some kind of odd specimen; he looks at the human side of a man whose phenomenal abilities put him in a class by himself.

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