The narwhal: a serious case of nerves

"Narwhal or unicorn"

Timeline, 2006: The narwhal has a history as striking as the animal itself. Vikings kept the narwhal a secret for centuries even as they peddled its “horn” as that of a unicorn. Narwhal tusks were so prized that monarchs paid the equivalent of the cost of a castle just to have one. They were thought to have magic powers, render poison ineffective, cure all manner of diseases, and foil assassins.

A tooth and nothing but a tooth

As it turns out, the horn is really just a tooth, an extremely long, odd, tooth. The narwhal tusk, which usually grows only on males from their left upper jaw, can reach lengths of six feet or more. Sometimes, males will grow two tusks, one on each side. The tooth turns like a corkscrew as it grows, stick straight, from the narwhal’s head. They are such an odd sight that scientists have been trying to figure out for centuries exactly what that tusk might be doing there.

Some have posited that the narwhal uses the tusks in epic battles with other male narwhals. Others have fancifully suggested that the animal might use the long tooth to break through the ice, ram the sides of ships (nevermind the disconnect between when the tusk arose and when ships entered the scene), or to skewer prey—although no one seems to have addressed how the narwhal would then get the prey to its mouth.

Gentle tusk rubbing

The facts are that the narwhal rarely, if ever, appears to duel with other narwhals. Its primary use of the tusk appears to be for tusking other males, in which the animals gently rub tusks with one another. They also may be used in mating or other activities, although that has not yet been demonstrated. But what has been discovered is that the narwhal ought to be suffering from a severe case of permanent toothache.

Arctic cold strikes a narwhal nerve

Anyone who has ever had exposed nerves around their teeth knows that when cold hits those nerves, the pain usually sends us running for the dentist. Now imagine that your tooth is six feet long, has millions of completely exposed nerve endings, and is constantly plunged in the icy waters of the Arctic. You’ve just imagined being a narwhal.

Dentist on ice

A clinical instructor at the Harvard School of Dental Medicine who thinks of nothing but teeth made this discovery about the narwhal. The instructor, Martin Nweeia, can wax rhapsodic about teeth and how central they are to our health and the stories they can tell even about how we lived and died. He has carried his tooth obsession beyond his own species, however; his passion led him to spend days on Arctic ice floes, watching for the elusive narwhal, or at least one of the tusks, to emerge from the deadly cold water. He also befriended the local Inuit, who rely on the narwhal as a source of food and fuel oil.

His fascination and rapport with the Inuit people ended with his viewing several specimens of narwhal tusks. What he and his colleagues discovered astonished them. The tusks appeared to consist of open tubules that led straight to what appear to be millions of exposed nerve endings. In humans, nerve tubules are never open in healthy teeth. But in the narwhal tusk, which is an incredible example of sexual dimorphism and the only spiral tooth known in nature today, these open tubules were the norm.

Sensory tooth

The researchers speculated that the animals may use this enormous number of naked nerves as a finely sensitive sensory organ. In addition, it is possible that the teeth transmit voltage through a process called the piezo effect, in which crystals generate voltage when a mechanical force rattles them. In the case of the narwhal, who swim quickly through the water, water pressure might provide the force. Because narwhals are among the most vocal of whales, the tusks could also be sound sensors.

Why would dentists be so interested in the tusks of a whale? Examinations of the narwhal tusks have revealed that they are incredibly flexible, unlike our teeth, which are strong but also rigid and comparatively brittle. It is possible that understanding the narwhal tusk might have clinical applications for developing flexible dental materials for restoring pearly whites in people.

Chinese winemaking aged 9000 years

Tracking ancient alcohol production is tough

The fermented grain has been the centerpiece of much of the development of human civilization. According to archaeologists, wines and beers contributed to the formation of religious practices, commerce, social interactions, and community structure. So it’s only natural that we would want to find out how and when we began purposely making such beverages to imbibe.

But alcohol evaporates easily, and being a liquid, isn’t usually preserved for archaeologists to discover thousands of years after the fact. Yet scientists have managed to get lucky and to apply a little smarts to figuring out the mysteries of ancient alcohols, and some of the best information on such beverages is now coming out of China.

The dawn of “real” human civilization?

In China, there is a famed Neolithic archaeological site where some of the oldest musical instruments and Chinese pictographs have been found. The Neolithic age, or New Stone Age, dates back to about 8000 or 9000 years, and this particular site in northern China has yielded abundant resources for investigations into the period, often viewed as the dawn of real human civilization.

Among these resources are pieces of pottery from vessels used to hold liquids. Researchers determined that these pots probably held fermented beverages because they were so similar to vessels from later periods that were known to have stored wines. To investigate their ideas, they collected pieces from the bottoms of 16 different vessels from the northern China site. The bottoms of the pots, they reasoned, would have absorbed more of the liquid and precipitates than the sides, and would thus yield more information.

Archaeo-chemists identify fine old vintage

Using various methods to identify the chemical makeup of the residues on the pots, the archaeo-chemists, as they are called, determined that the vessels once held wines made of rice or millet and flavored with tree resins, honey, and flowers. The methods they used, which included gas and liquid chromatography and mass spectrometry, pinpointed the flower residues as hawthorn or wild grape. One key component they identified was tartaric acid, which is the primary organic acid in grape wine.

At the same time they were performing these analyses on pot fragments from a 9000-year-old village, the scientists were also investigating the evidence from another lucky find. They had discovered some vessels that were part of a burial site for elite individuals living during Shang and Western Zhou dynasties, from about 1250 to 1000 B.C. These vessels had become tightly sealed as their lids had corroded and formed a barrier around the top. Perfectly preserved inside were the liquids they held, probably intended as accompaniments for the dead on their way to the next world, or possibly used in burial or visitation rituals.

Truly ancient Chinese recipes

The archaeo-chemists analyzed the contents, which looked and smelled very like the rice and millet wines that are still made today in China. They found that the vessels contained wines made of the very same components as those identified in the 9000-year-old pot fragments from the Neolithic village. The recipes appear to have been used for millennia.

The finds also indicate that the people who made the wines had a sophisticated understanding of the fermentation process. They used cakes made of various molds to break down the carbohydrates in rice or millet into simple, fermented sugars. They appear to have known that substances like wormwood—which was found in the Shan/Western Zhou analysis—would enhance the fermenting activity of the yeast considerably.

A Chinese record–for now

China now holds the record for the world’s oldest known human-directed fermentation. Iran held the previous record, based on wines found in two jars at a Neolithic site dating to 5400 B.C. The oldest known reference to a fermented beverage recipe comes from Iraq, where a clay tablet mentions how to brew beer as part of a hymn to the goddess of brewing.

The evolution of language

Language has families, too

We think of English as being a language distinct from, say, Hindi, but they both belong to the Indo-European family of languages. Family members include French, Spanish, German, and Walloon, spoken in a tiny area of France and by descendents of settlers in Green Bay, Wisc. Language, like genes, is passed on from generation to generation, and through time undergoes changes and additions, just as genomes do.

In the 1950s, a linguist named Morris Swadesh developed a field known as lexicostatistics, which studies linguistic family trees through quantitative analysis of a core group of words. These 100 to 200 words, known as Swadesh lists, identify the commonalities in any language, and according to Swadesh’s ideas, were thus less likely to change over time. To trace language lineages, Swadesh compared these groups for similarities and words—cognates—that appeared to have a common ancestor. The more cognates two languages shared, the more closely related they were presumed to be.

A fun word to learn: Glottochronology

In a study published in Nature, authors Russell Gray and Quentin Atkinson take the Swadesh approach into the realm of glottochronology, a way of determining the timing of divergence of languages. Based on their computations, they determined that the root of the Indo-European family tree traces back almost 9000 years ago to an area of what is now Turkey, where farmers grew crops and spoke Hittite. As they migrated, they took their languages with them. Gray and Atkinson’s findings counter another proposed origin of the Indo-European family tree, which posited that invading horsemen from the steppes of Asia brought their language with them as they prosecuted their warlike endeavors 6000 years ago.

What does this have to do with biology?

It is both inspired by and inspiring to biological evolutionary study. Swadesh developed his ideas at about the time that Watson and Crick were making their startling elucidation of DNA structure and copying mechanism. In their analyses, Gray and Atkinson used tools very similar to those biologists use to develop phylogenies to explore how species are related. Instead of gene or amino acid sequences, the authors used a series of letters that formed words; instead of identifying mutations, they identified changes in letters or syllables; and instead of orthologues—genes derived from a common ancestor—they identified cognates to elucidate relationships.

But Swadesh preceded biologists in one sense, in that he proposed using his analyses of Swadesh lists to determine time lapses as language developed and diverged; in other words, to use any divergences in cognates as a sort of clock to measure the time over which changes occur. One of the basic assumptions of this approach is that the changes will occur at a relatively constant rate when averaged out over time, giving a reasonably accurate assessment of how far back a relationship can be traced. This idea was only later taken up in biology as the idea of the “molecular clock,” in which biologists use the presumption of a constant rate of change in some gene or amino acid sequences to infer the timing of genetic divergence.

Problems with either approach

There are, of course, problems with either approach, and again, the problems are remarkably similar, whether the field is biology or linguistics. One common problem in building phylogenies is determining which changes occur because of environmental similarities (convergence), instead of relatedness; convergence is also an issue in the linguistic analysis, where words may appear to be cognates when they really are not. Another question that arises in biology is whether or not the genes being examined are suitable markers of evolutionary change; again, the same problem arise in linguistics—are words in the Swadesh lists, for example, suitable choices for comparison among languages? In spite of these inherent problems, Gray and Atkinson’s work has opened up fresh avenues of discovery and debate and brings biology and language closer to one another than ever.

Africa ahead of Europe in civilization?

Seashells with holes and a smudge

A handful of small seashells with holes and a smudge of red have muddied the waters of human history yet again. Previously, researchers found some seashell beads very much like these in South Africa, beads obviously used for adornment and made about 75,000 years ago. The latest find, shells of the mollusk Nassarius gibbosulus, date back even further, to about 82,000 years ago, making them among the oldest examples of human civilization.

Much to the chagrin of experts who have argued that such artistic endeavors arose in Europe and the Middle East around 40,000 years ago, these beads—clear evidence of what the news media are calling the earliest “bling”—were found in Morocco, in northern Africa. Their strong similarity to the shell beads from South Africa suggest a free exchange of culture and symbolism. In fact, there are only two kinds of shell from this period that have been found in Africa and the Near East, although the people living in these areas had many more choices. This selection of such similar shells also signals a universally understood symbolism involving these beads.

A record competition

The truly oldest beads found so far were from Israel. They were two little beads dating back as far as 100,000 years, although the dating on these is iffy because they were found in the 1930s. Today’s dating methods are much more precise; in fact, the researchers who discovered the 13 Moroccan beads applied four different approaches to dating them, all of which agreed on their age.

The beads were found in the strangely named Cave of Pigeons (Grotte des Pigeons) in Taforalt, Morocco. Around the beads, the researchers also found stone tools and the remains of animals. They concluded that the tools, which were sharp, pointed rocks, were probably spearheads used for hunting. The animal bones, primarily from wild horses and rabbits, had simply been the remains of dinner.

Humans, artistic humans

Each of the small shells, no bigger than a thumbnail, had been perforated deliberately. Some showed signs of wear, as though they had been strung or beaded onto clothing or as a bracelet or necklace for regular use. And the shells bore the traces of red ocher, a pigment that also features in the beads identified in South Africa.

The researchers who found the beads weren’t actually looking for an earth-shattering archaeological find. Their true goal in investigating the limestone cave was to glean information about how climate change might have affected ancient humans. Instead, they found these shells, obviously transported to this inland cave, which at the time the beads were made was about 25 miles from the sea. The people who made them had the self-awareness necessary to desire adornment, and they also had an understanding of objects as symbols, rather than simply as the objects they actually are. In this case, the shells could have symbolized beauty or fashion, or even some form of currency.

Africa moves ahead of Europe

These finds are a blow to those who maintain that humans didn’t achieve any form of cultural modernity until they were in Europe around 35,000 years ago. No one has found items of such ancient origin in European sites. Thus, it seems that humans in Europe, rather than being ahead of their African peers, were actually lagging behind. The north and south Africans were apparently exchanging bead fashion tips tens of thousands of years before the shells were anything but, well, shells to humans in Europe.

The researchers couldn’t just find the beads and date them and then call it done. They had to prove that the snail shells had gotten to the site by human interference. To demonstrate this, the scientists had to rule out the presence of these animals in the walls of the cave, or that the shells were transported by a predator.

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