Determining Migratory Patterns of Early Humans — With Earwax!

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Earwax is mostly gross, but it serves a few purposes: protecting our ear canals from bacteria and dryness, assisting in cleaning and lubrication, and — surprisingly — helping anthropologists determine the migratory patterns of early humans.

While most native English speakers have wet, amber-to-brown colored earwax, there's a second type — dry, gray, and flaky. Which type of earwax you have is determined genetically, with the dry type being recessive and perhaps the result of a genetic mutation somewhere along the way. For some reason, the mutation is common among East Asians. An estimated 97 to 100 percent of people of European and African descent have the wet-type earwax, while 90 percent or more of those descended from East Asians have the dry type.

The gene that controls the relative wetness of earwax is tied to sweat, generally, and the prevailing belief amongst researchers is that the recessive gene, insofar that it reduces sweat output, had advantages in the colder climates of northern China (where, along with Korea, dry earwax is most common), where the mutation seems to have begun.

But for the rest of the world population, earwax makeup is mixed. Native Americans and people from southeast Asia, for example, exhibit dry earwax in 30 to 50 percent of the population, and it appears to occur more densely in some communities thereof than others. Armed with this information, researchers can determine in part the ancestral routes of different people and how those ancestors got to where their descendants now live.
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BONUS FACT: Whales' earwax increases over time without (mostly) discharging. This makes the amount of earwax in a whale's ear proportional to its age. As many whales (for example, baleen whales such as the blue whale, the world's largest mammal) do not have teeth, earwax buildup is one of the best ways to determine how old the whale is. For toothed whales and dolphins? Their teeth grow in layers and, much like the rings of a tree's trunk, the layers are used to determine the animal's age.

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Wisconsin Department of Natural Resources
Why Is Ice Slippery?
Wisconsin Department of Natural Resources
Wisconsin Department of Natural Resources

If you’ve ever shakily stepped onto the ice at your local skating rink, you are intimately familiar with the fear of falling on slippery ice. But what makes ice so slippery in the first place? Interestingly enough, scientists are still trying to figure that one out.

Physicists used to believe that ice became slippery when it was exposed to applied pressure. This pressure, they theorized, lowered the melting temperature of the top layer of ice. They believed that when a person went ice skating, the pressure from the blade caused the topmost layer of ice to melt. The thin layer of water allowed the ice skate to glide easily over the surface. After the blade passed, the top layer of water refroze.

However, most scientists today claim that this theory is wrong. “Ice is a very mysterious solid,” Robert M. Rosenberg, a chemistry professor at Lawrence University, said in an interview with The New York Times.

Scientists found that while pressure does lower the melting point of ice, it only does so by a fraction of a degree. Instead, they proposed that the friction from an ice skate causes the ice to melt beneath it.

Others believe that ice naturally possesses a fluid layer comprised of unstable water molecules. While these molecules search for stability, they move chaotically over the ice’s surface and create a slippery layer.

The Last Five Members of the Akuntsu Tribe

Dan Lewis runs the popular daily newsletter Now I Know (“Learn Something New Every Day, By Email”). To subscribe to his daily email, click here.

Rondônia is a state in the northwest of Brazil that shares a border with Bolivia. Covered mostly by rain forest (or, more commonly, deforested area that was once rain forest), Rondônia is the 13th largest Brazilian state (of 26) by area, but only the 23rd by population. It covers an area of just over 90,000 square miles, roughly the size of Michigan, Romania, or the United Kingdom, but it has only 1.5 million inhabitants.

Five of those people—the only five anywhere—make up the Akuntsu tribe.

Indigenous to Brazil, the Akuntsu tribe was all but unknown to outsiders until 1995. By the time government field workers made contact with tribe members that year, their population had dwindled to seven people: Konibu, their chief, a shaman currently believed to be roughly 70 years old; another male, Pupak (pictured above with Konibu), approximate age 40; Ururu, the female elder; and four other women in their 20s or 30s. The Akuntsu population was likely much larger in the 1970s and 1980s, but as development in the rain forests grew, so did violent land-grabbing — leading, sadly, to the deaths of an unknown number of undocumented aborigines.

Today, the Akuntsu population numbers a mere five members. In 2000, during a storm, a tree fell onto one of the Akuntsu's two houses, killing one of the younger women. In October 2009, Ururu, then likely in her 80s, passed away as well.

We'll likely never know the tales the survivors tell, because the Akuntsu have their own language — one that no one outside their tribe fully understands. The little we do know: the tribe are hunter/gatherers and, to a lesser degree, farmers growing corn. They believe in the supernatural, with Konibu known to use tobacco to communicate with the spirit world. The stories of violence are real: the two surviving men have scars from bullets. And, given the likely ages of the existing members, the extinction of the tribe is a near-certainty.

Survival International has a wonderful video of the final six Akuntsu before Ururu passed away:

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