When Did Humans Reach North America? The Question Keeps Growing More Complex

By Megan Gannon, SAPIENS | September 19, 2019 10:30 am
Native Americans have been visiting Calvert Island off the Canadian coast for more than 10,000 years. (Credit: Pacific Northwest Sailing/Shutterstock)

Humans have long found comfort on Calvert Island, just off the coast of mainland British Columbia. For millennia, they have climbed the island’s rocky outcrops, walked through its rainy conifer forests, and waded through its chilly intertidal pools to collect crabs, mussels, and other marine life.

There, in 2014, a group of Canadian researchers uncovered human footprints pressed into a prehistoric layer of soil. The footprints, 29 in total, are the oldest found in North America. They suggest an intimate scene in which, 13,000 years ago, at least three people may have hopped out of a boat onto the damp shore. One person appears to have slipped as the group walked toward drier land. The footprints also speak to a much larger and contested story—the tale of the humans who first set foot in North America.

North and South America were relatively lonely places for our species 13,000 years ago. The continents were the last major landmasses in the world to be populated by Homo sapiens. But the explanation of how and when this peopling happened has needed to be heavily revised in the last two decades.

“This field is bonkers right now,” says anthropological geneticist Jennifer Raff of the University of Kansas. “I think there’s a new important paper coming out every three or four months.” Indeed, no tidy, new framework has arisen to take the place of older theories. Instead, new data, including genetic findings, continue to complicate the story of how these continents came to be peopled.

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CATEGORIZED UNDER: Living World, Top Posts

Misophonia, Or Why I Hate the Sound of Chewing Salad

By Nathaniel Scharping | September 18, 2019 4:00 pm
young child boy doesn't like specific sound
Misophonia is an aversive reaction to specific sounds that emerges in childhood, most often with annoyance that quickly turns to anger. (Credit: mamaza/Shutterstock)

It was the salads that got me. On nights when my parents started off dinner with some leafy greens, I left the room. The habit quickly became a ritual, and to my family’s credit – or not –  no one ever remarked on it. It was just another quirk, like biting fingernails, or sticking your tongue out when you concentrate.

You see, to me, the sounds of chewing salad were unendurable. The crisp crunching noises and the scrape and squeak of utensils on ceramic dinnerware felt like a personal affront, a stimulus manufactured to induce rosy-red rage inside. I felt an inexplicable urge to hurl plates and bowls against the walls. So, I left the table.

As I grew up and moved away, the problem faded into the background, or, at least, I learned to deal with it. Not till much later did I discover that there was a name for these irrational fits of anger, and a diagnosis to accompany it.

Misophonia is an aversive reaction to specific sounds, often in the form of annoyance that turns quickly to anger. Eating, chewing gum and typing on keyboards are all commonly listed triggers. But it varies from person to person. Human-made noises are most likely to cause the reaction, and these sounds typically come from people who misophonia sufferers are close to, like family and friends. The condition typically starts during childhood or adolescence. And while scientists don’t know exactly how many people are affected, one study of almost 500 undergraduates found some level of misophonia in 20 percent of them.

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CATEGORIZED UNDER: Mind & Brain, Top Posts

Homo heidelbergensis: The Answer to a Mysterious Period in Human History?

By Bridget Alex | September 17, 2019 11:56 am
Cranium 5 Homo heidelbergensis
Cranium 5, a skull found at Sima de los Huesos and thought to be either a late Homo heidelbergensis or an early Neanderthal. (Credit: Rept0n1x/Wikimedia Commons)

There’s a murky chapter in human evolution, one that occurs right before our species entered the scene.

Over 1 million years ago our ancestors belonged to the primitive-looking species Homo erectus. Jump to 300,000 years ago and Earth is home to at least three lineages of big-brained humans: Homo sapiens, Neanderthals and Denisovans. So what happened in the intervening 700,000 years?

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CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: human origins

Cows Burp Out Tons of Methane. Feeding Them Seaweed Could Help

By Jennifer Walter | September 16, 2019 5:13 pm
Cows Methane
Adding seaweed to cows’ diet would help tamp down their methane emissions. (Credit: Jan K/ Shutterstock)

Every morning, Breanna Roque goes out to the barn to feed the cows. But this isn’t your typical farm – in fact, it’s a laboratory. The University of California, Davis graduate researcher spends her time among bovines, tweaking their diets so that they burp less. Why? Less burps means less methane. And less methane, on a global scale, could mean slowing down climate change.  

Roque is part of a team feeding cows a special diet, one that includes small portions of a sticky, red seaweed called Asparagopsis taxiformis. It’s not the typical fare for the grass-happy bovines, but the seaweed-infused feed serves a specific purpose – keeping the cows’ prodigious methane production in check.

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CATEGORIZED UNDER: Environment, Living World, Top Posts

9 Ways to Instantly Cut Your Environmental Impact

By Anna Groves | September 13, 2019 4:43 pm
thrift store shopping
Buying clothes and other items second hand is a great way to cut your environmental impact. (Credit: Cabeca de Marmore/Shutterstock)

Helping the environment might seem like an impossible task, especially when there are a couple billion other people out there, still doing their thing. But even just cutting your current environmental impact a little is better than doing nothing at all. So, here are a few ideas to get you started.

Buy Stuff Second Hand

What has less of an impact than buying the most sustainable new product on the market? Not buying it. Or anything new, for that matter. Any product that’s manufactured requires resources, energy, packaging and transportation. And that’s also true for products that are a “sustainable alternative” to something else.

But our world is already so full of stuff. It’s waiting for you in thrift stores. Second-hand shops. Yard sales. Used car lots. The back of your friend’s closet. In fact, the resale industry is booming: A report by First Research estimates the used merchandise industry in the U.S. hit $17.5 billion in 2019.

How many copies of Pride and Prejudice are in circulation right now? (Hint: It’s something like 20 million.) Do you really need one from Amazon that’s never been read?

But if you’re a material girl, living in a material world, and can’t imagine wearing someone else’s shoes — the least you can do is be sure to donate (or even resell) the stuff you’re done with instead of throwing it in the trash.

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CATEGORIZED UNDER: Environment, Top Posts

How the Government is Working to Combat Fake Images and Videos

By Christye Sisson, Rochester Institute of Technology | September 11, 2019 11:04 am
It can be tricky to make it look like people are doing things they never did. (Credit: Alexander Sobol/Shutterstock)

Lots of people – including Congress – are worried about fake videos and imagery distorting the truth, purporting to show people saying and doing things they never said or did.

I’m part of a larger U.S. government project that is working on developing ways to detect images and videos that have been manipulated. My team’s work, though, is to play the role of the bad guy. We develop increasingly devious, and convincing, ways to generate fakes – in hopes of giving other researchers a good challenge when they’re testing their detection methods.

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CATEGORIZED UNDER: Technology, Top Posts

Americans Commonly Eat Orange Roughy, a Fish Scientists Say Can Live to 250 Years Old

By Kate Evans | September 11, 2019 10:30 am
Orange roughy live in the deep ocean, where they’re often caught by trawling ships. (Credit: New Zealand National Institute of Water and Atmospheric Research)

Would you eat an animal if you knew it was as old as the U.S. Constitution? 

Scientists in New Zealand have aged a fish called an orange roughy at between 230 and 245 years old, making it one of the longest-lived fin-fish on record.

The ancient fish was born in the late 1700s — and then caught in 2015 by a New Zealand commercial fishing boat on the Louisville Ridge, a chain of seamounts in the South Pacific around 930 miles east of the mainland.

The spiny, scarlet creature was hauled in by a trawl net from its deep, dark home more than 3,000 feet below the surface, along with many hundreds of its schoolmates. But before it was sold and eaten, New Zealand government observers on board the ship extracted samples from inside the creature’s head to determine its age.

Orange roughy — known as “slimehead” before a marketing makeover in the 1970s  — are mainly caught off the coast of New Zealand and Australia, then sold abroad, mainly to the U.S.

Whole Foods, Trader Joes and some other retailers refuse to stock the species, citing sustainability concerns and the environmental impacts of bottom trawling. For researchers, the species’ great age highlights the need for a precautionary approach to fisheries management.

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CATEGORIZED UNDER: Environment, Living World, Top Posts

The Sima Hominins: An Ancient Human Cold Case

By Bridget Alex | September 10, 2019 4:19 pm
sima de los huesos skull
A skull from Sima de los Huesos showing evidence of blunt force trauma. (Credit: Sala et al./PLOS One)

From the scene, authorities recovered DNA, a stone handaxe and more than 7,000 scattered bones, including a bashed human skull. It was a case for the ages. But there was one complication: the events unfolded 430,000 years ago.

The evidence was unearthed by anthropologists beginning in the 1980s at Sima de los Huesos — the “pit of bones” — in Spain’s Atapuerca mountains. The spectacular cave chamber, nearly 100 feet below the surface, has yielded remains from at least 28 hominin individuals. Ancient DNA analysis of the fossils — the oldest human genetic code ever sequenced — indicates that these people were ancestors to Neanderthals.

After more than three decades of research, the remains have revealed much about Neanderthal evolution. But the circumstances surrounding the group’s death and burial remains contentious. Found in a jumble at the base of a 45-foot chute, some say the bodies were deliberately dropped there after meeting violent ends — a Stone Age cold case.


Since systematic excavations of Sima began in 1984, researchers have discovered thousands of hominin fossils there, but only one artifact: a teardrop shaped handaxe of red and yellow stone, nicknamed Excalibur. There’s more digging to do, though: It’s thought more than half the deposit of sediments and fossils has yet to be excavated.

The human remains include at least 28 individuals from both sexes and varying ages. The exact species the Sima individuals belong to is still a topic of debate, but the rich collection has enabled anthropologists to uncover intimate details about their lives as well as their place in the broader story of human evolution.

Compared to modern humans, the Sima humans were short, stocky and smaller-brained. It’s estimated males were about 5 foot 7 and 170 pounds, whereas females stood around 5 foot 2, weighing 125 pounds. Average skull volume was 1230 cm3, about a half cup less than Neanderthals (1410 cm3) or modern humans (1350 cm3).

Based on physical appearance, anthropologists have long argued the Sima hominins were Neanderthal ancestors. The skeletons possess some traits definitive of Neanderthals, which lived about 200,000 years later in Europe. But they lack other classic Neanderthal features, which were yet to evolve.

The proto-Neanderthal hypothesis gained strong support from a 2016 Nature study, which reported DNA from one femur bone and a tooth dated to roughly 430,000 years ago. Although the sequence was just 0.1 percent of a full genome, it is the oldest hominin DNA ever recovered by nearly 300,000 years. It was also enough to place the Sima humans securely on the evolutionary branch leading to Neanderthals, after it split from the lineage leading to Homo sapiens

Hidden for a Half Million Years

Today, the Sima chamber sits a quarter-mile’s walk from daylight, deep within a network of caves, which includes other fossil sites between 1000 and 1.2 million years old. There may have been shorter routes 430,000 years ago — when the Sima bones likely accumulated — but researchers studying the cave’s architecture think the only entrance to the chamber itself was the same then as today: a 45-foot vertical chute from a higher level of the cave.

Scientists have proposed a number of hypotheses to explain how the fossils got there. The hominins may have been dragged by carnivores, carried by flood waters or trapped after venturing too far. Meanwhile the excavation team offered a more provocative explanation: The individuals were already dead and intentionally deposited by other humans. This would substantially push back the origin of mortuary practices in human evolution. The earliest well-accepted burials occur only after 130,000 years ago, among full-fledged Neanderthals and H. sapiens.

Over the years analyses have made some of the alternatives less probable, and the “deliberate disposal” hypothesis more compelling. But the matter remains unsettled.

Take the carnivore explanation: In addition to proto-Neanderthals, researchers recovered fossils from more than 175 bears and a smaller number of other carnivores, including lions and fox in the cave. However no typical prey animals like mountain goat or deer were found. So was Sima a den for carnivores with an appetite for human meat?

Probably not. No known carnivores — living or extinct — exclusively eat humans. Nor do they make dens so deep in caves. Furthermore, in a 2014 Quaternary Science Reviews study, researchers scrutinized 2401 human and 1200 carnivore specimens from Sima under the microscope, looking for tooth marks. Just about 4 percent of the human and carnivore bones had bites. This suggests scavengers, at some point, chomped on a small number of these bones, but the site was not a carnivore den.

It seems none of the humans were eaten to death by carnivores. But some may have been beaten to death. According to a 2015 PLOS One paper, one skull had two fractures, likely caused by a blow from a blunt implement during face-to-face combat. Though not as definitive, another study the following year identified trauma on eight additional Sima skulls.

It seems to be a convincing case of Stone Age homicide. But that still doesn’t explain how the dead bodies entered the chamber. Were the perpetrators hiding their victims? Or did loved ones inter the corpses, suggesting proto-Neanderthals held beliefs about death and afterlife? That part of the mystery may never be solved.

In any case Sima de los Huesos is one killer pit of bones.

CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: human origins

Cement Mixed on ISS Helps Pave the Way for Future Space Colonies

By Jake Parks | September 9, 2019 5:21 pm
As cement hardens through a process called hydration, the molecules within the mixture develop millions of microscopic crystals, like those seen in this screenshot from the NASA video below. These interlocking crystals help the cement molecules bind with each other, as well as other concrete ingredients like gravel, sand, and small rocks. (Credit: NASA ScienceCasts)

Concrete, in one form or another, has been a staple of human construction for some 5,000 years. Now, researchers have finally brought the ancient technology to outer space. For the first time, scientists have successfully mixed cement — a primary ingredient of concrete — in the microgravity environment aboard the International Space Station (ISS).

As part of an experiment called the Microgravity Investigation of Cement Solidification, researchers sent the basic building blocks of cement — tricalcium silicate, hydrated lime, and distilled water — to the ISS. The ingredients were then mixed in pouches and allowed to harden for 42 days through a process called hydration.

The results show that cement mixed in microgravity can indeed solidify much like it does on Earth. But unlike Earth-made cement, space cement has some unique microscopic features.

Because the new research is the first to compare cement mixed in space to a control batch mixed on Earth, it opens the door to developing better ways to manufacture the substance in various gravitational environments. And if humans are to build a Moon Village or a martian colony in the years to come, we’ll likely need to master mixing cement on other worlds.

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CATEGORIZED UNDER: Space & Physics, Top Posts
MORE ABOUT: space exploration

Did a Single Genetic Mutation Make Humans the Heart Attack Species?

By Cody Cottier | September 9, 2019 2:05 pm
woman heart attack
(Credit: halfbottle/Shutterstock)

There are many things that set us humans apart from other species: large brains, bipedalism, a predilection for puns. But we’re also defined by our singular vulnerability to cardiovascular disease.

Heart attacks and strokes, the leading causes of death in humans worldwide, are rampant in our species and our species alone. Even chimpanzees, our closest relatives in the animal kingdom, suffer from cardiovascular disease at far lower rates, and for different reasons. So how did we get stuck with a plague of plaque-filled arteries?

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CATEGORIZED UNDER: Health & Medicine, Top Posts
MORE ABOUT: genetics, heart disease

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