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What Killed the Neanderthals?

Neanderthals, our closest extinct relatives, roamed the Earth for about 300,000 years. They hunted, made tools, and lived amongst one another in complex social groups. But about 40,000 years ago, they disappeared.

What killed them has been a topic of tense debate for some years. “The issue of Neanderthal extinction is very complex, and very little is agreed upon,” Anna Goldfield, a doctoral candidate in archaeology at Boston University, told LiveScience. Was it climate change? Or a volcanic eruption? One theory even suggests that Neanderthals’ big eyes are to blame for their downfall.

But most researchers agree that modern humans had something to do with it. Indeed, within just 5,000 years of our arrival, Neanderthals had vanished. A new theory suggests that our mastery of fire is the key to why we thrived while they did not. “Fire use would have provided a significant advantage for the human population,” Goldfield said at the annual meeting of the Society for American Archaeology. 

leted, Flickr // CC BY-NC 2.0

Aside from keeping us warm, fire allowed us to cook food, which has huge benefits, according to The Economist

“Cooking alters food in three important ways. It breaks starch molecules into more digestible fragments. It ‘denatures’ protein molecules, so that their amino-acid chains unfold and digestive enzymes can attack them more easily. And heat physically softens food. That makes it easier to digest, so even though the stuff is no more calorific, the body uses fewer calories dealing with it.”

It’s not that Neanderthals didn’t use fire — some of them did. Despite their historical portrayal as dimwitted cavemen, these hominids were masters of tool use, and archaeologists think they created sparks by striking flint against iron pyrite. And they did use fire to heat some of their meals. They even cooked with herbs

But Neanderthals may not have made use of flame as regularly or as efficiently as our ancestors did, according to archaeologist Dennis Sandgathe. Early modern human bodies were smaller and more efficient, which meant that cooked food was more beneficial for them. And the more that modern humans utilized the power of flame, “the more likely the human population was to increase slightly.” Over time, this disadvantage may have sealed the Neanderthals' fate.

As archaeologists continue to investigate, we’ll learn more about what really killed off our hominid relatives. “I suspect genetics will help,” says Richard Wrangham, an anthropologist at Harvard. “If we can pin down the genes underlying the adaptation to cooked food, we may be able to date the control of fire close enough to settle the big question.” Either way, the next time you turn your oven on to cook dinner, give thanks to the first modern humans for keeping the fire burning.

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Today's Wine Glasses Are Almost Seven Times Larger Than They Were in 1700
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Holiday party season (a.k.a. hangover season) is in full swing. While you likely have no one to blame but yourself for drinking that second (or third) pour at the office soiree, your glassware isn't doing you any favors—especially if you live in the UK. Vino vessels in England are nearly seven times larger today than they were in 1700, according to a new study spotted by Live Science. These findings were recently published in the English medical journal The BMJ.

Researchers at the University of Cambridge measured more than 400 wineglasses from the past three centuries to gauge whether glass size affects how much we drink. They dug deep into the history of parties past, perusing both the collections of the Ashmolean Museum of Art and Archaeology at the University of Oxford and the Royal Household's assemblage of glassware (a new set is commissioned for each monarch). They also scoured a vintage catalog, a modern department store, and eBay for examples.

After measuring these cups, researchers concluded that the average wineglass in 1700 held just 2.2 fluid ounces. For comparison's sake, that's the size of a double shot at a bar. Glasses today hold an average of 15.2 fluid ounces, even though a standard single serving size of wine is just 5 ounces.

BMJ infographic detailing increases in wine glass size from 1700 to 2017
BMJ Publishing group Ltd.

Advances in technology and manufacturing are partly to blame for this increase, as is the wine industry. Marketing campaigns promoted the beverage as it increasingly became more affordable and available for purchase, which in turn prompted aficionados to opt for larger pours. Perhaps not surprisingly, this bigger-is-better mindset was also compounded by American drinking habits: Extra-large wineglasses became popular in the U.S. in the 1990s, prompting overseas manufacturers to follow suit.

Wine consumption in both England and America has risen dramatically since the 1960s [PDF]. Cambridge researchers noted that their study doesn't necessarily prove that the rise of super-sized glassware has led to this increase. But their findings do fit a larger trend: previous studies have found that larger plate size can increase food consumption. This might be because they skew our sense of perception, making us think we're consuming less than we actually are. And in the case of wine, in particular, oversized glasses could also heighten our sensory enjoyment, as they might release more of the drink's aroma.

“We cannot infer that the increase in glass size and the rise in wine consumption in England are causally linked,” the study's authors wrote. “Nor can we infer that reducing glass size would cut drinking. Our observation of increasing size does, however, draw attention to wine glass size as an area to investigate further in the context of population health.”

[h/t Live Science]

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Researchers Pore Over the Physics Behind the Layered Latte
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The layered latte isn't the most widely known espresso drink on coffee-shop menus, but it is a scientific curiosity. Instead of a traditional latte, where steamed milk is poured into a shot (or several) of espresso, the layered latte is made by pouring the espresso into a glass of hot milk. The result is an Instagram-friendly drink that features a gradient of milky coffee colors from pure white on the bottom to dark brown on the top. The effect is odd enough that Princeton University researchers decided to explore the fluid dynamics that make it happen, as The New York Times reports.

In a new study in Nature Communications, Princeton engineering professor Howard Stone and his team explore just what creates the distinct horizontal layers pattern of layered latte. To find out, they injected warm, dyed water into a tank filled with warm salt water, mimicking the process of pouring low-density espresso into higher-density steamed milk.

Four different images of a latte forming layers over time
Xue et al., Nature Communications (2017)

According to the study, the layered look of the latte forms over the course of minutes, and can last for "tens of minutes, or even several hours" if the drink isn't stirred. When the espresso-like dyed water was injected into the salt brine, the downward jet of the dyed water floated up to the top of the tank, because the buoyant force of the low-density liquid encountering the higher-density brine forced it upward. The layers become more visible when the hot drink cools down.

The New York Times explains it succinctly:

When the liquids try to mix, layered patterns form as gradients in temperature cause a portion of the liquid to heat up, become lighter and rise, while another, denser portion sinks. This gives rise to convection cells that trap mixtures of similar densities within layers.

This structure can withstand gentle movement, such as a light stirring or sipping, and can stay stable for as long as a day or more. The layers don't disappear until the liquids cool down to room temperature.

But before you go trying to experiment with layering your own lattes, know that it can be trickier than the study—which refers to the process as "haphazardly pouring espresso into a glass of warm milk"—makes it sound. You may need to experiment several times with the speed and height of your pour and the ratio of espresso to milk before you get the look just right.

[h/t The New York Times]

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