# Wasps Have the Ability to Use Logic, According to a New Study

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Your reaction to wasps probably consists of mild panic over a possible sting, followed by a quick escape indoors and concern over whether a nest is taking up residence on your property. New research into their behavioral processes may not minimize that reaction, but it could give you some newfound respect for these winged wonders. They're not only smart, but they might even be better at deducing logic than some humans.

A recent study by researchers at the University of Michigan and published in the journal Royal Society Biology Letters took 40 wasps (of the Polistes dominula and Polistes metricus species) and put each one of them into a rectangular container that featured one of five different colors at each end. Each color was labeled from A to E, though that was more to assign the colors a hierarchy for the human observers.

Researchers attempted to educate the wasps on the sequence of colors, with boxes labeled A and B, B and C, C and D, and D and E. An electric shock was housed under the later letter of the alphabet in each pair. If a container had colors labeled B and C, for example, the shock would be under the C. In this way, the wasps learned which color was "better." Blue was better than green, and green was better than purple. But could the wasps understand blue was better than purple?

To find out, the wasps were then placed in containers with colors marked B and D and A and E. In order to avoid getting a shock, the wasps would have to understand a color higher up in the letter ranking was associated with the shock. Over 65 percent chose B over D, better than chance, and A over E. (The latter was an easier decision, as E always delivered a jolt.)

This kind of reasoning is known as transitive inference, or the ability to take two separate bits of information and draw conclusions. The wasps knew B delivered a shock over A, and that D delivered one over C, but not that D delivered one over B. They had to extrapolate that based on independent experience.

The report is said to be the first indication invertebrates can use logical deduction. It might be related to the wasp hierarchy, where the insects are confronted with figuring out who holds dominant roles in their society.

This isn't the first time wasps have impressed scientists, either. An earlier study showed that they can identify facial patterns in other wasps, and recognize them during subsequent encounters.

[h/t New Scientist]

# Why Does Humidity Make Us Feel Hotter?

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With temperatures spiking around the country, we thought it might be a good time to answer some questions about the heat index—and why humidity makes us feel hotter.

## Why does humidity make us feel hotter?

As you probably remember from your high school biology class, one of the ways our bodies cool themselves is by sweating. The sweat then evaporates from our skin, and it carries heat away from the body as it leaves.

Humidity throws a wrench in that system of evaporative cooling, though. As relative humidity increases, the evaporation of sweat from our skin slows down. Instead, the sweat just drips off of us, which leaves us with all of the stinkiness and none of the cooling effect. Thus, when the humidity spikes, our bodies effectively lose a key tool that could normally be used to cool us down.

## What's relative about relative humidity?

We all know that humidity refers to the amount of water contained in the air. However, as the air’s temperature changes, so does the amount of water the air can hold. (Air can hold more water vapor as the temperature heats up.) Relative humidity compares the actual humidity to the maximum amount of water vapor the air can hold at any given temperature.

## Whose idea was the heat index?

While the notion of humidity making days feel warmer is painfully apparent to anyone who has ever been outside on a soupy day, our current system owes a big debt to Robert G. Steadman, an academic textile researcher. In a 1979 research paper called, “An Assessment of Sultriness, Parts I and II,” Steadman laid out the basic factors that would affect how hot a person felt under a given set of conditions, and meteorologists soon used his work to derive a simplified formula for calculating heat index.

The formula is long and cumbersome, but luckily it can be transformed into easy-to-read charts. Today your local meteorologist just needs to know the air temperature and the relative humidity, and the chart will tell him or her the rest.

## Is the heat index calculation the same for everyone?

Not quite, but it’s close. Steadman’s original research was founded on the idea of a “typical” person who was outdoors under a very precise set of conditions. Specifically, Steadman’s everyman was 5’7” tall, weighed 147 pounds, wore long pants and a short-sleeved shirt, and was walking at just over three miles per hour into a slight breeze in the shade. Any deviations from these conditions will affect how the heat/humidity combo feels to a certain person.

## What difference does being in the shade make?

Quite a big one. All of the National Weather Service’s charts for calculating the heat index make the reasonable assumption that folks will look for shade when it’s oppressively hot and muggy out. Direct sunlight can add up to 15 degrees to the calculated heat index.

## How does wind affect how dangerous the heat is?

Normally, when we think of wind on a hot day, we think of a nice, cooling breeze. That’s the normal state of affairs, but when the weather is really, really hot—think high-90s hot—a dry wind actually heats us up. When it’s that hot out, wind actually draws sweat away from our bodies before it can evaporate to help cool us down. Thanks to this effect, what might have been a cool breeze acts more like a convection oven.

The National Weather Service has a handy four-tiered system to tell you how dire the heat situation is. At the most severe level, when the heat index is over 130, that's classified as "Extreme Danger" and the risk of heat stroke is highly likely with continued exposure. Things get less scary as you move down the ladder, but even on "Danger" days, when the heat index ranges from 105 to 130, you probably don’t want to be outside. According to the service, that’s when prolonged exposure and/or physical activity make sunstroke, heat cramps, and heat exhaustion likely, while heat stroke is possible.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

# Chimpanzees Bond by Watching Movies Together, Too

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Scientists at the Wolfgang Kohler Primate Research Center in Germany recently discovered that, like humans, chimpanzees bond when they watch movies together, the BBC reports.

In the study, published in Proceedings of the Royal Society B, researchers stationed pairs of chimpanzees in front of screens that showed a video of a family of chimps playing with a young chimp. They found that afterward, the chimps would spend more time grooming and interacting with each other—or simply being in the same part of the room—than they would without having watched the video.

They gave the chimps fruit juice to keep them calm and occupied while they viewed the video, and they chose a subject that chimps have previously proven to be most interested in: other chimps. They also used eye trackers to ensure the chimps were actually watching the video. If you’ve ever watched a movie with friends, you might notice similarities between the chimps’ experience and your own. Drinks (and snacks) also keep us calm and occupied while we watch, and we like to watch movies about other humans. Since this study only showed that chimps bond over programs about their own species, we don’t know if it would work the same way if they watched something completely unrelated to them, like humans do—say, The Lion King.

Bonding through shared experiences was thought to be one of the traits that make us uniquely human, and some researchers have argued that other species don’t have the psychological mechanisms to realize that they’re even sharing an experience with another. This study suggests that social activities for apes don’t just serve utilitarian purposes like traveling together for safety, and that they’re capable of a more human-like social closeness.

The part that is uniquely human about this study is the fact that they were studying the effect of a screen, as opposed to something less man-made. The chimps in question have participated in other studies, so they may be more accustomed to that technology than wild apes. But the study demonstrates that we’re not the only species capable of social interaction for the sake of social interaction.

[h/t BBC]

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