Are Addictions a Byproduct of Evolution?

iStock/Charles Wollertz
iStock/Charles Wollertz

Franklin Veaux:

Addictions are a byproduct of chemical warfare.

Plants evolved chemicals like caffeine, opioids, nicotine, cocaine, and theobromine because they are chemical poisons that protect the plant from being eaten by pests. They work by disrupting signaling in the brain, usually by binding to receptors for neurotransmitters in the brain.

They’re extremely potent neurotoxins that kill insects. A plant can’t run away from predators, so it uses chemical warfare instead: It secretes these chemicals that disrupt brain signaling, insects try to eat the plant, insects die.

Animals like humans are much bigger than insects. Doses of these chemicals that
disrupt an insect’s brain signaling to the point where insects die disrupt our brain signaling in ways that feel pleasant to us.

Many of these chemical poisons are effective at killing insects because they mimic natural neurotransmitters, but they are more effective than normal neurotransmitters. They grab hold of receptors and don't let go, or they persist longer than natural neurotransmitters—or both.

Your brain tries to maintain a normal baseline. If you take a chemical that disrupts brain signaling, it tries to work around the disruption to get things back to normal.

Let’s say you take a chemical that activates opioid receptors, like morphine. Your opioid signaling system starts sending out a flood of signals. You perceive this as pleasure.

Your brain says “hang on, the opioid signaling system is going crazy. I’m going to turn it down to get back to normal.” So it changes the number of opioid receptors.

You take the morphine again, and you don’t feel that incredible pleasure, because you have more opioid receptors in your brain for the morphine to activate. This is how tolerance works.

So you take more. Now you feel that rush of pleasure again.

But your brain says “Hang on, something still isn’t right. The opioid signaling system is still going bonkers. I better dial it down some more.” So it changes the number of receptors even further.

Now you stop taking the drug. Your brain has turned the opioid signaling system way way down, since you were blasting it with a chemical that sends it into hyperspace. Now you’ve stopped taking that chemical that was sending it into orbit, which means now it’s underactivated. You perceive that under-activation as intense pain. This is what withdrawal is.

This post originally appeared on Quora. Click here to view.

Will the Sun Ever Stop Shining?

iStock.com/VR_Studio
iStock.com/VR_Studio

Viktor T. Toth:

The Sun will not stop shining for a very, very long time.

The Sun, along with the solar system, is approximately 4.5 billion years old. That is about one-third the age of the entire universe. For the next several billion years, the Sun is going to get brighter. Perhaps paradoxically, this will eventually result in a loss of carbon dioxide in the Earth’s atmosphere, which is not good news; It will eventually lead to the death of plant life.

Within 2.5 to 3 billion years from now, the surface temperature of the Earth will exceed the boiling point of water everywhere. Within about about 4 to 5 billion years, the Earth will be in worse shape than Venus today, with most of the water gone, and the planet’s surface partially molten.

Eventually, the Sun will evolve into a red giant star, large enough to engulf the Earth. Its luminosity will be several thousand times its luminosity at present. Finally, with all its usable nuclear fuel exhausted and its outer layers ejected into space, the Sun’s core will settle down into the final stage of its evolution as a white dwarf. Such a star no longer produces energy through nuclear fusion, but it contains tremendous amounts of stored heat, in a very small volume (most of the mass of the Sun will be confined to a volume not much larger than the Earth). As such, it will cool very, very slowly.

It will take many more billions of years for the Sun to cool from an initial temperature of hundreds of thousands of degrees to its present-day temperature and below. But in the end, the remnant of the Sun will slowly fade from sight, becoming a brown dwarf: a cooling, dead remnant of a star.

This post originally appeared on Quora. Click here to view.

Why Do So Many Airports Have Chapels?

Inside Our Lady of the Airways Chapel at Boston Logan International Airport
Inside Our Lady of the Airways Chapel at Boston Logan International Airport

There are only so many ways to kill time during a long layover. You might browse the magazines at a Hudson News or take the time to test out a travel pillow or two. If it's a particularly trying travel day, you may want to while away a few hours at an airport bar. But if you’ve killed enough time in enough U.S. airports, you've probably noticed that most of them have chapels tucked into a corner of the terminal. Some of them are simple, some of them are ornate. Some cater specifically to members of one religion while others are interfaith. So where did they come from, and why are they there?

The biggest surprise in answering the latter part of that question might be that airport chapels weren't originally built for airport passengers at all. According to Smithsonian.com, the first U.S. airport chapel opened in 1951 at Boston's Logan International Airport and was specifically created for the airport’s Catholic staff, largely to offer mass services for workers on longer shifts.

Dubbed “Our Lady of the Airways,” Boston's airport chapel concept was quickly embraced by Catholic leaders around the country. In 1955, Our Lady of the Skies Chapel opened at New York City's Idlewild Airport (which was renamed John F. Kennedy International Airport in 1963). Other Catholic chapels followed.

In the 1960s, JFK added both a Protestant chapel and a Jewish synagogue to its terminals. By the 1980s, Protestant chapels had opened in the Atlanta and Dallas airports as well.

Single-faith chapels dissipated for the most part during the 1990s and into the new millennium. In 2008, The Christian Index ran a story about the changing face of on-the-go religious spaces and declared "Single-faith chapels a dying breed at U.S. airports." As interfaith chapels became the new normal, this inclusiveness extended to the chapels' patrons as well. Instead of remaining gathering places for airport employees, the chapels opened their doors to the millions of passengers traveling in and out of their cities each year.

Today, more than half of America's busiest airports feature chapels, the majority of which are interfaith. Most existing chapels are welcoming to people of all faiths and often include multiple religious symbols in the same room. They have become important spaces for meditation and reflection. Many of them still offer worship services for each of their represented practices, including places like the interfaith chapel at Washington Dulles International Airport, which hosts a Catholic mass on Saturday evenings as well as daily Jewish prayer services. Though each airport chapel is unique in design and services, they all endeavor to offer a much-needed spiritual refuge from the hassle of air travel.

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