How Did Ancient Medics Determine the Medicinal Properties of Substances?

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Drew Smith:

For the most part, they didn’t. At the dawn of the age of scientific medicine (the mid-19th century) there were only a handful of remedies that we would recognize today as safe and effective.

But why? Our ancestors were not dummies, and did not require scientific methods to create sophisticated and effective technologies. The Romans built what is still the largest unsupported dome structure in the world 1800 years ago. Gunpowder, in concert with metallurgical advances, steadily developed from a Taoist elixir to a city-destroying technology by the 1600s. Sailing technology created worldwide trade networks even earlier. Scientific methods would have sped the development of these technologies, but were not required. Trial and error—plus lots of time—sufficed.

Yet traditional medicines largely suck. Hundreds have now been tested in clinical trials. Few show any benefit at all, and even fewer show a benefit comparable to modern scientific medicines. There is little evidence that the remedies of 1800 CE were any more effective than the remedies of 1800 BCE. Moliere’s quip in 1673 that “More men die of their medicines than of their diseases” was very much on the mark.

This is a mystery, at least to me. Unlike other sophisticated modern technologies, such as jet aircraft or telecommunications, medicines are largely discovered rather than invented. They don’t rely on an entire edifice of previous scientific discoveries.

In fact, effective medicines sometimes come and find us. The ancient Nubians drank a beer (more like a gruel, really) fermented by Streptomyces bacteria. It was so loaded with tetracycline that their bones fluoresce under UV light. Tetracycline is a very effective broad spectrum antibiotic that can be used to treat plague, TB, diarrheal diseases, and respiratory, skin, and urinary tract infections. Tetracycline beer, used judiciously, could well have slashed infant mortality, leading to a Demographic Transition in Central Africa in 400 CE.

But it didn’t.

The ancients were also capable of creating, not just finding, sophisticated medicines. Bard’s Salve, resurrected from a 10th century Saxon text, is an effective remedy for wound infection in mouse models.

More surprisingly, every component—and the precise process for producing it—is required in order for it to work. This is a clear example of an effective ancient medicine that answered a critical medical need. Its formulation was written down, allowing it to spread and be improved upon. Instead it was forgotten.

Why?

I’m sure there is no single answer, but I will posit this: In a Malthusian world, effective medicines were a liability, not an asset.

Up until about 1800, everyone in the world, to a first approximation, was a poor subsistence farmer. Despite substantial technological advances, like the ones I described above and many others, the standard of living of the world’s population advanced not at all. Any improvement in agricultural technology, such as the horse collar and improved plow designs, led to increased food production but subsequent population increases ate up any gains in living standards.

We think of historical plagues as disasters, but they were in fact a great benefit—at least to the survivors. Life expectancy increased after the Black Death of 1350:

So did wages:

Fewer mouths to feed and a scarcity of labor leading to increased bargaining power led to more resources per person and a more equitable distribution of those resources.

In our modern innovation-driven economy, we consider more people to be a good thing.

We fret that declining birth rates will cause economic growth to stagnate. But prior to 1850, a growing population meant growing poverty.

Saving lives—particularly the lives of economic sinks like small children—did not make societies stronger. This is not to say that parents did not mourn the loss of their children. They did. But societies operated under what was a reverse Tragedy of the Commons, where what was bad for the individual was good for everyone else.

I think our ancestors were perfectly capable of making effective medicines. They chose not to, not out of perversity or ignorance, but because those medicines would have caused more suffering than they prevented. Medicine was not intended to cure; its role was to provide comfort. It was a form of social support, not unlike religion. Looked at from that perspective, traditional medicines are very effective. They did exactly what their creators intended them to do. I’m not sure that we can always say the same today.

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

What Would Happen If a Plane Flew Too High?

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Tom Farrier:

People have done this, and they have died doing it. For example, in October 2004, the crew of Pinnacle Airlines 3701 [PDF]  was taking their aircraft from one airport to another without passengers—a so-called "repositioning" flight.

They were supposed to fly at 33,000 feet, but instead requested and climbed to 41,000 feet, which was the maximum altitude at which the aircraft was supposed to be able to be flown. Both engines failed, the crew couldn't get them restarted, and the aircraft crashed and was destroyed.

The National Transportation Safety Board determined that the probable causes of this accident were: (1) the pilots’ unprofessional behavior, deviation from standard operating procedures, and poor airmanship, which resulted in an in-flight emergency from which they were unable to recover, in part because of the pilots’ inadequate training; (2) the pilots’ failure to prepare for an emergency landing in a timely manner, including communicating with air traffic controllers immediately after the emergency about the loss of both engines and the availability of landing sites; and (3) the pilots’ improper management of the double engine failure checklist, which allowed the engine cores to stop rotating and resulted in the core lock engine condition.

Contributing to this accident were: (1) the core lock engine condition, which prevented at least one engine from being restarted, and (2) the airplane flight manuals that did not communicate to pilots the importance of maintaining a minimum airspeed to keep the engine cores rotating.

Accidents also happen when the "density altitude"—a combination of the temperature and atmospheric pressure at a given location—is too high. At high altitude on a hot day, some types of aircraft simply can't climb. They might get off the ground after attempting a takeoff, but then they can't gain altitude and they crash because they run out of room in front of them or because they try to turn back to the airport and stall the aircraft in doing so. An example of this scenario is described in WPR12LA283.

There's a helicopter version of this problem as well. Helicopter crews calculate the "power available" at a given pressure altitude and temperature, and then compare that to the "power required" under those same conditions. The latter are different for hovering "in ground effect" (IGE, with the benefit of a level surface against which their rotor system can push) and "out of ground effect" (OGE, where the rotor system supports the full weight of the aircraft).

It's kind of unnerving to take off from, say, a helipad on top of a building and go from hovering in ground effect and moving forward to suddenly find yourself in an OGE situation, not having enough power to keep hovering as you slide out over the edge of the roof. This is why helicopter pilots always will establish a positive rate of climb from such environments as quickly as possible—when you get moving forward at around 15 to 20 knots, the movement of air through the rotor system provides some extra ("translational") lift.

It also feels ugly to drop below that translational lift airspeed too high above the surface and abruptly be in a power deficit situation—maybe you have IGE power, but you don't have OGE power. In such cases, you may not have enough power to cushion your landing as you don't so much fly as plummet. (Any Monty Python fans?)

Finally, for some insight into the pure aerodynamics at play when airplanes fly too high, I'd recommend reading the responses to "What happens to aircraft that depart controlled flight at the coffin corner?"

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

Why Are Some Men's Beards a Different Color Than Their Hair?

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Throughout civilization, beards have acted as a silent communicator. For some, it's a symbol of virility and power. For others, being hirsute is mandated by religion, marital status, or both. (Amish single men are clean-shaven; husbands are not.) Seeing an unkempt, scraggly beard could be an indication of a person's economic status or their lack of vanity. One man, Hans Langseth, sprouted a 17-foot-long chin warmer for the unique identity it afforded him. (He kept it neatly rolled over a corn cob when he wasn't busy showing it off.)

Langseth's whiskers, which wound up in the Smithsonian, present a curious timeline of his life. The furthest end of the beard was a vibrant brown, grown out when he was younger. The ends closer to his face—and to the end of his life in 1927—were yellowed.

While age can certainly influence hair and beard color, it doesn't explain why a younger man can sport a decidedly different beard tone than what's on the rest of his head. Other follicular forces are at work.

By default, scalp hair is white. It gets its color from melanin, turning it everything from jet black to dirty blonde. Pheomelanin infuses hair with red and yellow pigmentation; eumelanin influences brown and black. Like shades of paint, the two can mix within the same hair shaft. (Melanin production decreases as we age, which is why hairs start to appear gray.) But not all follicles get the same dose in the same combination. While you might sport a light brown top, your beard could be predominantly dark brown, or sport patches of lighter hairs in spots. Eyebrow hair will probably appear darker because those follicles tend to produce more eumelanin.

If you're wondering why these two-toned heads often have a red beard but not red hair, there's an answer for that, too. While all hair color is genetic, one gene in particular, MC1R, is responsible for a red hue. If you inherit a mutated version of the gene from both parents, you're likely to have red hair from head to toe. (Hopefully not too much toe hair.) But if you inherit MC1R from just one parent, it might only affect a portion of your follicles. If that swatch of color annoys you for whatever reason? There’s always beard dye.

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