How Do Scientists Know?

Those scientists dudes–and dudenas–are so smart! They can tell you how much oxygen a dinosaur was using. They can figure out where the bubonic plague came from, 700 years ago. They can use new computers to rescan old pictures to look for earth-nudging asteroids. Exploring the universe with tools, logic, and an understanding of the behavior of things, they can describe what happened in places they can’t see and have never gone. Knowledge spreads ever-so-slightly outward into the vastness of the unknown.

Drawing of Dr. Jasmina Wiemann’s test subjects from

Strangely enough, it gives me a warm and fuzzy sense of comfort. As the kids say, Science gives you All the Feels. But let’s not get it tangled up with Belief.

Hot Blood Begets Hot Thoughts and Hot Deeds

Whether dinosaurs were hot-blooded or cold-blooded is a century-old argument. It was two whole classes in my semester of Paleontology 2A, back in the 1980s. Dr. Jasmina Wiemann at CalTech may have come across clues that explain why it’s been so hard to determine. The answer is a little of both.

Dinosaurs were reptiles. They lay eggs, and they don’t have fur/hair–I will spare you the much longer explanation involving clades. Modern reptiles are cold-blooded, ectothermic; they rely on external sources to raise body temperature enough to move around. They have slow metabolisms, so are very thrifty with their energy movements. Mammals and other creatures are endothermic or warm-blooded, with fast metabolisms. We can move around even when it’s not warm or sunny, even though we’d rather burrow under the covers. And some of us have such low metabolisms that even thinking about Cheetos causes bloating. But I digress.

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B is for Black Death

Pieter Bruegel’s Triumph of Death 1562, from wikipedia.

It’s 1347 in Caffa. The Mongols have been besieging the Genoese for four years, and some of the newest recruits turn out to be stricken with a rather nasty disease that causes bleeding lumps. As soldiers die, the troops catapult the infected bodies over the walls, which some note as one of the first instances of biological warfare. Since Caffa is a port, many escape in ships, carrying the disease with them to Sicily. By the time the pandemic spreads across Europe, somewhere between 1/3 and 1/2 the population would die, and, in densely-populated cities, near 70-80%.

A 14th century French mass grave, photo from wikipedia.

The Pandemic After-Party

The Black Death didn’t launch the Renaissance, and it wasn’t even the only widespread calamity of the day. There were massive famines throughout the 14th century in Europe as a mini-Ice Age followed centuries of relatively warmer weather. A different kind of climate shift–a drying out in the grasslands to the far east–may have pushed rats out of those drying grass of Siberia down south and east, to the population centers nearer to Mongolia and China. Virus + fleas + rats + people on horseback and on ships, all moved west. (Of course, China and India also suffered massive casualties from the plague, earlier than 1347, which is often overlooked.)

Large-scale reduction in populations cause upheaval, but they can be followed by opportunity. When the peasants recovered, they were in high demand. Their standard of living increased dramatically.

Travel and trade had dwindled for decades, but now it was turbo-charged, with traders flying around the Mediterranean, the Silk Road, the round-the-tip-of-Africa route to carry goods again. People were healthier, food was more abundant, more resources were available. You could stop worrying about how soon you were going to die and start thinking about pillows, cinnamon, and how to paint Venus on a seashell.

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