Sunday Sciku | Seedy Places

Researchers at the Karolinska Institutet in Sweden have discovered what amounts to a reflexive negativity bias in our sense of smell, showing that bad smells are processed rapidly and unconsciously. The olfactory bulb can process and send a signal to the motor cortex in 300 milliseconds, alerting us to rotten food before we swallow or of the presence of predators. The processing speed is much faster for smells that alert us to danger than for those with positive connotations.

Meanwhile, we tried a new trail last week only to realize that a family of bears must be using it daily—and why.


another trail
downwind of the dumpsters
bear scat


Sunday Sciku | Play Ball

In a paper published this week, researchers at Florida State University demonstrated that having a sense of purpose makes our memories more vivid. It reminds me of past studies showing far less cognitive decline in residents of eldercare centers who were given a pet to care for—even a pet like a goldfish that required very little actual care.

Meanwhile, I was feeling nostalgic yesterday, taking Colin to his Little League game in the bitter cold of an early autumn morning. Then last night we watched The Sandlot. It’s easy to forget how meaningful simple days like this are at 7 years old, but I still have vivid memories like these from that age, and it will be the same for him.

Just for fun, I made this week’s sciku a sciga, too.


fall baseball
our footprints fading
in the dew


Sunday SciKu | Vandals Took the Handles

With a possible submission from the obvious department, University College London ran a study demonstrating that vandalism is a response to social inequality. (Link in the comments.) They had teams of participants compete in the video game Parklife. In half of the games, one group was given an unfair advantage, which became obvious as the game progressed, leading to frustration and ultimately to spontaneously coordinated acts of vandalism from the disadvantaged team.

What was interesting is that this occurred regardless of the psychological makeup of the team members, showing evidence against the “one bad apple” hypothesis, which says that riots are started by individuals who are already prone to destructive behavior. It seems to have more to do with our sense of fairness and group identity.

The topic reminds me of a lot of the hiking areas down in the foothills of our mountains. What were once the most beautiful trails are just covered in trash and graffiti, even the trees. But of course vandalized trees are nothing new.


over the heart
carved in an old oak
new graffiti


Sunday Sciku | The Great Unconformity

Here’s something I’d never heard of: The Great Unconformity. The Grand Canyon is like a timeline of earth’s history, with each layer going back farther in time as you descend its walls, all the way back to rock that formed 1.8 billion years ago at the bottom.

The only problem is that a billion years worth of rock is missing. The timeline jumps from the Tonto group of 700 million years ago to the Vishnu basement layer 1.6 billion years ago. Geologist John Wesley Powell was first to discover this way back in 1869, but still no one really knows what happened to all that rock.

There are several competing theories, apparently, and they all likely played some role. For example, rock layers were weathered away by ice during the snowball earth period.

Geologists at the University of Colorado, though, published work this week providing thermochronological evidence for what seems to be the primary cause.

During the breakup of the first Pangea supercontinent, the western end of the Grand Canyon region was lifted so high that the basement layer came to the surface, but it was still miles underground at the eastern end.

The whole North American plate seems to have tipped like a saucer as Rodina split apart, and millions of years of rock slid into the sea.


basement rock
exposed at the surface
the great divorce


Sunday SciKu | AMOC

The Atlantic Meridional Overturning Circulation is the conveyor belt that transports warm water from the tropics northward and cold water south, balancing the heat distribution in the Northern Hemisphere and allowing for the relatively mild temperatures in Europe. New evidence has emerged this week from the Potsdam Institute providing further evidence that the AMOC is undergoing a loss of dynamic stability and may be on the verge of collapse.

The culprit is climate change, as lighter freshwater from melting land glaciers accumulates on the surface of the ocean, reducing the sinking action that drives this circulatory current.

The new report made headlines, but few seem to be providing the details about what this could mean for our future. The triggers of abrupt climate change in the paleo record remain a mystery, but the leading hypothesis is that these Dansgaard-Oeschger oscillations are related to changes in the AMOC. What seems to happen is that this fresh meltwater from a warm period sitting on the surfaces of the northern oceans causes this current to stall, which make temperatures in the Arctic plummet. Because freshwater freezes at higher temperatures than saltwater, this surface layer leads to an increase in sea ice, increasing the polar albedo, making the temperatures in the Arctic even colder, creating a feedback loop with cooling progressing southward toward the equator.

Another factor at play is the Beaufort Gyre, a clockwise-swirling current in the Arctic Ocean that traps cold freshwater. Historically, the gyre has reversed every 5-8 years or so, releasing that cold down into the North Atlantic, but the reversal is now a full 8 years overdue, and it’s holding more freshwater than all of the Great Lakes. When the reversal finally comes, it will release even more cold freshwater into the North Atlantic, sending Europe into a freeze and adding to the problem of the stalling AMOC. The effect is large enough that researchers have called the Beaufort Gyre a “ticking time bomb“—one that’s still ticking 4 years later.

The most extreme example of what an AMOC collapse can do may be the Younger Dryas, where temperatures rapidly fell 10 °C in Greenland and 5 °C Great Britain. With human-released CO2 tipping the scales in the opposite direction, no one really knows what’s going to happen. But it’s long been my opinion that it was this sudden climactic shift that drove the mammoths and mastodons to extinction, along with 70% of the rest of North American megafauna, and not human predation. The situation reminds me of this 19th century drawing of all the mammoth tusks from Siberia sitting on the trading docks in London. To me, it looks like Hokusai’s The Great Wave.


a frozen ocean
mammoth tusks
for sale