by Shane L. Larson
Our senses — our sight, our touch, our smell, our hearing, and our taste — are the detectors we use to interface with the world. They are a biological sensor network of billions of cells, responsible for probing the world, gathering information, and delivering that information continuously to the brain.
The flow of information to your brain is tremendous, and you have adapted to ignoring most of it. Consider your sense of touch. Do you notice exactly how tight your shoes are right now? Did you think carefully about which direction you moved your leg a moment ago to make yourself more comfortable where you are sitting? How does your bracelet or watch feel on your wrist?
Consider your sense of hearing. Where ever you are, close your eyes for 20 seconds and see what you can hear. Do you hear the fans in your computer? Traffic passing by outside? Maybe sound from a TV or radio in another room or your office mate’s headphones?
All of this sensory data is constantly flooding into your neural network, but you are very adept at ignoring it. Scientists call this filtering — taking a huge amount of data, and separating and keeping just the bits you are interested in. In everyday life that means only listening to the person across the table from you, and not the cacophony of sounds that fills our world. It means looking only at the book or ereader in front of you and ignoring all the interesting things happening in your peripheral vision.
Our filtering is a habit, and given the constant demands on our attention from modern life, it is a completely necessary habit for coping with our overly busy and crowded lives. But it’s a habit we freely indulge in, so much so that we never lift the filter and notice all the wonder in the world around us.
Consider the following picture, taken of the trees outside my back door. What do you notice? Look out your window and jot down what you notice about the trees around you (hopefully you can see some trees — if not what else do you see? Just your quick impressions.).
My quick list might go like this: big and small trees; no leaves; grey bark; spring, but barely. All that can be gathered from a quick glance and without much thought or consideration, though at any given moment you may only register “trees,” if you even registered that at all. But what happens if I look closely at one? Take that large one in the center.
It’s bark is rough, and more or less aligned up and down the trunk. It is clearly ridged or grooved, and very rough to the touch. But careful inspection yields some odd color variations which, when viewed up close, are not bark at all!
If you didn’t look closely, you may never have noticed the off-color grey-green is a wavy sheet-like lifeform known as a lichen. This particular lichen is of the foliose (“leafy”) variety. Lichens are a symbiotic amalgam of a fungus and an algae existing together to each others mutual benefit. The algae contributes its photosynthetic powers to harvest sunlight and generate carbohydrates that are used by the alga and the fungus both. The fungus provides a matrix around the algae that protects it and collects water. Lichens have existed on Earth for at least 400 million years (the age of the oldest fossil that we are certain is of a lichen). They are extremely robust organisms, thriving in nearly every climate on the planet.
If I look around the tree bark a bit more, I encounter another lichen. This one is not grey-green at all, but orange. It is small, and hard to notice unless you are looking carefully. When I first saw it, I thought this particular lichen was of the crustose (“crusty”) variety. But if I look at the picture, it looks like it might still be foliose, just smaller and a different color. There’s nothing wrong with that — scientific knowledge evolves with consideration and reflection, and is driven by the collection of new and better data (in my case, a picture that showed me this lichen up close, way better than my eye could see in the bright afternoon sunlight!).
Lichens are common throughout the world, and you may or may not have encountered them in one of their many forms. But interestingly, lichens are a delicate probe of the environment in which they live — they are one of many types of organisms that are referred to as bio-indicators. Many species of lichen are sensitive to levels of sulfur dioxide (SO2). In the solar system, we find plentiful amounts of sulfur dioxide. On the moons of Jupiter it is found in the ice and frost of Io, as well as mixed in the crust and mantles of the other Galilean satellites, Europa, Ganymede and Callisto. On Venus, sulfur dioxide is one of the most abundant gases in the atmosphere, playing a role in the cloud and “rain” cycle and contributing to the runaway greenhouse effect. On Earth, it is generated naturally from volcanic activity, but vast quantities are created from industrial processes, particularly the burning of coal. Sulfur dioxide in the atmosphere is a precursor step to the production of acid rain which has dramatic impact on lichens as well as other plant communities.
Farther down the tree, on the shady side of the trunk, we find another organism that is not the tree. Dark green, with feathered spiny leaves but no real branches. This is a moss, a plant that belongs to a larger group of planets called “bryophytes” — plants that do not have branchy structures with a system to move water and nutrients around. Lacking a transport system, these plants stay small and close to the ground. Mosses do not flower; they instead release spores from tall stalks, and looking closely, I can spot a small forest of stalks, getting ready to spread more moss about my yard.
It was a cool spring day when I was looking at this tree — definitely not into the hot and humid part of the summer; it was pleasant in the sunshine and a bit chilly in the shade. As a result, much of the animal life is still hunkered down trying to keep warm. When I was peering close to this moss, I noticed one such denizen of my yard — a mosquito. Mosquitoes have been on Earth far longer than humans — almost 100 million years. There are more than 3500 different species known, though only a hundred or so actually use humans as a food source. Like most insects, they are cold-blooded, and prefer the temperature to be well above what we were experiencing this day. If this one saw me, it ignored the proximity of my phone as I snapped this picture.
All of this is right there in front of us, all the time. I just picked a single tree in my front yard. I could pick any other tree and would have discovered similar interesting things, and probably a handful of other different and interesting organisms. But let’s return to the #AdlerWall, which exhorts us to “see what’s hidden under rocks.”
A few paces from our tree, I found this rock. You’ll see it is covered with our old friends, lichens. This rock is partially buried in the dirt near my house and has likely been undisturbed for the entire time the house has been there (almost 30 years) — plenty of time for slow growing lichens and mosses to creep across the face of the rock, undisturbed as they push their frontiers quietly outward.
I’m definitely going to look under this rock, but one of the basic tenets of observing in science is there are two kinds of experiments — passive ones that leave the object of your attention in the state you found it, and active (possibly destructive) ones that manipulate the object for the purpose of study. This dichotomy is most dramatic at the extremes of physics — in quantum mechanics, the act of observing changes the nature of a system instantly and irrevocably (the point in the famous gedanken experiment known as “Schroedinger’s Cat”), and in astronomy we can’t do anything except watch passively (astronomy is a “spectator sport”).
Lifting up this rock is going to change it — I fully plan on putting it back, but there will be subtle changes none-the-less, so I carefully look around it before I move it at all, looking to see what I can notice. First, I don’t have a ruler that I can use for reference in pictures, so I use what I have at hand — my trusty pen-knife. By placing it in a picture, I can later know “how big is that rock?” During my initial inspection, the most significant thing that caught my eye was this little leafy plant, creeping up the edge of the rock. What’s it doing there? Did it try to grow straight up and just encounter the edge of the rock? Has there been a dormant seed under the rock for 30 years, or did the seed luckily fall directly next to the rock?Lifting the rock up, I find the truth — the leafy sprout is on the end of a very long root of some kind. Many plants grow new copies of themselves using propagative roots — roots that strike out under the ground, and then at some point sprout from buds on the roots and produce a new shoot growing above the ground. It looks like this might be of that variety — why else would this tiny sprout have made a gigantic root that threads its way under a rock that has been buried in this spot for almost 3 decades? I should find me a botanist and ask!
If you look closely, you’ll also notice an earthworm (an annelid) bunched up against the side of the root, probably more than a little disturbed that I had lifted the rock up. Worms play an important role in the processing of all the soil beneath your feet — their tunneling provides passageways for air and water to permeate the soil; their ingestion of dirt and organic matter breaks it down into deposits rich in the chemicals needed by plants (nitrogen, phosphates, potassium).
After my inspection, I dutifully put the rock back where I found it, replacing it in the divot in the ground I had lifted it from, covering once again the running root of our early spring sprout and returning our earthworm friend to darkness. There are many interesting things to be found around you. The challenge, always, is to notice. Don’t let the efficient habits of filtering prevent you from seeing what’s hidden under rocks. No interesting rocks around you? Look under sticks and logs. Look for interesting splashes of light or clouds you’ve never seen before. Look under leaves, and look under piles of leaves — what’s different? Snap pictures of what you see, jot some notes down, and share what you find online so we can see it too!
See you out in the world — I’m the guy on the side of the sidewalk, trying to take a picture of what I can see inside the big crack on the curb. Wanna take a look? 🙂
This post is part of an ongoing series about the #AdlerWall. I encourage you to follow along with the activities, and post your adventures, questions and discoveries on social media using the hashtag #AdlerWall. Links to the entire series are here at the first post of the #AdlerWall Series.