Who we are and what we're doing at any given moment is heavily dependent on specific events that occurred moments before—in the time immediately before “now.” At any moment an uncountable number of possibilities could happen, but only one does. All the other potential candidates remain mostly hidden to us. In our ignorance we view the one event that did happen as something that must have been destined to be so, as if fate or some superior power had decided ahead of time what would happen to us. An earthquake will be viewed by some as punishment from God. Winning the lottery may be perceived as a reward for being good.
Even if we don't see a divine hand steering every event, we want to believe that our personal lives have order, that there is meaning to the things that happen to us. We want to think that things have a reason for happening—that there is a purpose and continuity to this existence.
On the personal level we especially want to see a continuum to our lives. So we tend to adopt the belief that there is an understandable order in our lives—even that there is some guiding hand that propels us down a certain path. It's almost as if we were destined to become who we are. That belief is mostly untrue. Our lives instead are largely contingent on arbitrary events that continually happen to us—events that are unforeseen by us and mostly out of our control.
When I was 17 and a new driver of that several-thousand-pound vehicle called a car, there were a few times that I nearly got killed—but managed to survive them all. The grace of God? Pure luck? My first job out of college depended on a recruiter arriving a week late on campus and my spur-of-the-moment signing up to talk to him that day. A week earlier I was otherwise involved and would never have met him. Where else may I have gone to begin my career? I bought my favorite house after a stroke of luck (for me!) saw the previous buyer's financing fall through.
Why do we marry the certain person we do? What determines when our first pregnancy happens and the baby's gender? What brought us down with a near-fatal case of the flu in 1998? What made my plane land safely and the next one crash? Wasn't my birth dependent on a random string of events—for example the one sperm out of millions of my dad's that led to me? What if my parents had decided to make love another night, or a month later, when Mom had a different egg in her uterus?
At any moment countless possibilities, innumerable contingencies are waiting, just a few seconds into the future. What I will end up doing in the moment following will be only one of those things—but until it actually happens, I could be pushed in many unpredictable directions. I plan to go outside and weed the garden, but the phone rings and the caller dramatically changes my direction. I walk heedlessly out the door, sprain my ankle, and spend the next few days in bed. I go to a restaurant for a meal, order the “wrong” thing, and come down with food poisoning.
All contingencies, of course, are not unfortunate ones. For example, I was dating a certain lady years ago, who seemed like she'd make a good mate; but we soon broke up and I shortly found a gal who's made my life far happier. I took a drive in the country one day and found exactly the piece of land I'd been dreaming about.
More on contingencies next time...
Saturday, August 6, 2011
Wednesday, August 3, 2011
Sunday, July 31, 2011
Jerky Birds—Part 2
These ocular avian advantages come at a cost, however. With such massive eyes crammed into the tiny skull of small birds, there is no room for muscles that rotate the eyes, so they have to turn their head to change their field of view. In addition, in order to have a wide field of view—remember all those predators—their eyes are located on the sides of their head, so they can see almost all the way around themselves. The cost for this capability is they have no depth perception, because each eye views a different image.
It's pretty hard to tell how far away things are if you have no depth perception. That can be fatal, if a hawk is rapidly zeroing in on your location. (There are no one-eyed baseball players, since catching a ball would be pure luck with no depth perception.) So what's a vulnerable little bird to do? He moves his head rapidly, from one position to another. This action accomplishes two things: one, he can triangulate on objects and two, he can better detect a moving object. Triangulation can help discern the form of and distance to things. When the head stabilizes for an instant, the bird can better detect motion “out there.”
Songbirds, being tiny little critters, move much faster than we humans can. Their eyes can resolve rapid movements—about twice as rapidly as we can. So they flick their heads about, helping them quickly to spot and track the movements of any potential predator. It's their critical ability to reconnoiter their immediate territory, without it all becoming a blur.
I got my first clue about what's going on with the jerky habits of birds when a neighbor described to me how he spots deer when he's hunting. The best indicator of a deer's presence to him is detecting its motion, since Mother Nature has gifted deer with such excellent camouflage. If a human is continually meandering through the woods, he's likely to miss the slight movements of a deer (who is always on the alert for predator motion). My neighbor demonstrated his hunting technique to me: quietly, yet fairly quickly taking three steps and then freezing like a statue for a couple of seconds, while his eyes sweep the area. That gives him a much better chance of spotting a deer.
After that demonstration, the more I watched birds twitch their heads about, the more I saw that it resembled my neighbor's hunting technique. With that hint to guide me, matched to the amazing ability of Internet search engines, I was on my way.
It's pretty hard to tell how far away things are if you have no depth perception. That can be fatal, if a hawk is rapidly zeroing in on your location. (There are no one-eyed baseball players, since catching a ball would be pure luck with no depth perception.) So what's a vulnerable little bird to do? He moves his head rapidly, from one position to another. This action accomplishes two things: one, he can triangulate on objects and two, he can better detect a moving object. Triangulation can help discern the form of and distance to things. When the head stabilizes for an instant, the bird can better detect motion “out there.”
Songbirds, being tiny little critters, move much faster than we humans can. Their eyes can resolve rapid movements—about twice as rapidly as we can. So they flick their heads about, helping them quickly to spot and track the movements of any potential predator. It's their critical ability to reconnoiter their immediate territory, without it all becoming a blur.
I got my first clue about what's going on with the jerky habits of birds when a neighbor described to me how he spots deer when he's hunting. The best indicator of a deer's presence to him is detecting its motion, since Mother Nature has gifted deer with such excellent camouflage. If a human is continually meandering through the woods, he's likely to miss the slight movements of a deer (who is always on the alert for predator motion). My neighbor demonstrated his hunting technique to me: quietly, yet fairly quickly taking three steps and then freezing like a statue for a couple of seconds, while his eyes sweep the area. That gives him a much better chance of spotting a deer.
After that demonstration, the more I watched birds twitch their heads about, the more I saw that it resembled my neighbor's hunting technique. With that hint to guide me, matched to the amazing ability of Internet search engines, I was on my way.
Thursday, July 28, 2011
Sunday, July 24, 2011
Jerky Birds—Part 1
Have you ever watched a bird and noticed how rapidly it jerks its head about? It will hold its head still for less than a second and then almost instantly flick its head to a new direction. It will do this so fast that I wonder how it can see at all; why things are not just a disconnected, blurry series of images. What's going on?
I've puzzled over this behavior for some time and finally did a little research (with a tip from a neighbor) to discover what seems to be the cause of this curious mannerism. What's at the base of it is the bird's constant need to be alert to predators. Small songbirds pretty much sit at the bottom of the prey hierarchy. All kinds of critters that fly and run (think hawks and cats) love to make a meal of a little bird, which must perpetually remain vigilant.
Large birds of prey—hawks and eagles—don't twitch their heads like this. In fact, they'll very slowly scan their territory, head gradually turning and eyes slowly rotating. What's more, raptors have eyes on the front of their head, to give them good depth perception, for tracking and capturing prey. Similarly, we humans require depth perception in order to catch a ball.
Vision is the dominant sense for birds. Evolution has given them very large eyes, relative to their body size. Our human eyes comprise about 2% of the weight of our heads. (My, what a large brain you have!) In contrast, the typical small bird devotes some 15% of the weight of its head to its eyes—in fact, their eyes can even outweigh their brain!
A bird has two to three times the number of cone cells than the human eye does, and we've got over four million in each eye! This gives the bird a visual acuity that we can imagine only when we use binoculars. They can see two to three times more acutely than we can. Furthermore, they can see into the ultraviolet range of the light spectrum, giving them many useful visual clues that we miss. Special eye glands emit tiny drops of oil that sharpen color perception and reduce glare. (Thus they can avoid the cumbersome burden of a baseball cap and sunglasses.)
The downside of such keen vision next time...
I've puzzled over this behavior for some time and finally did a little research (with a tip from a neighbor) to discover what seems to be the cause of this curious mannerism. What's at the base of it is the bird's constant need to be alert to predators. Small songbirds pretty much sit at the bottom of the prey hierarchy. All kinds of critters that fly and run (think hawks and cats) love to make a meal of a little bird, which must perpetually remain vigilant.
Large birds of prey—hawks and eagles—don't twitch their heads like this. In fact, they'll very slowly scan their territory, head gradually turning and eyes slowly rotating. What's more, raptors have eyes on the front of their head, to give them good depth perception, for tracking and capturing prey. Similarly, we humans require depth perception in order to catch a ball.
Vision is the dominant sense for birds. Evolution has given them very large eyes, relative to their body size. Our human eyes comprise about 2% of the weight of our heads. (My, what a large brain you have!) In contrast, the typical small bird devotes some 15% of the weight of its head to its eyes—in fact, their eyes can even outweigh their brain!
A bird has two to three times the number of cone cells than the human eye does, and we've got over four million in each eye! This gives the bird a visual acuity that we can imagine only when we use binoculars. They can see two to three times more acutely than we can. Furthermore, they can see into the ultraviolet range of the light spectrum, giving them many useful visual clues that we miss. Special eye glands emit tiny drops of oil that sharpen color perception and reduce glare. (Thus they can avoid the cumbersome burden of a baseball cap and sunglasses.)
The downside of such keen vision next time...
Tuesday, July 19, 2011
Friday, July 15, 2011
Sounds from the Woods
We live in a very quiet area, so we're able to hear nature's soft sounds from quite a distance away. A thunderstorm can be heard coming from miles off. A songbird half a mile into the woods can be listened to, when there's little wind to mask it. Sometimes it's almost ghostly quiet when no animal or wind can be heard... almost like I've lost my hearing. But every now and then the silence can waft a disturbing sound my way, that is a little unnerving.
I'm sitting in the hot tub. As dusk comes on and the light level drops, the woods visually close in, while my ears can still reach deep into the gloom. I am drifting in reverie when I hear a slight rustling in the leaves, coming from somewhere back in the inky woods. I can tell it is not a little critter, like a mouse or squirrel. Maybe a deer? The leaves rustle for a moment and then go silent for a little while, as if the critter is pausing to check out its next move.
The sound is slowly moving my way. No, now I'm sure it's not a deer, since they move more quietly. It's coming closer, unnervingly noisy. I am very aware of my vulnerability—sitting naked, out there by the creek. Any determined critter could jump me before I could make it to the safety of the house.
I'm confident that a cautious animal like a deer or squirrel would stop when it spots me. But how about this critter that's approaching? Lordy, maybe it's a big ol' raccoon! Sometimes when a 'coon spots you, it'll keep advancing. All I have to defend myself is to launch a few cups of water in its direction. That might just piss him off and cause him to charge the tub.
I feel my once putty-soft body stiffen a little. I wish it wasn't so dark in those woods. Is it friend or foe? Timid or fearless? As it comes closer I begin to realize what I'm hearing is not something rustling in the leaves, but the sound of raindrops periodically falling on the carpet of leaves on the forest floor. Hmmm... how can that be? Now I remember that it sprinkled rain a little while ago. Maybe something is shaking the raindrops off the trees?
Yes, I decide it's some critter moving through the trees, dislodging drops of water and sounding like it's far larger than it probably is. I'm now thinking it's a small animal jumping from tree to tree. A squirrel, I hope? Please? In another few moments I can see a patch of nearby tree branches bouncing and then—finally to my relief—a squirrel emerges from the shadows.
Mystery solved. My heartbeat can again drop to a crawl. I contentedly watch the acrobatics of the squirrel. Beautiful!
I'm sitting in the hot tub. As dusk comes on and the light level drops, the woods visually close in, while my ears can still reach deep into the gloom. I am drifting in reverie when I hear a slight rustling in the leaves, coming from somewhere back in the inky woods. I can tell it is not a little critter, like a mouse or squirrel. Maybe a deer? The leaves rustle for a moment and then go silent for a little while, as if the critter is pausing to check out its next move.
The sound is slowly moving my way. No, now I'm sure it's not a deer, since they move more quietly. It's coming closer, unnervingly noisy. I am very aware of my vulnerability—sitting naked, out there by the creek. Any determined critter could jump me before I could make it to the safety of the house.
I'm confident that a cautious animal like a deer or squirrel would stop when it spots me. But how about this critter that's approaching? Lordy, maybe it's a big ol' raccoon! Sometimes when a 'coon spots you, it'll keep advancing. All I have to defend myself is to launch a few cups of water in its direction. That might just piss him off and cause him to charge the tub.
I feel my once putty-soft body stiffen a little. I wish it wasn't so dark in those woods. Is it friend or foe? Timid or fearless? As it comes closer I begin to realize what I'm hearing is not something rustling in the leaves, but the sound of raindrops periodically falling on the carpet of leaves on the forest floor. Hmmm... how can that be? Now I remember that it sprinkled rain a little while ago. Maybe something is shaking the raindrops off the trees?
Yes, I decide it's some critter moving through the trees, dislodging drops of water and sounding like it's far larger than it probably is. I'm now thinking it's a small animal jumping from tree to tree. A squirrel, I hope? Please? In another few moments I can see a patch of nearby tree branches bouncing and then—finally to my relief—a squirrel emerges from the shadows.
Mystery solved. My heartbeat can again drop to a crawl. I contentedly watch the acrobatics of the squirrel. Beautiful!
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