Esther Inglis-Arkell, of io9, brings us news that we have more senses than we may have realized. Ten Senses We Have That Go Beyond the Standard Five. We all know about touch, taste, smell, hearing, and sight. It turns out we have other specific senses as well.
10. The sense of when you have to go to the bathroom.
It doesn't seem impressive, but trust me, you'd miss this if it were gone. Now is, however, a good enough time as any to discuss what makes a sense. Scientists, for example, don't make 'social discomfort' a sense even though that certainly as strong as this sense. In order to make something a sense, there has to be some organ, or set of organs, that are meant to sense that one specific thing. In this case, there are special sensors in the rectum and the bladder that sense their stretch and communicate the need to urinate to the brain.
9. The sense of hunger and thirst
This wouldn't be as socially embarrassing as freely going to the bathroom all the time, but we do have special receptors that tell us when we are hungry and when we are thirsty. Technically these count as two different senses, though in some animals, like mammals that live underwater, they are one. If dolphins drink fresh water, they stop eating. Since they get their fluids from their food, they can't tell the difference between hunger and thirst.
Some, of these seem like variations, of the five senses we are familiar with, but others do seem different. Scientists have defined the need for there to be an organ, or set of organs, devoted to perception for this to be a sense.
Yesterday, I posted a story about the enteric nervous system, which is so extensive some scientists call it a "second brain." Maybe, this is the organ that allow us to know when we need to go to the bathroom?
Here's a summary list. Check out the article for a quick, fun, read.
1. Nocioception - the sense of pain.
2. A Sense of Time - the passage of time, and duration.
3. A Sense of Movement - Remember last time you were on an elevator? Is this just acceleration, or velocity as well. In an elevator I don't believe we can sense constant velocity. But, maybe outdoors the body uses other cues. Last time I was at Epcot Center, I read Disney engineers, have learned how to cue motion receptors in our peripheral vision.
4. A Sense of our location in the world.
5. Our bodies, position relative to ourselves - proprioception.
6. Temperature. - Thermoception.
7. Pressure.
8. Itchiness.
9. Hunger and Thirst.
10. Having to go to the bathroom.
2. The sense of time.
When we stumble out of the movie theater, after having watched a revival screening of Gone With the Wind, we don't get surprised that we've been in there hours instead of minutes. What's more, even though we've seen Scarlett go through the civil war, build up a successful lumber business, conceive, birth, and raise a child, and yell "Rhett" and "Tara" about a thousand times, we don't assume we've been in the theater for years. Our temporal sense does fail us, but even distracted by images and wooed by an epic narrative, we keep a fairly good sense of how much time we have.
1. The sense of pain.
Nociception is perhaps the least appreciated sense. It's our sense of pain. Getting rid of it would get rid of a lot of the problems of the world, and eliminate some of the most intensely unpleasant parts of life. It would necessitate a trade-off, though. Replacing that intensity would be a long, slow grind. Instead of intense moments of agony that would last a few seconds before we pulled away or did what we could to eliminate the cause of the pain, there would be the constant physical therapy needed to functionally heal from breaks, sprains, burns, strained muscles, cuts, and bruises. Without pain, there is no sense to tell people to pull away from behaviors that physically damaged them. In ancient cultures, pain probably kept people from dying. In the modern world, where the stakes are lower, it's more of a time-saver. One brief moment of agony keeps us from doing damage that would need months or years to heal.
I've seen other systems that break perception in to over a 100 sub-categories-- such as "motion towards," "motion away "brightnessl," "relative size," etc.
It seems as if there is some ambiguity, in what constitutes a sense. Is itchiness really a separate sense, or a sub-category of touch? The authors suggest to qualify as a separate sense, we need a separate organ, or organs? Where's the itchiness organ? Maybe, it is an identifiable network of neurons, this article didn't have time to go into?
And, on the other other hand, scientist have discovered that cats have special nerve sensors in their retina, that automatically perceive convergent lines, that enable them to immediately sense the edge of a cliff due to "parallax foreshortening." This alarm bypasses the normal visual field circuits, and cues an immediate crouching response to prevent them from falling off of a ledge. This does seem to constitute an "organ" or system of nerves that is a special sense. Bypassing four or five nerve links gives cats a better chance of survival.
Also, consider the special sick feeling we get politicians start to tell us lies, that immediately by-passes the brain, and causes indignation. This seems to qualify as a unique sense as much as itchiness does.
10:33 PM PT: I hope folks don't mind me promoting a very late night diary on the famine in East Africa.
HoundDog, of EcoJustice writes Worst Drought in 60 Years Brings Famine To Millions in Somalia, Kenya, and Ethiopia