What might ‘wanting’ be?

I have long wondered what ‘wanting’ is from a physiological standpoint.  Antonio Damasio (1999, The Feeling of What Happens: Body and Emotion in the Making of Consciousness) has given me an idea that, I think, accounts for the human experience of wanting.  Homeostasis.  The argument goes like this.  In unicellular organisms, homeostasis doesn’t have a lot of ways to operate.  When an organism becomes mobile, homeostatic processes can trigger behaviors that with better than chance probability (from an evolutionary standpoint) result in internal state changes that serve to maintain homeostasis.  In effect, evolution favors behaviors that can be triggered to achieve homeostatic goals. 

In complex organisms, there are homeostatic mechanisms that work on the internal environment directly, but there are some internal environment changes for which it is not possible to compensate adequately by modifying the internal environment directly.  Thence, hunger.  Hunger is how we experience the process that is initiated when homeostatic mechanisms detect an insufficiency of fuel.  (Actually, it’s probably more sophisticated than that—more like detection of a condition in which the reserve of fuel drops below a particular threshold—and maybe there are multiple thresholds, but the broad outline is clear.) 

All organisms have phylogenetically established (built-in) processes for incorporating food.  In mammals, there is rooting reflex and a suckle reflex.  Chewing (which starts out as gumming, but who’s worrying?) and swallowing are built-ins as well.  But those only help when food is presented.  Problem: how to get food to be presented?  Well, if food is presented before hunger sets in, it’s not a homeostatic problem.  If not, homeostatic mechanisms switch the organism into “need-fuel mode”.  In “need-fuel” mode, organisms do things that tend to increase the likelihood that fuel will become available.  Babies fuss, and even cry, sometimes lots and loudly. 

Pain is another place where internal homeostatic processes intersect with the external universe.  Pain is how we experience the process that is initiated when homeostatic sensors detect deviations from internal stability that arise from a physical process (heat, cold, puncture, etc.).  Again, evolution has sophisticated the process somewhat.  The pain process arises when a threshold condition is passed.  Pain does not wait for serious damage to take place, pain is triggered when it’s time to take action to prevent serious damage.   

Pain actually has to be a bit subtle, too.  Some pain may and should be ignored.  If fight is an alternative to flight, then fight arguably ups the threshold for debilitating pain. 

There are other obvious situations in which homeostatic considerations require some action with respect to the outside world.  Urination and defecation are two.  Similarly, vomiting (with its warning homeostatic signal, nausea). 

Our wanting, then, has its origin as the experience of a process that responds to some (serious or prospectively serious) homeostatic imbalance. 

As an aside, I want to propose that one of the characteristics that distinguishes reptiles from mammals is that when a reptile is in reasonable homeostatic equilibrium, it does nothing.  When a mammal is in the same state, it does something—explores its environment, plays, writes poetry, etc.  In the most general terms, it sets out to learn something.  This characteristic arguably confers at least a marginal advantage to animals that possess it, viz. it is possible that something learned in the absence (at the time) of any pressing need will turn out to be valuable in dealing with future situations in which there will be no opportunity to learn it.  So, the concept of homeostasis has to be broadly construed. 

My central point, however, is that ultimately our wants, wishes, desires, dislikes, disgusts, and delights all refer to internal homeostatic processes.  The fact that there are so many distinguishable variants of wanting suggests to me that the many shades of our experience reflect the many kinds of homeostatic processes that have been phylogenetically established in our brains and bodies, each presumably for the most part having proved advantageous over evolutionary time.

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