A trio of hikers are shown in the mountains at sunset.


The recent coronavirus has taken us back in time, from luxury travel last year to subsistence travel this year, from an inviting vacation world to countries barricaded in fear of disease-bearing migrants.

There is a big difference between the pursuit of pleasant adventures in other lands as we experienced travel a year ago, versus launching a race against starvation and thirst, predators, and disease hundreds of millennia ago, when any wanderlust genes might have evolved.

All in all, we’ve been on the move for a long time. You could say that moving around has made us what we are: smarter and, pandemics notwithstanding, healthier.

Why do some people travel eagerly, while others are stay-at-homes? Some writers attribute such  differences in the urge to travel to the presence or absence of a trait of wanderlust. This is not to say that wanderlust is necessarily adaptive, because it was once considered a disorder.

Furthermore, travel is not a single behavior. Although walking is universal, travel involves adapting to challenges along the way and great skill in not getting lost.

A traffic jam shows a line of cars with brake lights lit.

BIO: Travel has a biological origin, considering that we must forage for food even in times of famine, seek out others to avoid incest, and flee from disease. Travel can also be biologically constrained, as the recent coronavirus has shown.

We start life with postural reflexes as part of a complex system of balance. We are born with stepping and placing reflexes that give us the movements of walking, but we can’t keep our balance. As we age, we grow into the bodies we develop.

The infant needs to learn to put together vision and the vestibular system with proprioceptive feedback. The secret to balance is to keep our center of gravity (usually around the hips) over our base of support, our feet. Then to achieve walking we have to assimilate feedback from visual and proprioceptive sensation. We have to track our surroundings visually while we monitor what our joints are telling us. The whole body is participating as we walk. Our back muscles keep us from falling forward while our abdominal muscles keep us from falling backward in every form of locomotion, whether we’re walking or riding a horse or nailing the dismount.

Even though walking is a conscious, voluntary activity, it–like running–relies on a number of reflexes that we don’t think about.

Consider the stretch reflexes, also called myotatic reflexes, in which a stretch of a skeletal muscle elicits an immediate contraction. In the doctor’s office this reflex is tested by stretching the quadriceps muscle, the big anterior thigh muscle, by tapping the patellar tendon*.

In walking, stretch reflexes occur at the lower end of the leg to help the walker make faster strides.

The calf muscles contract to lift the heel. These two muscles can also be called the triceps surae muscle, as if they were a single unit. With each stride, the triceps surae is stretched to sharpen the next contraction of the calf and speed the walker on his or her way.

However, these distinctions between voluntary and reflex movements should not be taken as universal truths. Sometimes they’re hard to keep separate, as with many distinctions in nature. (Think of the nature-nurture dichotomy.) For example, consider the Lombard effect, or raising your voice in a noisy room. It may feel conscious, but it’s actually involuntary. It’s the reason that the noise in a noisy restaurant is bound to get louder.

It’s a complex system. It falls apart at the worst times, like the last 50 years of life. It’s worth a little effort to keep it in working order. (Why are fitness and comfort always at odds?)

*The kneejerk or patellar reflex is a great example of unconscious movement. The physician or trainer taps a tendon with a Taylor hammer just below the kneecap–or patella–and observes a little jerk of your lower leg. (S)he could also tap your chin and observe an upward jerk of your jaw in response; stretch reflexes are all over.

If you trace through the reflex anatomically, you find that it occurs entirely at a spinal level. That’s a good clue to its unconscious nature. 

The stretch reflex guards against overloading a muscle by making it contract against the load; that’s also a reason for doing stretch exercises gradually if you’re an athlete.

Here’s a book chapter that tries to get into the neuroanatomy of it. (The late Masao Ito was a highly respected researcher.) This review adds pictures.

PSYCHO: Travel would be unremarkable if we didn’t harbor a competing urge toward territoriality.  Not only is our walking constrained by walls and fences, but migration is limited today by statutory borders. We even mark our territory in a restaurant by leaving a coat on the seat if we have to step away for a moment.

Are travelers people without a territory? Not today’s drivers, who transport their territories with them! We don’t perceive a private car as public transit, though we might defend even a bus or subway seat as a temporary territory. We mark our cars as our territories, and for a century or more we have felt that any traveler who approaches us too closely is an invader, and we react with road rage.

Road rage may be heightened by a personality disorder, intermittent explosive disorder, or IED. There may be inflammatory biomarkers that signal a vulnerability to IED, or even a brain parasite that could contribute.

What travelers in cars fail to do is to take the situation, the context, into consideration. By assuming that every rude driver is obeying an inner lack of disregard for others, we commit the fundamental attribution error. The driver who cuts us off could be late to work or racing to the hospital, for example.

Even stay-at-homes will be affected by the travel of others, and find themselves with new neighbors. But if some speculations are borne out, the new neighbors will be bright as new pennies.

SOCIAL: For millennia there have been nomadic societies scattered around the globe. Some of these cultures are dying away, largely through competition from the modern world.

However, the prehistoric forces of natural selection—disease, predators, war—have not ended. The past decades have been times of turmoil that forced people out of their homes and onto a road in the Middle East and Central America to venture hundreds or thousands of miles into strange territory. This has provoked resistance from the new territory’s natives in Europe and the United States, who have argued that immigrants do not assimilate, hardly pausing to reflect whether assimilation would be a satisfying outcome. Slowness in assimilation into the native population may be the result of strong cohesion that can arise within a group of travelers.

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