Sapolsky: Why Zebras Don’t Get Ulcers
We recognize the interaction between the body and the mind.
Emotions and personality can have a tremendous impact on the functioning health of virtually every cell in the body.
We are now living well enough and long enough to slowly fall apart.
90 years ago influenza was one of the biggest causes of death. Today, people under 70 rarely die of the flu.
Now we suffer from slow accumulation damage diseases—heart disease, cancer.
Stress can make us sick.
Many of the damaging diseases of slow accumulation can either be caused or made far worse by stress.
Interesting: most humans are stressed by traffic, money worries, deadlines, and relationships.
If we think like a zebra for a second, we identify different stressors—predators and starvation.
At the base, the most upsetting things in life are acute physical stressors.
Three categories of stressors
1. Acute physical stressors
You are a zebra, and a lion has just mauled your leg. You have to spend the next hour evading the lion as it stalks you. The body’s responses are brilliantly adapted to handling this sort of emergency.
2. Chronic physical stressors
The locusts have eaten your crops; for the next six months you must forage for miles to get enough food. The body’s stress-responses are reasonably good at handling these types of sustained disasters.
3. Psychological and social stressors
We humans live well enough and long enough to generate all sorts of stressful events purely in our heads. These events rarely correlate to actual danger. We rarely settle a fight with a family member with a fistfight.
When we activate our stress system for months on end worrying about mortgages or relationships, the system has not evolved to respond to this type of stimulus.
Stress = something that throws you out of homeostasis.
Ex. A subjection to great heat or cold.
Ex.2 The anticipation of something happening.
Stress response:
- Mobilize glucose and deliver it to your muscles as rapidly as possible. Heart rate, blood pressure, breathing rate increase.
- Your body halts long-term, expensive building projects. Digestion is inhibited. (You have better things to do than digest breakfast when you’re trying to avoid being someone’s lunch). Growth is inhibited. Reproduction is curtailed.
- The immune system is inhibited. A disease that will kill you in a month or a year is a problem to worry about later when you’re about to die right now.
- You experience stress-induced analgesia. Your perception of pain can become blunted (ex. A soldier shot rushing a stronghold doesn’t feel it).
- Cognitive and sensory skills shift. Your senses become sharper (during a horror movie a slight creak of a door makes you jump). Your memory recall improves (has this happened before, do I know the way, etc.). Cognition is sharpened.
Fight or flight is good for short term physical challenges. Pain is blunted, cognition sharpened. We get energy funneled straight to our muscles.
However, the stress response itself can become damaging.
If you experience every day as an emergency, you will pay the price.
If you repeatedly turn on the stress response, or if you cannot appropriately turn off the stress response at the end of a stressful event, the stress response can become as damaging as the stressor itself.
Hormones released by stress:
Epinephrine - adrenaline, stimulus, acts within seconds
Glucocorticoids - back epinephrine activity up over the course of minutes or hours. Raise circulating levels of glucose.
Vasopressin - stop the process of urine formation. Reabsorb the water into the bloodstream.
Hormones inhibited by stress:
Testosterone, insulin
The speed and magnitude of hormonal release depends on the stressor.
During stress response, points of bifurcation in your blood vessels wear down due to the increase in blood pressure. The smooth inner lining of the vessel becomes damaged, and glucose and fatty acids mobilized by the stress response can stick in the cracks. Epinephrine also makes circulating platelets more likely to clump together.
Chronic stress slowly causes the accumulation if plaque in blood vessels.
Being low in the dominance hierarchy turns on chronic stress response.
Being at the bottom of the dominance hierarchy means you cannot predict what will happen to you and that you have little control over your future.
If you couple social stress with a high fat diet, plaque formation goes through the roof.
Plaque formation is still severe with a low far diet and chronic social stress.
Our lives are filled with events that are ambiguous in meaning.
This is where your personality comes in.
If you are the type of person who habitually decides that those ambiguous events always mean something stressful, you will be at greater risk for various diseases.
Digestion quickly shuts down during stress.
You know you’re stressed or nervous when your mouth gets dry: you stop secreting saliva.
The parasympathetic nervous system shuts down.
Your mind has a huge capacity to affect pain sensitivity.
To mitigate psychological stressors, you need an outlet for your frustration.
This means believing you are in control, boxing, hugging, eating.
Even imagining such outlets can bring some relief
Stress-induced displacement of aggression is very effective - boxing, punching a wall, screaming
Amid a population of fifty elderly subjects, the average will be lower than for young subjects, but the variance is higher. This means that for six of the subjects, things are improving with age.
One factor is handling. A rat picked up for fifteen minutes a day for the first few weeks of its life lives much longer and better than a normal rat.
Best way to think about a stressor: “this is awful, but it isn’t the whole world.”
Takeaways:
Be able to distinguish between real stress and fake stress.
Be a take-charge type. If there is something threatening near you, don’t be the baboon who sits passively and waits for the fight, take control of the situation and strike first.
React differently when you win and lose a fight. Don’t be the guy who can’t tell the difference between winning and losing.
Confront and solve problems.
Increase control - pick your meal for the next day, care for something (plant, pet), initiate conversations.
Also be laid back about things that do not need correcting or cannot be corrected.