Fight or Flight? Why Our Caveman Brains Keep Getting Confused



In a yr marked by a pandemic, financial downturn, racial unrest, and an election that culminated with a mob storming the U.S. Capitol, we’ve come head to head with stressors we may by no means have imagined previous to 2020. The causes and well being impacts of stress have been extensively mentioned as have a number of instruments for tackling the mounting anxiousness we really feel in our day by day lives. However cortisol, among the many physique’s most essential steroid hormones, on the helm of our stress response, stays largely a thriller. Is our fight-or-flight response actually tied to our prehistoric ancestors? Has our fashionable world developed past the antiquated workings of our endocrine system? Right here’s what we all know. 

A Caveman Intuition? 

Cortisol, together with epinephrine and norepinephrine, activate the physique’s sympathetic nervous system, triggering a lineup of physiological responses that pace up respiration, constrict blood vessels, dilate pupils, and decelerate the digestive system. It’s referred to as a fight-or-flight response, and it permits muscular tissues to react extra powerfully and transfer quicker, priming us to, nicely, battle or flee. Alan Goodman, a organic anthropologist at Hampshire School in Amherst, MA, research stress in prehistoric people. He agrees that cortisol and the whole acute stress response system is an evolutionary design.  

“It’s an historical mammalian system tailored to guard hunter gathers,” says Goodman.  

Nonetheless, getting a window into the day by day stress ranges of prehistoric people is troublesome as a result of we will’t take a look at their blood, he says, and cortisol doesn’t protect nicely. Analysis printed within the Worldwide Journal of Paleopathology, checked out cortisol accumulation within the hair of two,000-year-old Peruvian mummies and located “repeated publicity to emphasize.” One other small pilot examine of the identical inhabitants discovered that hair samples counsel social, physiological, and environmental circumstances “strongly impacted stress ranges.” However the analysis, says Goodman, has its shortcomings. The examine authors can’t rule out chemical modifications to the samples over time and we’re unsure how accumulation within the hair corresponds to that of the blood. 

Goodman prefers to have a look at skeletal indicators of prehistoric stress as a result of cortisol manufacturing also can impression bone and enamel metabolism. He research historical populations within the Illinois River Valley from round 1200 AD, in the course of the transition from searching and gathering to farming.  

“Enamel on the enamel grows like an onion and you may inform from enamel’s layers the years when the physique was harassed,” says Goodman. 

His analysis reveals a stress response seemingly introduced on by the transfer from searching and gathering to the constructing of civilizations and institution of society. 

“Life turns into extra difficult as a result of societal buildings have a hierarchy,” he says.  

With the haves and have-nots, the winners and losers, stress turns into extra convoluted, not confined to instant threats. Goodman notices this within the enamel as people construct societies beneath chieftains.  

Though the enamel stops rising as soon as everlasting enamel develop, a development stunt, often called enamel dysplasia, is frozen in time. Just like the rings of a tree, you’ll be able to see the years when life was irritating. This too, says Goodman, is an imperfect mannequin as a result of an infection and malnutrition also can impression enamel manufacturing. However after spending his profession learning these populations, Goodman suspects it’s seemingly a mixture of all three. He says that it’s clear stress has been round for the reason that daybreak of time however immediately our response has change into extra extended and in some instances,


Power Illness and Cortisol Manufacturing  

In historical populations excessive cortisol ranges meant good well being, mainly indicating {that a} human may nonetheless compete for survival, however in fashionable populations it could spell catastrophe. Sudha Seshadri, a professor of neurology and founding father of the Glenn Biggs Institute for Alzheimer’s & Neurodegenerative Illnesses on the College of Texas Well being Science Heart in San Antonio, research the hyperlink between neurodegenerative ailments and excessive cortisol ranges. Cortisol ranges, she says, ought to range all through the day, highest within the morning once we’re probably the most energetic and lowest late at evening once we needs to be sleeping. If ranges don’t range or are overly elevated within the morning, cortisol manufacturing can begin to impression different elements of the physique. 

“Power activation of battle or flight could cause issues in sure areas of the mind,” says Seshadri.  

Her analysis printed within the journal Neurology, has proven that these with greater morning cortisol ranges usually tend to have issues with elements of the mind chargeable for reminiscence retention just like the hypothalamus, which will be an early indicator of dementia and Alzheimer’s illness. Power excessive cortisol ranges are additionally linked to hypertension, coronary heart illness, anxiousness, and despair. 

Lowering Cortisol Ranges 

Folks reply to stress with completely different levels of cortisol activation, says Seshadri, partially primarily based on genetics and partially primarily based on life experiences. “Hyper-activation” of battle or flight particularly throughout early childhood, is linked to exaggerated responses to emphasize later in life. 

“It’s a vicious cycle, the extra you’re uncovered to emphasize, the extra seemingly you’re to have an exaggerated response to it,” says Seshadri. 

For folks, monitoring responses to emphasize can have lifelong implications for kids. Research additionally counsel that meditation appears to cut back cortisol ranges, as does biofeedback, a way that displays coronary heart price, respiration, mind waves, muscle contractions, and perspiration and permits sufferers to reply to indicators within the second, constructing consciousness round and slowing their stress response. Moreover, train generates its personal constructive chemical substances for counteracting cortisol like dopamine, norepinephrine, and serotonin. 

Each Goodman and Seshadri agree that battle or flight is present in each fashionable and prehistoric populations. However it’s meant to assist people quickly react to a bodily menace after which snigger off their brush with loss of life later, not stew all evening over a perceived hazard that by no means occurs.  

“The issue with people is that we’re symbolic beings, continually discovering which means in conditions the place there wasn’t any,” Goodman says.   

Consultants contend that cortisol nonetheless performs an essential function in preserving us secure in our fashionable world. However the hot button is dampening your response as soon as the menace has lifted, as a substitute of regularly fearing the imagined sabertooth tiger lunging from across the nook. 


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