How Your Biology Affects Your Health: Crash Course Public Health #2

destiny we might think of it as that thing that brings two star-crossed lovers together or the thing that made us hit the jackpot in vegas or the thing that made our one true love break up with us because we went on to lose our vegas winnings but we don't often think about our health as being particularly intertwined with destiny we like to think our health is in our own hands and to some extent it is we look both ways before we cross the street to avoid being hit by cars we brush our teeth every night

before we go to bed and we eat vegetables to stay nourished a pickle counts as a vegetable right and this story of cause and effect makes sense to us our health doesn't feel particularly mystical or like it's been stitched into the cosmos but while there are no prophecies or chosen ones in the world of public health there are elements outside of our decisions that actually play a pretty big role in our well-being from the dna in our cells to the air quality right outside our homes there are countless factors that influence our health every day

all the time but thankfully public health experts are working behind the scenes to intervene with fate and give us all the best possible chance for living a healthy life hi i'm vanessa hill and this is crash course public health [Music] now the belief that we are the captains of our health destinies can be appealing because it suggests our actions are what determine whether we end up sick or well dead like in the epic saga of our health destinies we don't want to feel like we're just a character in someone else's movie script we want to

be you know the director when public health workers think about the ways that our actions factor into our health they're applying a behavioral approach to health for example experts taking a behavioral approach might say that when we smoke cigarettes we're engaging in a behavior that makes us up to 30 times more likely to get lung cancer than someone who doesn't smoke that's why a big part of many public health workers jobs is to encourage people to adopt healthier behaviors through things like don't text and drive messaging on billboards and anti-drug media ads but the behavioral

approach isn't the only way health experts think about our health for example public health experts could take a biomedical approach to health where they approach disease as a condition caused by germs or a problem with our organs rather than just a problem with our behavior for instance public health researchers might examine how smoking tobacco affects our brains but one of the most influential and comprehensive approaches to health that the one we'll be following most closely here at crash course is the social approach this approach acknowledges that our health choices and behaviors are impacted by the

entire world around us including social cultural political and environmental factors when addressing smoking a public health expert taking the social approach might look at how tobacco is portrayed in the media or what smoke-free policies are in place in businesses they may also pay attention to who is most affected by these decisions in the united states for instance advertisers tend to target smoking based marketing towards urban neighborhoods and neighborhoods with more black residents taking a social approach to health opens the door to the question of health inequity which is when different groups of people face different

health outcomes because of an uneven distribution of resources or because of structural differences in how they're treated health inequity is unfair and unjust and uncovering and addressing it is a big part of many public health experts jobs now the social approach doesn't imply that we totally lack control over our health destinies what it does tell us however is that we're not the only ones calling the shots in fact in the major motion picture of our health most of the action takes place off-screen what we're talking about are the determinants of health these are the conditions

in which we are born live and work that all have an influence on our health they span everything from our education level to our income level to even our zip code and our genetic code while there are many ways to frame the determinants of health in crash course public health it will place them into three main buckets there are the environmental determinants which consider how environmental factors like our water supply exposure to pollution and climate change factor into our health there are these social determinants of health which cover the relationship between our health and where

and how we live these include things like our income education system health policies put in place by our governments and how our access to resources is affected by our race and then there are the biological determinants of health these are the particular biological characteristics that can determine our health outcomes like our genes sex and age and in public health rather than looking at just like our kidneys we're focusing on the biological factors that could affect our kidneys like a family history of kidney disease as we'll see there are no hard borders between each determinant and

it's pretty much impossible to talk about one without stumbling into another one each determinant is related to the others and a complete picture of our health destiny will always consider all three but for now let's focus on just biological determinants looking at age as an example in a kind of wild statistic about half of all children will have at least one ear infection before they turn two and while it's easy to chalk this up to kids just acting in profoundly germy ways it turns out these ear infections are at least partially determined by kids biologies

for one children have shorter and more horizontal eustachian tubes which are these kind of neat and super necessary tubes that help drain fluid from our ears to the back of our throat but it turns out the particular shape of these tubes in children means that fluid is more likely to get trapped in the ear which makes it the perfect destination for bacteria to do some serious growing so just being a young kid actually turns out to be a major biological determinant of being prone to ear infections now while our age isn't really under our control

it still changes over time which affects the kinds of factors that influence our health too a lot of biological determinants are like this while they can seem permanent they can actually change due to time our behavior or our environment let's go to the thought bubble for more let's say there are two identical twin brothers gus and jack who want to set out and open an organic guacamole business together the brothers decide to split the business operations into two parts gus is in charge of growing avocados in an orchard out in the countryside while jack heads

to the big city to handle the business negotiations now jacka and gus are both healthy but they do have a family history of heart disease and skin cancer so in this case this shared family history is one of jack and gus's biological determinants of health anyways out in the big city a few years go by and jack is kind of crushing it in the business world he's creating a huge demand for his guacamole by networking with local grocers and promoting his guac all over the city jacket spends most of his day tied to his desk

busily tending to phone calls with potential buyers he doesn't have much time to exercise because well guacamole empires don't exactly run themselves after a few years in the city jack begins to notice a feeling like there's a persistent squeezing in his chest he goes to the doctor who diagnoses jack with coronary artery disease a condition which puts him at a higher risk of heart attacks meanwhile back at the orchard all that heavy duty avocado tending means that gus is in the best shape of his life his heart is healthy but working on the farm also

means he's spending a lot of time in the sun which is a serious risk factor for skin cancer sure enough gus begins to notice an asymmetrical mole with irregular borders on his neck which his doctor diagnoses as stage 1 skin cancer thankfully gus caught it early and was able to get it removed but remember kids always wear sunscreen thanks thoughtbubble now we can't know for certain if jack and gus were biologically inclined to have these particular health outcomes but what we do know is that despite sharing nearly identical dna and a family history of skin

cancer and heart disease each brother experienced unique health outcomes that were likely determined by differences in their environments to deepen our understanding of the relationship between our biologies and the outside world even further we can take a peek at a novel area of study epigenetics now we tend to think about genetics as an impenetrable stronghold of meanness at the center of our cells after all our genes are made up of segments of our dna and our dna is basically a big instruction manual that tells our bodies how to look and act and be well our

bodies but epigenetics says not so fast epigenetics is the study of the outside factors that determine how much some genes are expressed in our bodies according to epigenetics everything from air quality to stress levels can factor into how our genes are expressed now epigenetics doesn't mean your dna sequence is actually changing or mutating what's changing is your body's interpretation of your dna you can imagine epigenetics as a sort of chemical light switch inside your cells which your environment and behaviors can brighten or dim or even turn off completely let's travel back to the end of

world war ii to the dutch hunger winter a famine that occurred when the netherlands was experiencing a bitterly cold winter and a national food shortage during this time pregnant women who were starving were often giving birth to underweight malnourished babies over the following decades scientists continued to track these babies far into the future when the famine was a distant memory and all those babies had grown up what they found was that even decades later people born during the famine were more likely to develop diseases such as heart disease schizophrenia and impaired glucose tolerance a risk

factor for diseases like diabetes this suggested that their bodies were able to remember the stress experienced in the womb and wouldn't you know it researchers found that individuals born amid the famine had specific epigenetic markers on a gene that played a role in diabetes this was the first observed instance of early environmental factors like famine resulting in epigenetic changes with so many external variables at play it can feel like our health destinies are trapped behind a veil of unknowability but by continuing to study the determinants of health we'll start to nudge that veil aside and

get a peek at the complex factors at play next time we'll take a closer look into the deep and surprising ways that our environments act on our health and spoiler alert it's happening to you right now thanks for watching this episode of crash course public health which was produced by complexly in partnership with the american public health association if you want to learn even more about public health head over to apha's youtube channel to watch that's public health a series created by apha and complexly crash course was filmed in the castle garrity studio in indianapolis

indiana and made with the help of all of these delightful people if you'd like to help keep crash course free for everyone forever please consider joining our community of supporters on patreon [Music] you