1
Q
focus of darwinian medicine
A
- focus on questions associated with health/overall well-being
- specifically health, medicine, treatment, illness, from the perspective of what our bodies have evolved to do, what they’ve been selected for, and what we’re asking our bodies to do (and possible mis-matches between these things)
- we haven’t evolved to deal with our current environment
2
Q
mismatch hypothesis
A
- proposes that many modern diseases and conditions arise because our evolved traits are misaligned with our current, rapidly changing environments
- we no longer live in an EEA, but adaptations formed at this time still affect us
- as a result, our bodies aren’t always perfectly fit to the environment they’re placed in
- many of these issues deal with automatic processes that we can’t cognitively change
3
Q
hormesis
A
a biological concept describing a dose-response curve
4
Q
dose response curve
A
- small amounts of a substance can be very beneficial, whereas larger amounts can be problematic
- there are lots of things that are good for us, so long as we don’t overdo it
- not the case that some things are bad and some things are good for you, but that there might be a particular dose that’s good, whereas others could be counterproductive
5
Q
body weight and mortality
A
- the body doesn’t just maintain a weight based on calories in, calories out
- metabolism will shift depending on muscle mass, fat, etc
- metabolism protects against the riskiest situation and these have kept us alive throughout various evolutionary pressures
- e.g. tendencies to store fat, down- regulate our metabolism in starvation situations
6
Q
caloric restriction experiment assumptions
A
- maybe our bodies in this environment have gotten too fat because we have ample opportunity to?
- maybe we don’t need as much fat as we have a tendency to store?
- our bodies are selected to be very lean, on average, because our ancestral environment would have been very harsh
7
Q
caloric restriction animal research
A
- put a variety of species (ex. rodents, primates) on a calorie restricted diet
- control group on an ad libitum diet (at your pleasure): ex having a food bowl that’s always full, can eat as much and whenever they want to
- the ad libitum diet group lived to be ~3 years old, were fat, and quite slow
- found that restricting calories by 25% extended their lifespan → leaner, but still pudgy, lived several months longer
- fertile, in good condition, and didn’t have a big increase in disease - 55 + 65% group lived a lot longer → nearly 5 years, which is huge for a species that already only lives a few years → but didn’t have perfectly healthy long lives
- they were infertile, scrawny/gaunt, coats compromised (not enough calories to support healthy fur), which emphasized that living longer does not mean better health
8
Q
animal research relating to humans
A
- an ad lib control group doesn’t really exist in adult human populations
- on average, adults tend to restrain themselves at least a little bit (don’t eat whatever you want whenever you want always)
- in humans, some caloric restriction seems to be associated with a longer life that is somewhat healthier
9
Q
rhesus macaques
A
- have very similar diets to humans (omnivorous), and similar digestion
- prone to many of the same cancers and dietary-related diseases as humans (ex diabetes). - long living, and are second only to humans (in primates) in terms of taking over different environments, so have very flexible diets
- both of the following studies did research with macaques → each had control group and caloric restriction groups
10
Q
wisconsin study
A
- caloric restriction reduced a variety of diseases associated with obesity and aging
- control group was ad libitum → but these are not the types of diet that humans tend to have, therefore not ideal for generalizability to humans
- restricted diet was 25% less than ad lib group
- ~15% difference in body weight between conditions
11
Q
NIA (National Institute of Aging)
A
- found no differences in longevity or incidence of disease
- ‘baseline’ diet vs restricted diet
- restricted diet was 20% less than baseline
- did find difference in overall body weight (~12%) between the groups, but not quality of life measures
12
Q
differences in research
A
- seems to be that an ad lib diet is associated with shorter lifespan, increases in certain types of illnesses/physical problems
- but it would be a mistake to suggest that all humans are on an ad lib diet, because we’re not
- going back to hormesis → no food = bad for you; small amount = better than none, but not great
- there is a sweet spot of enough food, but as we increase the amount, we see diminishing returns, and it can eventually become problematic
- but we don’t know the exact sweet spot for each person → all have different genetic predispositions, metabolisms, etc
13
Q
mediterranean diet
A
- generally beneficial for the widest range of people
- lifestyle components: daily physical activity, mostly walking; daily naps/periods of leisure; community engagement
- diet has the best impacts when these behavioural/social components are added
- lots of variability → can make it vegetarian, low carb, high/low fat, etc
14
Q
‘evolutionary,” “ancestral,” diet marketing tactics problems
A
idea that there’s one diet that’s the best → but our species has adapted to eat just about anything
15
Q
carbohydrates
A
- the idea that carbs should be avoided is dangerous b/c we need carbs to survive
- carbohydrate refers to the chemical structure, but these can be found in a wide variety of different foods
- e.g. in vegetables and starches - carbs are building blocks for several neurotransmitters (ex serotonin, melatonin) and a lack of carbs can result in dysregulation
- lack of carbs associated with increase in compulsive and obsessive tendencies, increased anxiety
16
Q
simple carbohydrates
A
- things that your body doesn’t have to do much work to turn them into sugar
- e.g. Sugar - anything that is already glucose, fructose, sucrose, etc. is a simple carbohydrate
- in general, the sweeter a food is, the more simple carbs it has; and the inverse for complex
- when we eat food that is very high in simple carbohydrates (high-glycemic), gets converted to blood sugar
17
Q
complex carbohydrates
A
- body has to do some work to convert it into sugar
- e.g. vegetables, starches, etc. - on average, the more fibre the food has, the more complex carbs it has
18
Q
diabetes and carbohydrates
A
- food high in simple carbs gets converted into blood sugar
- increased blood sugar = increase in glucose, increased insulin
- insulin is what we use to be able to use the sugar
- high glycemic foods give us a bigger rush of sugar which corresponds to a high release of insulin (much higher than low-glycemic)
- as insulin deals with glucose in our system, drops over time which results in a sugar crash
- when we eat low-glycemic foods (lots of complex carbs or high protein) we still get an increase in blood sugar and insulin, but it’s not as dramatic, and it tapers off gradually without a crash
19
Q
theory for type 2 diabetes
A
- repeated exposure to these blood sugar/insulin spikes
- dietary correlates: higher rates of simple carbs vs complex carbs and proteins (lots of other factors too)
- also associated with yo-yo dieting: repeated exposure to starvation experiences
- mainly because it dis-regulates insulin production
- relatively uncommon in non-industrialized parts of the world → highly correlated with western, urban environments
20
Q
BMI as a measurement
A
- BMI is typically used as a correlate for body fat
- the BMI is a useful measure even though it is flawed
21
Q
BMI and weight status
A
- majority of people fall into the middle categories rather than the extremes
- the normal weight category is not necessarily the statistical norm, just the ‘ideal’ or preferred range for health
- obesity class 1 is the most common, with 60% of individuals in the States falling into it
- in Canada, the overweight category is the most common, with most people falling into the higher end of that category
- non-industrialized counties have lower body mass scores
- western and urbanized population tend to be heavier
22
Q
hormesis and BMI
A
- when looking at all cause mortality associated with body mass we find that there is a non-linear distribution of risk\
- both higher and low body weights can be the result of illness rather than the cause
23
Q
BMI and mortality study:
A
- got body mass information about people and then tracked them (longitudinal)
- normal = low risk of all cause morality
- the normal weight category and the bottom of overweight category are associated with lower overall risk
- too little or too much of something is associated with poorer outcomes
- the increased risk at the upper end of body weight is a gradual trajectory
- however, someones fitness level it is a much stronger predictor of overall health and longevity, regardless of where they fall of the BMI
24
Q
exercise and health
A
- not getting enough and getting too much are both bad for you
- research has shown associations of overall health and well-being based on type of exercise
25
cardiovascular/treadmill health study
- “do whatever you want group" and the other two groups entered systematic exercise program, with 3 workouts per week, they were weighed, VO2 max evaluated and measured stamina
- the group with 60 minute workouts had the most people drop out
- no significant cardio benefits above the 30 minute group
- VO2 max showed no significant change beyond 30 minutes
- exercising more is not necessarily better (hormesis)
- diminishing returns for increasing the amount of exercise you do past a certain threshold
26
downsides of overexercising
- bone and ligament damage
- cardiac vulnerability (increases risk of heart attack or acute heart problems)
- more cardio, and no/minimal protein intake, means your body will pull from your muscles to maintain the energy for cardio
27
mismatch hypothesis and exercise
- we don't have adaptations that tell us we should be exercising because this didn't exist for our ancestors because moving regularly would've been necessary
- walking , bending, lifting, stretching, etc, would have been a necessity
- we are adapted for short bursts of activity that get your heart rate up and for walking for long periods of time (hunting or migrating)
- we don't necessarily need an adaption tot ell us to move, what would have been selected for was conserving energy whenever you get the chance
- e.g. when you have time to relax do it, can you do something more efficiently, then you should
28
cross-training
- more likely to get injuries when repeating the same thing over and over
- more rounded fitness from multiple types of activity
29
weight-bearing
- more important for female bodies
- lifting weights or using your own body as resistance
- this includes walking → you are bearing all your weight
- builds muscle and bone density
- prevents deterioration of bone density → this is a risk with old age so it's important to build/maintain bone density
30
exercise fads
1. cross-fit
2. gluten-free & Atkins/low carb
3. 'Paleo diets
31
exercise fads - cross-training
- originally the military took a logic premise with cross-training
- our bodies have been selected for the types of exercise present in our ancestral environment, running, lifting, pushing, jumping
- implemented “cross-fit” based on functional skills and minimal equipment
- Kalisthenic exercise → aerobic, resistance with own body weight, lifting or pushing heavy items
- became more known to the public population and without the leadership from trained professional, intensity amped up
- Rhabdomyolysis and injury increased drastically
32
rhabdomyolysis
- consequence of muscles breaking down to quickly
- results in damage to the kidneys and eventually kidney failure
- peeing blood is a symptom
- cross-fit enthusiasts did not recognize the severity of this and felt it was “good”
33
culture of cross-fit
- done in groups to hold everyone accountable
- “work-out till you puke”
- blood in urine was a “badge of honour”
- acceptance of physical discomfort and pain
- weak if you don’t push though pain
34
exercise fads - gluten-free & atkins low card
- limit the amount of simple carbs and refined sugars
- avoiding something entirely doesn't necessarily give you the benefit
- this can lead you to lack nutrients if you give up all simple carbohydrates
- important to remember that when people talk about their own experiences, they are N=1
35
correlation and the third variable problem - gluten free and Atkins fads
- there are benefits to limiting refined sugars → doesn’t mean that all carbs = bad
- hormesis: avoiding something entirely does not necessarily give you a benefit, but can actually leave you lacking nutrients
- E.g. Avoiding fruits
- there are people who do need to avoid things from a medical perspective
- E.g.. Celiac disease → removing gluten has huge impact on overall wellbeing
- there are lots of people that go on a gluten-free diet that report that they feel better and they’re not wrong, but they conclude that gluten is a problem
- going back to the monkey studies, the quality of food made a difference and there is evidence that highly processed foods can result in lower health outcomes
- cutting out gluten also = cutting out wheat flour, pasta, muffins, beer, gravy, snack food
36
nocebo - gluten free and Atkins fads
- experiences negative side effects from a harmless substance or treatment due to negative expectations and beliefs about it
- e.g. asking to introduce high gluten foods into their diet, especially if they have avoided it for a while, they experience digestive upset as a consequence
37
'paleo' (caveman) diets
- overextension of a good idea that had logic
- mismatch between the environment we evolved in and the one we're currently in
- paleo diets are basically a form of eating that focuses on the food we have available in our environment
- e.g. raw food diet or carnivore diet
38
moderation is key
- body fat: you should have some
- carbs: more complex than simple
- gluten: if tolerant, irrelevant
- calories: about as many as you burn
- exercise: regularly, but not until you puke
- unless there is a medical reason to avoid something, you shouldn't
39
uncontrollable chronic stressors
- victim of DV, exposure to natural disasters, etc
- avoidance isn't possible in these situations
- do your best to make sure this stress doesn't become chronic
40
chronic stress
- very problematic
- HPA becomes overstimulated by the amount of stress
- high levels of cortisol and epinephrine which caused problems
41
sympathetic NS
- stress response
- engaged when big opportunities are ahead and when we are excited, not just negative stress
- deal with the situation and then the sympathetic nervous system recedes
42
avoiding stress
- isn't good for us
- exposure to anything in the world imposes stress onto our body in some way → our sympathetic nervous system is engaged even when we exercise
- small stressors are actually good for physical and cognitive and emotional resilience
43
parasympathetic NS
- in charge in peaceful situations
- deals with restorative things like digestion and sleep
44
sensory deprivation
- during sensory deprivation your parasympathetic nervous system does not engage
- in small doses it can create calmness and relaxation but prolonged periods of time increases likelihood of hallucination
45
HPA access
hypothalamus, pituitary gland and adrenal gland
46
hypothalamus
- connected to limbic system
- takes in information from your senses; information previously associated with meaningful stimuli like a threat or opportunity (e.g. chocolate cake or murderers)
- also takes in information about current bodily status like exhaustion, stress and hunger levels
- evaluates reserves and capacities for dealing with stimuli
47
pituitary gland
“master gland” because it is the gland of the endocrine system that sends other hormones to tell other endocrine glands what hormones to release
48
adrenal gland
- produces cortisol and epinephrine
- cortex produces cortisol
- epinephrine and norepinephrine are produced by the adrenal medulla
49
gonades
massive hormone producing glands
50
cortisol
responsible for regulating stress, metabolism, and inflammation
51
overexposure of cortisol causes:
- suppresses the immune system → likely because your resources are mobilized to immediate needs during stress
- cortisol is a steroid hormone meaning the more of it is in your system to more other steroid hormones being produced like testosterone are also suppressed
- antagonizes insulin → normally released when we eat, so when it is antagonized you increase the likelihood excess energy is stored as fat
- cortisol sensitivity is high in the hippocampus and this can cause damage → because it is responsible for memory consolidation, damage from overexposure to cortisol will reduce our capacity for learning new things
52
epinephrine (adrenaline)
- neurotransmitter that is associated with alarm
- also functions as a hormone and can be transmitted form hormone to hormone while also getting dumped into the blood stream to have action over other organs
- has stimulating effects on glands, organs or neurons in your brain
- responsible for increasing heart rate
- necessary for maintaining the energy levels necessary to respond to immediate threats → it is always present in your body
- chronic levels = hyper secretion
53
overexposure of epinephrine causes:
- imunosupressant
- elevate blood sugar → important for being able to mobilize energy in the moment like for running or fighting → but when it is chronic stress that excess blood sugar will start being stored as fat
- hypertension (high BP) → this is where there is an increased likelihood of high risk to damage to organs, veins and arteries begins
- cardiac irritability → heart receptors become sensitized overtime, meaning they are easier to trigger → this leads to tachycardia or arrhythmia
54
stress as a fitness gauge
- physiological stress responses can be adaptive
- the experience of stress can be thought of as information about where you stand in terms of fitness
- how well suited are you for the environment you are in?
- are you at risk of not surviving? Or are you in a good place to achieve safety, reproductive opportunity, and food?
- a negative emotion indicates you are moving away from fitness goals
- you are blocked from increased probability of survival and reproduction
- a positive emotion indicates you are moving closer to a fitness goal and increasing your likelihood of reproduction and survival
55
things that enhance stress
- things that threaten our social standing, physical safety, relationships, lack of resources, lack of social support, lack of reinforcement, unpredictability, exposure to trauma, high, discordant noise levels, crowding, presence of strangers, …all consistent with things our ancestors had to worry about
- our reactions are not a product of our modern environment, but an evolutionary need to belong
56
competition = stress
- tends to motivate us to perform very well — can be thrilling, exciting
- can also be perceived as uniformly negative
- we have some control over how competition feels (positive or negative)
- would have had a lot of competition in EEA — for resources, for mates, etc. It’s a very real threat to survival and reproductive success
- in the modern environment, we’re in competition with people we don’t know. We don’t even know how many people we’re competing against. We don’t even know what the rules are sometimes. (ex. Applying for a job, a scholarship, etc.)
57
mismatch and stress
- some of the stressors we experience are ones that we have to lean much more heavily on our cognitive resources for, rather than the built in adaptations we have for other types of stressors
- e.g. when we work out and our muscles get sore, we have a lot of adaptations that help make that a really beneficial experience for us
But competing against thousands of other students for getting into grad school?
58
addiction
- the limbic system is packed with dopamine receptors and dopamine can impact emotion regulation and reward
- correlated with a sense of reward
- if dopamine is activated, tends to strengthen connections between areas responsible for doing a behaviour and enjoying a behaviour
- things that increase dopamine tend to be things we’re strongly likely to do again
59
addictions in EEA
- the things we have a tendency to become addicted to were likely not present in the EEA, so we don’t have any resistance to them
- in the EEA, we might not have had access to those things in large enough doses for it to be problematic
- e.g. addictive-like processes in the consumption of sugar → we definitely had simple carbs in EEA, which are associated lots of calories, and with things that are not available all the time (ex. honey, ripe fruits) → so, we would eat a lot of them
- for things that weren’t present in the EEA, we don’t have a lot of adaptations that tell us to limit or stop them
- this is where we run into problems like eating too much Halloween candy, playing video games for too long, drinking too much, etc
- we had a variety of substances in EEA that could have been intoxicating like alcohol → decomposing, fermenting foods
60
drinking and alcohol in the wild
- species that have access to naturally occurring alcohol → will be individuals in each population that try to exploit it
- there are genes associated with the metabolism of alcohol
- in human population, those who lack the genes tend to get a greater toxicity from alcohol than the general population, and don’t get the same enjoyment (these people will tend to avoid alcohol altogether)
- in general, ~5% of population (incl. cross-culturally) has a real problem with alcohol → counterproductive effects on them, mainly socially
61
hamsters and alcohol
- not a lot of plant matter available to eat, and what is available is toxic
- through selective pressures, the hamster has developed a liver that is incredibly good at filtering out toxins
- means that it can’t get drunk very easily → can drink 10x more than rats and still not get intoxicated
62
alcohol-preferring rats
- no better at metabolizing or developing preference, but really liked alcohol
- had different personalities → more outgoing, lower fear responses… suggests personality correlates with preference for alcohol
- in contrast, alcohol avoiding rats are less social, more cautious
63
alcohol in EEA
- alcohol would have been relatively rare but not entirely absent
- low concentration (<5%)
- you're being manipulated by fruit
- benefits of low doses
- risk of high doses
64
alcohol rareness - EEA
- fruit would need to be suitably ripened; when the fruit is gone, it’s gone
- don’t have selective adaptations for avoiding intoxications
65
being manipulated but the fruit - EEA
- the way that fruits (and other plants) manage to exploit their environment and become more reproductively successful is to spread their seeds as widely as they can
- do this by sending out information to the world that says “I’m ripe, delicious, sweet, come and get me” → animals come and eat them, and then poop out the seeds all over the place
- we have developed perceptual biases (incl. colour perception, olfaction, taste buds, etc.) to detect fruits that are ripe
66
co-evolution
two different species building adaptations that are depended upon each other
67
benefits of low doses of alcohol - EEA
- digestive benefits
- but, you can get the same benefits from other types of fermented foods (ex. kimchi, kombucha)
68
risk of high doses of alcohol - EEA
if we think about things that we haven’t developed an off switch for, it’s probably connected to an adaptation that would have increased our chances of survival/reproduction, but we wouldn’t have had such unlimited access to them, so we need to rely on our cognitive resources to avoid them now..which is hard
69
psychosis variability
- variability and facultative adaptations
- it’s not a yes or no, binary distinction between someone who has a disorder and someone who doesn’t → have to think about it as a spectrum, where there are some traits that are beneficial in some doses, and counterproductive in other doses (hormesis)
70
bipolar disorder
- when you look at diagnostic criteria, there are a few categories
- bipolar I: periods of mania
- bipolar II: alterations between mania/hypomania and periods of depression
71
bipolar → adaptive value of hypomania/mania
- during periods of hypomania, there is less risk (because you can assess risk appropriately), and people likely get a lot of shit done! Increased motivation, productivity, while staying connected to reality
- if we have an overabundance of certain types of genes, we can sometimes end up with a version that is maladaptive (ex. People who not only have hypomania, but debilitating bouts of depression, or full blown mania where they cause problems for themselves and others)
- just because something is categorized as a disorder, doesn’t mean there are no upsides to it, and that it wouldn’t be present in the EEA
72
mania
psychotic, lost contact with reality, still lucid and functional, but no longer have accurate assessment of risk, might experience delusions, etc
73
hypomania
an increase in motivation and energy, decreased need for sleep, increased creativity, etc
74
hypomania - polygenic traits
if people with hypomania are incredibly successful (at surviving and reproducing), then the genes associated with the trait will become common in the environment
75
schizophrenia
- adaptive value of creativity, abstract thinking
- the idea that magical thinking, or making connections between things that others aren’t, can be very adaptive in both the EEA and the modern environment
- e.g. in places where creativity is rewarded
- much like anything else, there could be a dosage of psychosis that can lead to success
psych 373: evolution & human behaviour
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