Last week our lab held the last meeting for the semester. And to celebrate a great productive year we had… chocolate-covered insects. It’s a bizarre tradition carried over from ~1 ago when the lab studied disgust towards eating different animals 🙂
I will miss working with our fantastic undergraduate apprentices! This semester we focused on 2 projects: 1)using process tracing software to examine how much different types of information matter for making food healthiness judgments, and 2) measuring household wealth (& how it affects health) across the world.
The first project was my “baby”: after mostly survey and interview work over the past several semesters, I really wanted to try learning a new method. I both hated and loved it: the learning curve can be brutal, but once we got some preliminary results things felt worth it!
We used a process tracing software that allows you to analyze the decision making process of participants. We used this program to have people rate different foods on healthiness after checking some information about them. We gave them two types of information- positive (e.g. presence of vitamins) and negative (e.g. presence of artificial ingredients). Our pilot confirmed the hypothesis that people do in fact spend more time checking out negative information! (See chart: time/Y axis is in milliseconds)
For the other project I spent the last 7 MONTHS harmonizing and cataloguing the many assets and services used to assess household wealth in low-income countries. The main question for this project is to examine how economic inequalities shape global health outcomes (e.g. obesity in adults and child growth) and to test whether different pathways to wealth might shape these things differently. I’m happy to announce that we in fact DID finish all the data harmonization and merging (it was no spring picnic) and the lab will now begin analyzing the data and examining different dimensions of wealth.
Uhh I will miss this amazing team for sure.. but hey- in about a week I graduate! What a strange feeling it is!
Ta-da! Finally. Mine and Dr. Hruschka’s paper is finally out in the Journal of Cognition and Culture. This survey work was done over 2 years in both Eastern Europe and Southwestern U.S. So glad to see it in print!
HERE is the PDF: CognitiveDifferences_Paper2017. Also, if you don’t feel like reading it, i just recorded a 5-minute overview of the paper (recorded between meetings.. after 2 cups of coffee.. sorry if I talk quickly!).
Short intro: Cooking food is a unique human activity spanning across all cultures, and humans appear to be evolutionarily adapted to this crucial aspect of their diet (Wrangham and Conklin-Brittain2003). The value of cooking lies in its ability to widen the range of foods that are safe to eat (whether by making their digestion easier or neutralizing toxic compounds) as well as extract more energy from the foods ingested. Both human and animal studies illustrate that the more cooked food there is in a diet, the greater the net energy gain for the eater (Carmody and Wrangham2009), and a diet of raw foods is energetically inadequate even when various nonthermal processing methods are employed (Koebnick et al.1999). The effect of cooking on the energy gain from eating includes several mechanisms: increasing digestibility and thus caloric value of ingested foods, lowering the body’s energetic costs of digesting, and mounting an immune defense against food pathogens.
My first encyclopedia chapter is finally published!
I was researching and writing this one while traveling across 3 countries this summer and collecting data, so the whole process was not necessarily a piece of cake. Thus, i’m extra pumped this is finally available! If you want to read the chapter but can’t access it, feel free to email me and i’ll send you the PDF 🙂 -> mvoytyuk (at) asu.edu
NOTE: It’s actually highly ironic for me to write on how cooking could have been instrumental in the evolution of our large brains- I spent 2 years as a highly motivated raw vegan! Indeed, I took several “raw cooking” and educational courses in different parts of the U.S. (Illinois, California), was a private raw “chef”, and taught raw veganism workshops for over a year at a food co-op I managed.
This chapter doesn’t actually comment on whether there could be health benefits to eating a diet higher in uncooked foods. It does focus on highlighting the fact that we appear to be particularly adapted to cooking. So, I’d say it does notsupport a 100% raw vegan diet as a worthy endeavor.
Click HERE for the encyclopedia page, and here is the short intro:
The disproportionately big human brain is a conundrum – it is larger than would be expected for a primate of our size, and it is a very energetically expensive organ. Since human basal metabolic rate (BMR) is not elevated to match such a big brain, the extra energy needed to sustain it suggests a dietary explanation. Feeding the large brain would likely require a shift to a high-quality diet: one comprised of energy-rich, easily digestible foods. This hypothesis is supported by a number of anatomical features: smaller teeth, jaws, stomachs, and a shorter large intestine. Two key elements of human subsistence – cooking and meat eating – have been proposed as a possible means of achieving this high-quality diet.
It was a Saturday afternoon- I spent all morning writing one of my dissertation articles. It was unfortunate that i had to be on campus instead of enjoying my morning coffee at home, but some syncing error got me panicking as I couldn’t find my latest saved draft.. So here I was with only 25 minutes before my aerial fitness class: I made a quick stop at an empty campus store, grabbed something to eat and rushed out to my car, still deeply pensive over some changes I should make- I am writing about lay interpretations of healthy eating context.
I looked down to see what it is I was holding in my hand, because it seemed like i made my snack choice in some auto-pilot mode:
OK, it made sense. Considering the context. And then I thought- I just spent 4 hours writing up my article on healthful eating beliefs.. how would I go about finding out what rationale was behind my food selection right now?
I pretended to ask myself in an interview format- “why did you choose these items?”- and immediately imagined a word cloud of my transcribed answer: there was a whole bunch of stuff there, but several most salient words stood out: calories, protein, satiety, light. The transcribed text would read:
“…so I was not starving yet, but it was almost 1pm and I had an intensive aerial class that I anticipated i’d want energy for… i needed to feel full but not physically full (so, light)- can’t eat anything big before hanging upside down on the aerial hoop! I know protein is satiating, and I like this bar because it’s damn delicious (i’m aware of the halo effect that “protein” has in this situation – extrapolating the “goodness” of protein to unrelated product characteristics, such as it’s overall healthiness… it’s really just a candy bar! but the health claims on the package do pacify the guilt splendidly). I also know that sweetness may provoke hunger on it’s own, so I have to balance the taste with the umami-ness of string cheese. This combo is also just about 300 calories, which is my upper limit for a snack (I gage it, though I know i’m exactly on point with the number despite not checking the nutrition label)… I don’t really count calories- I think it’s not a helpful behavior and one can become fixated on it, which might get detrimental for your dietary quality. Yet I also can’t help being somewhat vigilant- I know eating gets more “fun” later in the day, so I want to leave enough of an energetic allowance to indulge in my evening netflix/playstation time. Calories definitely matter- i’m so tired of people’s hopeful attempts to fight this truth and discover a loophole in the first law of thermodynamics. Sure, there are nuances- cooking and processing can change the availability of calories to your body, but those are just nuances to me- at least that’s my current stance based on the literature.”
Wow, that’s a whole lot of rationale for an “auto-pilot” choice that took 20 seconds without conscious effort. Of course, eating perceptions and choices are my research topic, so I am quick to self-reflect in detail. Yet for many respondents, who hold their own complex mental models of healthy eating, this can be like pulling teeth- it’s not easy to explain things that seem obvious or natural to us (unless maybe you’re writing a dissertation on it). My reasons are good examples of cognitive heuristics- “rules of thumb” used to make choices in complex situations, such as eating (we make about 200 eating decisions daily, according to Dr. Wansink- too lazy to give you the specific study name.. just google it 🙂 ) The “Protein- satiety- good” connection is a simple heuristic, the “power” and “energy” words on the bar signaled appropriateness of this snack before a workout, the familiarity of the products (I know this bar and it’s taste; bought it before) also played a role.
But anyway: I’m almost done writing my first chapter now. I’m in the process of shortening it actually……… by about 10,000 words :S It’s such a painful process to let go of your findings- perhaps I’ll post a bunch of interesting results here in the coming months! I could be sporadically posting cool quotes on twitter or Instagram too, but honestly- that’d get attention of maybe 10 people. Meanwhile my latest quick sketch of a friend pulling off an aerial trick just got more than 1000 likes… So forcing myself to tweet the dissertation is lacking in motivation at the moment. In the meantime- enjoy whatever it is you might be eating right now! Don’t overanalyze it, I suppose?
I stopped by the campus store on this fine “dissertating” morning, and got the protein bar again + another item to illustrate my previous point. This probably won’t shock anyone, but i’d say i was quite correct in stating 2 days earlier “it’s really just a candy bar!”
At least if you consider the energy content and, really, majority of ingredients (i will admit- “monk fruit” sounds mysteriously awesome, though it is the last ingredient (so there’s like a trace amount of it).
Now, obviously there’s a difference- and that’s the difference that drives the high price point of the protein bar (as well as it’s healthiness message): the power bar has more protein (13 g vs. 3) and less sugars (5g vs 21g). On another hand, the power bar has a bit more saturated fat and cholesterol. That last point is most likely less relevant to an average reader- so far, my interviews and surveys show people vilify sugar much more than fat (again, you’re probably not shocked and i’m definitely not the first one to notice- the low fat fad is over, it’s been all about the horror of carbs for awhile).
Now, protein appears to be more satiating than sugar, according to a bunch of studies (go check out Google Scholar), so perhaps you indeed might eat more later after the Kit Kat, despite eating the same amount of calories as from the Power Bar. And something like that can be tested in a nicely designed experimental study (probably has been). Despite all of this, next time i make a quick stop at the store, i’ll probably still reach for the Power Crunch bar. Buying a Kit Kat is too bizarre- I don’t eat candy! And though i know the bar is really just another candy- well, it just leads to less cognitive dissonance 😛
It’s taking me awhile to “digest” all the information (hehe), but I found the seminar fascinating and wanted to summarize some main points. Lots of open questions remain, but John Pepper of National Cancer Institute really shows how examination of any health problem needs to focus not only on proximate causes, but the ultimate or evolutionary causes.
So.. Pepper asks- why is mammal meat bad for humans, specifically?
In humans, red meat (he refers to it just as mammal meat) is linked to inflammatory diseases (cardiovascular, alzheimer’s, arthritis). What’s the mechanism behind this?
The inflammation from mammal meat has to do with our antibodies attacking something coming from other species.. When we eat mammal meat, we in fact incorporate something non-human from the diet- sialic acid.
Both human and other mammals have sialic acid in their tissues, actually, but humans have a unique mutation that replaces the form found in other mammals (ancestral form- Neu5Gc) with a different one- uniquely human (Neu5Ac).
So.. if we eat meat we get the new aquired ancestral sialic acid, it becomes part of our cells, and the small structural differences in the two get recognized by the immune system.. which responds with a defense- inflammation!
Chimpanzees are humans’ closest evolutionary relatives, sharing a common ancestor 6–7 million years ago..
WHY does human sialic acid differ uniquely? The “Malaria hypothesis” (see Martin&Rayner, 2005) proposes that in Africa, early humans escaped from the ancestral pathogen they shared with chimpanzees. They managed to do so by replacing the pathogen’s binding target (ancestral sialic acid Neu5Gc) with novel Neu5Ac. With time, a population of that old evaded pathogen evolved to infect humans again by recognizing the new Neu5Ac..leading to the origin of malaria.
If the Malaria Hypothesis explains why the initial change in humans happened.. why has it remained the same to this day? I mean, it’s been some several million years now- has this mutation been advantageous this whole time? It’s an important question because this sialic acid mutation poses a COST on our health: this trait causes chronic inflammation in people who eat mammal-derived foods + it also now causes vulnerability to malaria.
The hypothesis for why the human sialic acid modification is still around is that it
provides benefits- specifically, protection from parasites and pathogens via increased inflammation. This is relevant because of what humans have been doing for the last ~15,000 years. Animal domestication!
Humans are more vulnerable to shared pathogens from other mammals (than from non-mammals). So being around cattle, for example, carries a risk of catching pathogens from which that cattle suffers. Such animal pathogens impose a strong selective pressures on humans.. Pepper suggests that the uniquely human sialic acid (Neu5Ac) allows our diet to adapt us to the issue of animal pathogens by adjusting our inflammatory tone (how much inflammation we are experiencing): “those human populations that are exposed to domesticated food-mammals and their pathogens are also eating mammal-derived foods that are pro-inflammatory (both meat and dairy).”
Inflammation is a great example of a trade-off. It both has benefits (protection from parasites & infections) and costs (chronic disease, metabolic expense of mounting an immune response). The optimal balance for this trade-off would depend on how strong of a pathogen pressure you’re experiencing.
This increases inflammatory PROTECTION only where it’s most needed (like around animals). So this auto-immune inflammation from mammal foods in the diet not only increases likelihood of chronic disease, but protects against shared mammalian pathogens.
….. …… ……
It got me thinking about human culture and our ability to modify our environment in all sorts of ways- an example of “maladaptation” to modern times! Living in cities, not exposed to higher pathogen load from being around domesticated animals..yet having access to all the mammal meat we can buy = all put you in a situation where the good old sialic acid mutation might do more harm than good. Should people go vegan? Should they simply cut down on red meat? There was no discussion on the effect size of mammal meat eating and chronic disease, so I wouldn’t necessarily jump onto any lifestyle changes based on this talk. Yet the process of understanding this health concern through the lens of evolutionary medicine is quite fascinating!
P.S. I’m not an expert on this topic. If you have something to correct or add, please comment 🙂
Got it- to FAST? 😀
The past week has been a treat in terms of great talks on campus. At ASU we are super-lucky to have the Center for Evolution & Medicine, which holds weekly talks by amazing speakers.
When I saw that the upcoming seminar was related to diet and eating..or more specifically NOT eating or “dietary restriction”, I of course RSVPd in a heartbeat.
“Eat breakfast yourself, share dinner with a friend, give the supper to your enemy”- Russian Proverb
I’ve been in fact fascinated with caloric restriction for years now (I wrote a whole research paper on it in the first year of my master’s degree). You might have heard of intermittent fasting (e.g. popular in the CrossFit world), or the CR Society ( http://www.crsociety.org/ )- all are related to the concept that restricting food intake results in health benefits (from extending life to preventing and reversing disease).
I’m sure you can Google caloric restriction and find a bunch of information on its reported benefits..you would see this chart at the CR society website- the lifespan of calorie-restricted (CR) mice vs non-CR mice. You can see that those whose food intake was restricted by more & more % lived longer. Why do many animals (and perhaps humans) appear to be so well-adapted to eating less? The traditional interpretation of this CR phenomenon is that the dietary restriction effect “has evolved as a way to enhance survival & preserve reproduction during periods of naturally occurring food shortage”. In other words- being adapted to do well on restricted food intake during rough times would have helped our ancestors survive them & stay healthy to have kids later when the food situation improves.
The traditional interpretation of this CR phenomenon is that the dietary restriction effect “has evolved as a way to enhance survival & preserve reproduction during periods of naturally occurring food shortage”.
Experimental evidence with animals, however…supports a different hypothesis- the one Dr. Austad (Professor & Chair of the Department of Biology at the University of Alabama) presented to us last week. Again, I wouldn’t be able to cover everything he discussed during the seminar, but I do want to highlight a couple of main points!
I. First, even though the first book on dietary restriction (DR) dates back to the late 16th century, we still do not know the mechanism behind why DR seems to extend life and vigor in animals + delay disease such as cancers. METABOLISM was the original suspect, as metabolic rate goes down with fasting.. however, metabolic rate drops initially yet gradually goes back UP (takes 6-8 weeks to happen).. Since DR changes an unbelievable amount of physiological parameters (see screenshot ->) it is very hard to determine its mechanism.
II. Second, while many sources cite mice experiments showing life extension with caloric restriction.. those experiments are done with lab mice. When DR studies are done with wild mice, DR has no effect on longevity. WHAAAT!! I’ve never heard this before- in fact i was under the impression that CR/DR extends life in animals, period. Well, NO STUDY has ever found that DR extends life or improves health in nature (or even “nature-like” conditions). Mice in the wild actually do not have enough fat stores to reduce feeding except very briefly (wild mice has about 4% fat while a regular lab mice has 15%; also lab mice do not reproduce). In fact, mice in nature simply do not live long enough for the survival benefits of DR to be important. Another challenge to the original hypothesis that adaptation to dietary restriction enhances survival, is that DR increases mortality from some infections. Lastly, DR increases cold sensitivity (and cold is a major source of death in wild mice) and slows down wound healing.
Sounds like animals in the wild would not benefit from adaptation to dietary restriction… yet why is the positive DR effect observed in so many studies so common?
III. Well, even though wild mice do not live longer with restricted diets, DR still results in cancer protection for them. But even more importantly, DR has been found to protect against acute effects of many many toxins! Dr. Austad talks about this discovery in the following way:
.. if animals can not afford to wait to reproduce..and they have to do it even when food conditions are poor, what they will do is broaden their diet. This means they might be ingesting a lot of toxins they are not normally exposed to (foods infected with fungi, new seed types that are well defended by the chemicals they wouldn’t normally encounter). So the hypothesis is that DR acutely induces broad defense mechanisms from a broad range of toxins
Toxicology studies have shown that mice that are calorically restricted survive a wide range of toxins. DR also acts as an acute (vs. chronic) protectant against other problems (see slide below). Renal ischaemia reperfusion injury (IRI) is a common cause of acute kidney injury and we can see that while ad libitum mice are dying steeply by day 7, those on DR of various proportions survive (30% DR is only 70% of normal food intake; ad libitum stands for eating as much as one wants). This is quite impressive!!!
These acute benefits of DR have very important implications. We can think about these effects actually protecting the body against the toxins it itself produces (like free radicals).. it also has clinically relevant advantages- e.g. patients on very strong drug cocktails fasting to avoid harsh side-effects. This suggests that the protective effects of DR could have clinical relevance unrelated to chronic benefits like life extension.
The new hypothesis explaining the evolutionary advantage of this paradoxical effect is that dietary restriction arose as a defense against novel exposure to toxins during food shortage.
So in conclusion.. we saw evidence suggesting that dietary restriction would NOT enhance survival in nature. Yet research has shown that DR increases health and life in a diversity of species. The new hypothesis explaining the evolutionary advantage of this paradoxical effect is that dietary restriction arose as a defense against novel exposure to toxins during food shortage.
My conclusion? I’m still excited about this topic- more than ever before!!! There is a lot of work done now on the timing of food intake as well (not just restricting the amount, but restricting the timing of eating and human health) and I can’t wait to post more about this (after I collect some necessary data though :). Watch out for early May as I’ll be sharing some more info!