Jeff Leach has given himself a fecal microbiome transplant from a Hadza hunter-gatherer. Yes, this is exactly what it sounds like.
What is the Paleo diet? Should we eat like our stone age ancestors? How did our ancestors eat, exactly? How far back should we go to identify humans’ healthiest diet? Can modern hunter-gatherers be a stand-in for our ancestral hominins in terms of diet?
1) Quickly skim this recent piece in the Huffington Post
2) Next read Eaton (2006)-Ancestral human diet
3) Most importantly, read this review:
4) Then read about artificial sweeteners here
5) Optional extra. Paleo microbiota
For Tuesday: Pima Indians (Tohono O’odham) of Arizona have the highest rates of diabetes in the world. They eat processed foods and refined carbohydrates like other Arizonans (the typical American diet). Their Pima relatives who farm in the Sierrra Madre of Mexico eat a more traditional diet and have much less diabetes and obesity. In light of the Paleo diet hypothesis and the backlash it has generated, how would you explain the differences in diabetes between the two closely related groups
Optional Extra credit Writing Assignment:
Several papers have been written about balancing selection, evolution and Factor V Leiden (FVL) mutation since the Lindqvist paper was published 6 years ago. Skim these and see if you can find any evidence to back up the hypothesis that FVL helps women survive bleeding in childbirth (or if another idea makes more sense).
John Hawks posted a great discussion of the aquatic ape hypothesis.
Sweet ‘N Low contains saccharin, an ingredient that was the subject of a recent study in the Journal Nature: “Artificial sweeteners induce glucose intolerance by altering the gut microbiota.” Click below to read the article, which describes changes in microbiota that are responsible for the adverse effects of saccharin and other artificial sweeteners. This study suggests that non-caloric sweeteners interact with gut microbes to cause metabolic changes, like those seen in diabetes and obesity.
Each group will present their assigned article on 9/23/14
The name of the game of these presentations is to present the major ideas of the article and to provide a critique. Each student will need to make part of the presentation individually.
Each group must decide whether they think the article is a good one or not. There is at least one questionable article in the bunch.
Each group will have 20 minutes to make their presentation. Each group will need to meet or Skype to discuss how you are going to divide up each topic for presentation next Tuesday.
Grading will be based on how well the student is able to explain the following:
1) What is the condition or disease described in the paper?
2) What is the proximate explanation for the disease (no more than a sentence or two).
3) What are the evolutionary hypotheses to explain the condition? If there are multiple hypotheses, each student should present an individual idea. The evolutionary reasoning should be carefully explained so that the audience can understand the concept.
4) Does the paper present any data? Are the ideas supported by evidence?
5) Does the logic of the paper make sense? Is it a flawed paper that whose conclusions are questionable?
6) Which hypothesis makes most sense to you? Would you recommend the paper for the next year’s class?
Additional points towards the grade will be given for presentation style. This includes good eye contact and understandable speech.
What does personalized medicine mean in the era of inexpensive gene sequencing? What can we make of our own personal genetic variation? We will explore these ideas in next Tuesday’s class, with Katina Krasnec’s guest lecture.
Here is the essay question for next week:
Do you think personalized medicine and genome sequencing is the way of the future? What are the risks and benefits of having this genetic information? How should patients and medical professionals use personal genomic data in light of privacy concerns and potential treatments?
1) Galvani and Novembre. The evolutionary history of the CCR5 Δ32 HIV-resistance mutation. Microbes and Infection (2005) vol. 7 (2) pp. 302-309 Microbes and Infection 2005 Galvani
2) Vargas et al. Pros and cons of a missing chemokine receptor—Comments on “Is the European spatial distribution of the HIV-1-resistant CCR5-Δ32 allele formed by a breakdown of the pathocenosis due to the historical Roman expansion?” by Eric Faure and Manuela Royer-Carenzi (2008). INFECTION, GENETICS AND EVOLUTION (2009) vol. 9 (4) pp. 387-389 INFECTION GENETICS AND EVOLUTION 2009 Vargas
3) Glass. CCR5 deficiency increases risk of symptomatic West Nile virus infection. Journal of Experimental Medicine (2006) vol. 203 (1) pp. 35-40 Journal of Experimental Medicine 2006 Glass
4) Caulfield et al. Reflections on the Cost of “Low-Cost” Whole Genome Sequencing: Framing the Health Policy Debate. Plos Biol (2013) vol. 11 (11) pp. e1001699 Plos Biol 2013 Caulfield
5) The man who had AIDS and now does not
Optional extra:8) Optional Reading Allers et al. Evidence for the cure of HIV infection by CCR5 32/ 32 stem cell transplantation. Blood (2011) vol. 117 (10) pp. 2791-2799 Blood 2011 Allers
and 9) NYT
In this weeks class, we introduced the idea of normal in medicine. What is normal? Can the concept of adaptation help guide what to do with an “abnormal finding”? We confront these questions all the time in the hospital. Now it is your turn to weigh in.
Lets start with a patient case: He is 48 years old, with a history of alcohol abuse, and a fever for 2 days. He has been coughing with grey sputum and bloody streaks for the last 24 hours. Increasingly short of breath, he calls 911 and is brought to the emergency department.
His chest x-ray looks like this:
His temperature is 40°C. Anything above 38°C (100.4 °F) is considered a fever.
Blood cultures are drawn and antibiotics given. He is transferred to the ICU because his oxygen levels and blood pressure continue to drop. In the ICU, his doctor diagnoses him with septic shock. She also orders a dose of acetaminophen (also known as tylenol or paracetamol) to reduce the fever. Medications like tylenol that reduce fever are known as antipyretics, and are commonly prescribed for febrile patients in and out of the hospital.
Was the tylenol a good move or a bad one?
Evidence from animal studies support the view that fever is beneficial (read the abstracts in the links in this section). Matthew Kluger back in the early 1970s showed that a behavioral fever was critical in keeping lizards alive after experimental infection with gram-negative bacteria. Kluger subsequently showed that fever improves bacterial killing by immune cells.
One relevant fact, arguing for the evolution of fever, is the fact that it exists in a wide variety of organisms, as reviewed here. Even some invertebrate organisms exhibit a behavioral fever, including grasshoppers, honeybees and snails. Animal studies suggest that antipyretic use (aspirin) increases mortality from Streptococcus pneumoniae infection With these lines of evidence, you would think that we should certainly not treat fever with tylenol. But we still do, all the time. The human data is not as clear as the animal studies. Some evidence suggests that treating fever is not harmful for our patients.
Carefully read all the links in this section:
1) Young and Saxena’s review in the journal Critical Care on fever and its treatment.
“Remarkably, at present we do not know what effect treating fever in critically ill patients with infections has on patient-centered outcomes.” In other words, legitimate controversy exists about whether to give a patient tylenol or not.
2) Drewry and Hotchkiss argue for giving antipyretic treatment for patients with sepsis (blood infection).Point- Should Antipyretic Therapy Be Given Routinely to Febrile Patients in Septic Shock? Yes
3) Moer and Doerschug argue against using antipyretics in sepsis.Counterpoint- Should Antipyretic Therapy Be Given Routinely to Febrile Patients in Septic Shock? No
Optional: Schortgen et al, about using external cooling blankets for critically ill patients. I recommend reading this if you think we should be treating fever.
Writing assignment – consider the following statement (Young and Saxena 2014):
“arguments based on the evolutionary importance of the febrile response do not necessarily apply to critically ill patients who are, by definition, supported beyond the limits of normal physiological homeostasis. Humans are not adapted to critical illness.”
This logic was expressed by Foddy (2012) who wrote: “The argument from evolution assumes some degree of continuity in environmental circumstances, but at present there are strong discontinuities in the structure of our world. Given these changes, it would be foolish to place too much trust in the adaptive quality of traits that evolved across aeons of nomadic hunting and gathering.” One such discontinuity is the availability of ICU care, right?
On the other hand, consider the argument from Fukuyama (2002) who wrote:
“There are good prudential reasons to defer to the natural order of things and not to think that human beings can easily improve on it through causal intervention. This has proven true with regard to the environment: ecosystems are interconnected wholes whose complexity we frequently don’t understand, building a dam or introducing a plant monoculture into an area disrupts unseen relationships and destroys the system’s balance in totally unanticipated ways. So too with human nature … doing nature one better isn’t always that easy, evolution may be a blind process, but it follows a ruthless adaptive logic that makes organisms fit for their environments.”
Depending on your point of view, fever, even if evolved, might or might not be helpful or adaptive for our sickest patients. The ICU is a novel environment that keeps (some) patients alive who would otherwise die. It is not the environment that humans evolved in (think gene-environment mismatch). With this in mind, do you think that evolution and adaptation is irrelevant for hospital patients who are closest to death? Defend your answer with your own logic, and with examples from the readings and quotations above. Should we treat patients with fever in the ICU with tylenol (yes or no)?
Strongly recommended – listed to this excellent talk by an expert on fever:
Skip the intro by going to minute 3:48.
Additional optional references:
Best and Schwartz. Fever Evolution Medicine and Public Health (2014) 2014 (1): 92. doi: 10.1093/emph/eou014
Fukuyama, F. (2002). Our posthuman future: consequences of the biotechnology revolution. New York: Farrar, Straus and Giroux.