Evolutionary medicine

Evolutionary medicine or Darwinian medicine is a way to think about how and why evolution changed our bodies over time to make us sick or healthy. People use Darwinian medicine to study biomolecules. They think about how these small molecules in our bodies work together through something called physiological mechanisms. Physiological mechanisms are things our bodies do that make us feel either sick or healthy. People who study Darwinian medicine use these ideas to think about how those mechanisms have changed over time. Understanding these changes can be important to know why some people are more likely to be sick than others.
Core principles
Experts who practice Darwinian medicine use 5 main ideas when thinking about people's health.<ref></span>Grunspan DZ, Nesse RM, Barnes ME, Brownell SE (2017-12-26). "Core principles of evolutionary medicine: A Delphi study". Evolution, Medicine, and Public Health. 2018 (1): 13-23. doi:10.1093/emph/eox025. PMC 5822696. PMID 29493660.</ref> These main ideas help experts to decide what things might affect a person's ability to be sick or healthy. Below is a list of these ideas and their meanings for Darwinian medicine.
Question Framing: The questions that experts in Darwinian medicine ask usually focus on 2 ideas. They ask questions about the molecules working together in our bodies, and how evolution has changed the way they work together. They ask questions with these 2 ideas in mind when looking at traits of a person, to understand how those traits might make one person more likely to get sick than another.
Evolution: Experts think about actions in evolution such as natural selection, genetic drift, mutation, and non-random mating. They also think about why some traits that would make people healthy are not always passed on.
Evolutionary Trade-offs: Experts think about how changes in one trait that make people healthy might lead to changes in other traits that make people sick. They also think about the life cycle of people, such as having children and getting older and less healthy with age.
Reasons for Vulnerability: Experts think about how our bodies fight sickness and what the signs of sickness are. They also think about the place a person is living which might make that person more likely to get sick.
Culture: Experts think about different cultural practices. Cultural practices show how people from one place might do things differently than people from another place. Differences in types of medicine, types of birthing practices, or types of food could mean that some people from different cultures could be more likely to get sick than others.
Human adaptation
There are some adaptations that have changed our traits over time. Some of these adaptations have made people more healthy. But there are constraints that keep some traits from changing. The presence of constraints means that adaptations that could make people more likely to be healthy are not able to happen. Also, sometimes adaptations can happen but with trade-offs. This could mean changes in one trait that make people healthy might lead to changes in other traits that make people sick.<ref></span>a b Stearns SC (2005). "Issues in evolutionary medicine". American Journal of Human Biology. 17 (2): 131-40. doi:10.1002/ajhb.20105. PMID 15736177. S2CID 42756608.</ref>
Constraint examples
DNA is split and copied almost 2 trillion times a day. Because DNA is copied so many times, mutations can occur.<ref></span>DNA replication: https://phys.org/news/2018-06-short-dna-replication.html#:~:text=The%20DNA%20in%20each%20human,and%20give%20rise%20to%20disease. </ref> This means that diseases like cancer are not able to be removed from the human population.
Humans are not able to produce our own vitamins. This means we must get our vitamins from the food we eat. This can lead to problems for people who are not able to get foods with vitamins in it. People or communities that are not able to get food with vitamins could be more likely to get sick than people who are able to get foods with vitamins.
Trade-offs examples
One adaptation that has shown a trade-off is as humans have evolved to become bipedal, the pelvis has changed to make childbirth harder.<ref></span>Sagan D, Skoyles JR (2002). Up from dragons: the evolution of human intelligence. New York: McGraw-Hill. pp. 240-1. ISBN 978-0-07-137825-3.</ref>
Another adaptation that has shown trade-offs is that darker skin pigmentation helps protect people from UV rays, but can also mean problems breaking down vitamin D.
Disease of civilizations
A long time ago, we think humans used to hunt and gather food and stay in small tribes. The way humans have evolved supports this. There are communities today that still live a hunter-gatherer lifestyle, but there are also many people who have a very different way of living than how our ancestors did.<ref></span>Eaton SB, Konner M, Shostak M (April 1988). "Stone agers in the fast lane: chronic degenerative diseases in evolutionary perspective". The American Journal of Medicine. 84 (4): 739-49. doi:10.1016/0002-9343(88)90113-1. PMID 3135745.</ref><ref></span>Knowler WC, Bennett PH, Hamman RF, Miller M (December 1978). "Diabetes incidence and prevalence in Pima Indians: a 19-fold greater incidence than in Rochester, Minnesota". American Journal of Epidemiology. 108 (6): 497-505. doi:10.1093/oxfordjournals.aje.a112648. PMID 736028</ref> Evolution takes a long time to happen, and evolution has not caught up with how many people are living today. Because of this, some experts in Darwinian medicine believe that people who do not practice a hunter-gatherer lifestyle are more likely to have problems being healthy. This idea of our evolution not matching the way many humans live today and causing health problems is called "diseases of civilization" or "diseases of affluence".
Diet
Many people eat types of food that are much different than what we ate a long time ago. A long time ago we ate things that grew from the ground and animals from the land or sea. Today there are more options to eat. Some options we have are foods that are made in factories, which have a lot of sugar, salt, and fat. These sugars, salts, and fats, coming from factory foods are not good for people to eat, and can lead to sickness.<ref></span>Eaton SB, Strassman BI, Nesse RM, Neel JV, Ewald PW, Williams GC, Weder AB, Eaton SB, Lindeberg S, Konner MJ, Mysterud I, Cordain L (February 2002). "Evolutionary health promotion" (PDF). Preventive Medicine. 34 (2): 109-18. doi:10.1006/pmed.2001.0876. PMID 11817903. Archived from the original (PDF) on 2008-12-17. Retrieved 2008-08-21.</ref><ref></span>Eaton SB (February 2006). "The ancestral human diet: what was it and should it be a paradigm for contemporary nutrition?". The Proceedings of the Nutrition Society. 65 (1): 1-6. doi:10.1079/PNS2005471. PMID 16441938.</ref><ref></span>Milton K (September 2003). "Micronutrient intakes of wild primates: are humans different?" (PDF). Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology. 136 (1): 47-59. doi:10.1016/S1095-6433(03)00084-9. PMID 14527629.</ref> Some examples of sickness that can come from food are dental caries, obesity, and diabetes.
Life expectancy
How long we live is changed by how we live today. There are a lot of sicknesses that are more common now than they were a long time ago. Some of these include cardiovascular disease, cancer, arthritis, cataracts, hypertension, and Alzheimer's disease. All of these sicknesses are more likely to happen the older you are.
Exercise
A long time ago, more people used to exercise than people do now. Back then, when people didn't exercise, it was usually because they were sick or hurt.<ref></span>Abuissa H, O'Keefe JH, Cordain L (2005). "Realigning our 21st century diet and lifestyle with our hunter-gatherer genetic identity" (PDF). Directions Psych. 25: SR1-SR10. Archived from the original (PDF) on 2008-12-17. Retrieved 2008-08-21</ref> When a person would rest, it would change mechanisms in the body, and would lead to inflammation. Some people believe that people who don't exercise have more inflammation in their bodies. This can cause more sicknesses.<ref></span>Charansonney OL, Despres JP (August 2010). "Disease prevention--should we target obesity or sedentary lifestyle?". Nature Reviews. Cardiology. 7 (8): 468-72. doi:10.1038/nrcardio.2010.68. PMID 20498671. S2CID 9560960.</ref>
Cleanliness
People a long time ago were less clean than humans are now. Being clean has helped people be more healthy, but there are trade-offs to being clean. There are some microorganisms that are important for humans to have so that we can have strong immune systems. Some microorganisms that grow strong immune systems can come from dirt and animals.<ref></span>http://www.microbemagazine.org/index.php Archived 2013-10-17 at the Wayback Machine? option=com_content&view=article&id=4700:a-darwinian-view-of-the-hygiene-or-old-friends- hypothesis&catid=950&Itemid=1301</ref> Without these microorganisms, people can have weak immune systems. This means they could be more likely to get sick.
History
Darwinian medicine comes from ideas that came from Charles Darwin. Although Charles Darwin had many ideas, the most important pieces that helped form Darwinian medicine came from his work on germ theory of disease. A lot of biologists learned of his ideas and quickly saw how germ theory of disease could help people think about how pathogens evolve, and how people evolve to protect themselves from these pathogens.
Some papers that have been written and have helped grow the field of Darwinian medicine include a paper by Paul Ewald in 1980, "Evolutionary Biology and the Treatment of Signs and Symptoms of Infectious Disease".<ref></span>Ewald PW (September 1980). "Evolutionary biology and the treatment of signs and symptoms of infectious disease". Journal of Theoretical Biology. 86 (1): 169-76. Bibcode:1980JThBi..86..169E. doi:10.1016/0022-5193(80)90073-9. PMID 7464170</ref> Another paper written by Williams and Nesse in 1991, "The Dawn of Darwinian Medicine" was also important to the growth of the field.<ref></span>Williams GC, Nesse RM (March 1991). "The dawn of Darwinian medicine". The Quarterly Review of Biology. 66 (1): 1-22. doi:10.1086/417048. PMID 2052670. S2CID 40357032</ref> These papers made people think more about Darwinian medicine. A book called "Why We Get Sick" was written, and later an online journal was made in 2008 called "Evolution and Medicine Review.