On pages 205-206, Dr. Moalem sums up his book with the toddler analogy. After completing the book, our understanding of the impact of diseases on our evolution should have become more nuanced and complete. Dr. Moalem addressed hemochromatosis, malaria, Type 1 diabetes, the common cold, as well as others. But like all books, Dr. Moalem cannot address every single disease that exists and the impact that it had upon our evolution, our Big Idea 1. That would become an infinitely long book. But what can be done is to take the knowledge that was given and use it to expand what we know.
Look up a disease of your own choosing. Find if the disease may have offered a selective advantage in certain regions. What ethnic groups are most affected by your disease? In a well-developed paragraph (or paragraphs), delineate your findings.
(Gabriel Antoniak gantoni4@students.d125.org)
Inflammatory bowel disease (IBD) involves chronic inflammation of all the parts of the digestive tract and is a genetic disease. IBD is often painful and can lead to life-threatening complications. Some symptoms of IBD include diarrhea, abdominal pain, blood in the stool, and weight loss. According to the Mayo Clinic, researchers believe that the immune system may have a role in causing the disease.
ReplyDeleteGiven that IBD is a genetic disease and may involve the immune system, scientists have come up with a hypothesis that states the genes that predispose to IBD provided a selective advantage in the form of mucosal immunoprotection for people living in unsanitary conditions. Mucosal immunoprotection involves protecting an organism’s mucous membranes against infection. Mucous membranes line internal organs such as the stomach and places where there is an opening like the nostrils, eyelids, etc. Mucous membranes are responsible for secreting mucus which can help trap a pathogen or kill the pathogen. Mucosal immunoprotection is very important because if an organism’s mucous membranes are infected, then the organism will lose mucus as a line of defense against pathogens.
Today, IBD is highest in frequency in the Ashkenazi Jew population from middle Europe. The Ashkenazi Jews in this part of Europe were frequently exposed to unsanitary conditions due to overcrowding of the ghettos. Therefore, the IBD gene may have been a selective advantage for the Ashkenazi Jews living in the unsanitary conditions because the people with the IBD gene would have the advantage of mucosal immunoprotection against the pathogens of the environment. While the poor sanitation techniques of the past selected for the IBD gene, many people who live in developed countries today are still affected by IBD even with good sanitation techniques. According to the book “Inflammatory Bowel Disease: From Bench to Bedside”, since IBD predisposing genes are not adequately used in mucosal defense today because of better hygiene, one of two events could occur: either when a person is exposed to a pathogen, their immune system could be hyperstimulated resulting in chronic inflammation or an autoimmune response could occur. So even though the sanitation techniques of the modern era are better than sanitation techniques in the past, pathogens can still find a way to infect humans, which could result in IBD for those people with the IBD gene.
The idea that the IBD gene could have been a selective advantage for people in the past corresponds with big idea 1 which states “the process of evolution drives the diversity and unity of life”. Dr. Moalem states on page 207 that “our relationship with disease is often much more complex than we may have previously realized.” Even though people today see IBD as a painful disease, the IBD gene could have helped many people in the past by providing protection against pathogens.
(Laura Gu, laugu4@students.d125.org)