Since we talked about lactose intolerance in class this week, and I’m lactose intolerant, I decided to look a little more into it. Most people know that this problem is caused by a lack of lactase, which breaks down lactose into glucose and galactose. What’s interesting is that most animals become lactose intolerant after infancy and weaning, so no one is born lactose intolerant. The continued production of lactase in humans is actually known as lactase persistence and a relatively recent evolutionary development (http://www.ncbi.nlm.nih.gov/pubmed/14616060).
Even more surprising is that most of the human population is lactase non-persistent. So one way of looking at it is being lactose intolerant is actually the norm! This persistence is caused by several mutations (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3048992/). It is interesting to see how the development of society has selected for certain mutations and actually changed the physiology of certain populations that are more reliant on dairy in their diets. Lucky for those who are lactose intolerant, there are so many dairy substitutes that taste almost like the real thing, such as Lactaid, which provides pre-made lactase!
It’s quite interesting to see that we think as “more dominant” in the population actually derived from mutations! We always think of mutations as being harmful to us, but sometimes it seems to be quite beneficial!