Welcome back from the holidays and Happy New Year! To those of you who applied to Oxbridge last autumn, I hope that in the last two weeks you have received the letter in the post that you have been hoping for. For those of you beginning your Oxbridge application journey, come right in! I do hope that you will keep reading this blog through the rest of the coming year for interesting science and medical updates, as well as advice on writing your personal statement, tips for your extra-curricular reading schedule and of course, guidance on how to ace those December interviews.
2016 was a year of surprises and the unexpected and we can expect no less in 2017, especially from the world of science. This year I will use this blog to pick up on interesting topics that I think would be useful for you to know about as you prepare yourselves for the Oxbridge application and interview process. To keep with the theme of surprises and the unexpected, I wanted to open this year with a news story about the appendix.
Now the appendix itself is often brought up in Oxbridge interviews, after all – why on earth would the body contain something like the appendix? It apparently holds no function or value to the body except for having a notorious reputation for its tendency to become inflamed (appendicitis), often resulting in surgical removal or if not operated upon, death. There have been multiple theories as to its current or historical role, but recent research suggests that the appendix may serve an important purpose. In particular, it may serve as a reservoir for beneficial gut bacteria. Several other mammal species also have an appendix, and studying how it evolved and functions in these species may shed light on this mysterious organ in humans.
A team from Midwestern University Arizona College, is currently studying the evolution of the appendix across mammals. The research team gathered data on the presence or absence of the appendix and other gastrointestinal and environmental traits for 533 mammal species. They mapped the data onto a phylogeny (genetic tree) to track how the appendix has evolved through mammalian evolution, and to try to determine why some species have an appendix while others don’t.
They discovered that the appendix has evolved independently in several mammal lineages, over 30 separate times, and almost never disappears from a lineage once it has appeared. This suggests that the appendix likely serves an adaptive purpose. Looking at ecological factors, such as diet, climate, how social a species is, and where it lives, they were able to reject several previously proposed hypotheses that have attempted to link the appendix to dietary or environmental factors. Instead, they found that species with an appendix have higher average concentrations of lymphoid (immune) tissue in the cecum. This finding suggests that the appendix may play an important role as a secondary immune organ. Lymphatic tissue can also stimulate growth of some types of beneficial gut bacteria, providing further evidence that the appendix may serve as a “safe house” for helpful gut bacteria.
They also found that animals with certain shaped ceca (tapering or spiral-shaped) were more likely to have an appendix than animals with a round or cylindrical cecum. Therefore, they concluded that the appendix isn’t evolving independently, but as part of a larger “cecoappendicular complex” including both the appendix and cecum.
While this research casts some new light on the often misunderstood organ, I think it serves as a great example of how new research can completely re-frame something that we once thought we understood. Be ready for more surprises and twists as 2017 unfolds…