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Networks in Nature? PageRank Can Help


Networks have a broad impact in our everyday lives as they aid in the expression of complex systems that surround us. Often times, however, interpreting these complicated webs becomes an incredible challenge. Thankfully for algorithms like Google’s Page Rank, we have the ability to organize the information presented to us.


The importance of Google’s algorithm and how impressive it is, stems from not only how well it works, but also its applicability to a variety of situations. We learned in class how PageRank interprets a given page’s relevance by analyzing the number of links to that page and who these links are coming from. This system verifies that a page is not only getting a lot of links, but also that these links are from trustworthy and reliable sources. A good analogy used to describe this algorithm was asking people you know for restaurant recommendations. When surveying your friends, some restaurants may get a lot of votes, but there are also people who you trust more and as a result weigh their recommendation more heavily. Only after taking into account trustworthiness, are you able to make a final decision.


The article linked discusses a very interesting application of PageRank – what species are most critical when it comes to the destruction of ecosystems. By setting up complex networks based on ecosystems in real life, scientists were able to apply Google’s algorithm and figure out how an ecosystem would be affected by the extinction of a certain species, and further, which ones were most crucial when it comes to sustaining the ecosystem. Similarly to how certain web pages are more important because of the number of trustworthy links attached to them, so are given species because of their importance in the food web and the fact that other important species are connected to them. Scientists also cleverly tackled the issue of “dead ends” in a food chain, by having those species be linked back through their eventual decomposition. In doing so, scientists were able to create a circular network that PageRank could then be used on.


This novel use of Page Rank proves to not only help in terms of protecting nature but will also hopefully inspire people to think of nature more in terms of a network where certain actions may have significant hidden consequences.



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October 2016