Eli Pariser describes all this in great detail in his excellant book, The Filter Bubble.

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Modern evolutionary biology as we understand it, which is to say variation via genetic drift, mutations, duplications combined with the pruning filter of natural selection, certainly explains a great deal.

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"One of the things that is unique about this filter is even if you didn't have arsenic in the water and you only had iron, this is still a great filter to filter iron, " said David Nunley.

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The site's simple enough for anyone to use but also offers several advanced features -like a profanity filter - which is great if you want your kids to explore the site but are worried about some of the posts.

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The Versailles bakery next door does great empanadas, fruit juices and Cuban coffee, which is an entirely different beast from the regular American filter variety.

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"If you are capturing your life as you walk around and you can simply and easily filter through that when you get home and get the important shots, that is going to be of great value to people, " said Mr Robson, manager of the Bristol Digital Media Lab.

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