Blog-spam copy of the following which was discussed last month:<p><a href="https://mosaicscience.com/story/why-do-we-have-blood-types" rel="nofollow">https://mosaicscience.com/story/why-do-we-have-blood-types</a><p><a href="https://news.ycombinator.com/item?id=13856007" rel="nofollow">https://news.ycombinator.com/item?id=13856007</a>