Open thread, Sep. 14 - Sep. 20, 2015

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If it's worth saying, but not worth its own post (even in Discussion), then it goes here.

Notes for future OT posters:

1. Please add the 'open_thread' tag.

2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)

3. Open Threads should be posted in Discussion, and not Main.

4. Open Threads should start on Monday, and end on Sunday.

Grain is just food that happened to possess two essential features:

Making it was sufficiently productive, that is, a group of humans could grow more grain than they themselves would need;
It could be stored for a long time with only minor spoilage. Having reserves of stored food to survive things like winters, droughts, and plagues of locusts is rather essential for a burgeoning civilization. Besides, without non-perishable food it's hard to have cities.

You left out an important property:

Making it requires that the makers stay in the same place for a large fraction of the year. Furthermore, if they are forced to leave for any reason, all the effort they have expended so far is wasted and they probably can't try again until next year.

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