The alkali earth metals form the two left-most column of the periodic table of the elements, other than hydrogen. See wikipedia articles:
Now "alkali" means that these are in a sense the opposite of "acid". One of the ancient uses of alkali materials is in the conversion of corn into hominy (or, for those in the southern US, grits similar to posole, polenta or farina ).
The conversion of corn to hominy is of ancient origin. From a nutrition point of view it is useful because it increases the availability of the lysine and tryptophan proteins in the corn. See http://www.practicallyedible.com/edible.nsf/pages/hominy This helps prevent the nutritional disease pellagra http://en.wikipedia.org/wiki/Pellagra
In ancient times, hominy was manufactured by soaking corn in a mixture of water and ashes. This is equivalent to the modern method, which is to soak the corn in lye.
So my question is this: why is it that ashes are alkali?