You may want to consult 'Practical English Usage':
339.10 Another use of may/might: typical occurrences
In scientific and academic language, may is often used to talk about typical occurrences - things that can happen in certain situations...
With this meaning, might can be used to talk about the past.
e.g. In those days, a man might be hanged for stealing a sheep.
Michael Swan, 'Practical English Usage', OUP, 3d Ed., p.318
Hope, it could help.