Hi,

In 1990, Syracuse University did a study of the mineral fluctuations in
forage grasses of the Serengeti in Africa. the study showed that the vast
herds that seasonally migrate in this area do so for more than just water.

http://syllabus.syr.edu/bio/mcnaughton/ecominutr.html

The needs of the animals varied from season to season, and different grasses
had quite different mineral contents.  Perhaps the animals evolved their
rhythms from the habitat.

So I will restate my question from a few days ago:
Are there different nutritional need in humans that evolved seasonally and
are perhaps triggered by the length of daylight?

Tom Barber