Here is one perspective:
When and why did humans begin consuming eggs?
Humans have been consuming eggs since the dawn of human time. The history is complicated and diverse; the culinary applications are innumerable. When, where, and why have people been eating eggs?
When? Since the beginning of human time.
Where? Wherever eggs could be obtained. Differerent kinds of eggs were/still are eaten in different parts of the world. Ostrich and chicken are the most common.
Why? Because eggs are relatively easy to obtain, excellent protein sources, adaptable to many different types of recipes (from simply boiled, fried, or stuffed to complicated quiche, custards or meringue), and fit the bill for meatless fasting days required by some religions. In this last role? Eggs have been the object of much socio-religious symbolism and tradition. Over time, some groups have encouraged the consumption/decoration of eggs in celebration of certain events. Others have decided eggs are filthy food which must avoided. None of this is arbitrary.
"It is likely that female game birds were, at some time in the early history of man, perceived as a source both of meat and of eggs. Men discovered that by removing from the nest eggs that they did not wish to have hatch (or that they simply wished to eat), they could induce the female jungle fowl to lay additional eggs and, indeed, to continue to lay eggs throught an extended laying season." ---The Chicken Book, Page Smith and Charles Daniel [University of Georgia Press:Athens] 1975 (p. 11-12)
"Eggs have been known to, and enjoyed by, humans for many centuries. Jungle fowl were domesticated in India by 3200 B.C.E. Record from China and Egypt show that fowl were domesticated and laying eggs for human consumption around 1400 B.C.E., and there is archaeoligical evidence for egg consumption dating back to the Neolithic age. The Romans found egg-laying hens in England, Gaul, and among the Germans. The first domesticated fowl reached North America with the second voyage of Columbus in 1493."
---Encyclopedia of Food and Culture, Solomon H. Katz, editor, William Woys Weaver, associate editor [Charles Scribner's Sons:New York] 2003, Volume 1 (p. 558)