Archaic and ancient humans recognized the cyclical pattern of nature, the endless cycle of life and death. Until very recently, this cycle dominated even the lives of modern peoples, and its influence remains in our summer vacations and our seasonal holidays. For people dependent on agriculture, the fertility of the soil meant life and death for them. In the Nile River Valley, the seasonal flooding of the Nile allowed crops to grow. In the North, spring meant release from the dead of winter and the renewal of life.
The Oxford Companion to World Mythology gives this definition of fertility myths:
Fertility deities and myths exist nearly everywhere that agriculture is important--that is, in most parts of the world. Animistic myths involving the sacrificial dismemberment and "planting" of body parts and the subsequent germination of crops are obvious fertility myths. The Hainuwele myth of the people of Ceram is an example, as are the many Corn Mother myths, such as those we find in Native North America and in the Slavic tradition.
Myths of sacrificed and resurrected gods-- the grain god Osiris in Egypt; Attis, the son of the earth goddess Cybele in Phrygia; Adonis in Phoenicia and Greece; Narcissus and Hyacinth in Greece--who die and are reborn as plants may be said to be fertility myths. The fertility aspect of many deities is indicated by their being depicted ithyphallically, as in the case of several gods in Egypt, or as bulls, as in most parts of the Middle East.
Storm or weather gods--such as Tlaloc or Chac in Mesoamerica, the Assyrian Aramean Adad-Hadad, and several Hittite- Hurrian deities--whose power brings the new life associated with rain, are fertility deities, as are the many goddesses--the Mesopotamians Ninhursag and Inanna/ Ishtar and the Canaanite Anat/ Astarte--who descend and return from temporary death in the dark underworld. The many-breasted Artemis of Ephesus is a clear representation of human fertility. Other important fertility goddesses are Freya and Frigg in the Norse pantheon, Brigid in Ireland, and Demeter/ Ceres and her daughter Persephone in Greece and Rome.
Whole classes of deities, such as the Vanir in Scandinavia, are fertility figures, representing female-centered agricultural societies, as opposed to later patriarchal, male-centered warrior societies represented by such groups as the Norse Aesir gods.
Farmer god myths of the Balts and Slavs are obviously fertility myths. The Nummo twins of the African Dogon creation story are fertility deities who, like many such culture hero figures, teach the people how to grow things.
In Arthurian lore, the loss of fertility is depicted in the failure of the Fisher King. In other cultures, such as those of Japan and the Hittites-Hurrians, for example, that loss is depicted by the disappearance of a sun deity. ("Fertility Myths")
Ancient peoples often practiced a variety of fertility rites designed to insure the fertility of the soil. Our modern practices of praying before a meal and our Thanksgiving holiday are extensions of these rites into modern times.
Gender also played a significant role in how people viewed the gods. In their attempts to understand and describe the gods, they often fell back on the metaphors of gender. Male gods were defined by social roles common to human society: judge, king, father, son. Female goddesses were defined by the cycle of the seasons: goddesses of life, death, and regeneration. These metaphors became archetypes for how people viewed the gods and goddesses.