Many Egyptologists and anthropologists have suggested theories about how the gods developed in these early times. Gustave Jéquier, for instance, thought the Egyptians first revered primitive fetishes, then deities in animal form, and finally deities in human form, whereas Henri Frankfort argued that the gods must have been envisioned in human form from the beginning. Some of these theories are now regarded as too simplistic, and more current ones, such as Siegfried Morenz' hypothesis that deities emerged as humans began to distinguish themselves from and personify their environment, are difficult to prove.