Which common element do the cultures share at
Teofilo's burial?

The old man Teofilo has died peacefully while tending sheep out at the sheep camp, away from the village. Leon and Ken find him under a cottonwood tree, but because his sheep have wandered away, the two brothers-in-law first collect them and put them in the corral. Then they prepare Teofilo for burial by painting his face, tying a gray feather in his hair, and wrapping him in a red blanket. On their way back in the truck, they meet Father Paul, who asks about Teofilo. Leon turns the question aside, avoiding the imposition of a Roman Catholic funeral. After the medicine men have performed the traditional funeral, Louise—Teofilo's granddaughter and Ken's wife—tells Leon that she thinks the priest should sprinkle holy water so that Teofilo will not be thirsty. Leon invites Father Paul to bring his holy water to the grave. In spite of the irregularity—Father Paul tells Leon that last rites and a mass should be said before a proper Catholic burial.

sprinkling the ground

The book shows that Sinclair believed reform was necessary.