Furthermore, both relationships are often egalitarian in nature, although unlike sibling relationships, friendships are voluntary.
The specific roles of each relationship also differ, especially later in life.
Sibling attachment is further accentuated in the absence of a primary caregiver, when the younger sibling must rely on the older one for security and support.
These cultures also extend caregiving roles to older siblings, who are constantly expected to watch over younger siblings.
A relationship begins with the introduction of two siblings to one another.
Older siblings in these cultures are sometimes given responsibilities to watch over a younger sibling, but this is only occasional, with parents taking on the primary role of caretaker.
In contrast, close sibling relationships in nonindustrialized cultures are often obligatory, with strong cultural norms prompting cooperation and close proximity between siblings.
Still, this time period marks great changes for both siblings.