Final answer:
The most common descent principle used in North America is bilateral descent, considering both paternal and maternal ancestors.
Step-by-step explanation:
In North America, the most common descent principle in use is bilateral descent. This means that individuals trace their ancestry through both their mother's and father's lines, which includes paternal and maternal ancestors, related by blood, marriage, or adoption. In fact, 60 percent of societies, mostly in modernized nations, follow this descent pattern. As opposed to bilateral descent, unilateral descent involves tracing kinship through just one parent, and it is practiced in the remaining 40 percent of the world's societies, particularly in pastoral cultures.