They Walked Together Paisley Cave in Oregon provides some of the earliest evidence for humans in North America. Jenkins et al. (p. 223 ) provide a wide variety of additional evidence of early human occupation of this site, including a series of radiocarbon ages extending back to nearly 12,500 radiocarbon years ago (about 14,500 calendar years ago). The find includes examples of projectile points representative of the Western Stemmed Tradition dating to about 11,100 radiocarbon years ago. The Western Stemmed Tradition has been thought to have evolved after the dominant Clovis technology, but the find suggests that the two cultures overlapped in time.