I started this blog almost nine years ago, not being sure I had enough for nine days' worth of posting. To get myself started I prepared about 15 posts in advance of launch. As I began my research, almost immediately I came across the notion of "joint attention," two or more individuals paying attention to the same thing and knowing they are sharing their attention. Joint attention turns two individuals into a self-conscious unit, and supports cooperation by enabling members of the unit to think of themselves as an us. Linguistic interactions depend upon joint attention. In an early post I reported where this research had led me: "If you are ever pressed to state the difference between humans and the rest of the world's fauna in 10 words or less, try this one: We alone pay attention to the thoughts of others." I ended the post, "Once the world had creatures who paid joint attention to each other's subjective ideas, people had appeared. It may have been a long time before they could pronounce things clearly, and organize their speech into recursive sentences, but they were already people."