SS: Chapter 7 of Tim Urban's The Story of Us. You can find the series' table of contents here: https://waitbutwhy.com/2019/08/story-of-us.html https://waitbutwh

SS: Chapter 7 of Tim Urban's The Story of Us. You can find the series' table of contents here: https://waitbutwhy.com/2019/08/story-of-us.html https://waitbutwhy.com/2019/08/story-of-us.html