The Great Mental Models, Volume 2: Physics, Chemistry and Biology

by Shane Parrish

Perspective often comes from distance or time. If you’re trying to solve a problem and you’re stuck, try shifting your vantage point.

Life is an iterative and compounding game. In the words of Peter Kaufman, it pays to “go positive and go first.” Also, remember that people make mistakes. Assuming there is no maliciousness, it pays to forgive.

The Red Queen Effect was first used in the context of evolutionary biology by Leigh Van Valen in 1973. In his research, he noticed something interesting: that at no point was a species protected from extinction. Evolution is an ongoing process, and all species must continually respond to pressures in their environment or die off. What’s more, constant adaptation is something that everyone is doing, all the time. Hence the use of the Lewis Carroll character from Alice’s Adventures in Wonderland. The Red Queen tells Alice, “Now, here, you see, it takes all the running you can do, to keep in the same place.”16

Dunbar identified the following scale of closeness for humans in groups. Note that each group includes the individuals from the smaller groups, and each number is about the maximum that could be maintained at that level. 5 people: This is our inner core of closeness, the people who we support and who support us on a daily basis, such as partners, family, best friends. 15 people: This is our close friend group. These people are integrated into our lives to the extent that we have an excellent understanding of their behavior, even if we may not see them all the time. 50 people: This includes our basic friends and acquaintances. We hang out occasionally, probably more often in groups, and know a bit about what is happening in their lives. 150 people: This is the size where you feel you are a part of a community. “This is the number of people you can have a relationship with involving trust and obligation—there’s some personal history, not just names and faces.”2 500 people: This category includes friends of friends, people you know something about but don’t know as well and don’t make a sustained effort to know. 1500 people: This is the upper limit and includes all the faces you can put names to. Dunbar’s number is useful in terms of reminding us about working with our biology. Our brains can only process so much of the information required to maintain social groups. The larger the group, the more brain power required. Eventually we are going to run out. In addition, and we d...