Brain
The rest is fear of raptors.
The rest is fear of raptors.
Growing up, many children grow a fascination with tree houses. Tree houses are a child's own special place to do stuff away from their parents, have some autonomy, perhaps form a club. The obsession with tree houses usually fades once a child reaches their teenage years, but of course some of us never grow up. Being an adult geek/scientist who still enjoys childish things, Randall wants to build a sophisticated tree house rather than a simple one.
The Swiss Family Robinson is a novel by the Swiss pastor and writer Johann David Wyss. In the novel, a shipwrecked family builds a tree house as good as a normal house complete with library and mechanical contraptions.
The title text makes reference to the regular xkcd joke about how terrifying Velociraptors from the movie Jurassic Park are. But they could never reach a tree house.
"Raptors" might refer to the informal bird group, hawks and owls and such, a joke relying on the previous infatuation with velociraptors.