We subjoin an engraving […] which will give the reader a far better notion of the structure than any verbal description could convey to the mind.

We made an odd party before the arrival of the Ten, particularly when the Celebrity dropped in for lunch or dinner.

A two-way chart; a two-way table.

The pre-cultural society was promiscuous, and the change to cultural society meaned a change to monogamy. That might better explain our difficulties in adaptating to monogamy (depending on when we put the origin of 'culture') but not the existence of promiscuous cultures of H. sapiens.