In what ways has the pigs behavior come to resemble human behavior?
An easier question to answer might be in what ways have they NOT come to resemble human behaviors because there are so many ways they do.
Each of the commandments the pigs, I mean animals, created were to establish a distinguishing difference between themselves and humans. As we watch the pigs break these and change them subtly throughout the book, more and more human characteristics occur.
I think a very pointed thing to notice is the humans that the animals come to resemble, those magnified by the efforts of communism that Orwell intended to criticize. I also think it ironic that the animals chosen to mimic humans were pigs.
From the beginning, Squealer's manipulation through propaganda resembles the human effort to control other humans thoughts.
In Chapter 9, when Napoleon generates a new liter of pigs almost single-handedly, we see the natural effort of humans to create a superior race. Throughout history, as different leaders have risen to power, their 'kind' whether that be in race or religion or something else, tends to have privileges, just like the new liter of pigs were about to receive special treatments by the other animals, and education.
The most obvious human-like trait is when the pigs start walking on two legs at the end of the book. The construction of the windmill is also a key to becoming more human. It's often said that one of the things that separates humans from other animals is the use of tools and this fits that category. In Chapter VI, the pigs move into the farmhouse and start sleeping in beds. Also in Chapter VI, Napoleon announces that they will start trading with neighboring farms. This trading and establishment of an economy, at this level, is a kind of social integration that is a human practice. Animals do hunt together, live together, but the function is strictly for survival. At this point in the novel, Napoleon and the pigs are initiating a regime who's goals (reached via the other animals' labor) are more than just for survival. They are for luxuries that only the pigs will enjoy - like alcohol.
Of course, the pigs (and some other animals) write and speak as well! Probably the more obvious human traits. The pigs also rewrite history through the use of propaganda, so they have a media spinner (Squealer) for their government ideology: all human social institutions.