Were I an anthropologist who had specialized in primate behaviors I would be positively impressed at how present-day hominids ride BART and buses. As noted previously, I was the only one wearing a San Francisco Giants cap in a car full of Oakland Athletics fans. Despite being outnumbered and surrounded, I was not attacked. There was an Oakland fan who was very drunk (at 11:30 AM) and everyone tried to benignly ignore him. Better yet, a scientist would observe there were annoying limits on space, little water, less food and plenty of individuals of breeding age, yet no signs of conflict. On the way home a young man was obviously off his medications because he was in effect having a conversation (in loud tones) with someone nobody else could see. The car was not crowded so no one was sitting with him or in the seats adjacent to him. On the other hand, no one called the train operator to ask for police.
Looking backward in time and space somewhat, there have been many formidable carnivores that preyed on early hominids: eagles, terror birds, monitor lizards, large snakes, big cats, wild dogs, wolves, bears and bear-dogs (or dog-bears = Amphicyonidae). Since our ancestors never had fangs or claws or massive bodies, even with stone tools there would have been little chance. What our ancestors had (and really, all that they had) was each other. So while we have had more than our share of world wars and driven former apex carnivores to extinction, we have managed, with a few bumps along the road, to build cities and cathedrals and schools and cemeteries.