When people are in the company of each other and they want to get along, they often go out of their way to show that they have something in common. This is generally a prominent part of friendly or business interactions. In order to make those interactions move along a certain way, people often find and settle on certain topics, activities, etc. that show they have some sort of common ground. They might discuss a topic that's popular and in the news, eat the same or similar foods or have the same or similar drinks, dress a certain way, use similar terminology, focus in on shared interests, tastes, views, and activities, or do a number of other things that show some sort of sameness. They ultimately conceal what they don't have in common, emphasize what they do have in common, and even feign certain interests and beliefs. And by doing so, they create some sort of sameness.
According to Brian Regan, "People will adjust what they just said based on other people's reactions to it. I've always been amazed by that. They'll just change what they just said. No matter how much you would think they would stick to what they just said. 'I think it's wrong to kill people with a machine gun.' 'Oh, I kill people with a machine gun.' 'Well, sometimes it's OK. But what I'm saying is I don't think you should kill like a lot of people with a machine gun.' 'Oh, I've killed scores of people.' 'I'm talking about the people who are always killing people. Day and night. Killing people with a machine gun. I don't think you should do that.' 'Oh, no. I don't do that.' 'Yeah--that's what I'm saying.'"
"When in Rome, do as the Romans do." This suggests that it's generally a good idea to go along with local customs and culture. A region like Rome has an established set of ideas, beliefs, practices, activities, etc.--and if we want to thrive among the people there, it often helps to "do as the Romans do."
But this phenomenon isn't exclusive to what's popular in a region. During most social interactions, people also create some sort of "common culture and customs," and then go along with that creation. In other words, when a group of five people get together, they create some sort of culture belonging to that group. And the members of that group tend to go along with that culture.
What this often does is create the illusion that people are far more similar than they really are. When we take those interactions for what they appear to be, it seems like people are very similar in many ways. After all, when they're interacting with each other, we see a great deal of similarities, and not that much in the way of differences.
But when we consider what people are at their very deepest levels, it becomes apparent that although they do in fact have many things in common, they also differ in many ways. They're not "Romans" so much as they're chameleons who appear Roman. In order to properly perceive what people are, it's important to see the chameleon root and the Roman branch. If we think that people are as similar as they seem--we might form false ideas about what people really are, and the differences between them.