What does Person 1 keep doing to Person 2? Going off on tangents to distract but whats that called exactly?

Both were obviously talking about modern man, then person 1 instead of conceding to a correction he pretends like he was talking about other species millions of years ago? And then when that started to fail he starts talking about Alligators... How frustrating is this.

Person 1: Posts meme that says, "If you have blue eyes, you are probably related to every other blue-eyed person in the world. Blue eyed people descended from just one ancestor who's genes mutated 6,000 to 10,000 years ago. Before then, all people had brown eyes. 

Person 2: And white skin is even younger than Blue eyes. So, same with white skin too but even more so.

Person 1: Nah, depigmentation was evident about 30,000 years ago as humans migrated to areas where dark pigment wasn't needed, but actually started several million years ago when we had full body hair. The skin was pale under the hair. Whether it's called white or pale, it wasn't dark until we lost hair.

Person 2: Nah, light skin is due to a lack of vitamin D in our diet that resulted from the invention of farming and civilization that started around 7k years ago. Its why the Eskimos have dark skin still because their diet of blubber is rich in vitamin D. Blue eyes came first, then white skin.

Person 1: You are focusing on modern man....Neanderthals had white skin and red hair nearly 40,000 ya in Europe. Reading articles online will only confuse you.

Person 2: Well yeah, because I thought we were talking about modern man since the time ranges we are talking about are few 1000 years or more.

Person 1: No, i stated above that it went back as far as several million years.

Person 2: You are a modern man, I am a modern man, no other hominid species left and the meme says modern man evolved blue eyes 7k years ago and I am saying modern man evolved white skin ever after that so white skin is younger in modern man than blue eyes is in modern man.

Person 1: So the modern alligator isn't the same alligator before himans existed?

Person 2: Huh? Alligators are a totally different class of animals. Not sure what other tangents we are going off on now with alligators?

Person 1: This could go on 4 ever, much like creation vs evolution.