Nick Cannon's under fire for comments he made about melanin, white people and why they became "savages" long, long ago -- and some are even calling him a "black supremacist."

"The Masked Singer" host has recently been accused of spewing anti-Semitism on his podcast, "Cannon's Class," but now it's this brief clip from his June 30 episode with Professor Griff -- formerly of Public Enemy -- that has people riled up.

Nick said that the power of melanin -- or lack thereof -- made white people "a little less" than darker-skinned people ... and claims this deficiency leads to fear.

He was speaking anthropologically -- meaning the very first white people in modern-day Europe -- but went on to say white people's fear made them lack compassion and ultimately ... become evil.

Nick then referred to these white people of the past as "savages," "barbaric" and added ... "They're the ones that are actually closer to animals, they're the ones that are actually the true savages."

Now, some people are calling him out for the remarks, including black British rapper Zuby, who tweeted, "Nick Cannon has gone full black supremacist. This is 100% certified racist."

Cannon's controversy comes on the heels of allegations of being an anti-Semite and spreading anti-Jewish theories on his podcast ... so rough week so far.