Gould "The Geometer of Race"

a)What is Could mainly trying to say through Blumenbach's example?
He wants to say some ideas or statements are affected by society. It means public opinions or environment can change statements. He says Blumenbach did not intend to do some racial descrimination. From that point, new opinions  can be transformed into ideas that people want to believe. Also, public people think that the theory supported by scientists are right so sometimes, wrong or crazy ideas are believed...

b)What do you think about his argument?
I think his argument is meaningful because people are always in some society so they can not run away from that effect. There might be a kind of mind control by a big organization like a government. Also, he says "An old tradition in ....."(9-5 l.14) and I thought tradition disturbed new findings or unfamiliar beliefs.
However, I do not understand "This change has been missed...."(9-3 l.2). He says scientists did not grasped the vital principle but I also think they ignored that point intentionally because it was not good for their ideas.