Paragraph #1, Mapping Human History, by Steve Olson
“Anyone walking along the sidewalk of a large city can’t help but be struck by the incredible variety of human beings...”
Not intended to be scientific. The phrase “can’t help but be struck” is obviously colloquial.
“Some have skin the color of heavy cream...”
Scientific. There are color charts which could be used to verify this statement.
“The shapes of people’s faces are ... unique.”
Scientific. It is possible to imagine, given unlimited time and resources, a digital survey of all the faces of all the people living on earth. Such a study is not practical, of course, but scientific logistics are not important for our purposes here.
“Partly we’re attuned to these differences because we use them to identify people we know.”
Not intended to be scientific - an opinion regarding common human motives.
“But our diversity is not an illusion.”
Not intended to be scientific - rhetorical device of a flamboyant sort.
“Human beings really are one of the most physically varied species on earth.”
Pseudoscience. This statement takes the form of a testable hypothesis, but the degree or amount of physical variation is not measurable across species. Even with unlimited time and resources, physical variation within a population of red oak (for example) is not comparable to variation within a population of humans. This pseudoscientific statement was probably written to advance the generalizations regarding racism that follow in the next four paragraphs.