What makes you say that? Why does accepting evolution lead to that conclusion?
Darwinian theory, today known as Evolutionary theory/biology, teaches its adherents to accept disparities between human races as the result of natural selection. Africans fall at the bottom and the White people are at the top. Read on Eugenics.
Read Darwin's books. They are available online in PDF files.
Here is google quote from Darwin in His book "The Descent of Man"
The Western nations of Europe . . . now so immeasurably surpass their former savage progenitors [that they] stand at the summit of civilization. . . . The civilized races of man will almost certainly exterminate and replace the savage races through the world.
This is the man behind natural selection theory as expressed in the statement above. He actually believed in his ignorance back then, a cow would give birth to something else other than a cow given time.