Final answer:
Humans should not be classified according to race as the biological basis is invalid, the concept lacks scientific justification, and racial categories are merely social constructs without clear-cut biological differences.
Step-by-step explanation:
Why Humans Should Not Be Classified by Race
There are three reasons why humans should not be classified according to their race. First, the biological basis for race is invalid; genetic variation within so-called racial groups is often greater than variation between them. Only a tiny fraction of genetic markers, about 15 of 45,000, for example, are responsible for skin pigmentation, which cannot account for complex racial classifications. Secondly, race as a concept has no scientific justification. Characteristics such as skin color or blood type show that there is substantial overlap and diversity within any racial category, making it impossible to differentiate discrete biological groups. Lastly, racial categories are fundamentally social constructs, not based on consistent or clear-cut biological differences, but rather on arbitrary physical traits like skin color, hair texture, and eye shape, which are poor indicators of overall genetic makeup. These categories impact society and can lead to discrimination, yet they do not align with the genetic evidence.