Physiological differences are part of the same package that make an ethnic group or 'racial subgrouping' have a unique designation to begin with. Why are males more physically dominant? Because our historical gender roles made physical strength a desirable trait. Women reared children and took charge of domestic affairs, so they tend to excel more at multi-tasking, intuition, and social interaction. African Americans are represented in athletics in greater proportion than the overall population would suggest because we imposed physical labor on them for centuries, so again you see the same skew towards it as seen in men vs. women.
However, we shouldn't make the mistake of applying some broad trends (which may not be true at all in other parts of the world) to individuals we've just met (or simply observed from a distance). It is also possible that a shift in social attitudes about what traits are 'desirable' will mean a totally different paradigm in another few centuries. Most importantly, of course, is that while there might be some slight differences in tendencies towards certain kinds of tasks a given group possesses (and again, this is typically far more localized than we think), but their core identity as fellow human beings is key.
It's depressingly rare to hear a discussion about observable differences as they exist now or did exist at some point in history without someone eventually starting to introduce overtones that suggest some people are valued differently from others.