The æsthetic preferences individuals have evolves over time, covering various domains of intellectual life from art to engineering. Æsthetics, in various domains, sometimes embody implicit values (e.g. the notion of elegance in a design can be said to be æsthetic, but in this field, the beauty of a given solution has an often-uninvestigated tie to various values that cause that solution to create the emotional reaction of an æsthetic. This tie to recognisable values is not always simple, and in some fields we can only presume it to be noise, either genetically rooted, in which case it may represent survival values present in the EEA but not today or may be a side effect of such well-rooted values, or developmental in possibly shorter-lived and more complex ways (that is, things an individual picks up because of life experiences).
We may presume there to be a biological tendency to dislike variations of the human form too unlike what one is familiar with, particularly those that are so different as to be a result of mutation, grievious injury, or terrible illness. In evolutionary scales, this tendency benefits the gene pool both by reducing risk to tribes and protecting gene pools from either direct severe mutation or tendencies towards risky behaviour. Feelings of revulsion at these variations are thus a remnant from the EEA, no longer strictly applicable today because we have altered our environment and selective process enough so as to have significantly changed the nature of selection.
Given this particular ingroup-outgroup mechanism, we find that as we mature we find ourselves developing dislike for those different enough, somnething that comes across particularly often as people encounter different races. Æsthetics can and will differ between groups of humans, just as a given human may find themselves drawn to see æsthetic appeal of certain breeds of dog, cat, plant, or other things and creatures in their environment. This variance, while usually of little harm in other domains, poses a particular risk in humans, both because we have higher levels of interaction with each other than with other species, and because we have higher standards of treatment for each other. Notions like finding cocker spaniels unappealing merit little social attention, while notions like finding hispanics or africans unappealing merit significant social attention because the latter plays into our nature as a social animal - we are more apt to demonise and violate our higher standards of good treatment of other humans if we find them, as a group, to be unappealing.
This conclusion leads us to a few obligations. First, we should encourage presence of great variety in upbringing for all groups of society, so as to reduce mutual other-ness of groups, and second, as individuals we should strive to alter our perceptions to eliminate any broad æsthetic dislike of groups in society. Æsthetics is known to be mallable. Instinct, as Freud has shown us, is routinely masked in modern society to make society's continuance possible, and much is entirely constructed. It becomes a helpful step in self-betterment to reshape oneself to have less æsthetic-racial preference, in order to make make racial relations easier.
Æsthetics in human form and figure are not to generally be discarded, and this obligation or good in reshaping æsthetic judgement should be applied carefully. We may imagine there being a cost in moving one's æsthetics too far from one's natural æsthetics, leading to neurosis and other mental disorder. Similarly, some æsthetics still serve a function - those heavily overweight, those who have legitimate degeneracy (e.g. Down's), and similar cases still merit concern, and the natural stigma of such groups thus serves a function. Racial difference represents a potential "false positive" for this generally useful and naturally-respectable mechanism and merits special attention and handling, although this does not justify the complete masking of the mechanism.