As we work to establish equality, fair treatment, and color-blindness in our society, science is slowly embarking on a controversial course of study involving race.

Scientists are looking seriously at whether human genetic material, in all its complexity, will reveal differences among the races.

It is science charged with emotion, as well as with earnest desire to get it right in the scientific sense and in the cultural sense.

It runs counter to DNA findings of the past decade. Earlier results showed that the DNA variation within a racial group is much greater than the DNA variation among racial groups.

Continued study, however, reveals new complexity and simplicity to our genetic blueprint.

In the category of simplicity, Dr. Keith C. Cheng of Pennsylvania State University and his colleagues have found that a mutation of a single base pair, out of 3.1 billion in our human DNA, in one codon of one gene, is responsible for the white skin of Caucasians.

The mutation appears chiefly in people of ancestry in northern and western Europe. The mutation is a change from the ancestral dark-skin gene. It appeared 30,000 to 50,000 years ago, as a new wave of humans was emigrating out of Africa.

The new mutation became prevalent over time because it must have been advantageous. White skin can produce more bone-strengthening Vitamin D than dark skin in the low sunlight levels of Northern Europe. This benefit may be the chief cause of the mutation becoming widespread.

Other racial differences are being revealed as well. For example, doctors prescribe the heart medicine BiDil for black patients but not whites because it has been shown that blacks are genetically predisposed to respond well to the medicine.

Today, we can buy inexpensive DNA tests for certain genetic markers that will tell us the likely place of origin of our ancestors.

The problem, of course, is that rough-hewn genealogy is just the starting point.

What do we do when DNA testing begins to be tied to behaviors, emotions or intelligence? Are we naive if we believe that such ties will not appear?

The challenge for us as a society is to use new information wisely.

This is always the challenge of innovative science and technology. They repeatedly lead our ethical standards, cultural norms and laws.

This challenge is that our knowledge of differences among individuals cannot and must not be used to treat people differently.

But the example of the prescription drug BiDil raises the cautionary flag: We are already in an era in which, for good reason not harm, we treat people differently because of their genetic makeup.