Anna DiRenzo
Best of Chicago voting is live now. Vote for your favorites »
AD: Animals needed these genes to deal with toxic chemicals in plants and the environment and to metabolize hormones. These genes also produce an enzyme involved in metabolizing cortisol, which plays a role in maintaining the salt and water balance in the body.
HH: Many people have a “broken” or nonfunctional variant of the gene known as CYP3A5 [which acts to retain salt in the kidney]. Why?
AD: Other biologists get interested in a picture of a gel or a particular color in a result. We get a good P value [a probability value showing a statistically significant result] and we’re excited.
HH: So this tends to confirm the salt-retention hypothesis: when humans left Africa for different, cooler environments, the functional CYP3A5 gene–for retaining salt–no longer contributed to survival. Did it just not matter, or was it an actual hazard to life?
AD: It makes sense, but there is a lot of variability among native Africans. African-Americans themselves are drawn from many different African gene pools and have mixed with other ethnic groups in this country. So generalizations about this have to be taken with a large grain of salt.
