In 1999 Chen and colleagues observed that populations who migrated farther in the past 30,000 to 1,000 years ago had a higher frequency of 7R/long alleles.
1999年，陈（音）及其同事 观察到那些在过去3万年到1万年间迁移得比较远的人类群体带有7R/长等位基因的频率较高。