Cynthia Kenyon, a biogerontologist at UCSF, has declined to review Aubrey de Grey’s Strategies for Engineered Negligible Senescence (SENS). De Grey, a computer scientist and theoretical biologist at the University of Cambridge, believes he can defeat human aging within the lifetime of those now living. I asked Dr. Kenyon if she would comment on de Grey’s prescriptions almost three months ago; she agreed; and I announced her “By Invitation” column on this blog last week, asking readers what issues they would like her to address. But after a great deal of work, Dr. Kenyon very graciously told me she simply felt she couldn’t do an “effective” job. I remain committed to finding a biologist who will criticize SENS: after Technology Review’s profile of de Grey, Do You Want to Live Forever?, many of his admirers challenged me to have a working scientist say why de Grey’s ideas were impractical–if they were impractical. So far, I have been unable to find one biogerontologist who felt comfortable writing about SENS–which is telling perhaps. But I shan’t give up yet.