Reflexology Trial", Simon Singh states that if indeed the hands and feet "reflect" the internal organs, reflexology might be expected to explain how such "reflection" was derived from the process of Darwinian natural selection; but Singh says that no argument or evidence has been adduced. In the United Kingdom, reflexology is coordinated on a voluntary basis by the Complementary and Natural Healthcare Council (CNHC). Registrants are required to meet Standards of Proficiency outlined by Profession Specific Boards, but since CNHC is voluntary anyone practicing can describe themselves as a reflexologist. When the CNHC began admitting reflexologists, a skeptic searched for, and
Reflexology found, 14 of them who were claiming efficacy on illnesses. Once pointed out, the CNHC had the claims retracted as it conflicted with the UK's Advertising Standards Authority code. Reflexology is one of the most used alternative therapies in Denmark. A national survey from 2005 showed that 21.4% of the Danish population had used reflexology at some point in life and 6.1% had used reflexology within the previous year. A study from Norway showed that 5.6% of the Norwegian population in 2007 had used reflexology within the last 12 months. Practices resembling reflexology may have existed in previous historical periods.