A prize-winning paper suggests that humans are hairless apes because Stone-Age mothers regarded furry babies as unattractive

Medical Hypotheses, an Elsevier publication, has announced the winner of the 2006 David Horrobin Prize for medical theory. Written by Judith Rich-Harris, author of The Nurture Assumption and No Two Alike, the article, "Parental selection: a third selection process in the evolution of human hairlessness and skin color" was judged to best embody the spirit of the journal. The £1,000 prize, launched in 2004, is awarded annually and named in honour of Dr. David Horrobin, the renowned researcher, biotechnology expert and founder of Medical Hypotheses, who died in 2003.

Harris' paper describes Stone Age societies in which the mother of a newborn had to decide whether she had the resources to nurture her baby. The newborn's appearance probably influenced whether the mother kept or abandoned it. An attractive baby was more likely to be kept and reared.

Harris' theory is that this kind of parental selection may have been an important force in evolution. If Stone Age people believed that hairless babies were more attractive than hairy ones, this could explain why humans are the only apes lacking a coat of fur. Harris suggests that Neanderthals must have been furry in order to survive the Ice Age. Our species would have seen them as "animals" and potential prey. Harris' hypothesis continues that Neanderthals went extinct because human ancestors ate them.

This year's prize judge was Professor Jonathan Rees FMedSci of Edinburgh University, Scotland - co-discoverer of the 'red hair gene'. Professor Rees said: "This paper is an excellent example of the kind of bold thinking and theorizing which David Horrobin intended to encourage when he began Medical Hypotheses. I hope that Judith Rich Harris' idea provokes debate and further investigation of this topic."