London, Aug 10 : His contributions in the field of science are immense, but Charles Darwin also devoted a part of his time in unravelling a rather less weighty puzzle: do blondes have more fun?
According to letters that have been discovered as a part of a major project of Darwin, the great Victorian naturalist used his formidable intellect to find whether hair colour affects a woman's ability to find a mate.
He set out to examine a theory that the prevalence of dark hair in the general population was increasing because brunettes were more likely to get married and have dark-haired offspring, while blondes tended to stay single and childless.
In order to further his study, he asked a doctor at Bristol Royal Infirmary to compile and send him data on the hair colour of married and single female patients at the hospital.
The investigation took place a decade after the publication of The Origin of Species, Darwin's tome of 1859, which led to the theory of evolution.
Dr Alison Pearn, assistant director of the Darwin Correspondence Project at Cambridge University Library, said that Darwin took the blonde question quite seriously, and had made extensive notes and calculations on the letters sent to him from the doctor.
"Darwin was fascinated by questions of hair colour and the role it might play in choosing sexual partners. He was keen to test whether English blondes really were more likely to stay single, with a resulting decrease in blonde hair in subsequent generations," the Telegraph quoted her, as saying.
"There are nine sets of calculations in which Darwin and his son George, who was about to take up a fellowship at Cambridge, combined and reanalysed the data," she added.
Darwin received three letters from Dr John Beddoe in 1869, which contained data from the doctor's observations of female patients coming into the hospital.
The first set of data showed that 52 per cent of the married women were dark-haired while just 15 per cent were blonde.
On contrary, only 39 per cent of the single women had dark hair and 22 per cent were blonde.
After analysing the data, Darwin eventually concluded that the evidence was not good enough to prove the theory, and that the predominance of dark hair in married women could be due to the natural darkening of hair with age.
He wrote a note in the corner of the last letter from Beddoe: "I must give up the whole case."
Dr Pearn said that Darwin seemed to have been researching the theory as part of his work on sexual selection, the process that causes traits in a species to become more common because they are seen as more attractive by potential mates, before publishing The Descent of Man in 1871.
"Sadly, so far none of Darwin's letters to Beddoe have been found. There are no fewer than nine sets of calculations in which Darwin and his son, George, who was just about to take up a fellowship in Cambridge, combined and reanalysed the data," he said.
"Eventually Darwin came to the conclusion that the experimental basis was not good enough. Both Beddoe and Darwin came to the conclusion that the original results were misleading and didn't make sufficient allowance for the darkening of hair with age," he added.