Transportation to Australia was undoubtedly a grim experience for 18th and 19th century convicts, many of whom had only committed petty crimes in Britain.But a new study has shown there was one unexpected benefit from the dubious practice: happier marriages that have lasted to this day.According to researchers of the University of New South Wales, so many men were sent to Australia that it dramatically altered the sex ratio between men and women.As a consequence, women were prized and so could choose better husbands who were more capable providers and were less likely to stray. It meant both sexes enjoyed marriages that were stronger, stable and happier and fostered a highly-respectful attitude towards women that has lasted more than 150 years, the authors conclude.Dr Pauline Grosjean, Associate Professor, of the School of Economics from the University of New South Wales, said: “This inadvertent sociological experiment changed mating market conditions.“We find that both men and women are happier, and the happiness gap within married couples is smaller in areas where convict-era sex ratios were heavily male-biased.“One interpretation of this result is that because women have higher bargaining power they are more picky and search for a better match, and as an indirect effect, those men who do marry also benefit from this better match quality. A second possibility is that married men’s happiness is contingent on the happiness of their wives.“The present study establishes for the first time that these effects persist and still influence women’s relationship and life satisfaction over 150 years later.” Thee Charlotte, part of the First Fleet, which left from Portsmouth in May 1787 Credit:Frank Allen’s The Ships of the First Fleet, 1987. Mitchell Library, State Library of NSW. Between 1787 and 1868 around 157,000 convicts were transported by the British government to penal colonies in Australia, with men outnumbering women by approximately 16 to one.Most prisoners served sentences of around seven years before being released. But their numbers altered the local population so greatly in penal colony areas, that by 1820 there was three men for every woman.The male bias was further exacerbated by immigrants, who were mostly men following the Gold Rush of the 1850s. The research was published in the journal Philosophical Transactions of the Royal Society B. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.