In an 1886 letter to Herbert Spencer, Thomas H. Huxley (“Darwin's Bulldog”) wrote that he considered himself “too much of a skeptic to deny the possibility of anything.” From his fundamental scientific method stance, Huxley would have deeply admired Roger Highfield's Can Reindeer Fly? The Science of Christmas. Highfield presents the science behind Christmas traditions, from the Virgin Birth to optimal turkey preparation, with wit, insight and — most important — scientific rigor. In this newly revised edition of his book, Highfield takes into account recent advances in genetics (is Santa's girth the result of a leptin or agouti mutation, and is it or should it be treatable?), quantum mechanics and nanotechnology (how does Santa get around so fast on Christmas Eve and deliver so many presents?), and sensory psychology (how do you choose the perfect present, or is the choice already made for you?). The result is both scientifically enlightening and very funny. Rather than outright deny events colored by thousands of years of tradition, Highfield tries to understand them from a rational point of view. For example, why is Christmas on December 25th? A ranging look at astronomy and astrology reveals that it was more likely that Jesus was born in April, perhaps 4 years earlier than tradition holds. However, there were certainly astronomical events that could argue for the star in the East and the interest of pagan “Magi.” Was there a Virgin Birth? Parthenogenesis, in all its forms, is considered, although Highfield does point out that the closest animal to humans in which this has been documented is, appropriately for the season, the turkey. The traditions surrounding Santa Claus are also thoroughly dissected and reassembled in light of scientific understanding. In addition to his obesity, Santa's incredible age is examined in light of possible telomerase mutations (goodness knows that his age cannot be accounted for by limited food-intake, which is known to increase lifespan in other mammals). And what about those flying reindeer? One has to consider Einstein's relativity, homeotic mutations, and advanced aerodynamics to make a case. Incidentally, Rudolph's red nose is likely to be true, but probably is the result of a common parasitic infection rather than bioluminescence. A slightly sickening but no-less-interesting chapter deals with “Festive Fare.” The thermodynamics behind cooking the perfect turkey are documented down to the nauseating details of muscle fiber type and collagens, and the juices that go into gravy. A taste for bitterness is examined in the context of brussel sprouts and evolution of protective gustatory mechanisms. The chapter becomes somewhat more palatable in the examination of the addictive properties of chocolate. Followed up with a chapter on “Christmas Spirits” (including a suggestion for treating hangovers based on the science of this dreaded post-party affliction), Highfield's book could replace both The Joy of Cooking and Martha Stewart Living in the scientific kitchen. Despite its tongue-in-cheek approach and its dicier conclusions, this book has immense educational as well as entertainment value. It takes a highly symbolic holiday and shows how science doesn't spoil the celebration, but adds even more value. To this end, this kind of “popular science” approach is more successful than Richard Dawkins's Unweaving the Rainbow, as Highfield targets the whole congregation where Dawkins ends up preaching largely to the choir. Although it may not replace ‘Twas the Night before Christmas as reading material in many homes on Christmas Eve, it should at least be considered.