When it came to mammoths, females had all the luck. Males were more likely to die in natural traps such as tar pits, ice lakes, mudflows, and bogs, according to a new study in Current Biology of DNA extracted from 98 fossilized woolly mammoths found across the Siberian landscape. Because the harsh environment destroys exposed fossils, most remains known to scientists were preserved in such traps (such as the La Brea Tar Pits in Los Angeles, California, pictured above, which trapped Columbian mammoths—close relatives of their woolly cousins). Researchers were examining the genomes of these mammoths for a separate study into mammoth population genetics when they noticed that their dead remains skewed male: About 70% of those caught in natural traps carried a Y chromosome. Woolly mammoths are thought to have had family structures similar to modern elephants, where herds consist of females and young elephants, whereas adolescent and adult males disperse from the herd and roam in smaller bachelor groups or alone. Forced into unknown lands and lacking guidance from older, experienced elephants, male woolly mammoths were likelier to accidentally traipse into a trap and die, the authors conclude. Researchers of extinct mammals should be aware that fossil remains may be skewed toward a particular sex or age, and thus may not represent the whole population, they add.