There are several reasons why girls are often perceived as surviving better than boys. Some believe that this is because girls tend to be more nurturing and empathetic, which makes them better equipped to form deeper connections with others. Additionally, girls may be more likely to seek help when they need it, while boys may be more likely to bottle up their feelings and not ask for assistance. Ultimately, survival is a subjective and individual case, and can be influenced by many factors beyond gender. Females have two X chromosomes while males have an X and a Y. The theory is that the extra X in women has a protective effect against harmful mutations and that this holds true in other species. The author of the new study on mammals says that both pieces of research are complementary.