In humans, women live an average of 5.4 years longer than men, but we’re not the only species where one sex outlives another. In birds, it’s the males that tend to live longer – by an average of 5 per cent in the majority (68 per cent) of species. But if this were the only factor, males would live longer across all bird species. So sex chromosomes can only be part of the story.”What else is at play? That means the longer the mother lives, the longer she can care for her offspring.