The deaths at Truckee Lake, at Alder Creek, and in the snowshoe party were probably caused by a combination of extended malnutrition, overwork, and exposure to cold. Several members became more susceptible to infection due to starvation, such as George Donner, but the three most significant factors in survival were age, sex, and the size of family group that each member traveled with. The survivors were on average 7.5 years younger than those who died; children aged between six and 14 had a much higher survival rate than infants and children under the age of six, of whom 62.5 percent died, including the son born to the Kesebergs on the trail, or adults over the age of 35. No adults over the age of 49 survived. Deaths were "extremely high" among males aged between 20 and 39, at more than 66 percent. Men have been found to metabolize protein faster, and women do not require as high a caloric intake. Women also store more body fat, which delays the effects of physical degradation caused by starvation and overwork. Men also tend to take on more dangerous tasks, and in this particular instance, the, men were required to clear brush and engage in heavy labor before reaching Truckee Lake, adding to their physical debilitation. Those traveling with family members had a higher survival rate than bachelor males, possibly because family members more readily shared food with each other.