No abstract

Sex differences in lifespan exist in most countries in the world, with women outliving men. This difference has existed for as long as records have been kept.  This gap is not a uniquely human phenomenon; it exists in many animals as well.  This is an important health issue that is not fully understood.  Aging is a complex process.  In this review we will examine the scientific basis for sex differences by focusing on four hypotheses that begin with examining why women are different from men.  Men and women differ in our DNA.  Women have two X chromosomes and men have an X and Y sex chromosome.  Women have a second copy of the genes on the X chromosome which could be protective.  Other hypotheses focus on the physiological difference between the sexes that result from the ratio of our sex hormones.  Estrogen physiology changes women’s body shape, affects the major organs like the heart and as a result impacts longevity.  Sex differences in longevity are important because this becomes a lens for us to examine nutrition, health and wellness.