"The difference between survival and reproduction is shown with "antagonistic pleiotropy," referring to traits that increase reproductive fitness early in life yet decrease life span. For example, primates' prostates have high metabolic rates, enhancing sperm motility. Upside: enhanced fertility; downside: increased risk of prostate cancer. Antagonistic pleiotropy occurs dramatically in salmon, who epically journey to their spawning grounds to reproduce and then die. If evolution were about survival rather than passing on copies of genes, there'd be no antagonistic pleiotropy.2"