ABSTRACT
Gudbjarnason and colleagues after measuring the DHA content of heart muscles of various mammals proposed a provocative concept for predicting life span (Gudbjarnason, 1989; Gudbjarnason et al., 1978). Their DHA theory of aging states that the longest-lived mammals will have the lowest DHA content in contrast to mammals with a short life span exhibiting greater DHA enrichment of their membranes. Their data on DHA content of heart muscle are consistent with an inverse relationship between DHA levels and life span. This simple relationship allowed Gudbjarnason to correctly place mammals on a ladder scaled according to life span. Gudbjarnason originally noted that heart rates of mammals are directly related to levels of DHA in cardiac tissue. That is, the mammal whose heart beats the fastest has the highest enrichment of DHA in its heart muscle, and vice versa. Thus, large whales with the lowest heartbeat and lowest DHA content are predicted to be the longest-lived mammal, a point discussed in detail later in this chapter. Whereas Gudbjarnason is credited with opening up this €eld, Hulbert and Pamplona, respectively, are regarded as co-fathers and champions of the membrane pacemaker theory of aging (Couture and Hulbert, 1995; Hulbert, 2003, 2010; Pamplona, Barja, and Portero-Otin, 2002; Pamplona et al., 1998) discussed in detail next.
