It's misleading to argue that our ancestors had a life expectancy of only 25 to 30 years. While that may be true, it's also true is that infant and childhood mortality were much higher due to a lack of medical care, knowledge and numerous other factors. So that statistic doesn't hold much weight as a criticism of paleo eating. Let's assume paleo Jane lived until she turned 60, paleo Joe got killed by a sabertooth tiger at the age of 13, and paleo baby Trudy died of an infection at age 1. The average lifespan of these three paleo people would have been thus 37. However, one lived significantly longer than 37 and two died significantly earlier than 37. So an average lifespan means nothing if you have "extremes" on both ends of the spectrum.You can find an excellent analysis of the life expectancy in the Paleolithic era here.