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Human Life Expectancy, Are We Reaching Our Limits? |

Living Life’s Stages

• In perhaps one of the greatest accomplishments of humankind, global life expectancy – the average number of years a person can expect to live – has increased substantially in the last two centuries. (Franco et al 2009) (Oeppen et al 2002) (Franco, Kirkwood et al 2007).
• For both men and women, the increase appears to be linear with no indication of slowing down or stopping this upward trend. (Oeppen and Vaupel 2002)
• This gain in life expectancy has been the result of the collective effort of society in improving living conditions i.e. hygiene, sanitation and good quality drinking water, nutrition, education, and health care. For example, in the United States, improvements in both health care and positive modification of risk factors for cardiovascular disease have contributed to a decrease in mortality from heart disease by almost 50% between 1980 and 2000.
• The last two centuries of efforts to improve the health of the population have meant a doubling of global life expectancy, such that the average mean life expectancy in the best country in class is forecasted to be 96.4 years in 2050 centuries. (Franco, Karnik 2009) (Oeppen and Vaupel 2002).
• While the prevention of mortality continues to progress, fertility rates continue to fall, leading to an unprecedented shift in demographics, and an increasingly older population.
• Globally, the proportion of people aged above 60 years is expected to increase from 10% to 21% in the next 5 decades.
• From 1950 to 2005, the total resident population of the United States increased from 151 million to 296 million, representing an average annual growth rate of 1.2%. During the same period, the population 65 years of age and over grew, on average, 2.0% per year, increasing from 12 to 37 million persons. The population 75 years of age and over grew the fastest (on average, 2.8% per year), increasing from 4 to 18 million persons. (Cheeseman-Day 2008)
• By 2029, all of the baby boomers (those born in the post World War II period 1946 – 1964) will be age 65 years and over. As a result, the population age 65 – 74 years will increase from 6% to 10% of the total population between 2005 and 2030.
• In 2004, life expectancy at birth was 76 years for white males compared with 70 years for black males and 81 years for white females compared with 76 years for black females.
• Murphy and Topel have calculated the potential monetary gains emerging from past, present and prospective future improvements in longevity and mortality rates. (Murphy et al 2006)
• Gains in life expectancy over the century were worth over $1.2 million per person to the current US population. From 1970 to 2000, gains in life expectancy added about $3.2 trillion per year to national wealth. It may be inferred from these analysis that gains in life expectancy directly translate into economic gains for individuals and society as a whole. (Murphy and Topel 2006).

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• Life Stages (also called the ‘aging Process!) can be considered as an inherent process of human existence, that is highly complex, and that involves multiple interacting mechanisms at multiple levels and not just a single mechanism or explanation (Kirkwood 2005, Kirkwood et al 2000) (Partridge et al 2002). The progression through these stages however can and ought to be a very healthy process.
• The aging process is often characterized by a progressive decline of functional capacity and a continuous deterioration in the metabolic mechanisms of health that concomitantly result in an accumulation of damage. This increases vulnerability to the effect of environmental challenges and ultimately leads to decreased fertility and an increased risk of morbidity with advancing age (Franco, Karnik 2009) (Kirkwood 2005). The good news is that with proper nutrition and exercise these changes can be slowed and delayed.
• Although aging is the most significant risk factor for the appearance of morbidities and it is generally considered an exclusivity of elderly beings, the aging process starts in-uterus and is not necessarily accompanied by the presence of disease and poor quality of life. (Franco, Karnik 2009).
• Life and aging are practically synonymous and one cannot occur without the other. How we maximize all of stages of life is important to the quality of life we can live.
• There is one aspect of life that is unlike aging and does not necessarily have to accompany it – poor health.
• Poor Health is not a sine qua non condition of life, and as life starts so does the chance of departing from health. This chance increases with aging and is determined by an intricate network of mechanisms that aim to maintain or recover corporal and mental homeostasis. (as presented in the spring model of aging).
• Over the life span, the trajectories of aging and the stages of life can be individually defined by personal experiences, response to events in life and the interaction of multiple modulating factors (Franco, Karnik 2009).
• How to meander through life maintaining adequate corporal and mental homeostasis and abstaining from crossing the confines of major chronic disease and cognitive and physical impairment remains one of the most relevant challenges for science and humankind.
• Delimiting that immaculate trajectory – that we dub as the healthy aging phenotype - and exploring solutions to help the population to stay or return to this trajectory should be one of the top priorities for the scientific community and society in general.

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