Saturday, May 08, 2010

Fossil Records: Past and Present

Fossil records provide some of the most valuable bits of information about the past. These records provide us with a sense of the diversity of species that once, but no longer, roamed this planet. They provide valuable information about the migration, biology, diet, etc. of different species.

Fossil records can also help provide us with a sense of the risks that our species historically faced in different places, and at different times, in the 150-200 000 years that homosapiens have roamed the planet.

Looking at our species' history through the lens of fossil records can also help us get a better sense of our priorities, with respect to public policy. Here I offer a few reflections on how they can do this.

Looking back over our species' history, as told in fossil records, what do we find? This insight from Hayflick is important:

Prehistoric human remains have never revealed individuals older than about 50 years of age, and humans had a life expectancy at birth of 30 years or less for more than 99.9% of the time that we have inhabited this planet.

For 99.9% of our species' existence most humans died in early or mid-life. The extrinsic risks of infectious disease (1415 species of infectious organisms in the world have been identified as causing disease in humans) , poverty, war, etc. meant that our species' survival depended on high fertility rates. And our biology reflects this reality.

Comparative biology teaches us that reproduction is life’s solution to the inevitability of death in the hostile environments of Earth (source). Reproduction is thus made a higher biological priority than the longevity of a parent.

So for most of our species' history there was little progress in terms of increasing life expectancy at birth. But things began to change in the 19th century. Advances in technology (e.g. the sanitation revolution), medical knowledge, material resources and changes in behaviour helped change the future course of our species. The hard work and innovation of people like Chadwick, Snow, and Jenner, Pasteur, helped humanity escape a world dominated by early and mid-life morbidity and mortality.

The fossil records of the 21st century will be unique in our species' history for two reasons. Firstly, there will be more human remains this century than in any other century (because of the size of the human population). Furthermore, the vast majority of these deaths will be caused by chronic disease and will afflict people after the age of 60.

Isn't it odd, given how many people are projected to suffer and die from chronic disease and given the rapid progress that is being made in the biomedical sciences, that we don't invest more of our energies into tackling the leading cause of chronic disease? Namely, aging.

When future generations look back at the 21st century they will wonder why we didn't act sooner to try to ameliorate the high risks of morbidity and mortality that currently ravage our bodies and minds. They will wonder why we were so easily distracted by the stories that dominate the evening news. And why so many bright academics who were employed to educate future generations seemed so detached from the realities of their own time.

If only a population could see, analyze and react to, fossil records in "real time". That might help us take a more rational approach to improving the health prospects of today's aging populations.