Are we the weakest link? (Part I)

In December of 1831 a small insignificant sailing vessel departed on a routine survey expedition. On board was a young man that was to make a journey of discovery that would eventually challenge the accepted understanding of both the natural world and humankind's place within it. Five years later the HMS Beagle and her crew sailed back into Plymouth Sound. Charles Darwin disembarked that night with a pile of notebooks and specimens that would consume the rest of his life. On the 24th of November, 1859, Darwin released a summary of his life's work in a publication with the cumbersome title, "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life". Somewhat ironically, 13 years later the unworkable mouthful evolved into a more elegant title, "The Origin of Species". Although Darwin's theory of evolution has stirred controversy for over 150 years and has been modified by over a century of new findings and better understanding, his findings have spurred on generations of biologists and anthropologists. One indisputable fact has come from all this study. With few exceptions in the natural world, the strong (best suited) survive and the weak (least adaptable) eventually die off.

At the risk of incurring the wrath of the rest of the creationists that have not already started writing, I would like to point out that humans are not exempt from evolution.
In the late 1600's, the famous astronomer Edmond Halley completed a study of mortality in Germany. He found that only 51% of newborns survived to see their 10th birthday. Less than 30% reached 50 and only 11% hit 70. Through the next two and a half centuries we experienced a slow increase in longevity until a turning point in the 1950's. Our expected mean lifespan jumped from the late 40's to the mid 70's in a mere 40 years. This sudden increase is undeniably the result of leaps in medical science. The unfortunate side effect, biologically speaking, of getting better at understanding disease and finding ways to combat the things that kill us off is that the overall strength of the species begins to suffer. Darwin's theory kind of muddled two theories into one. Natural selection and evolution are not exactly the same thing. All species undergo mutations to varying degrees, this is evolution. Many of these mutations have nothing to do with environmental factors. All mutations effect the viability of the species and this is where natural selection kicks in. If the mutation gives some members of the species an advantage over the rest of the population then that mutation will likely proliferate. Those without the mutation will struggle to survive. In the past, people with a genetic tendency toward disease would likely die of that ailment. The gene that contributed to that disease would likely not be passed on as they likely died very early in life. Logic would tell us that those that survived to reproduce, slightly more than 40% according to studies, would be those with fewer genetic weaknesses. As a species, we may not have lived very long but those that did likely would not die as a result of genetic disease. If we look at the skeletal evidence and records of the time, most deaths were a result of viruses, bacterial infections or wounds. Advancements in medical science have reversed this trend. Today, the majority of deaths are caused by mutations in our genetic code that result in cancer, heart disease and a myriad of other afflictions. Today relatively few people in the developed world die of bacterial infection or improperly treated injuries. Unfortunately, our ability to treat many of the genetic diseases that killed our predecessors has allowed us to pass on those mutations from generation to generation, all the while increasing the percentage of the population with those genetic weaknesses.

All this brings me to my intended discussion. The price we are paying for our artificially extended life expectancy is the increasing number of people living those lives on a steady diet of medications. More and more children that have more and more allergies, How many people over the age of 30 do you know that do not require corrective lenses? Modern medicine has brought us to a time when we have a very good chance of making it beyond our 70th birthday but not without almost continuous care and a suitcase full of drugs. Our dependence on processed food combined with a tendency toward a more sedentary lifestyle have contributed to the increased likelihood that our genetic deficiencies cause us to fall ill. Until science finds a way to identify the disease triggers in our genetic code and find a way to disable those switches we will continue to see an increase in genetic ailments. Vaccinations against known viruses and continued improvement in controlling bacterial infections may allow us to continue to extend our lives. Scientists believe that 120 years is maximum achievable lifespan for our species. Without defeating the spectre of genetic disease we will be merely trying to rewrite nature's law of natural selection.  If Darwin was right and the natural world evolves through  the survival of the fittest then the weaknesses we continue to spread throughout our species will eventually be our demise. We will no longer be "the fittest".