Thursday, October 10, 2013

Old Age is Essential

A number of years ago I found myself unhappily plodding through a humid Central American forest contemplating my own mortality. Our small group had been camping at the top of the very remote Mount Botaderos in northern Honduras for a few days and was now returning to the lowlands where we hoped to find transportation back to civilization. But I was quite sick and was experiencing my third day without food – imposed by an aggressive microbe my stomach could not tolerate.  

At several points in our descent the trail would climb over individual hills and around steep ravines. On one prolonged climb, I was feeling particularly down, barely able to keep myself walking. Suddenly the frayed rope securing one of my bags to the back of a mule snapped without warning. The bag, containing several days’ worth of valuable samples, broke free and bounced several hundred feet down a steep hillside and out of view.    

I was stunned and at the point giving up. There was no way I had the energy to descend a steep canyon and climb back to the trail with a 70-pound duffle bag on my back. I leaned against a rock and sighed disconsolately.

Then without saying a word, a 70-year-old gentleman named Vicente (a local guide that we had hired for the trip) took off his backpack, picked up a machete and began hacking his way down the hill through the thick vegetation. In less than half an hour, with bag once again secured, we were back on the trail.

I was amazed then – just as I am now that I recall the incident – that this aged man was so healthy. Honduras, after all, is a difficult place to make a living.  It is a land where rural people survive by working hard and being resourceful. It is a place where people often go hungry, and where the climate often breeds malignancies. It is also a place where people don’t live very long lives – at least on average.

Even so, it isn’t unusual to find healthy old people. In fact, when you get the chance to talk with one of them you get the faint idea that old age just might be a possibility for most of us, if we could just stay healthy. This is true in many countries and in many climates. It’s perfectly natural to have the suspicion that we are capable of living to the ripe old Biblical age of 120 years.

This might be more obvious if we weren’t so distracted by the many myths of naturalism. Regarding the age of man, the accepted evolutionary story is a little unclear but it centers on the human struggle to survive, and on the importance of living long enough to reproduce. But the meaning of longevity is left to speculation. For example, we have a handful of effective equations for measuring reproductive fitness. A high school biology student can cross two varieties of plants and record just how well they survive and reproduce in nature. This is not difficult.

But try figuring out how an old dog helps its offspring reproduce, and the discussion is different. It’s possible to imagine ways this can be done. But try measuring it in a way that eliminates the possibility of other influences. The point is that evolutionary thinking does not have a clear picture on the meaning of old age. We are left with the textbook model of primitive humans wandering through an African landscape gathering plants and hunting big game, even while other animals (including rival humans) hunt them in return. This is not a story where anybody is expected to live very long past the years of peak physical activity.

Taking other animals as models, it has been assumed that primitive man took no care for other humans that were sick or aging. If a person was no longer capable of contributing to his own survival or of simply keeping up with the band, death would not be far away – not unlike the failing zebra picked out by a pride of lions for their next meal.

Animals don’t worry about the moral or ethical implications of such things. And survival would have been just as difficult for primitive peoples as it is for the beasts they lived with. Or so we have been led to believe. But, in fact, this story is guesswork at best.

And it is obviously not the same story as specified in the Bible – I mean the story of human beings living several hundreds of years. Methuselah’s longevity (all 969 years of it) is enough evidence to many thinkers that the Bible is not trustworthy. To others it is evidence that the Bible must be read metaphorically and not as history.

I have no intention of trying to persuade anyone on how to read ancient texts. I’m a biologist, after all. But I do have a thing or two to say about longevity. And the Biblical age of man (as established after the time of Abraham at 120 years) is a good deal more realistic than the vague senescent notions of contemporary savants.

Here is the question in a nutshell: What does old age mean? Of the many possible answers we might come up with, I see only two as important. Either it is a relatively unimportant by-product of evolutionary processes, or it suggests that living things were made to live quite a bit longer than they currently do.

If this is true, it implies that our bodies just might contain a blueprint that transcends the random accumulation of genes that natural selection is supposed to have endowed us with. It means that there is something about us that was made to endure – something that goes well beyond the natural explanations of evolutionary chance.   

Of these two very different perspectives, the view from Genesis is based on faith in a religious tradition and on our own experiences, suggesting that we were made to live a long time. This view also accepts that our ancestors might occasionally have lived a long time as well. The “accepted” view, on the other hand, is an evolutionary deduction based on the age of other (especially primate) animals. This view believes that our current human longevity comes because of better health care and improved living conditions. It also assumes that ancient humans lived short lives. 

The Bible isn’t really all that clear on the intended age of man. In the 6th chapter of Genesis, right after the discussion of the extreme longevity of the Patriarchs, the age of man is set to be 120 years. This is said to be a result of the constraints of the “flesh”. Later on the Bible indicates that Abraham lived 175 years. So if you draw a graph of the history of the world and the expected age of individuals, the line begins to level off at 120 years soon after the time of Abraham. If the line continues, it will drop to less than half of this number before rising to the 70’s for affluent societies today.
Let me give an example of the differences in these two perspectives of old age. Not far from my home, in the Sierra Nevada wilderness, there are many impressive stands of trees. In fact California is one of the most diverse places in the world for conifers. There are 55 species in the state.

The biggest pine tree is the sugar pine (Pinus lambertiana) which is known to grow up to 275 feet tall. This, of course is a very atypical height. Sugar pines are the trees with the very long cones measuring over a foot long that your mother may have collected on one of your recent vacations.

Most sugar pines live for one to two hundred years and typically reach a height of less than 150 feet before dying. The typical causes of death are diseases, insect pests, and lightning. Very often a chance abrasion – say from a nearby falling tree – will leave an opening that allows for disease to enter and then spread. Eventually an accumulation of this sort of wear and tear leads to sickness and death.

A sugar pine tree that dies – let us say at 100 years of age – will probably have produced thousands of seeds. Many of these will have been food for squirrels and birds. Some of the seeds will have germinated and produced a new generation of trees. Clearly the constraints of natural selection will have been satisfied. Chance and the genetic diversity that comes from the formation of new seeds will have produced future generations with different reproductive potential. This is the Darwinian world in which we live.

Every now and then, however, you might come across a real sugar pine giant. Trees growing over 200 feet are uncommon and their age is also exceptional but they do exist. It is thought that the oldest known giants are close to 500 years old.

Looking at these ancient trees is an awe-inspiring experience. Their size alone numbs the imagination. You may be tempted to take a picture for future reflection, but you will probably be thwarted. It’s just too difficult to get a shot that does justice to the entirety of the tree.

Such a tree could easily pass as a standard for the species. Of course, in thinking this way, you would be ignoring the many smaller and more typical forms. But this is not important. The majestic giant in front of you is such a superb specimen, that it deserves this kind of recognition. You want to remember sugar pines by this specific tree.

It is also worth noting that most of these giants – especially the ones you remember as remarkable – are well-formed and stately trees. They are not senescing as old twisted remnants of their former healthier (and reproductively successful) selves. They have become impressive far beyond the demands of any Darwinian requirements. 

Why is this so? Why would anything live so long beyond its reproductive prime and then do so with such majesty – as if it were becoming the very standard for its kind? Well the truth is that we don’t know. And I have a confession to make: my acknowledging of this reality makes me an essentialist of sorts. And essentialism is one of the things that I was educated to avoid.

Let me explain. Until modern ideas changed our way of seeing the world, living things were believed to be imperfect representations of another reality – a more complete reality. Plato argued that individual beings belonged to clearly defined groups and that each group had an essence (his word was eidos). In this world the individual plants and animals that we see are only imperfect representations of this essence. We can sometimes get a hint of these essences, or types, in remarkable individuals but ultimately we experience the reality of these higher forms only as if they were shadows on a cave wall. This thinking about ideal types or forms has been called essentialism – a belief, if you will, in essences or essentials.

This, of course, was a view of the world that was incompatible with evolutionary thinking. Natural selection worked on individuals within a population. And these populations changed over time. Darwin and his followers have considered these changes to be the engine that drives evolutionary change. Species are formed by these changing populations. A static essence would obviously not work.

But if essentialism was incompatible with evolutionary thinking, it has been quite the opposite with Christianity. It is very compatible with Christian beliefs about the Creation. In fact Platonic essentialism and Christianity have lived side-by-side for hundreds of years. Perhaps the Bible is not clear about individual essences for living things, but it is clear regarding a premeditated created order. Some Christian biologists believe that the Creation involved evolutionary processes. Yet even this thinking requires a thoughtful process that very well may have involved essences or types. The Book of Genesis is clear about individual animals and plants being created after their own kind.  

Even the earth itself confirms these created distinctions. The fossil record shows clear breaks between species that are as obvious as the breaks we see in nature today. This is a hint that some sort of essential mechanism is involved. A strict population perspective would suggest that no clear lines exist between species, only vague geographic zones of overlap.

We do know that populations of plants and animals change. Sometimes they change quite a bit. Many dedicated scientists have measured these changes and the environmental conditions that have solicited them. In the end, though, it isn’t clear that these changes drive major evolutionary novelty. To many of us they appear to be built-in genetic devices enabling created beings to adapt to a world of changing conditions. In the end, this may be the only significant contribution of Darwin – That is, natural selection accounting for adaptability, with the true mechanism of species or generic differences lying elsewhere.

So what does all this mean as we stand beneath our old sugar pine tree and marvel at its age and grandeur? It means to me that the real world may indeed be a fallen place but that there are hints here of something more. To me, superannuated majesty looks a lot more essential than Darwin. And yes, the pun is intended.

In recent years there has emerged further evidence that humans lived longer anciently. Some of this evidence is coming from field studies of rural peoples. Other evidence comes from the dry vaults of ancient Egypt – from ancient mummies. And this evidence is requiring scientists to look differently at the so-called transition of erstwhile primates to humans.

By way of comparison, the chimpanzee (claimed to be our closest living relative) lives, on average, 13 years. The life expectancy for humans living in developed countries now exceeds 75 years. This is a significant difference and not one easily predicted by evolutionary theory.

Scientists have long assumed that modern health practices are the reason for the advanced ages often encountered in Western society today. Earlier humans would obviously not have lived so long. It isn’t hard to find old anthropology texts arguing that early human females were having babies in their early teens (or even earlier) – the implication being that our ancestors were more like Paleocene primates than like Methuselah. 

But things are changing. Heather Pringle, writing for Scientific American, tells us of the recent field work done in Tanzania with the Hadza - a group of hunter-gatherers living in the Lake Eyasi basin.

The Hadza live in a world surrounded by all the diseases and risks associated with wilderness living. And they do so almost entirely without the benefits of modern medicine. This is a world not so different than the world of chimpanzees. But the Hadza live a lot longer than chimpanzees. On average, the Hadza live over 30 years. But this isn’t the whole story. Death takes a disproportional number of children and youth, as it does in most societies. Individuals that manage to survive these years often live much longer. It is not unusual for some Hadza elders to live into their 80’s.

Another fairly recent finding is that many ancient Egyptians also lived longer than expected – longer than the evolutionary model predicted. The clues are coming from mummies that are well enough preserved for scientists to study their immune systems. What these scientists are finding is that ancient Egyptians suffered from many of the same kinds of diseases that we do – diseases that scientists once thought only existed among long-lived humans enjoying the benefits of modern health care. 

The closer we look at the world the more we find long-lived beings. An individual Giant Tortoise from Aldabra recently died after living 255 years.  An Andean condor has lived to the age of 80. A Cockatoo living in the Brookfield Zoo (Illinois) lived 80 years.

Elephants have been known to live over 80 years, with unverified accounts of individuals many times that old. A domestic cat from Austin, Texas died a few years ago at the age of 38. In the oceans of the world, long-lived creatures can be even more surprising. Lobsters are occasionally found that are over 100 years old. Specimens of the Red Sea urchin have been found that are over 200 years old.   

Just recently while travelling along the Columbia River in northern Oregon, Kathy and I stopped at the fish hatchery near Bonneville Dam just east of Portland. It was a sunny afternoon in early October and the few deciduous trees were turning yellow – highlighting the various shades of evergreen blanketing the surrounding hills. We were surprised at the size of the rainbow trout in several of the long cement ponds. But the real surprise was tucked away in the back of the hatchery in a pond near a small waterfall.

A small structure had been built into the ground beside the pond with a large glass window extending below the waterline. From the window it was possible to see three very large fish. These were not trout, although they were fish that lived part of their lives in fresh water. They were sturgeons, a kind of primitive bony fish that seem more related to sharks than other true fishes.

These sturgeons were as long as I am (over six feet long) and were fairly old - one of them had lived 70 years. This is impressive although sturgeons have been found that were over 12 feet long and probably much older than 70 years. What makes this particularly impressive is that sturgeons typically begin laying eggs before they are 10 years old and only a few feet long. These individuals were truly ancient for their kind.

The apparent early age of reproduction makes sense considering their habitat. They live much of their lives in the ocean and are themselves targets for other predatory fish and mammals. If they had to wait until they were 5 feet long before laying eggs, there probably wouldn’t be any sturgeons around anymore.  

Every once in a while individuals live a lot longer than expected. Maybe these are just extreme outliers in an otherwise very predictable span of temporal diversity. Or maybe they are more obviously temporal hints. Maybe, living things are made to live longer than we think.

I do find it quite interesting that the oldest known human beings live to the biblical age of man – just at, that is, 120 years. Jeanne Calment of France, the oldest human being whose age has been confirmed in modern times, lived 122 years. The oldest modern male was Jiroemon Kimura from Japan who lived 116 years.   

Perhaps John Henry Newman understood what this meant better than most. He observed that, “it is a plain fact, that most of us who die, die, not by any law of death, but by the law of disease; and some writers have questioned whether death is ever, strictly speaking, natural.”

This is something to think about. Maybe death isn’t natural in a different place. But here, in our fallen world, it’s easy to assume that old age is just the flip side of inevitable death. Such a view means that if you live to an advanced age, you will do so because of luck.

The other view is much more interesting. It is also much more inspiring. And to be quite frank, it makes more intuitive sense. Old age is a hint of who we are. And we were made for greater things.


The reference to Methuselah’s age is Genesis 5:27. The age of Abraham is given in Genesis 25:7. Heather Pringle’s article, Long Live the Humans, is found in Scientific American (October 2013) pages 48-55. Ronald M. Lanner’s colorful and interesting book Conifers of California (published by Cachuma Press, 2002) is my main source on sugar pines. My main source for essentialism is Ernst Mayr, especially his The Growth of Biological Thought (Belknap Press, Harvard, 1982). For an interesting list of long-lived individuals of many species see the Wikipedia listing for “List of Long-Lived Organisms” [accessed September 2013]. My source for old humans comes from Wikipedia’s article “Oldest People”. John Henry Newman’s statement is from A Grammar of Assent, Chapter VIII, part 1 of Informal Inference. 

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