Feeling Old? Envy the Lobster

The certainty of death is hard enough. But aging as a prelude—the wrinkling, weakening, deteriorating and the rest of the assault—can feel downright demeaning! Is there a benefit here for survival of the species, or for any species, that no one told me about before I reached 73?

lobster (anvilcloud.blogspot.com)

(anvilcloud.blogspot.com)

Not all species go through their version of this. The paths that organisms follow after maturity vary enormously. Some plants live for one year only, others come back every season. Bacteria clone themselves and don’t die from age at all but from hostile organisms and conditions in their environment. Seabirds age very slowly; as long as they can fly, they can stay ahead of most predators.  Lobsters don’t age; they can continue to grow and remain fertile for 45 years or more in the wild, dying only when they can no longer molt and grow a larger shell.

How and why the declines of aging are included in the final phases of some species’ lives is complex. Wikipedia’s “Senescence” introduces the range of theories and uncertainties. Here are three insights from the evolutionary perspective that make sense to me.

One is that certain harmful genetic mutations switch on later in life after an organism’s reproductive period has ended. Many cancers in humans do, for example. Because they don’t impact the number or health of the offspring, such genes do no harm to the persistence of the species and so they are unlikely to be lost over the generations. The diseases of the elderly get passed along by the young.

Even more unfortunately, some mechanisms in our bodies boost our health when we’re young and then come back to bite us when we get older. Digesting calcium, for instance, builds strong bones early on but helps clog and stiffen arteries decades later. As long as such a function improves our fitness to make and raise babies, whatever damage it does later on doesn’t matter much in the very long run.

A third way in which selection seems indifferent to the pains of aging is statistical: even if natural selection did reduce the ravages of aging and prolong the fertile period, the population of such organisms would still decline with age as accidents and predators took their inevitable toll. The body invests its resources where they are the most effective for the future, in youth and early reproduction, not in a comfortable old age.

In these ways and others, aging is linked to the importance of reproduction and the dangers of predators and other external forces. For primates, including me, we reproduce early because the big cats—leopards, jaguars, cougars, tigers—stalked us for millions of years in the forests and grass lands. And for most other species as well, the safest bet for species continuity is simple: reproduce early. Still, the exceptions are fascinating. Lobsters in their suit of armor run little risk from ancient predators, so they can reproduce throughout their lives without ever aging into genetic irrelevance.

So, armed with such insights, do I experience my weakening muscles, declining sexuality, distracted thinking,  and dulled senses with any less resentment? Yes, a little. Knowing that the decline has its place, even though it’s a melancholy one, in the evolution that brought me to being in the first place is some consolation.

 

Stem Cells: How To Build and Maintain Bodies, Including Plants

Until recently, I didn’t know much about stem cells except that they produced other kinds of cells and that the medical research on them was controversial. In the context of the history of life, it turns out, their importance is as fundamental as you can get.

It took more than a billion years for the first cell with a nucleus to come together. Since then, the only reliable source for a new cell has been another cell. Every cell is an offspring. True for plants as well as animals.

An embryonic stem cell (Wikipedia)

An embryonic stem cell
(Wikipedia)

But while cells are specialized for one task or another, they are not always very good at dividing and reproducing. Muscle cells, blood cells, and nerve cells don’t reproduce at all. Other cells in the body divide only under some circumstances or only a limited number of times.

But reproduction is the stem cell’s specialty. When it divides, it produce another stem cell, ready for the next round, along with a muscle cell or blood cell or nerve cell or a cell of another organ. It looks the part for such flexibility—blob-like, unstructured, not committed until needed.

Stem cells are stationed throughout the body, small groups of them in each organ, like local hospitals on call to repair the sick and damaged. They are a profound piece of bodily engineering, a design for the long-term, like a futuristic car that carries little 3-D printers throughout the engine and chassis to create new parts and replace the old parts automatically.

In human embryos, in contrast to adults, stem cells literally build the body. When an embryo is only a few days old, its stem cells begin to form all—all—of the specialized cells needed in a body, some 200 of them.

In this root tip, the number 1 marks the relatively unstructured stem cells in the meristem. (Wikipedia)

In this root tip, the number 1 marks the relatively unstructured stem cells in the meristem.
(Wikipedia)

Plants have stem cells too. Located near the tips of the roots and stems in a layer called the meristem, plant stem cells divide into both specialized cells for the plant and additional stem cells. Stem cells are, in other words, the place where a plant grows.

One of the wonders of any living thing is the sheer variety of its parts, the inventory of its tubes, organs, fluids, surfaces, protrusions, electric circuits and rigid pieces. As we pause to appreciate this profusion, sing the praises of the smudgy cell that creates and repairs them all.

Steven Pinker on Emotions and Genes

Steven Pinker’s How the Mind Works might well be subtitled “And the emotions too.” It’s one terrific book. It offers a barrage of insights and connections about humans and evolution that can feel intoxicating. It stirs up the nature-nurture controversy with a blender. It does not see you as you almost certainly see yourself. And it is often very funny.

Despite the book’s title, Pinker talks more about emotions than about the mind itself. He sees them working together. The mind, he says, is computational: it processes information. Much of this information comes from the body’s biological systems. Emotions are units, modules, that use this bodily information to take direct steps—fear, anger, hunger, lust, egotism, empathy—that will promote survival and reproduction.

Humans, Pinker writes, are not, as we often believe, divided into thoughts and feelings that work against each other.

The emotions are adaptations, well-engineered software modules that work in harmony with the intellect and are indispensable to the functioning of the whole mind. The problem with the emotions is not that they are untamed forces or vestiges of our animal past; it is that they were designed to propagate copies of the genes that built them rather than to promote happiness, wisdom, or moral values. We often call an act ‘emotional’ when it is harmful to the social group, damaging to the actor’s happiness in the long run, uncontrollable and impervious to persuasion, or a product of self-delusion. Sad to say, these outcomes are not malfunctions but precisely what we would expect from well-engineered emotions. (Kindle location 7688)

So the good news is that our seemingly perverse emotional moments do not mean that something is wrong with us. But the not-so-good news is that our emotional acts are more deeply engrained in us than our well-meaning searches for happiness, wisdom, and virtue.

So are we doomed by the genes that build these emotional responses, responses that often mean we get  carried away just when we want to stay cool and collected? Pinker addresses this issue often, here in a discussion of love:

The confusion comes from thinking of people’s genes as their true self, and the motives of their genes as their deepest, truest, unconscious motives. From there it’s easy to draw the cynical and incorrect moral that all love is hypocritical. That confuses the real motives of the person with the metaphorical motives of the genes. Genes are not puppetmasters; they acted as the recipe for making the brain and body and then got out of the way. (8342)

I like the recipe metaphor. As I take it, genes are like the list of the ingredients and the steps for making a cake, but the flavor and texture of the cake itself is quite different from that sheet of instructions.

A human

A human “cake” and his genetic “recipe”
(images.nationalgeographic.com)

But if the genes have built emotions to keep us alive, doesn’t that mean those emotions are quite inflexible? Yes and no. Our own emotional core might not change much in our life time, but in species-time, the story is different.

Might the software for the emotions be burned so deeply into the brain that organisms are condemned to feel as their remote ancestors did? The evidence says no; the emotions are easy to reprogram. Emotional repertoires vary wildly among animals depending on their species, sex, and age. Within the mammals we find the lion and lamb. Even within dogs (a single species) a few millennia of selective breeding have given us pit bulls and Saint Bernards. (7721)

Pinker, in conclusion, tells us about ourselves in ways we may have difficulty recognizing. Modules and systems fine-tuned to an ancient past may seem non-human and even anti-human. But it’s not so difficult to absorb how science depicts the machinery of our emotions at the same time that we are inquiring thoughtfully about the meanings of our lives. Or, to put it another way, we can come to understand our recipe while we ponder what it is like to be the cake.

For more on the man, the book, and the debate, here is a lively and helpful article.