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.

 

The Most Amazing Thing About Life

“The most impressive aspect of the living world is its diversity. No two individuals in sexually reproducing populations are the same, nor are any two populations, species, or higher taxa [categories of organisms]. Wherever one looks in nature, one finds uniqueness.” So wrote Ernst Mayr in This is Biology, published in 1997.

Grains of sand under an electron microscope (wikipedia)

Grains of sand 
(wikipedia)

This was, to an extent, a new idea to me. Clearly each species is different from the next. But I had not fully absorbed the notion that every single organism, if it reproduces in pairs, is different from every other in its species. Every individual grass plant, every tree, every insect, every ant is as different from the one next to it as two human beings are. Why? As Mayr explains, diversity ensures that some individuals will fit the environment; as the environment weeds out some versions, others will survive.

But what about the diversity in the non-biological, inanimate world? “Nature” includes not only living things but also rocks, water, air, light and other forces and materials. Aren’t they unique in their own ways? Snowflakes are famously singular. Clouds are constantly changing. So is the surface of the ocean. Air flows and spins. I’m pretty sure I’ve never seen two rocks that are identical. It’s a good bet that every asteroid, planet and star is different from the others in some ways. Looking out over the dessert, the ocean, or the skies, we certainly see diversity in shape, motion, color and light.

Diversity and fertility in grass (www.kvkcard.org)

(www.kvkcard.org)

Still, I think the diversity of living things does “impress” us, as Mayr wrote, in a distinct way. The variety of the organisms in a species is more individualistic, unique, than the motions, colors and contours of the elements around us. And it captures our attention partly because of the sheer power of fertility. New life is always thrusting itself in front of us—in a sister’s baby, in a new puppy, among the trees at the back of the backyard, in the horde of ants and bees and birds of spring. In Origin of Species, Darwin wrote, “There is no exception to the rule that every organic being naturally increases at so high a rate, that if not destroyed, the earth would soon be covered by the progeny of a single pair.”

Diversity is the music, but fertility is the amplifier. It’s the combination that gets our attention. And we are not remote observers. We are both notes in the music and members of the orchestra.