Evolution proceeds through the natural selection of traits within a species' genome, traits that favor the reproductive success of individuals possessing and passing on those traits to their surviving progeny. The individual is a link in a lineage; the traits are what persist through the generations, the traits are what evolve.
That's a mouthful, and it is difficult to grasp. So consider in contrast the antithesis of evolution: civilization.
Civilization strives through the intervention of technology to favor the survival and reproductive success of everyone who has access to health care. Ideally, there is no selection of traits, no bias toward any set of characteristics inherited or learned.
That's a mouthful, too, but in a different way. The idea is easy enough to grasp although it is proving quite difficult to fully implement. It is a mouthful of promise yet to be delivered.
The starkest contrast between evolution and civilization is not about death, but about life. People die invariably, inevitably, inexorably, regardless of their health care, because we all are mortal. We evade that truth, mostly, hoping that the ultimate achievement of medical research within our lifetime will be the attainment of affordable immortality, preferably with some restorative component, so that we will not only live forever, but enjoy eternity in the bodies of 30 year olds.
The ideal of individual immortality is what most distinguishes civilization from evolution, the prolongation of the person rather than the persistence of traits passed on through a lineage of persons.
Bear in mind that evolution results in the longevity of traits which favor reproductive success as they are passed on through the generations. The elderly, well beyond their reproductive years, don't matter to evolution except for what they contribute to, or detract from, child rearing. The opportunity to pass on traits concludes with the end of fertility, but through the assistance of grandparents, those traits in grandchildren have a better chance of being passed on again. The altruism of kin is likely a self perpetuating trait.
Consider that civilization, in contrast to evolution, seeks the longevity of the person, the actualization of the self through the whole arc of life. Civilization at its most idealized, is the negation of evolution, even the negation of lineage, through the elimination of natural selection as a threat to individual lifespan and wellbeing.
For example, pandemic diseases, left to their own devices, can create natural selection events. The survivors whose traits, whether behavioral or physiological, confer better odds of survival will pass on to their offspring their resistance to the disease.
But diseases are not left to their own devices. Civilization has waged a seemingly successful war against disease through the eradication of pathogens. Generations which have never been exposed to a given disease have no resistance to it without vaccination. And if vaccination succeeds spectacularly, as it did with polio, people assume they don't need resistance to a pathogen that no longer exists.
But if a war against a pathogen achieves less than eradication because there are strains of the bug with resistance to the treatments used, then the surviving strains persist and rebound. Nosocomial infections contracted in hospitals are notorious examples of how evolution and civilization can be at loggerheads. It is fair to say that the intensively antibiotic environment of hospitals has bred badder bugs. We are selecting only the resistant pathogens, we are not selecting for the humans with natural resistance.
On the whole, we seem to be exerting no selective pressure on our own species.
Wars and the hazards of place (like living in the path of a tornado or on a flood plain) do not count as selective pressures because they do not differentiate between inheritable traits. A total nuclear war might create a bottleneck effect, with a few survivors providing a restricted genome for the recovering population, the survivors' traits becoming the dominant features. But while natural selection would be at work for the generations hence, the catastrophic narrowing of the human genome to a bottleneck would sort victims and survivors by chance alone; luck is not an inheritable trait.
Surveys of the human genome show that the genetic variation of the species is expanding. Selective pressure has not acted recently upon the human genome to winnow our traits to a subset favoring reproductive success. We can take this as evidence that modern civilization has triumphed over evolution, at least for now.
Evolution made us what we are. Now that we have halted human evolution in its tracks, it is not clear that anything is making us into something else. We are yet the same species we were as the last glaciation melted away and we went on to till the soil, building from the first agricultural societies ten millennia ago the global civilization of today. Any early example of homo sapiens, if robbed from the cradle and transported through time, would fit into the modern world quite naturally.
Evolutionary forces are alive and well, but leaving humanity alone for awhile. Meanwhile, we have just begun tinkering with ourselves, engineering our genome and melding flesh with non biological materials, fusing our brains with computers. None of these chimera have the time-tested durability of what evolution can produce, but they might add something important to the genome for natural selection to work with someday.
I wish for a selective event that steers the human species toward empathy as a dominant trait. I cannot imagine what kind of event that would be, as nothing recorded by history has had that effect. As much as people of a certain sensibility might value empathy, it is more known for its rarity than its prevalence. And yet, empathy is encountered frequently enough to provide some hope for humanity. Someday, an instinctive, compulsive empathy might be just the trait we need in order to squeak through a narrow scrape with extinction.
