Human Evolution (?)

While, of course, the foreseeable future is a blink in the span of eviolution… well, I’ve been reading a lot on the process of evolution in plants. Single-gene mutations that happen to survive better than the parent species and go on to replace (or at least outnumber) them and all that.

Have we reached the numbers that it would be difficult for a single-mutation evolution to take hold?

The best I can imagine is natural selection for immunity to specific diseases.

In this case I foresee three scenarios:

In one, we genetically engineer ourselves, effectively doing conscious and selective mutation and evolution. In essence, do to us what we’ve done to so many plants and animals.

In the other, genetic mutations are shunned by society and medicine and kept from reproducing, consciously or subconsciously (eg, “it isn’t right for us to engineer supermen and do human experiements as outlined in the previous example”)

In the last, a random genetic mutation that unlocks some higher brain function or some such is sucessfully reproduced, starting the path to another species (or rather, the next step in our species) starting in one family branch over a very long period of time.

So, where does the line get drawn on human mutation? Should it be encouraged, discouraged, engineered, controlled, or what? Will we end up with engineered sub-species in the future? Will they simply be immune to more types of diseases, or will they be stronger, smarter, and faster? Can a program of selectively breeding humans based on intelligence and/or other traits create a “better human”? Is that right? Is it inevitable? Is the human species destined to splinter into genetically more disparate groups, or can we stay within a species level?

Is the entire issue a strawman, and the power of genetics being thrown around as a boogeyman for dysutopians?

Or are we slowly and continuously doing selective breeding experiments naturally, sped up many fold by modern science?

Or is science enabling the less-fit to survive and compete with the more fit, leveling the playing field?

I am not a biologist, but I did have a zoology class last semester that covered something simlar to this. We were taught this: The Hardy-Weinburg Equilibrium states that frequency of allels in a population does not change over generations if the following are true:

*There is no selection
*There is no mutation
*The population is large
*Mating is random

I would say the human population as a whole definately has the last two qualifiers. I think it could be argued that it also represents the first conditon. There is no selection.

It’s quite possible that genetic engineering could create multiple “species”, if we keep to the definition of a species being populations that can’t or don’t interbreed naturally. But at that point, the technology should also exist to allow laboratory mating of individuals who couldn’t mate naturally. In that case, of what use is the term “species”?l

A non-engineered species split is highly unlkely, unless we begin colonizing other planets and create isoltate populations. Populations that freely interbreed are unlikely to split into seperate species. Even if we blasted ourselves back to the stone age, it seems unlikey that populations would remain isolated long enough to form different species. Everyone everwher would have to remain primitive hunter-gather types for over 100k years.

We already walk amongst you. We are best appeased by offers of cash and sexual access.

And we don’t take American Express.

I would disagree that mating is random. Random mating implies that any individual has an equal chance to mate with any other individual. This is largely true of plants, which by their sedentary nature don’t have the means to “choose” a mate: they pretty much have to leave it up to the prevailing winds, or the whims of bugs.

Humans, on the other hand, are notoriously choosey (well, some anyway…). Of course, what humans base current choices on often has little to do with genetics, so natural selection still probably has a more reduced role than it would in similarly-large, non-human populations.

Who does?

Of course we are evolving. We are not the same as we were a mere hundred years ago! In 1900 the average human life span was 47. Not sure of the current exact figure, it’s changing annually, and so far growing greater, but it has us living at least 20 years more, on average.

Our technology affects our survivability, and we are evolving, but it only counts for an individual if they produce offspring. That’s the point of survival, to survive long enough to pass on your genes. If you do that your evolved genes will pass to the next generation. If, however, your longer lifespan also includes a longer reproductive life, then your chances of your genes surviving past the next generation are increased. More offspring = more chances at genetic survival.

Then let’s consider who is reproducing and who is not. Frequently, upper-class couples will defer reproduction or avoid reproduction altogether. Adoption is considered a viable option for “politically correct” intellectuals who wish to keep their figures and avoid the pain. While on the other hand the lack of adequate sex education for the lower classes (poorer people) are resulting in an increase in multiple unmarried teen pregnancies. “Politically-correct” planned parenthood clinics (anti-abortion) are also creating a glut of babies with a lower social support system, fewer opportunities for meaningful occupations and a rewind/replay of their parents’ generation, creating another generation of cheap labor, social-services-dependent, drug-addicted criminals to pass on their culture to their offspring.

Since we are cultural animals, we are in the unique position of having the handing down of our culture affect our survivability and evolutionary success as well.

So, think:

How have we changed, both physically and culturally?
How will these changes affect our ability to survive long enough to pass these changes on to subsequent generations?
What will be the result of these changes on future generations?

If we keep up these current trends we will develop a less-homogenized, more segmented social order comprising three groups: the wealthy elite, small in number, with relatively few well-educated offspring who inherit their parents’ wealth and cultural tools, and who take on positions of authority (a sort of ‘modern royalty’); the wish-they-hads, the working class, who shoulder the majority of the tax burden in the US and most of the skilled labor elsewhere, they have a moderate number of children with a modicum of education who in turn produce a slightly-increasing number of workers to support the world; and the have-nots, who live increasingly on charity or government stipends, who produce massive amounts of offspring, but many of these are incompetent and poorly educated due to drug exposure as well as cultural values and cultural exposure, who (at least according to M. Moore) form the bulk of the military, and eventually become disposable people.

Of course all this is just off the top of my head, so I welcome refinements.

Zagada,

Just to clarify a bit about evolution. Evolution is not a march forward, to more complex, smarter organisms. It is merely that those hereditable features that end up keeping promoting more copies of itself in future generations, will become more numerous. Would a suddenly more intelligent human do that? Probably not, at least in the developed world. The individuals might live better, the individuals might contribute more to the culture at large. But not likely have more kids. And all would benefit from their contributions, not just those of their kinship.

Snake is partly right. Large family size is correlated with poverty and specifically with lack of female education. This is, however, a cultural rather than genetic attribute. As cultures evolve, this changes, at least if the cultural evolution includes a rise in female education and standard of living. In perhaps more than just a metaphoric way, the organism under selective pressure now is the culture, a meta-organism, and there are different rules of heredity that apply. (BTW, for most cases you mischaracterize the choice to adopt, but that is another thread to be had.)

Clearly there is going to be some change in the frequency of various alleles over the next several thousand years, but barring some major catestrophe*, survival to reproductive age and size of family is not so tightly correlated with genetic fitness. Changes are more likely to be drift than anything else. On the other hand cultural evolution will continue at a breakneck pace.

The bottom line for evolution always has been and always will be one thing. It is the age of the bacteria. There are more of them than there are of us. Than all other life on the planet put together. They can exist without us but we cannot without them. They were here before us, and they’ll be here when we are gone. We are really well developed mobile Petri dishes. That thought helps keep me humble.

*Besides human-caused disasters, new diseases can occur that could wipe through societies in pandemic fashion leaving only those with some particular genetic allele surviving.

So much you have said, DSeid, is right on. There is so much to consider here that is an active component in evolution; I missed a few.
We all need to keep thinking, go beyond the framework of the paradigm, if we are to undover any aspects of survivability that will impact our survivability. You give us some good thought-lines to follow! Thanks!