Last night, I caught up with a documentary that I’ve been waiting to view (lack of time) since early February. The subject, and title, of the documentary was the question, ‘Are We Still Evolving?’. And, as with many subjects that I digest, it sparked a number of thoughts, all of which are relevant to the shape of humanity in the distant future – which is directly relevant to any science-fiction setting. Because of this relevance, I thought I would take a few minutes to expound my thoughts on the subject.
Let’s start by revisiting the fundamental assumptions.
What is evolution?
Evolution is the process by which traits emerge, are conserved from one generation to another, and accumulate until the species is so transformed that it is no longer compatible with the previous form of the species (if any representatives survive). Where these traits are only preserved in a limited subpopulation of a species, it eventually gives rise to a new species.
Survival is not sufficient
The driving force behind evolution is Natural Selection. It used to be thought that the driving force behind Natural selection was the capacity to survive, and this remains a key factor during times of extreme environmental distress – if you don’t survive, you don’t pass on your genes and any mutations that they may contain – but these days we know better. It’s not enough merely for an organism to be better adapted for survival than another member of the same species, it also has to be able to reproduce. The capacity for survival is simply one of a number of criteria that, in combination, determine whether or not an individual will successfully reproduce.
Consider that if a mutation renders a species incapable of reproduction, there will be no new generation competing for food supplies and other resources, and hence more to go around for the existing members of the species, who are more likely to survive as a result. This shows that a pro-survival evolutionary trait can actually be counterproductive in terms of the survival of the species.
The distinction lies in the false assumption that what is good for the individual is also good for the species. It ain’t necessarily so, and neither is the converse: that what is bad for the individual is also bad for the species. In both cases, the statement can be sometimes true and sometimes false, depending on which specific benefit to the individual we’re talking about.
It’s the journey that matters, not the destination
It also used to be thought that once humans had achieved intelligence and began manipulating its environment to enhance its capacity to survive and prosper in relative comfort, that evolution stopped, because there was no environmental stimulus to select one characteristic over another. The human form was therefore described as the pinnacle of evolution, perhaps in need of a few tweaks here and there, but overall perfection and inherent superiority to every other life-form on the planet. These days, we know better concerning this misapprehension as well.
There are still factors that can wipe out large segments of a population. 400 years ago, one in three children survived to reach adulthood. 200 years ago, that had gone up to two in three. The ability to resist those diseases was clearly an evolutionary factor – and if the diseases remained unchanged, we would have evolved a resistance to them long ago. Influenza used to be a killer, and I don’t just mean the rare ultra-virulent strains, I mean the everyday ordinary household variety. These days, most children survive the flu with nothing more than bed rest – and even that treatment is more concerned with comfort, effectiveness, and restraining the spread of the disease than actually curing it. So long as our environment poses a threat to our health and hence our ability to reproduce to our maximum biological capacity, evolution is at work. The journey never ends, and hence the destination – perfection – is a chimera, and has no significance. What matters is accumulated generations of adaptability to whatever the environmental conditions happen to be – the ongoing process of evolution.
But isn’t evolution just a theory?
I don’t intend to get into a big arguement about science vs. religion at this point. What any individual believes and how they reconcile those beliefs with the accumulated understanding of the way the world works is none of my business, and I’m happy to keep it that way. This “counterargument” is a different kettle of fish entirely, and comes from fundamentally misunderstanding science or willfully distorting what Science is.
At its heart, Science is simply a process for proposing and validating theories about the nature of reality. No scientific principle is ever etched in stone, immutable and eternal; it’s a best approximation of our current understanding. All scientific theories must continually face attack from people looking for flaws, for holes in the logic, for exceptions that disprove the universality or accuracy of a theory. Science, in other words, gives the term “Theory” a slightly different meaning to that of colloquial English, and employing the term in its colloquial sense misrepresents the meaning.
The colloquial meaning of ‘theory’ (note the lowercase) is more akin to the scientific usage of the term ‘hypothesis’ – an untested, unproven explanation for an observed event or condition that may or may not be accurate. Only once a hypothesis has undergone rigorous testing and verification by independent scientists can it advance to the point of being called a Theory. Becoming a theory means that the hypothesis has been analyzed and codified mathematically to the point where precise predications can be made, and that those predictions are testable by controlled and repeatable experiments and have been so tested, and the results verified. In general, it is also true that no new hypothesis will be accepted until there is some observed condition or phenomena that the existing theory does not adequately explain. That doesn’t eliminate its viability as a good approximation in most cases.
Einstein’s was not the only Theory Of Relativity. There were half-a-dozen or more of them. But its predictions were closer to the observed reality than that of the others, and so it is the one that’s accepted – and remembered – these days.
That, by the way, is where the arguement for creationism being taught in the classroom falls down. Creationism, or Intelligent Design as it is now named, is a hypothesis, but it has not been subjected to the rigorous development and testing of evolutionary theory, and it cannot point at an event or phenomenon that it explains but existing theory does not. To its adherents I say: find those exceptions and do that research, and then make your case. You might even be right, but propounding dogma and rhetoric as logical arguement will never prove it, and until you do, its about as scientific as fairies at the bottom of the garden.
We used to think there were natural laws that, once stated, would stand inviolate as the last word on a fundamental principle of the universe. As our understanding of what Science is has grown, we have become less arrogant. It was not uncommon for scientists in the 19th century to believe that a complete understanding of physics was possible within their lifetimes, and several lamented that soon we would know all that there was to know, and speculated on what we would do once that had been achieved. We now double the sum of human knowledge every X years (it used to be 10, I think it’s now approaching 1 – but it may even be beyond that numeric threshold) – and there is no end in sight. But it’s not the broad principles that elude us – its the details, and the extrapolations of those broad principles beyond the limits of our understanding, and the causes and relationships between them.
The principles of Evolutionary Theory are just as solidly verified and as widely accepted as the Theory Of Gravity.
Evolution in the lab
In fact, you can watch evolution take place in the lab. Time-lapse photography of the growth of antibiotic-resistant E. Coli showed evolution in action as part of the BBC documentary “Defeating the superbug”. While this documentary is not apparently available on official DVD (it’s an episode of the BBC2 “Horizon” Science series), a Google search reveals a number of sources which claim to permit one to watch it online (well worth the effort). The images were of an experiment in which panels of successively stronger doses of an antibiotic were incorporated into a growth medium for the bacteria, until the final panel which had an antibiotic dosage as high as a human could medically tolerate and survive – any stronger and it would kill the patient outright. In the course of a week or two, bacteria which were just a little more resistant to the antibiotic successfully colonized one panel after another, growing more resistant at each step, until finally they invaded and conquered the strongest panel.
Of course, this produced only a new strain, like a new breed of dog. To actually change the bacteria so much that they became a new species, much more time would be required.
By way of comparison, how long would it take for an equivalent amount of change in humans? Well, typical bacteria double in population (assuming adequate food supplies, etc) every 20 minutes. Two weeks is therefore equivalent to 1008 generations. The human equivalent is roughly 20 years – so about 20,000 years could produce a similar amount of change – at least in theory. There’s a secondary consideration: persistence of environmental influences. In the lab experiment, there was no significant change in the environment in the course of those 1000+ generations; the same can’t be said of a time-span of 20,000 years. For one thing, there is a complete seasonal cycle in each one of those years. So, rather than constantly selecting for the one criterion, we would be diluting the evolutionary trend – the question is, by How Much? To one-fifth? That’s 100,000 years. One-tenth? That’s 200,000 years. One-twenty-fifth? That’s half a million years. Anatomically modern humans first emerged about 200,000 years ago, according to the fossil evidence, while our immediate forerunners evolved between 250,000 and 400,000 years ago. That’s the sort of timescale we’re talking about. Evolution is SLOW.
At least, most of the time. The theory of Punctuated Equilibrium suggests that evolution occurs more rapidly in small populations or geographically restricted habitats – that there are long periods of stability and then some environmental catastrophe or cataclysm that triggers a period of rapid change. This theory is not universally accepted, as a quick scan of the “criticism” section of the Wikipedia Page linked to above, shows.
I find it quite credible that following a mass-extinction event, or some more local equivalent, there might well be a drastic increase in population amongst the survivors and occupation of multiple ecological niches which would lead to rapid differentiation. In the short-term during the recovery from such an event there would be decreased competition for food, permitting rapid expansion of population levels. The natural behavior of population growth is for numbers to increase unchecked to the point at which the food supply is barely adequate for survival plus one generation of expansion that crosses the line from sufficient food to drastic competition. Those subspecies that have diverged sufficiently to have occupied an ecological niche outside of the primary niche formerly learned have a clear advantage in this climate of drastic competition, and so begin the transition from one species to another.
But that doesn’t mean that evolution would stop at other times. It just means that the rapid increase in numbers and the availability of empty ecological niches promotes an acceleration in the rate of evolution.
Actually, evolution would still be slow – but the rapid increase in numbers would compensate. The overall rate of evolution is dictated by the base rate multiplied by the total population, multiplied by environmental/competition distress, multiplied by the number of opportunities for sustainable differentiation of sub-populations. At least, that’s my hypothesis. On certain occasions, all these factors line up and the result is rapid evolution when viewed as a species; the rest of the time, most of these factors are muted, and serve to inhibit differentiation from the norm, because each such differentiation exposes the species to a new source of competition from the current occupant of the ecological niche in question.
Evolution in the modern world
Another segment of the documentary revealed that the Sherpas of the Himalayas actually have a slightly different anatomy to the rest of us, and that this is the reason they can breathe the rarified air without the problems that plague the rest of us in that environment due to the relative atmospheric density and resulting shortage of oxygen. Less convincing was a study of the residents of a small town over a period of more than 60 years by a single scientist. This study suggested that evolution was continuing in that town, favoring a slight decrease in average height and a slight increase in average weight. While interesting, I have reservations about this research. The sample size seems too small, as does the time span; the social factors (such as the general rise in obesity in the western world) have been discounted, but the results would seem to be well within the consequent margin of error.
But that actually leads me to the key topic within this subject that this article is intended to address.
There was an elephant-in-the-room that the documentary completely failed to address. In fact, there was a whole herd of them.
Social Stratification and evolution
Selection of preferred mates continues throughout the human population. Over time, this can’t help – if sustained – but differentiate the population. But the criteria used to assess the suitability of a mate are different at different social strata; just as there are ecological niches, modern society has defined social niches. The key here is sustainability of this evolutionary pressure – for it to have any long-term impact, it will have to be sustained for millennia.
Economic flows and evolution
In pre-modern societies, and even into the early industrial age, wealth was a dominant factor, because the wealthy had better health care. Wealthy individuals could support larger families, and hence as a proportion of the population, the descendants of wealthy individuals would make up a larger segment of society. Once the feudal model of the “eldest son inherits all” was abandoned, this had the effect of dispersing that wealth more evenly amongst this segment of the population – a general migration of the wealthy into a new middle class.
At the same time, modern technology brought new means of creating wealth and new paths for the flow of money through an economy. This elevated whole segments of what were once considered ‘the lower classes’ into that middle class, eventually forming a continuum.
In modern society, the economic capability of an individual to provide for children is one of several social factors that dictate the size of a family. The gradual elimination of any social stigma attached to women in the workplace over the last century has produced a social evolution in which two-income families have become the norm of that middle-class, and in fact a way for those who are slightly lower on the economic scale to take a step up into that middle-class.
There are still a few families in which being a member of the aristocracy or the gentry – coming from ‘the right family’ – are dominant criteria for the selection of marriage partners, but these days they are viewed as being out of step with society, anachronisms and dinosaurs. They are lampooned, ridiculed and pitied in various measure by modern media; witness the character of Charles Emerson Winchester III in MASH. Increasingly, they comprise a shrinking pool of genetic diversity which is slowly being eroded by exogamy.
The overall result over the last century has been a more even distribution of wealth, position, and authority, and hence a reduction in the traditional criteria which had previously been used to determine the desirability of potential partners.
Society and evolution
You only need to examine a few “dating” websites to realize that the number of possible factors unwed individuals look for in a partner has diversified tremendously over the last century or so. A search for “What men look for in a partner” reveals no fewer than 262,000,000 results on the subject; the distaff equivalent search yields 307 million results. In combination, that’s a total of 569 million sites on the subject!
This is natural selection of the most ruthless variety: individuals excluding potential mates from consideration based on socio-economic and personality criteria. It seems logical to me that these same criteria are extant within society in general, though the choice of a partner from a more diverse community would blur the selectivity. I don’t think it is going to far to suggest that the dominant driver of human evolution is now social in nature and not biological.
This is so radical a change in behavior that it is as though the evolutionary landscape had been completely flattened; the old criteria are just one factor in many. In the short-term, this cannot help but reinforce those elements of the social and personality traits deemed desirable that derive from the genetic makeup of the individual. It is as though the entire human population suddenly exists within an environment that had been subjected to a mass-extinction event; the old criteria for opportunity to secure potential mates no longer apply.
Consequently, it can be argued that human evolution is about to kick into high gear, especially if any of the other driving factors in evolutionary explosion apply.
It has been suggested that this multitude of criteria has the effect of diffusing the evolutionary impact. In one generation, an individual seeks intellectual stimulation as their dominant criteria; a child of that generation might seek emotional sensitivity; the child of that generation might seek artistic capacity, or generosity of spirit, or adventurousness, or physical attractiveness, and so on.
This suggestion relies on the assumption that advancing in a different direction negates whatever evolutionary trend occurred as a result of previous generation’s choices, that each generation is resetting the evolutionary clock to zero and setting off in a different direction. This is an oversimplification that cannot be supported on closer inspection.
Each generation, statistically, the species overall within an isolated social or geographic confine would be selecting for those criteria, in the overall priority assigned by surveys of what people are predominantly seeking in potential partners. An individual from the next generation doesn’t have a completely uniform field to draw from, they have the results of the union subpopulation who selected for that individual’s desirable criteria. “Progress” may be slowed, but overall, the race is still selecting for the same capabilities in order of statistical superiority.
Unless one criterion is directly opposed by another – and there are some which are, such as security vs. willingness to risk security for advancement – the evolutionary steps will accumulate, generation after generation.
Fake it ’till you make it
There have been two developments over the last half-century or so that will act as an accelerant to these evolutionary imperatives. The first is the increase in accessibility and desirability of plastic surgery, and the quest for perfection. The dark side of that quest is the rise of new psychological disorders such as Anorexia Nervosa. In evolutionary terms, this is as much about concealing imperfection as it is achieving some personal view of perfection; it amounts to an elimination of physical characteristics as a reliable determinant of suitability as a mate, and hence elevates other characteristics to primacy.
One of those secondary characteristics is the capacity to afford such artificial “perfection”. Economic prosperity has found a new means of expression. At the same time, there is a natural reaction against such social imperatives for whom they are not available, and I suspect that the current trend toward tattoos and piercings is as much related to distancing oneself from false “perfection” and being perceived as a real person (i.e. ‘genuine’ and ‘honest’) as it is about personal expression. This is a new cultural divide and a collective identity for a counterculture, and as such it will probably have a limited lifespan, just as the members of past countercultures have been reabsorbed into the mainstream of society.
The second development is genetic screening and gene therapy. It is becoming entirely possible for an individual who has achieved an artificial “perfection” via plastic surgery to perpetuate that idealized self-image to the next generation by manipulation of the genetic inheritance of their unborn offspring prior to conception. As with all such technological developments, there are deep and complex ethical issues to be resolved, but the technology already exists and is already being used in a limited way.
The immediate consequences will be apparently beneficial, as IVF clinics routinely screen for genetic diseases and defects; given enough time, these will be eliminated or reduced in impact on society. The longer-term impacts and potential psychological and social consequences will take longer to emerge, let alone be recognized. It’s easy to envisage a teen in arguement with his or her parents exclaiming, angrily, “I’m exactly what you wanted me to be, so let me be me!”
In evolutionary terms, this represents the collapsing of many generations of development into a single child, a tremendous acceleration of the evolutionary trend of potentials towards those deemed desirable by parents.
Of course, Genetics is not that simple. The potential for intelligence is not controlled by a single gene, but by a number of them, and a complex relationship amongst them. For anything more complex than Blue Eyes or Blonde Hair, this is true. A single gene may affect more than one attribute, and while it may be possible to select for potential, there is no way to guarantee that this potential will be realized in any specific case. The individual is a complex blend of many different genetic, social, and environmental factors.
It’s even going too far to label some genetic attributes as desirable or unwanted. Doctors learned that lesson from Sickle-cell Anaemia (drepanocytosis), where it was discovered that having a single sickle-cell gene conferred a resistance to Malaria. At the price of having 1-in-4 children suffer from the Anaemia, 2-in-4 children gain resistance to a more serious medical problem – an evolutionary ‘win’ for the overall population at the price of individual heartbreak.
I was once involved in the creation of a Traveller campaign in which genetic engineering was combined with medical teleportation technology (something akin to Star Trek’s transporters, incapable of beaming anyone or anything anywhere due to the data storage, transmission, and energy requirements) to permit anagathic restoration of individuals through a very expensive process. Only the ruling class of Nobles could afford this treatment – and only years later was it discovered that there were all sorts of side effects, including a high incidence of birth defects, a compromised immune system, a tendency to develop aggressive forms of cancer, and an ongoing dependency on the treatment. The Nobles of the Imperium were all hundreds of years old, (some pushing four figures), sustained artificially, and hopelessly out of touch with the normal population as a consequence. With one stroke, they had transformed themselves (unwittingly) into an entirely separate species of human. The overall plot of the campaign was going to centre on the nobility’s search for a “cure” to these side-effects, employing ruthless medical experimentation on commoners, producing an extremely dystopian society, which in turn would result in a rebellion to be (eventually) led by the PCs in a very Star-Wars-esque narrative. (This was all worked out one New Year’s Afternoon over a decade ago by myself and my friend Stephen. We never got to run it.)
When selection takes place naturally, the effects are relatively gradual, giving the species the opportunity to weed out undesirable reinforcements and complications – even to abandon the selection if the genetic cost is too high. When selection is taking place in the test-tube, we will have to live with the consequences with no editing. This will cause an escalation of natural selection in at least some cases.
Equating genetic screening for social, intellectual, and secondary characteristics with Thalidomide is probably going too far, but at least some varieties of genetic manipulation of the species will undoubtedly result in similar problems. (I am not unsympathetic to those affected by the Thalidomide crisis; my cousin, the same age as me, was one of them, missing one forearm and hand and needing to wear a leg brace. I was always aware that ‘that could have been me’). We may yet be thankful, as a society, that not everyone will be able to afford such genetic treatments.
I made the point earlier that human evolution could be about to kick into high gear, especially if any of the other causes of Evolutionary Explosion applied. One of the causes I identified earlier is environmental distress.
Pollutants and Evolution
Modern urban populations are facing threats and environmental factors that the species has never had to deal with before. Every possible form of pollution is a consideration and present to some extent – even deliberately induced, in terms of the fluoridation of our water supplies. This environmental stress has been blamed for the sharp rise in incidence of allergies and dietary intolerances, though specifics of the logical relationship have been short. While it is possible to demonstrate the existence of a connection statistically, the causative connection has not been identified (to the best of my knowledge). The best explanation I am aware of rests on the stimulation of the immune system by pollutants to become hypersensitive to compounds found within some foodstuffs, which sounds plausible, but only talks about the how and not the why.
I propose the possibility that the environmental distress on the population caused by pollution is causing rapid (if slight) evolutionary changes in our immune systems as a species, and that while some of those changes may yield a dividend in tolerance for contamination of our environment by pollutants while others are dead ends in that respect, some of them have also resulted in alterations to the biochemistry of individuals that has conferred allergies and dietary intolerances.
I include in the category of pollutants another possible vector for the association, the manipulation of feed provided to our food supply, including the practice of lacing feed with antibiotics.
In the long run, if this theory is correct, a new evolutionary equilibrium will be attained. At the moment, we are seeing an overreaction to the modern environmental distress, one with undesirable side effects. While we have been able to mitigate those side effects through adjustments to individual diets, every such adjustment carries an economic pricetag that will slowly impact the relative proportions of afflicted sufferers in the population. Assuming that one exists, chance will evolve a tolerance for atmospheric pollution that doesn’t have any unwanted side effects, and that will spread through the urban population. It will only take 100,000 years or so – at most. But the genetic butcher’s bill will still have to be paid at some point.
The revenge of biology
Did I really write that human evolution is now more socially-driven than biologically-driven? In terms of selection of mates, perhaps it is so, but biology won’t be ignored that readily.
I’ve already touched on the rise of antibiotic-resistant diseases. Add to that the resurgence of viral diseases such as Ebola and HIV – there is evidence that both have been around for hundreds of years, periodically exploding into brushfire epidemics – and mad cow and bird flu and… new and potentially deadly diseases have been coming out of the woodwork in droves over the last couple of decades, or so it seems.
So far, the race as a whole seems to have dodged these bullets. But it’s fair to suggest that the modern environment is stimulating the evolution of our microbiological ‘natural enemies’ at a ferocious pace, and that the result is not only eventually going to be another pandemic like the Spanish Flu of 1918, which killed between 50 and 100 million people, up to three percent of the world’s population, but is an ongoing assault on our viability as a species. An additional evolutionary pressure stemming from our environment, in other words.
Health authorities have long warned that dissemination through modern transportation systems will eventually result in a pandemic that is far worse than the Spanish Flu. The problem with such prophecies is that they only have to come true once to be catastrophic. If it’s three times worse, that’s about 10% of the population – dead. Five times: 15%. Then factor in the economic cost in terms of lost productivity alone, never mind the costs of producing and distributing vaccines that may or may not be effective, at least at first.
Some areas will undoubtedly be harder-hit than others, depending on the epidemiology and local conditions. The inevitable result will be yet another evolutionary spur as those most susceptible are eliminated from the population.
Not only does this point to an eventual catastrophe-induced evolutionary spurt, but there is also the slow, ongoing, impact of this continual assault. Make no mistake: as more diseases become drug-resistant superbugs, resistance to those diseases will play an increasing role in the capacity to contribute to future generations. History is replete with waves of virulent diseases being followed by periods of relative freedom from that disease. Then the virus or bacteria evolve into something against which that acquired resistance is less effective, and a new epidemic spreads.
I’ve written about my reservations concerning the “Menace” of “Human-caused” Global Warming (refer to The Frozen Lands: A Science-Fiction Campaign Premise). I’m not going to go into that again, here.
Global Warming, as a trend, is relatively indisputable. And that’s yet another source of environmental pressure on the human race to evolve.
It’s also potentially catastrophic in another sense: we are, if the trends are to be believed, approaching a time when weapons will be cheaper than food. In other words, under this doomsday scenario, it will be cheaper to buy weapons and take someone else’s food. As if the global warming and potential drowning of the majority of humanity (80% of the population live on a coast) weren’t enough.
With three (or more, depending on how you count them) sources contributing, that’s a second causative factor to rapid evolution that’s conclusively in place, in my opinion. And the third?
According to Wikipedia, there are currently 7.07 Billion people on the earth. If that’s not population pressure, I don’t know what is. It’s also fair to state that we have, as a species, already occupied all the ecological, social, and economic niches available to us as a species. How many more people can the world sustain? Well, that depends on a great many factors. Western agriculture is currently retreating (slowly) from the agricultural practices that supported the booms of the mid-20th century – herbicides, pesticides, and so on. Free Range is the buzzword.
The capacity of the food supply will further shrink if (as I fervently hope) the practice of lacing animal feed with antibiotics is banned world-wide – it’s already happened in some places, while others are holding out.
In other words, we are reducing our food production to the point where it will be insufficient – if we haven’t done so already. And yet, there are other developments that have increased food production, such as the development of Norin 10 Wheat, sometimes referred to as Dwarf Wheat. Judicious genetic engineering of crops promises further increases in agricultural capacity.
Couple that with uncertainty as to how the world population will change in the future, as shown in the graph above, and there is great uncertainty as to whether or not capacities will be sufficient. There are social and economic factors at work that are not applicable to other species, and which make prediction especially difficult. That’s ignoring any reduction in arable land as a result of Global Warming, of course.
All of that adds up to: there is existing population pressure contributing to the evolutionary rate of humankind. This pressure may increase or may decrease in the future, possibly drastically – but for right now, it’s definitely present.
Crystal Ball Gazing
With all three of the primary requirements for an evolutionary explosion within the Human species demonstrably present (the extent may be subject to debate), if the hypothesis proposed holds any validity, we’re in for a period of dramatic change in the very definition of what it means to be human.
But what does that actually mean? What are the changes that can be anticipated in our biology, and how quickly might they occur? How might the implications manifest in a sci-fi game? This final section of the article will attempt to do a bit of crystal-ball gazing.
We’re not talking about everyone suddenly sprouting little green tendrils, here. I would expect little-or-no gross anatomical changes. What we might get is a trend towards the ideal man and woman as described by the dating sites as what the other gender are looking for. More muscular, prettier, higher potential for intelligence and desirable personality traits, etc. Most people won’t exhibit all of these, many will exhibit none at all. The potential might be there but social and environmental factors will determine who taps into that potential and what they can do with it.
Allergies will continue to rise for quite a while, then slowly decline – unless humanity drastically cleans up its environment. However, these will become more general throughout the population and less specific to individuals. Regional trends will appear in response to variations in evolutionary stimuli. Depending on what these are and where, these could have anything from minimal impact (an allergy to goat’s milk wouldn’t bother most Australians) to socially catastrophic (an Italian allergy to tomatoes).
There might be some minor changes to jaw lines, cranial shapes, nose sizes, etc. Most of these will be cosmetic and within the range of normal appearance we are used to; it will simply be that more people will have a given characteristic.
As food supplies are stretched ever thinner, the ability to survive on fewer calories will emerge somewhere (probably Africa). This would be coupled with adaptions increasing the tolerance to Heat described below (presupposing the accuracy of Global Warming trends).
Different foodstuffs will become dominant in various regions of the world based on the allergy/intolerance factor mentioned above. This will subtly alter national cuisines.
Some of these changes will be the result of faster evolution of the digestive bacteria that we keep in our gut, a symbiosis that permits a more rapid evolutionary response than we, as a species, are capable of achieving.
The more people there are, the more attractive a target we make to emerging diseases. The virulence of some dangerous diseases will moderate even as we struggle to develop new treatments for them. Consequently, many of these will become survivable with only palliative care and support, just as the common flu is now.
Tolerance to Heat
If the world is really growing slowly hotter, we will begin to adapt to the climatic changes. This will take the form of a darkening of skin tones, and perhaps a greater systolic pressure in some cells facilitating improved retention of water. As the area most strongly affected by thermal climatic conditions and heavily populated without external technological support, it is most likely that this change would emerge in the Middle East.
The Rate of evolution
If explosive evolution is not a reality, these changes would take place over a period of about 100,000 years. If explosive evolution, as I have described it, is a reality, then it might take as little as 10,000 years. Which means that from one generation to the next there would be about 0.2% change – spread over the entire human population. That’s 1% change a century. Even explosive evolution is SLOW.
Have you ever seen pictures of Neanderthal Man dressed in a business suit? I don’t have one handy, but the fact is that you would be hard-pressed to see anything abnormal about them. Neanderthal Man still fits generally within the range of appearance variations of humans.
If the race comes up with any sort of workable FTL drive, or decides to launch generation ships, all bets are off. Not only will increased mutation rates be probable due to radiation exposure, but what we will end up with is a bunch of isolated communities pre-primed for rapid adaption. The one thing that’s for certain: within 1,000 years of settling an alien world, differences in physiology would be noticeable; within 10,000 years, citizens of different worlds would show as much variation as we have on earth – everything from Pigmies to Eskimos, and all points in between, plus variations we’ve never seen before.
Impact On Society
These changes should have a marked impact on Society. Note that ideals of beauty have changed over the centuries in some details but there are many aspects that have remained consistent. That means that even if exhibiting pronounced diversification as a result of a diaspora, the general trend will be for changes to be internal and not external.
Beyond This Horizon by Robert A Heinlein
Heinlein’s second-published novel, Beyond This Horizon, is not his best work, by any measure. I have a vague memory of reading that he himself disliked it immensely, especially the John W. Campbell-esque focus on telepathy and psionics in the latter half. And yet, even without accepting the materialistic utopia that he proposed, the genetics and their impact on society seem increasingly on the mark to me, combining scientific progress both responsible and irresponsible with very human fallibilities and good intentions.
If evolution is being driven by society while spurred on by external pressures – and that is the thesis of the day – then the results of that evolution will reflect the society from which it emerged. What’s more, since this is a characteristic of any sufficiently intelligent organism to be readily simulated in a human RPG, it should also be true of any alien species populating that RPG. That’s something to bear in mind as you develop settings and encounters, personalities and cultures. You can either work backwards from some physical development you want to the culture necessary to spawn it, or integrate the consequences of a historical outline into the modern-day biology of your creations. Either way, evolution serves as a signpost on the road connecting what was with what will be.
Food for thought.