Evolution of the fittest - the shape of humans to come

If you take a look at the variety of species within any given branch of evolution, it is not hard to understand the fascination that captivated Darwin and the Victorian imagination. From a single common ancestor some 37 species of cats evolved, each uniquely attuned to its climate, food sources, and the ecological challenges which faced it. Similarly around 37 species of dogs radiated from a single ancestor (evidently a magic number), and that is before we account for the hundreds of domestic breeds engineered by humans. Despite the stunning natural radiation of cat and dog species, we are still asked by scholars from the Victorian school to believe that we humans represent a unique and ultimately sophisticated branch within evolution. Apparently there was no radiation, at least none that survived, and we alone reign supreme within the annals of evolution. Our nearest primate relatives, the chimpanzees, gorillas and Orang-utans, are a distant memory of our evolution over five million years old.

In fact, this romantic Victorian view could not be further from the truth. There was indeed a radiation of the human species, much of which has only recently been brought to light. Indeed we are constantly evolving in response to changes in our diet, lifestyle, technology and climate. We know about our cousins the Neanderthals who were believed to have become extinct some 25,000 years ago, even though they had spread throughout Asia and Europe some 70,000 years before ‘modern humans’ were believed even to have emerged from Africa. It is hard to believe that our human ancestors made it to Europe over 350,000 years ago and that humans arrived so late to the party, but then again, we were not believed to have reached North America until some 14,000 years ago, even though human settlements dating back at least 50,000 years have recently been discovered in South America. Clearly evolutionary historians substituted assumption for evidence and are (still) in error.

Facial reconstructions of Neanderthals skulls have in fact shown that they looked remarkably similar to us, so remarkably similar that a reconstructed Neanderthal face didn’t even turn heads in a busy shopping street. Perhaps early humans bred with Neanderthals and blended into a single species, or perhaps they did become extinct, only their DNA will say for sure… There is however an example from recent history that may shed some light upon this controversy. Although none of the original black African slaves imported into Portugal before the formal abolition of slavery remain, some otherwise apparently ‘white’ families in modern day Portugal have inherited sickle-cell anaemia, a genetic disorder which arose in black Africans. This evidence suggests the original black slave population did not become extinct; rather they interbred with their captors and blended into their gene pool. Perhaps the modern people of the Mediterranean owe much of their stocky inheritance to some Neanderthal ancestry?

The great human radiation

The reported demise of the Neanderthals by the Victorians appeared to put to rest the uncomfortable notion that we humans are merely a small branch of primate evolution. However, the remains of tiny Homo floresiensis, or Man of Flores, were discovered on a remote Indonesian island in 2003. Seven incomplete skeletons of this tiny human relation have so far been uncovered from a community that has been dated at between 13,000 and 18,000 years old, around the period of the last great glacial meltdown which flooded the modern Mediterranean and destroyed ‘Atlantis’. Is the discovery of Homo floresiensis really a revelation? Not really, we have known of the existence of pygmies in the jungles of Africa and South America for centuries, each group of humans having evolved uniquely and independently to survive within their densely vegetated habitat. At the other end of the spectrum, Gigantopithecus was a genus of giant ape which anthropologists believe existed as recently as 100,000 years ago. There are however innumerable modern reports of giant ‘ape men’ living today in Australia (the Yowie), in the USA and Canada (Sasquatch), and within the Himalayas (Yeti). Can so many modern sightings of these giant relatives living in remote and clearly defined habitats across the world all be misleading?

Another common phenomenon is that some species evolve to feed upon their relatives. Killer whales are toothed whales that eat other whales, vampire bats are anything but vegetarian, and chimpanzees kill and eat smaller apes and monkeys as a preferred food source. We humans on the other hand prefer not to think that a species related to us evolved to eat us or to drink our blood, even though countless vampire legends arose independently around the world. The Maya, Inca and Aztec civilizations were renowned for their bloody sacrifices which continued to recent history. Indeed their priests, who traditionally performed such human sacrifices, were worshipped, even deified. The preserved canine teeth of some of these priests were found to be extraordinarily long, perhaps providing a potential explanation for many regional vampire legends? Cannibalism was recently proved to have occurred in the four corners region of North America less than a thousand years ago, a practice which still continues in Papua New Guinea today. Is the evolution of a human vampire relative really so preposterous? Well not at least according to countless examples of radial evolution within other animal families. So whilst the idea of the evolution of vampire cousins continues to feed folklore and the imagination, there is perhaps little doubt that the evolution of Homo vampirii was far from an improbability.

So did the radiation of modern humanoids end with pygmies, Neanderthals, cannibals and giant ape men? Perhaps not, as geographical isolation, extreme climates and very different food sources can trigger rapid evolution. Until the recent arrival of international air travel, Aborigines and Eskimos colonised the extreme climates of the globe in isolation, separated in space, time and climate by at least 50,000 years. During this time their digestive systems, fat metabolism, water conservation, heat regulation and skin biology reached notable extremes. Each of these two finely tuned branches of humanity would die within weeks if left in isolation in one another’s worlds, yet each race is uniquely refined and superbly adapted to survive within their respective climates. Aborigines and Eskimos are as elegant a demonstration of evolution as stunning as anything described by Darwin. The definition of a distinct species is the inability of two individuals to reproduce and give birth to fertile offspring, not that anyone has demonstrated that Aborigines and Eskimos can in fact do so. Whether Aborigines and Eskimos did actually separate into distinct human species, or are in fact sub-species (races), is a contentious issue, but there is no doubt that they would ultimately have done so if it was not for the great blending of the human races which has been brought about by international mass migration.

Evidence for our present evolution

It was once widely thought that evolution was an immeasurably slow process, one in which a discernable change in the size, shape or function of a species takes many thousands of generations to achieve. Given that our own generation gap has steadily risen to almost 30 years, any change in the characteristics of human offspring may occur only three or four times per century. However within a short time colossal selective pressures may be exerted upon the survival of a species due to disease, changes in food availability, or rapid and extreme changes in climate. Take for example the bubonic plague of the 14th century which wiped out almost half the population of Europe. In many cases only those who were resistant to the plague parasite Yersinia pestis were left to pass on their genetic legacy. Similarly the use of warfarin to kill rats and mice in the 1970s led to almost complete resistance to this pesticide within only a few generations, and so it is not just viruses and bacteria that undergo rapid evolution. In the same way the 1918-9 pandemic of Spanish influenza radically altered our genetic landscape, as will the modern epidemics of HIV, type 2 diabetes, and obesity.

Disease and climate change are however not the only drivers of evolution. In the 1980s the first primitive home computers were introduced and were quickly colonised by a generation of those widely ridiculed as ‘socially inadequate’ or ‘nerds’. Within only a single generation the nerds of the 1980s have become the super rich of today, earning the right to marry the most attractive partners. Nowadays everyone needs at least some advanced computing skills, as much of our personal and professional advancement depends upon our gainful adaptation to computer systems and networks. People without such ability have fewer prospects for advancement, and their offspring are in turn less likely to be successful. In a similar vein, those who can learn quickly and filter out gainful information from the vast streams of data to which we are constantly exposed are more likely to prosper. So, within a single generation, the criteria for success have shifted from social skills to technological ability, and from those with powerful memories to those who are problem solvers with the ability to filter out and retrieve information from vast databases. The social alpha male is no longer exclusively tall and broad shouldered, he hunches for much of the day in front of a computer screen. The modern alpha female is intellectually keen, time efficient and an effective communicator, if not always eloquent or elegant.

Hand written letters have been replaced by emails, the Encyclopedia Britannica by Wikipedia, and the library by Google. Children no longer spend their spare time playing sport or learning direct social skills in the local community. As a consequence of our rapid technological evolution, the modern teenager spends much of his or her life online, either in the classroom or in the bedroom. Competitive activities have shifted from the sports field to video games, and open air communities have been replaced by online networks like Bebo or MySpace. The dawn of sexuality in girls is occurring earlier, whilst their male counterparts are taking longer to mature. Children are becoming less ‘fit’ as social pressure for physical development is replaced by pressure for mental development. Obesity in children is rampant, and the genetic consequences of these social changes will reverberate for generations. Within the next twenty years it will no longer be the survival of the fittest; it will become the survival of the sharpest. Careers that once spanned a lifetime are being replaced by portfolio careers that contain cycles of education, and those who show the necessary mental plasticity will produce the affluence to have children who will ultimately evolve into Homo intelligensis.

Our diet is changing rapidly too. Historically it was once rich in nuts, berries, wild grains and fresh meat, although it was gradually replaced over the past 20,000 years by a diet which contained a larger proportion of complex carbohydrates and dietary fibre. Our bodies consequently evolved to deal with a diet which was rich in complex carbohydrates, often to the exclusion of all else, as we consumed fewer simple sugars, animal fats and proteins. Suddenly and very recently, Western affluence transformed a society which once endured seasonal feasts and famines into one that was constantly exposed to processed foods which were poor in fibre and rich in calories. Meals have become more frequent, periods of fasting are usually only voluntary, and our diet has become ‘unnaturally’ rich in fats, proteins and sugars. Perhaps more concerning is the introduction of many new dietary components such as oil seed rape, ‘trans’ fats and corn oil which are entirely unnatural. Those whose metabolism and appetite can adapt will thrive, and those whose genes are attuned to feasting and storing excess calories as fat will become obese and fail to have children. You may believe that this process requires thousands of years to accomplish? Not so, as scientists now believe that environmental events are transmitted within a single generation simply by switching genes on or off in the sperm or egg cells, a process known as genetic imprinting.

The future of human evolution

So are diet, climate change, disease and technology the only evolutionary pressures at work on human nature? Apparently not it seems, as we appear increasingly attracted towards the extremes of human endeavour. Much as gladiators enthralled the Roman public, so the football stars, athletes and fighters of today hold TV audiences spellbound. The capacity for war is inherent within our primate natures as any period of human history will attest. Much of this warlike social energy is channelled into sport, whether the sport of choice is boxing, soccer or athletics. The biggest, fastest and most agile win the box office, enhancing the prospects of their descendants. Sports stars need to become ever fitter, faster and more dextrous to be competitive, as only the fastest among the ranks of Homo velocii will make the cut. Their larger and more powerful cousin, Homo giganticus entertains us within the arenas of basketball, wrestling and gridiron, becoming ever bigger, faster and stronger in the attempt to maintain viewing figures. Science fiction you might think? Not at all - this is very much science fact. Look at the average distances thrown by athletes in the shot put, a test of pure strength, over the past century. Distances achieved have almost doubled in four generations, an effective doubling in strength of Homo giganticus. Now look at the average times for the fastest ten 100 metre runners over the same century. Homo velocii has become much more rapid, with women running 20% faster and men 13% faster within only a hundred years. The average height of basketball players is increasing rapidly, as is the size and weight of the linemen of American football. Homo giganticus appears to be evolving even more rapidly than his smaller, more athletic cousin Homo velocii.

Within the coming centuries separate lines of human evolution will emerge, each attuned to the extreme requirements of their social specialism. One line will produce increasingly ‘athletic’ humans who will remain lean and have a faster metabolism (Homo velocii), a process that will be maintained by a social and sexual preference for lean and muscular body types (somatotypes). If we continue on our current path as an affluent, technological society, most of the human gene pool will become leaner, taller, faster and stronger due to a social and sexual preference for these characteristics. However it is perhaps more realistic to predict that our perennial food surpluses will soon disappear, and with them the reproductive advantages of being leaner and having a faster metabolism. A bold mind might suggest (in the absence of a global cataclysm) that a large proportion of Homo intelligensis will show a drift towards a larger brain size (cranial cavity), a more rounded and less athletic physique, and a tendency to store fat.

The extreme competitive demands presented within each walk of human life, namely academics, athletics, war and communications, will mean that there will be insufficient time for ‘super individuals’ to compete successfully within more than one field of endeavour. Those who fail to thrive within their respective niche of human society will typically fall into the skilled manual, clerical or unskilled sectors of the labour market. However, recent suggestions by Oliver Curry that such individuals will evolve into an evolutionary subclass of human are unlikely for several reasons (unless of course a ruthless and prolonged selective human breeding program enforces such change). First, dominant ‘alpha’ males are programmed to be promiscuous, and most women are sexually attracted towards dominant men. Therefore alpha males generally have more than their fair share of children, opposing the tendency for species to separate within a given community.

Second, the most common route for species to separate remains geographical isolation, as exemplified by Aborigines, Eskimos and Pygmies. The trick is to gauge at what point extreme variations within individuals constitutes true divergence. Danny DeVito is only 4 ft 10 in height, despite his immense charm and intellect, whilst basketball star Yao Ming would tower over him at 7 ft 4 in. This in of itself does not make Mr. DeVito and Mr. Ming members of distinct species. It would take distinct human populations many thousands of years of geographically separate evolution to become sufficiently different that they could not intermarry and have fertile offspring. With the advent of international mass migration there has came an unprecedented blending of the human races which could not have been imagined at the time of Columbus. Over 50,000 years of evolutionary drift towards distinct races has been reversed by a few hundred years of international mass migration. This tendency for gene pools to intermarry is favoured by the ‘attraction of opposites’, a strategy which promotes the blending of extreme heritable characteristics, maximising the likely advantages of any offspring. For example tall, thin men often find short, voluptuous women desirable, and vice versa, and black men are attracted to Caucasian women, and Caucasian men to coloured women. Perhaps the most famous example is that of President Thomas Jefferson, who fathered a child with his black slave Sally Hemings, demonstrating that men who have the choice still choose to spread their genetic legacy as widely as possible to maximise their chances of producing successful offspring.

Third, individuals of substantially lesser ability or physical form do not tend to form their own separate breeding population. Many will fail to have children, others may have children who themselves will be less likely to succeed, whilst some will successfully mate with promiscuous alpha males to re-enter the productive gene pool. An underclass is generally formed by less successful individuals within a society, rather than through selective breeding of such a population per se. Moreover, the selective pressures within a ghetto or underclass are often so extreme that successful individuals duly emerge. Much of the elite of modern American sport and politics came from the underprivileged classes. However, it is entirely possible that the social tendency for ghettos to form and produce labourers might ultimately lead to the appearance of a visually distinctive worker caste, although this caste would be unlikely to become a separate species for the reasons given above.

So where is all of this human evolution taking us? The answer may lie just beneath our feet, well at least much of the time. Ants are complex social animals which have had hundreds of millions of years longer to evolve than humans. What was their ultimate solution? Separate castes evolved within ant societies, each uniquely specialised to fulfil a specific role within a complex society. However each ant within a nest derives from a single queen by the switching on and off of genes (imprinting) to fulfil specialised roles. These castes include young alpha females (queens) and males (drones), soldier ants, nursery ants, and worker ants. Through this analogy it is tempting to speculate that our society will become ever more complex, sub-specialised and intelligent. Physically the finest individuals amongst Homo intelligensis, Homo giganticus and Homo velocii will bear productive young, increasingly by assisted reproduction. Less able individuals will become the soldiers, manual workers and clerical staff of tomorrow, and will be less likely to raise successful offspring. The ‘intelligentsia’ will become more intelligent and ‘egg-headed’, the physically large and powerful will become more so, and the fast will become human greyhounds. We will evolve into an increasingly specialised society of workers, queens, drones, soldiers, athletes and entertainers, with ever more distinctive physical and mental characteristics. The queen is dead, long live the queen!