Jan 19, 2011
I have long admired Hieronymus Bosch(1) and his triptychs depicting the various stages of Heaven, Earth, and Hell with their resident populations, particularly the infernal chimeras of man and beast, replete with fantastical limbs, feathers, and salamander skin. One can almost chart the metaphorical evolution of man, on canvas, from primordial form to a more familiar present day phenotype, blissfully populating the ethereal heights of heaven.
In their co-authored text, Homo evolutis – A Short Tour of Our New Species, futurists and serial, venture capitalists, Juan Enriquez and Steve Gullans PhD, assert that the natural order of evolution, based upon what is presently known of the hominid fossil record, involves multiple subspecies of hominids co-populating Earth and evolving in tandem (e.g. Homo erectus, Homo heidelbergensis, Homo floresiensis, Homo neanderthalensis, and Homo sapiens). This idea evokes mental images very much reminiscent of a Boschian world and all its variegated inhabitants.
Just as this evolutionary arc led to modern man, Enriquez and Gullans argue that humans are entering a new era of accelerated evolution. This “hypernatural” evolutionary state will culminate, they argue, in Homo evolutis, a hominid that, “directly and deliberately controls the evolution of its own and of other species.” One can imagine an exponential process whereby the confluence of technological advances: genetic and cellular engineering, microbial modification, vector development for targeted gene delivery, synthetic biology, tissue engineering, and robotics—portend ever accelerating rates of evolution in an approximation to Moore’s law. Certainly, we have already seen early conceptual proof of this not only in terms of computer processing power but also in other arenas such as DNA sequencing and genotyping capabilities(2). While human agency is central to the creation of Homo evolutis, machine generations will quickly supersede human generations in delivering measureable evolutionary outputs, particularly given the hypothesized integration of robotic prostheses and brain-machine interfacing.
Traditional population genetics and evolutionary theory are based upon an interrogated understanding of genetic evolution and the associated effects on the fitness, or reproductive success, of individual species. These disciplines examine the effects of selection, recombination, mutation, and drift on genes and their alleles. Thus, classically, evolution is seen to act on populations over generations, never on individuals within a single lifetime. Although not stated explicitly within the text, Enriquez and Gullans are essentially proposing a paradigm shift in this long held tenet of evolution. Henceforth, human agency will influence adaptive mechanisms to elicit discrete and accelerated forms of speciation and thereby enable individuals as well as populations to evolve. One example of such an act of speciation would include the capacity to insert genes into the human retina in order to alter radically our perception of sight. With the help of brain machine interfacing, it may someday be possible to see the world using additional pigments or even alternate electromagnet wave forms, such as infrared or ultraviolet light, akin to butterflies, serpents, and honey bees, for example.
Enriquez and Gullans raise several profound ethical issues in their text. Uneven access to biomedical advancements in healthcare has already created profound inequalities across continents, and it is clear that we will face similar inequalities with respect to access to those technologies likely to bring about this new, accelerated speciation. This trend toward increasing inequality, perhaps unavoidable, threatens to challenge further much of the driving force behind social policy, since the eradication of slavery and certainly for the last 50 odd years, a policy premised upon the doctrine of human equality. The authors rightly stress a need for proper dialogue in order to construct a framework whereby these ethical conundrums may be resolved. To this end, they leave the debate very much open-ended and solicit the expertise and insights of appropriate third party entities.
The idea of inserting novel mutations or entire genes into genomes in order to elicit novel functionality is compelling, particularly as this pertains to germline engineering, gene therapy, and microbial modification, technologies albeit in their infancy. Sceptics will likely draw upon the considerable body of research involving the genetics of complex disease, which demonstrates that a majority of the identified, underlying risk (or protective) alleles confer relatively modest effect sizes (odds ratios of less than 1.3), and it is therefore reasonable to question if such findings will ultimately prove amenable to therapeutic intervention, notwithstanding their utility in highlighting mechanisms and pathways through genetic inference.
In a further extension of this scepticism, complex traits, such as human height and weight, may prove extremely difficult to manipulate genetically and may, therefore, render small acts of speciation harder to effect. Researchers in this space will no doubt have to grapple with the underlying complexities of heritable traits. Perhaps early inroads will target, by necessity, rare variants (at less than 0.05% frequency within the population) capable of eliciting unambiguous gain or loss-of-function mutations through classical Mendelian forms of inheritance. Despite these challenges, the authors provide a tantalising glimpse into one potential future in which significant alterations to the human physique become theoretically possible.
The lion’s share of this manuscript is more historical and cartographic rather than futuristic, a point readily admitted by the authors themselves. In this capacity, Enriquez and Gullans provide an exemplary overview of disparate fields, such as evolutionary biology, genetics, and infectious diseases, and highlight the manner in which the evolution of humankind has been conditioned through selective pressures of all kinds, including infectious agents and dietary changes. To this end, Homo evolutis provides numerous examples of the role of selective pressures in significantly altering the prevalence of alleles in populations, resulting in small acts of speciation on a limited scale.
With respect to infectious disease, for example, there have been major selective events within the last seven hundred years. These events have profoundly affected the distribution of alleles within populations. Examples include the bubonic plague, the small pox epidemic in the early Americas, and the 1918 “Spanish” flu pandemic. Such critical, population-wide infectious exposures were arguably significant enough to have prompted small acts of immunologic speciation, the vestiges of which remain visible today. Accordingly, the immune systems of ethnic groups, such as European Caucasians and Yoruban Africans, reflect the overarching prevalence of diseases historically endemic to these populations (e.g. Bubonic plaque and malaria) as a result of which ethno-specific susceptibility to myriad other diseases has now ensued in contemporary society. Hypertension, lupus, and kidney failure, for example, are more prevalent among individuals of African descendent due to the inheritance of discrete susceptibility alleles.
Also addressed within the manuscript is the fascinating role of gut bacteria in modulating and maintaining immunologic and nutritional homeostasis. One tremendously compelling idea posits a future micro-biome tailored to the individual and designed to counteract an individual’s innate susceptibility to disease(s), as determined via genetic analysis. Similarly, the authors suggest that bacteria may act as simplified repositories of gene networks (metagenomics) to assist the work of synthetic biologists in generating bespoke organisms with targeted aims. One related example might be gut bacteria engineered to provide novel forms of intra-intestinal nutritional supplementation. With respect to the programming of unicellular organisms with hitherto unseen capabilities, the possibilities are seemingly endless.
While human agency forms the centrepiece of this manuscript, I would argue that stochastic factors such as plague, famine, and natural disasters will undoubtedly continue to shape the genetic landscape of Homo evolutis as equally and profoundly as they have that of Homo sapiens. Examples of stochastic factors affecting the latter include the great drought of Africa in the Late Pleistocene period, mentioned in the manuscript, which almost drove humankind to extinction, and the “Out of Africa” hypothesis, which informs our appreciation of how migration and founder effects may have fundamentally altered the genetic landscape of humankind today.
The above arguments each support an overarching thesis that technological advances will soon rapidly drive future speciation of humankind into new forms of hominids. A final and no less powerful argument asserts that future acts of speciation may ultimately serve to increase the net numbers of alleles at specific genetic loci within a population (or amongst multiple species of hominids). Should this occur, it may help to render population(s) more resistant to the likely unabated onslaught of omnipresent selective pressures such as famine, infectious agents, and the environment. Therefore, as argued by Enriquez and Gullans, we should embrace, rather than reject, the idea of utilizing human agency to engineer increased genetic diversity.
I would highly recommend this thought-provoking and thoroughly enjoyable read on our evolutionary past and future to lay readers and scientists, alike. It sheds light on cutting edge research and invites the reader to consider possible implications for future generations of Homo sapiens and – perhaps –future generations of Homo evolutis. As I put down the manuscript, the future, to my mind, seemed less a Boschian series of dystopias and more a form of paradise regained, a world filled with untrammelled possibilities for new forms of human life where anything is possible, including immortality.