“Surfing Uncertainty” by Andy Clark

Clark is a philosopher who specializes in logic and metaphysics. However, this book combines neuroscience and embodied cognition to give a theory of the predictive brain. Clark has coined this process predictive processing and it relies heavily on Bayesian logic. “It is the kind of automatically deployed, deeply probabilistic, non-conscious guessing that occurs as part of the complex neural processing routines that underpin and unify perception and action…. Brains like ours…. are predictive engines, constantly trying to guess at the structure of the incoming sensory array. Such brains are incessantly pro-active, restlessly seeking to generate the sensory data for themselves using the incoming signal (in a surprising inversion of much traditional wisdom) mostly as a means of checking and correcting their best top-down guessing. Crucially, however, the shape and flow of all that inner guessing is flexibly modulated by changing estimations of the relative uncertainty of (hence our confidence in) different aspects of the incoming signal. The upshot is a dynamic, self-organizing system in which the inner (and outer) flow of information is constantly reconfigured according to the demands of the task and the changing details of the internal (interoceptively sensed) and external context.” Our brains are constantly in action, making top-down guesses about the sensory data to learn about our external world. The brain is creating models and then slowly modulating them, based on past experience, to improve future predictions. Crucially, the brain is not a passive system. Action plays a critical role in predictive processing. “Our massed recurrent neuronal ensembles are not just buzzing away constantly trying to predict the sensory stream. They are constantly bringing about the sensory stream by causing bodily movements that selectively harvest new sensory stimulations. Perception and action are thus locked in a kind of endless circular embrace…. [The brain is able to] use action upon the world to reduce the complexity of its own inner processing, selecting frugal, efficient routines that trade movement and environmental structure against costly computation.”

The brain is constantly learning as it is constantly predicting everything that will happen to the body in the next moment, in an ever-rolling cascade. Perception is very near-term top-down prediction modified by the senses. “Prediction error [is] a kind of proxy for any as-yet-unexplained sensory information. Prediction error here reports the ‘surprise’ induced by mismatch between the sensory signals encountered and those predicted…. Perception is indeed a process in which we (or rather, various parts of our brains) try to guess what is out there, using the incoming signal more as a means of tuning and nuancing the guessing rather than as a rich (and bandwidth-costly) encoding of the state of the world.” It is actually our expectations, to a large extent, that determine what we see, smell, and hear. A prediction does not create our sensory world, but it does focus our attention. “Brains like ours are constantly trying to use what they already know so as to predict the current sensory signal, using the incoming signal to select and constrain those predictions, and sometimes using prior knowledge to ‘trump’ certain aspects of the incoming sensory signal itself. Such trumping makes good adaptive sense, as the capacity to use what you know to outweigh some of what the incoming signal seems to be saying can be hugely beneficial when the sensory data is noisy, ambiguous, or incomplete.” Again, the non-passive nature of the brain is crucial. “Action is not so much a ‘response to an input’ as a neat and efficient way of selecting the next input, driving a rolling cycle. These hyperactive systems are constantly predicting their own upcoming states and actively moving about as to bring some of them into being.”

Each percept is constructed with the help of the brain’s priors. These priors influence future expectations in a probabilistic manner. The brain then combines the likelihood of these priors with raw sensory data. “Attention, thus construed, is a means of variably balancing the potent interactions between top-down and bottom-up influences by factoring in their so-called ‘precision’, where this is a measure of their estimated certainty or reliability.” When evaluating sensations, the brain is constantly separating the signal from the noise, using prior knowledge. This process happens through hierarchical Bayesian inference based on precision-weighted guesses at every level. These predictions then influence future action in a proactive fashion. Memory is also crucial in predicting our future. Fernyhough suggests, “if memory is fallible and prone to reconstructive errors, that may be because it is oriented towards the future at least as much as towards the past…. similar neural systems are involved in both autobiographical memory and future thinking, and both rely on a form of imagination.” In the end, perception is the brain’s best guess as to reality. “Perception (rich, world-revealing perception) occurs when the probabilistic residue of past experience meets the incoming sensory signal with matching prediction.”

Prediction allows our bodies to live in the present. As Franklin and Wolpert assert, “delays are present in all stages of sensorimotor system, from the delay in receiving afferent sensory information, to the delay in our muscles responding to efferent motor commands…. we effectively live in the past, with the control systems having access to out-of-date information about the world and our own bodies.” This is overcome by predictive processing. “Forward models provide a powerful and elegant solution to such problems, enabling us to live in the present and to control our bodies…. you treat the desired (goal) state as observed and perform Bayesian inference to find the actions that get you there…. Motor control is, in a certain sense, subjunctive. It involves predicting the non-actual proprioceptive trajectories that would ensue were we performing some desired action. Reducing prediction errors calculated against these non-actual states then serves…. to make them actual. We predict the proprioceptive consequences of our own action and this brings the action about….. ‘Active Inference’ then names the combined mechanism by which perceptual and motor systems conspire to reduce prediction error using the twin strategies of altering predictions to fit the world, and altering the world to fit the predictions.”

Frith makes the case that “our perceptions are fantasies that coincide with reality.” Hohwy suggests, “what we perceive is the brain’s best hypothesis, as embodied in a high-level generative model, about the causes in the outer world…. Conscious experience is like a fantasy or virtual reality constructed to keep the sensory input at bay.” Thus, the human brain is bounded by an external reality. “Prediction-driven learning delivers a grip upon affordances: the possibilities for action and intervention that the environment makes available to a given agent.” The brain is then constantly making its best guess as to what course will reduce prediction error. This might be by modifying its predictions or it might be through acting. This results in “‘affordance competition’ in which…. possible motor responses are being simultaneously prepared, and in which ‘the human brain does not wait for a decision to be completed before recruiting the motor system but instead passes partial information to prepare in a graded fashion for a probable action outcome’…. Such pro-active readiness, to be genuinely useful, must necessarily be multiple and graded. It must allow many possible responses to be simultaneously partially prepared, to degrees dependent upon the current balance of evidence.”

The world that humans perceive is “our world” in that it is the world best understood by humans. “What we perceive is (when all is going well) the structured external world itself. But this is not the world ‘as it is’, where that implies the problematic notion of a world represented independent of human concerns and human action repertoires. Rather, it is a world parsed according to our organism-specific needs and action repertoire.” Humans create and actively modify our own world. Through language “our own thoughts and ideas now become available, to ourselves and others, as potential objects for deliberate processes of attention…. Courtesy of all that material public vehicling in spoken words, written texts, diagrams, and pictures, our best predictive models of the world (unlike those of other creatures) have thus become stable, reinspectable objects apt for public critique and systemic, multi-agent, multi-generational test and refinement. Our best models of the world are thus able to serve as the basis for cumulative, communally distributed reasoning…. Our human-built worlds are not merely the arenas in which we live, work, and play. They also structure the life-long statistical immersions that build and rebuild the generative models that inform each agent’s repertoire for perception, action, and reason.”

“Houdini’s Box- The Art of Escape” by Adam Phillips

In this short book Phillips switches back and forth between chapters “analyzing” Harry Houdini and an unnamed male patient with a sexual fetish and commitment issues, while ruminating on life as continual escape. In the life always focused on escape there is a constant basic tension. “What we want is born of what we want to get away from.” Phillips also reminds that the act of escape is a verb- a doing. “Getting free was the adventure, not being free.” There are two parts to every successful escape- a beginning and an end or a before and an after, if you like. “A person running away from something, the psychoanalyst Michael Balint once remarked, is also running towards something else.” What we are running away from maybe more known to us than what we are running to. We may be more sure of that (and the why). “Phobias remind us, in all their unreasonable urgency and their frantic commitment to safety, just how fundamental a sense of our avoiding things is to our sense of ourselves…. It is as though if we can keep ourselves sufficiently busy escaping, we can forget that that is what we are doing. The opposite of fear, one could say, is choice.” Sometimes escape is the easiest option. Sometimes that is because it is no option at all. Whatever escape is, however, it is only a beginning. “One can escape into doubt about what one wants, or one can escape from doubt about what one wants.” Escape is the easy part. It is only then that one’s options truly begin. Phillips concludes by pondering the fate of Emily Dickinson. No one knows what she was escaping from. Her escape was inward, into seclusion- physically, emotionally, and intellectually. “There is, she seems to say, no freedom in the notion of escape; it merely reveals what the prison is really like.”

“Who We Are and How We Got Here” by David Reich

Reich is a professor in the Department of Genetics at Harvard Medical School. This is a book intended to educate the layman on the recent technological advances in genetics. Specifically, it details how the mapping of the complete human genome, along with subsequent tests on samples from prehistoric and modern humans in the last decade, is changing the received wisdom about patterns of migration and inter-breeding of different populations from 70,000 to 1,000 years ago, previously based on techniques from archeology, linguistics, skeleton morphology, and anthropology.

The first five examples of complete ancient human genomes were only published in 2010- a few archaic Neanderthal genomes, an archaic Denisova genome, and a four-thousand-year-old individual from Greenland. Since then, hundreds more samples of genome-wide data have been analyzed, studied, and published. This was a vast improvement on previous techniques that only analyzed small stretches of the genome, such as mitochondrial DNA. “The genome is written out in twin chains of about three billion chemical building blocks…. What we call a gene consists of tiny fragments of these chains, typically around one thousand letters long.” By analyzing the complete genome, scientists have been able to divine much more detailed information about humanity’s collective past, historical migration patterns, and when human lineages broke off from one another and perhaps came back to co-mingle. “The most recent African ancestor of all the branches [of modern humans], “Mitochondrial Eve,” lived sometime after 200,000 years ago. The best current estimate is around 160,000 years ago.”

In this book, Reich first analyzes the relationship between modern humans and Neanderthals. “When we tested diverse present-day human populations, we found Neanderthals to be about equally close to Europeans, East Asians, and New Guineans, but closer to all non-Africans than to all sub-Saharan Africans…. We found that non-African genomes today are around 1.5 to 2.1 percent Neanderthal in origin.” This Neanderthal DNA probably mixed with modern human DNA somewhere between eighty-six thousand to thirty-seven thousand years ago, so we can be certain at least some Homo Sapiens and some Neanderthals were having children together at that point in history. But that was not all. Homo Sapiens were also inter-breeding with Denisovans. “We eventually estimated the separation between the Neanderthal and Denisovan ancestral populations to have occurred 470,000 to 380,000 years ago, and the separation between the common ancestral populations of both of these archaic groups and modern humans to have occurred 770,000 to 550,000 years ago.” From that point on, however, there was still inter-breeding between all these human sub-groups. “Interbreeding between Denisovan and New Guinean ancestors occurred fifty-nine to forty-five thousand years ago…. We estimated that about 3 to 6 percent of New Guinean ancestry derives from Denisovans…. The Denisovan-related ancestry in East Asians is about a twenty-fifth of that seen in New Guineans- it comprises about 0.2 percent of East Asians’ genomes, rising to up to 0.3-0.6 percent in parts of South Asia.”

Reich goes on to detail the recent discovery of a ghost population, no longer are alive in pure form today, but who have passed on parts of their genome to present-day humans. These are the Ancient North Eurasians. “There was a population living in northern Eurasia that was not the primary ancestral population of the present-day inhabitants of the region. Some people from this population migrated east across Siberia and contributed to the population that crossed the Bering land bridge and gave rise to Native Americans. Others migrated west and contributed to Europeans…. All told, more than half of the world’s population derives between 5 percent and 40 percent of their genomes from the Ancient North Eurasians.” Reich describes the process of migration (and the breeding that went along with it) as more akin to a trellis, than the more common tree branching metaphor. These populations separated and then often recombined as they moved about, traded with or invaded others, and relocated around the globe. In fact, the Mal’ta genome (a boy found in south-central Siberia, who lived about twenty-four thousand years ago) has strong genetic affinity to modern Europeans and Native Americans, but has little resemblance to modern-day Siberians. “The analysis of the Mal’ta genome made it clear that Native Americans derive about a third of their ancestry from the Ancient North Eurasians, and the remainder from East Asians. It is this major mixture that explains why Europeans are genetically closer to Native Americans than they are to East Asians.” 

In Europe, further ghost populations were found in West Eurasia. “About ten thousand years ago there were at least four major populations in West Eurasia- the farmers of the Fertile Crescent, the farmers of Iran, the hunter-gatherers of central and western Europe, and the hunter-gatherers of eastern Europe. All these populations differed from one another as mush as Europeans differ from East Asians today.” The Bronze Age was the time when these distinct populations mixed and homogenized, perhaps as the result of technological and cultural integration as well. Furthermore, “five thousand years ago, the people who are now the primary ancestors of all extant northern Europeans had not yet arrived.” The Yamnaya were sheep and cattle herders who originally came from the Steppe. They promulgated, if not invented, the wheel and domesticated the horse. “In Germany, people buried with Corded Ware pots derive about three-quarters of their ancestry from groups related to the Yamnaya and the rest from people related to the farmers who had been the previous inhabitants of that region.” It is also likely that the Yamnaya were the ones who spread the origins of all Indo-European languages as they spread their genes, technology, and culture across Europe.

In India, Reich found the people today “are the outcome of mixtures between two highly differentiated populations, “Ancestral North Indians” (ANI) and “Ancestral South Indians” (ASI), who before their mixture were as different from each other as Europeans and East Asians today. The ANI are related to Europeans, central Asians, Near Easterners, and people of the Caucasus, but we made no claim about the location of their homeland or any migrations. The ASI descend from a population not related to any present-day populations outside India. We showed that the ANI and ASI had mixed dramatically in India. The result is that everyone in mainland India today is a mix, albeit in different proportions, of ancestry related to West Eurasians, and ancestry more closely related to diverse East Asian and South Asian populations. No group in India can claim genetic purity…. We found that West Eurasian-related mixture in India ranges from as low as 20 percent to as high as 80 percent.” This cut across all regions and castes, although the higher castes and males both tended to have a higher proportion of ANI ancestry. The Andamanese were the lone population with zero European genes at all, likely because of their secluded island location. However, within sub-castes in India, Reich did find long strings of identical genetic code, suggesting that “long-term endogamy as embodied in India today in the institution of caste has been overwhelmingly important for millennia.”

Reich’s analysis also provided revelations for the migration patterns of humans into the Americas. “There were at least two migrations that left a human legacy as far as South America and at least two whose impact was limited to northern North America.” These paths split more like tree branches than trellises, with little remixing after the initial separations. “The splits proceeded roughly in a north-to-south direction, consistent with the idea that as populations traveled south, groups peeled off and settled, remaining in approximately the same place ever since.” In the Americas, population displacement was not common. However, one unusual pattern was that “a sublineage of First Americans that originated well after the initial diversification of First American lineages in North America migrated back to Asia.” Migrations patterns are often not obvious, but the genetic codes do not lie.

Reich next moves on to East Asia, which “has been home to the human family for at least around 1.7 million years, the date of the oldest known Homo erectus skeleton found in China…. In Australia, archaeological evidence of human campsites make it clear that modern humans arrived there at least by about forty-seven thousand years ago, which is about as old as the earliest evidence for modern humans in Europe…. Chinese and Australians derive almost all their ancestry from a homogenous population whose ancestors separated earlier from the ancestors of Europeans.” As in West Eurasia, East Asian modern humans soon out-competed archaic humans and completely replaced them in every region that they migrated to. Today’s East Asians derive their ancestry from one of two ghost populations, one starting out around the Yangtze River Basin and the other from around the Yellow River. The Yellow River Ghost Population largely spread west, ending at the Tibetan plateau, while the Yangtze Ghost Population spread to southeast Asia and Taiwan. Often new genetic information in combination with traditional archaeology can yield revelations. For instance, in Japan “around twenty-three hundred years ago, mainland-derived agriculture began to be practiced and was associated with an archeological culture with clear similarities to contemporary cultures on the Korean peninsula…. Present day Japanese have about 80 percent farmer and 20 percent hunter-gatherer ancestry.” That genetic mix yields an approximate date of inter-breeding of sixteen hundred years ago. That means for hundreds of years, the two populations both lived on the islands of Japan, but with relatively little inter-breeding, until social segregation broke down, interbreeding began, and homogenization occurred.

As for Africa, “African genome sequences are typically about a third more diverse than non-African ones.” Most migration patterns moved in a north-to-south direction. “There is little if any sub-Saharan African related ancestry in ancient Near Easterners or Egyptians prior to medieval times.” Surprisingly, Ethiopian “caste” groupings have proven to have gone back generations further than even those in India. The modern Ari are the oldest example of strong endogamy that Reich has thus far come across, persisting at least forty-five hundred years. Another ghost population were the East African Foragers. “We also found that the East African Foragers were more closely related to non-Africans today than they were to any other groups in sub-Saharan Africa. The close relationship to non-Africans suggests that the ancestors of the East African Foragers may have been the population in which the Middle to Late Stone Age transition occurred, propelling expansions outside of Africa and possibly within Africa too after around fifty thousand years ago.”

Finally, Reich concludes his book with controversies associated with these genetic breakthroughs. Race may be a social construct, but it is still a touchy cultural subject. Racial variations are existent, if not determining. “Around 85 percent of variation in the protein types could be accounted for by variation within populations and “races,” and only 15 percent by variation across them.” Inter-breeding was also not propagated randomly. Cultural factors such as inequality played a role in whose genes were passed on. “The contribution of European American men to the genetic makeup of the present-day African American population is about four times that of European American women.” These numbers are even more skewed for the populations of South and Central America for obvious historical reasons. Somewhat less controversially, “8 percent of males in the lands that the Mongol Empire once occupied share a characteristic Y-chromosome sequence or one differing from it by just a few mutations.” The dating of such a “star-cluster” founder, estimated through the rate of the accumulation of mutations on the Y-chromosome, can be placed to between thirteen hundred and seven hundred years ago and then history can guess that Genghis Khan would be the best possible human match to fit such a profile. Finally, as of today the DNA revolution has been dominated by the testing of Europeans, both modern and archaic. “Of 551 published samples with genome-wide ancient DNA data as of late 2017, almost 90 percent are from West Eurasia.” That is because most state of the art techniques and labs were first developed in Europe, but also because DNA from warmer climates is more likely to degrade and harder to extract and many countries, such as India and China, limit the exportation of DNA material outside their borders. Scientists are still in the early days of this genetics revolution. Reich compares this technological breakthrough to the inventions of the microscope and of carbon dating in scientific significance. Genome-wide mapping is a burgeoning field and the future growth in new techniques is only going to expand the scope and scale of the DNA samples available for analysis.

“Untimely Meditations” by Friedrich Nietzsche (translated by R.J. Hollingdale)

This collection of four of Nietzsche’s essays broadly revolve around the theme of culture. The writings reflect on the characteristics of a cultured man, the role of the philosopher in society, truth and art, the uses of history in modern life, and, specifically, German culture after the Franco-Prussian war. “Culture is, above all, unity of artistic style in all the expressions of the life of a people. Much knowledge and learning is neither an essential means to culture nor a sign of it.” In his next essay, Nietzsche discusses the difference between the everlasting and the historical, “With the word ‘the unhistorical’ I designate the art and power of forgetting and of enclosing oneself within a bounded horizon; I call ‘suprahistorical’ the powers which lead the eye away from becoming towards that which bestows upon existence the character of the eternal and stable, towards art and religion. Science—for it is science which would here speak of poisons—sees in these two forces hostile forces: for science considers the only right and true way of regarding things, that is to say the only scientific way, as being that which sees everywhere things that have been, things historical, and nowhere things that are, things eternal.”

Nietzsche delves into the purpose of true philosophy in his essay championing his predecessor, Schopenhauer, “The truthful man feels that the meaning of his activity is metaphysical, explicable through the laws of another and higher life, and in the profoundest sense affirmative…. So it is that all his acts must become an uninterrupted suffering…. He will, to be sure, destroy his earthly happiness through his courage; he will have to be an enemy to those he loves and to the institutions which have produced him; he may not spare men or things, even though he suffers when they suffer; he will be misunderstood and for long thought an ally of powers he abhors; however much he may strive after justice he is bound, according to the human limitations of his insight, to be unjust; but he may console himself with the words once employed by his great teacher, Schopenhauer: ‘A happy life is impossible: the highest that man can attain to is a heroic one.’”

Finally, in an essay on Wagner, he again explicitly mentions culture, aesthetic truth, and art. “Danger and despair lie in wait for every true artist thrown into the modern world…. We can see how the most serious artist will try forcibly to impose seriousness on the institution of which he is part, an institution which has, however, been constructed frivolously and demands frivolity almost as a matter of principle; how he partially succeeds but in the end always fails; how he begins to feel disgust and wants to flee, how he fails to find anywhere to flee to, and is again and again obliged to return to the gypsies and outcasts of our culture as one of them.”

Nietzsche concludes, “The history of the evolution of culture since the Greeks is short enough, if one takes into account the actual distance covered and ignores the halts, regressions, hesitations, and lingerings. The Hellenization of the world and, to make this possible, the orientalization of the Hellenic—the twofold task of the great Alexander—is still the last great event; the old question whether a culture can be transplanted to a foreign soil at all is still the problem over which the moderns weary themselves.” Finally, Nietzsche describes the fate of any true artist, as opposed to the lone philosopher, who has to live within his cultural milieu, “For it is, to be sure, a life full of torment and shame, to be a homeless wanderer in a world to which one nonetheless has to speak and of which one has to make demands, which one despises and yet is unable to do without—it is the actual predicament of the artist of the future; he cannot, like the philosopher, hunt after knowledge all by himself in a dark corner, for he needs human souls as mediators with the future, public institutions as guarantees of this future, as bridges between the now and the hereafter.”