INTRODUCTION:
An Improbable but True Story
6 – 7 “The usual assumption is that something very unusual and special happened to human brains during evolution, and that we just need to find out what that something is. But Danny took a fascinating contrarian’s position, saying that we should not be looking for what everyone else was—the presumed special brain changes that made us human. Rather, we should be asking what has been holding back all the other intelligent species that, like humans, seem to have self-awareness of themselves as individuals—a list that may include chimpanzees, orangutans, dolphins, orcas (so-called killer whales), elephants, and even birds such as magpies. Danny asked: Why are there no humanlike elephant or humanlike dolphin species as yet, despite millions of years of evolutionary opportunity for making this transition?
The next mental step beyond basic awareness of one’s own personhood that many of the species mentioned above seem to possess could be awareness of the personhood of others—in other words, knowing that others of your own kind are also equally self-aware. But Danny argued that gaining this useful ability would also result in understanding the deaths of others of your own kind—and, consequently, realizing one’s own individual mortality. And he suggested that this all-encompassing, persistent, terror-filled realization would cause an individual who first made that critical step to lose out in the struggle to secure a mate and pass his or her genes to the next generation—in other words, such an individual would reach an evolutionary dead end. Danny suggested that we humans were the only species to finally get past this long-standing barrier. And he posited that we did this by simultaneously evolving mechanisms to deny our mortality.”
13 “Brower’s concept of a long-standing evolutionary barrier […] could [.] steer discussions of other uniquely human “universals,” such as the ability to hold false beliefs, existential angst, theories of after-life, religiosity, severity of grieving, importance of death rituals, risk-taking behaviour, panic attacks, suicide and martyrdom. If this logic is correct, many warm-blooded species may have previously achieved complete self-awareness and inter-subjectivity, but then failed to survive because of the extremely negative immediate consequences. Perhaps we should be looking for the mechanisms (or loss of mechanisms) that allow us to delude ourselves and others about reality, even while realizing that both we and others are capable of such delusions and false beliefs.”
CHAPTER 1:
Where Did We Come From, and How Did We Get Here?
22 – 24 “a general summary of knowledge about human origins as of the end of 2012. […] Among the apes, we are derived from a subgroup traditionally called the great apes, of which the other currently living species are chimpanzees, bonobos, gorillas, and orangutans.
The term great ape has now fallen out of favor, though, because it turns out that we are close genetically to chimpanzees and bonobos (so-called pygmy chimpanzees) than they are to gorillas and orangutans. Indeed, Jared Diamond was spot-on in saying that, from a strictly genetic perspective, we are nothing more than “a third chimpanzee.” The latest taxonomic classification, therefore, lumps all great apes and humans together as hominids, in recognition of our genetic similarities. The fossil species that appeared after our common ancestor with chimpanzees appeared are thus now called hominins, rather than hominids. To place all this in perspective, consider […] that we are genetically closer to chimpanzees than mice and rats are to each other!
The earliest hominin fossils have been found in Africa, dating back as far as around five to seven million years ago, presumably close to the time of our common ancestor with chimpanzees. The location and physical appearance of this common ancestor remains unknown, but fossils suggest that it was a bit more chimpanzee-like than humanlike, especially with regard to its smaller skull case. Apart from the emergence of an upright posture and bipedalism (walking on two legs), these species do not appear to have undergone very major humanlike changes for another three or four million years. Rather, they seem to have gone through various specializations, and a bushy, branching tree of various species apparently coexisted at the time. The best known of these species is Ardi, a more than four-million-year-old skeleton classified as Ardipithecus ramidus, which was described by Tim White and his colleagues, and Lucy, a more than three-million-year-old skeleton classified as Australopithecus afarensis, which was discovered by Don Johanson and his colleagues. Starting about two million years ago, one sees fossil evidence of species discovered by Louis and Mark Leakey and others classified under the genus Homo, in which there is some increase in brain size and the beginnings of stone tool use. A species called Homo ergaster then emerges in Africa, exemplified by the skeleton called Turkana Boy, discovered by Richard Leakey and colleagues, which is bigger in body size and appears committed to striding, bipedal walking, and, likely, long-distance running. Along with this change came a gradual increase in brain size, an increased sophistication in the making and use of stone tools, and evidence of more meat eating. Very similar creatures called Homo erectus are then found spreading throughout the Old World, migrating as far as present-day Indonesia, China, and Europe.
Over the next two million years or so Homo ergaster/erectus seems to have undergone only minor changes, other than further increases in brain size and limited improvements in stone tools. Beginning about a million years ago, we see evidence of continuing brain size increase in Homo, with the modern size being achieved around three or four hundred thousand years ago. But at that point there is still no archaeological evidence of what looks like so-called modern (present-day) human behavior, such as burials with funerary artifacts, representative drawings, ornaments, trade, and so on. Thus it seems that the final increase in brain size was not sufficient to allow the emergence of us “modern humans.” One of the best-documented species from this period are Neandertals, who were found throughout what is now Europe, the Middle East, and western Asia, often living in extreme climates associated with ice ages. These closest extinct evolutionary relatives were short, squat powerhouses with robust skeletal anatomy; their brains were larger than ours are even now, they used more specialized and complex stone tools than Homo erectus, and they were able to control fire. However, the first two hundred thousand years or so of their existence were not characterized by the kinds of artifacts associated with modern human behaviors, such as bead necklaces, symbolic art, and the like. The recent discovery of Denisovans (defined by a few bones found in a Siberian cave and the genomic DNA from these samples) has uncovered another branch of ancient humans, which likely shared common ancestors with humans and Neandertals a few hundred thousand years ago.
Skeletons very similar to those of present-day humans can be found in Africa, beginning about two hundred thousand years ago. However, these “anatomically modern humans” also did not leave behind many artifacts suggestive of modern human behavior (although there is some indirect evidence of symbolic thinking, such as the production of ochre colors that were presumably used for body decoration). We “behaviorally modern humans,” then emerged somewhere in Africa around one hundred thousand years ago (and DNA analysis of current-day humans says that we all came from a relatively small effective population size, which numbered only around five or ten thousand individuals or so). The first evidence for truly modern human behavior—evidence such as complex symmetric scratch marks on objects, bead necklaces, and burials with funerary goods—dates to about this time. Shortly thereafter some of us began to leave Africa (some may have also migrated back). These migrations appear to have first taken humans into what is now Palestine and Israel, and then along the coastlines of the Middle East, India, and Indonesia—eventually leading them into Australia (one of the first crossings of deep water in which the horizon would have shown no evidence of land on the other side). Around this time our ancestors also began appearing in what is now China and southern Europe. The later Cro-Magnons are incorrectly claimed to be the first human group to demonstrate modern human behavior. What was once thought of as a cultural “great leap forward” by these early Europeans (who made bead necklaces, spear-throwing implements, cave art, and performed ceremonial burials) is now felt to be a result of improved preservation and more sustained research in this particular region.”
30 “based on our current molecular knowledge of life, evolution by natural selection is unavoidable, and is a defining attribute of all life forms.”
316 – 318 NOTE 39 “A Proof of Evolution by First Principles
Over time, humans in many societies have classified living organisms into groups such as animals, plants, and fungi (and, more recently, microbes) based on our observations of similarities and differences.
Some humans further divided such groups into subgroups and into subgroups of subgroups, again based on observational criteria (initially, external appearance; later, internal features).
When a particular subgroup showed great similarities between individuals and they bred and reproduced, giving rise to similar individuals in the next generation, we humans called such a subgroup a species.
Much later, humans found that all known life forms require DNA as a “genetic code.”
It then emerged that the genetic-code lettering system of DNA is essentially the same in all life forms.
The relatedness of DNA sequences from different species was then found to be almost exactly in line with the prior classification of species based on other observations. So in the “tree of life,” living things appear related to one another by their DNA.
At the level of populations, all species show individual variations in DNA, their bodies, and/or their behavior, which can be beneficial, neutral, or detrimental depending on the environmental conditions.
Such variation is also common in the DNA of different individuals within natural populations.
During reproduction, the DNA of one generation must be passed on to offspring. This process introduces variation into the progeny by less-than-perfect replication of DNA.
Ongoing random mutations also introduce further variations and changes into DNA.
Most species produce far more progeny than can possibly survive. What prevents natural populations from explosive expansion is that only a small fraction of all progeny survive and reproduce.
Individuals who reproduce (pass their DNA on to progeny) are likely to be those whose variations were most beneficial and/or least detrimental under the circumstances (a nonrandom process).
Thus populations inevitably change over time, as DNA variations beneficial to prevailing environments accumulate over generations. This process can be called natural selection, and it results in adaptations to environmental conditions.
Many such adaptations eventually appear to be very exquisite designs, but on closer observation they are still imperfect and/or seem constructed in an illogical fashion.
Mate choice can influence which individual’s DNA is passed on. This is called sexual selection and can lead to astonishing features of no apparent survival value to the individual, e.g., the male peacock’s tail and the male moose’s antlers.
In addition to natural and sexual selection, the distribution of DNA variations and imperfections across populations can occur randomly, without selection. This is called neutral drift.
Working together, natural selection, sexual selection, and neutral drift can lead to differences between populations that are eventually large enough to generate barriers to successful mating.
Such “reproductive isolation” will eventually give rise to new species, as newly isolated populations accumulate independent DNA changes and cease to have any DNA exchange.
Once a beneficial DNA change becomes important for survival and reproduction, any further changes tend to be detrimental and cannot be tolerated without losing the individual in whom the change occurs (and hence that individual’s DNA). Thus some aspects of DNA remain “conserved” during passage to the next generation. This is called purifying selection.
Taken together, all this information can only be explained by assuming that all life forms are related by a single genetic code and have diverged over time into the different species we see today via processes such as natural selection, sexual selection, neutral drift, and purifying selection. The sum total of all these processes can be called biological evolution. It is today the only possible fact-based explanation for the existence of so many life forms on earth, with all their variations and imperfections. No other explanations come even close.”
320 NOTE 47 “Biological evolution is much slower than cultural and social evolution. So our lives are changing at a rate that has far outpaced evolution in our genes. There is a mismatch between the environments in which we evolved and the novel ones that we have created for ourselves. Yet we still carry our biological evolutionary baggage and must use this genetic tool kit to adapt to modern life. This insight is going to be true not only for aspects of our physiology but also for the evolutionary component of our personalities. It can be tempting to dismiss the effect of selection on behavior, since our behaviors don’t always seem to be well adapted to our lives. But the genetic component of our personalities was selected to flourish in an environment foreign to most of us today, and we changed the rules much faster than our genes can keep up with. If we realize that we were not evolved (by selection) to live in our current world, it becomes easier to understand that our behaviors will not always make sense. This becomes even truer when we realize that evolution’s “goals” are not necessarily ours.”
37 – 38 “the ability of our emotions to short-circuit rationality was probably an essential part of our evolutionary development.”
322 NOTE 16 FRANCIS CRICK “there are no [absolute] laws in biology—only gadgets.”
322 NOTE 16 “the “central dogma” of molecular biology [is] that life might by explained just by the phrase “DNA makes RNA makes protein.””
49 MICHAEL GAZZANIGA “Most of the evolution of the human brain, the presumed anatomy of intelligence, had occurred prior to any evidence for technological sophistication and, as a consequence, it appears unlikely that technology itself played a central role in the evolution of this impressive human ability.”
CHAPTER 2:
Becoming Smarter Shouldn’t Be Hard
59 “unlike our closest evolutionary relatives, the great apes, most of our brain development occurs outside the womb, under the influence of our environment—which includes exposure to other humans and their languages, ideas, and cultural practices.”
62 “ Studies in developmental genetics are also uncovering the extremely intricate webs of gene and protein interactions that turn a simple early embryo (a nondescript ball of cells) into the magnificently elaborate organisms we see today, with exciting connections to evolution that are sometimes called Evo-Devo. This kind of work provides a strong molecular underpinning to the notion that there is enough genetic variation in a large population of animals for evolution to exaggerate virtually any structure or physiological process, as long as there is sufficient evolutionary selective pressure to do so. Moreover, depending on the population size and degree of selection, these changes can happen over a relatively small number of generations.”
CHAPTER 3:
There Are No Free Lunches or Free Smarts
68 ERWIN SCHRÖDINGER “We are only now beginning to acquire reliable material for welding together the sum total of all that is known into a whole; but, on the other hand, it has become next to impossible for a single mind fully to command more than a small specialized portion of it. I can see no other escape from this dilemma … than that some of us should venture to embark on a synthesis of facts and theories, albeit with second-hand and incomplete knowledge of some of them—and at the risk of making fools of ourselves.”
68 – 69 “it is likely that there were trade-offs for any unusual trait that evolved in only one or two species—trade-offs that made such a trait rare in the first place. […]
Given the apparent uniqueness of some of the unusual mental abilities of humans, there must have been one or more major barriers against achieving this state.”
73 “Emotions have been shaped by selection over countless generations to guide our behaviors in the absence of exhaustive and perhaps futile analysis of situations.”
79 “as animals become smarter, they also evolved many filters that make “executive” decisions as to what should command attention. Humans, with our exceptionally powerful brains (especially the prefrontal cortex), have also become extremely good at generalizations. We deal with life in ways similar to the way a strategic thinker plays chess—makings moves that we “know” are good not because we are calculating each specific course but because we are unconsciously drawing conclusions from emotions, similar experiences, and other global patterns.”
CHAPTER 4:
Many Levels of Awareness
329 NOTE 9 JOSEP CALL and MICHAEL TOMASELLO “[self-awareness is] awareness of oneself as an intentional agent […; a rudimentary theory of mind is] understanding others as intentional agents in terms of a perception-goal psychology [… ; a full theory of mind is] understanding others as intentional agents in a fully humanlike belief-desire psychology and appreciating that others have mental representations of the world that drive their actions, even when those do not correspond to reality.”
87 “these arbitrary “stages” of [theory of mind] represent a continuum, with no shining bright line between these different stages of awareness.”
89 “the dog may be an exception to the proposed continuum. While they are not even self-aware, they may have a partial [theory of mind] of their human owners, perhaps because of artificial selection by humans for this very trait.”
101 “consciousness is actually a continuum, ranging from a minimal awareness of bodily needs all the way to the full-blown mental imagery and sophistication of human consciousness.”
109 “the evolution and stabilization of full [theory of mind] in human ancestors was originally held back by the recognition of mortality of others, which in turn results in awareness of personal mortality (a distressing and maladaptive situation).”
CHAPTER 5:
The Wall
113 “from both the genetic and natural selection points of view, there is no obvious reason why it took tens of millions of years to evolve from an animal with full self-awareness and rudimentary [theory of mind] to one with humanlike intelligence and a full and extended [theory of mind]. […]
Once the barrier is breached and full [theory of mind] is established, a species can continue down the path to greater intelligence essentially unrestrained, becoming much smarter than those still held in check—in other words, conventional natural selection would once more swing into action. But rather than assuming that emergence of humanlike cognition was a gradual, step-by-step, or piecemeal positive selection of a series of useful changes, we present a counterintuitive view—that the initial negative psychological cost to the individual of attaining a full [theory of mind] and a more complete appreciation of reality (especially awareness of one’s mortality) was too great to allow the first such individual to get past it, reproduce, and successfully propagate that [theory of mind] ability within a species, until humans finally broke through the barrier by simultaneously generating mechanisms for denial of reality and mortality.”
127 BOGIN and HOLLY SMITH “The most parsimonious conclusion that one may draw … is that all the features of the modern human adolescent stage of the life cycle evolved only in the H. sapiens line. Quite likely this would be no earlier than the appearance of archaic H. sapiens in Africa.”
127 “Once the psychological barrier was successfully breached, natural selection and sexual selection could then have taken advantage of the situation to quickly evolve a new species with fully human minds.”
129 “those individuals who first become fully able to attribute mental states to others (achieve full [theory of mind]) and thus become aware of their mortality are at greater risk of losing out, because they avoid mortality risk over opportunities to reproduce and therefore will not pass their genes on as effectively.”
131 – 132 “The entire system of behavioral drivers in an animal on the verge of full [theory of mind] has evolved to generate behaviors with a single end point—maximal reproductive fitness—which translates at the population level to species survival. Full [theory of mind] creates a very different new target of personal survival. And some of our most influential emotions, such as fear, are extremely capable of direction our behaviors to move us toward that goal. Our built-in fear response will be instantly heightened to enormous levels if we are suddenly obsessed with the consequences of death. What emotion or unconscious behavioral driver can compensate for that fear—or, more accurately, could possibly have already been in place to compensate for that fear—when our ancestors first attained [theory of mind]?
Loss of risk aversion should have gone through two phases. In the first phase, it would have been part and parcel of whatever neural mechanism(s) mediated denial of mortality and reality, thus allowing the establishment and selection of a full [theory of mind] in human ancestors. Once this psychological evolutionary barrier was breached by the emergence of appropriate neural changes, there was no turning back. The generalized blunting of risk aversion that one sees in humans today would have been one of the side effects of this transition. At first glance, this would seem to be detrimental for survival, placing humans at greater risk from various dangers. However, full [theory of mind]—not only understanding the minds of others but also having the ability to understand past, present, and future, planning ahead, and so on—came along in the package. Thus the blunting of risk aversion could now be put to positive use, allowing humans to take much greater (calculated) risks. And the benefits of doing so could be myriad, both for the individual and for the group.”
CHAPTER 6:
Breaking through the Wall
134 PSALM 23:4 “Yea, though I walk through the valley of the shadow of death, I will fear no evil: for thou art with me; thy rod and thy staff, they comfort me.”
151 “It seems reasonable to simply accept that spirituality is a denial-essential quality of humanity and to try to make our spiritual sides as congruent with reality as our individual psyches will permit.”
154 TALI SHAROT “While healthy people are biased toward a positive future, depressed individuals perceive possible misfortunes a bit too clearly. While severely depressed patients are pessimistic, mildly depressed people are actually pretty good at predicting what may happen to them in the near future.”
CHAPTER 7:
How Did Reality Denial Emerge?
164 “reality denial likely had to be waiting for us when we first achieved a full [theory of mind]. […] The improbability of such denial emerging just prior to the emergence of full [theory of mind] may be the reason why it took so long for even one species to become truly intelligent.”
169 “the development of self-deception as a mechanism [.] improved our ability to lie and therefore to influence others.”
CHAPTER 8:
Evidence for Reality Denial Is All Around Us!
174 ALBERT CAMUS “We always deceive ourselves twice about the people we love—first to their advantage, then to their disadvantage.”
174 “The human penchant for denial of reality is actually so obvious that it is surprising how long it has taken us to fully acknowledge it.”
177 JOSEPH GOEBBELS “If you repeat a lie often enough, it becomes the truth.”
177 “As anyone who has engaged in heated political arguments can attest, we are always sure it is the other person who is obviously deluded in his or her analyses of facts and events. As Robert Kurzban puts it, everyone else is a hypocrite.”
178 “false validation by repetition is a far more common problem in science than the very rare experimental fraud. It is also harder to detect, as the proponents of the false theory are true believers. Intelligent, educated people are no more or less susceptible to such repetition than anyone else; it’s an integral part of being human.”
180 “following the 1933 lifting of the prohibition against alcohol in the United States, there was a large federal government organization (the Federal Bureau of Narcotics) that no longer had enough work, and they went looking for something new to focus attention on. Largely for this reason, cannabis (renamed marijuana) was not only criminalized but also demonized as a “killer weed,” and an active attempt was made to characterize it as a much more serious problem than it had ever been. Fast-forward to the 1960s, and “pot” became the signature drug of the counterculture. As with alcohol during the Prohibition era, attempts to eliminate cannabis actually resulted in an increase in its use, and eventually made it into a favored revenue source for South American drug cartels as well as illicit growers in the United States.”
188 “There is convincing evidence that spending money on disease-prevention programs rather than on expensive cures gives the taxpayer a bigger bang for his or her buck. But despite all the evidence, those who try to encourage public health and disease prevention have the hardest time getting cooperation from individuals, from the general public, and even from the government. It has taken decades of public education to make even some limited progress in such matters.”
CHAPTER 9:
Too Smart for Our Own Good
220 “We evolved to become very smart very fast, in evolutionary time. Our numbers are increasing at an unsustainable rate, and our technology is galloping ahead at an ever-increasing speed. A few of us can destroy cities, countries, and the global environment by pushing a few buttons in a few capitals. We can create a disease pandemic that could spread around the world in a matter of days. We are polluting the earth and changing the climate in ways that we can’t predict precisely and likely, at some point, can’t easily reverse. If we’re so smart, why do we continue to sow the seeds for our eventual destruction? Since we are saddled with a brain designed by selection to cope with the ultimate disaster (death) by denying that it will occur, we also treat other impending disasters by denying that they will ever happen. If we can believe in heaven and reincarnation, how hard is it to convince ourselves that global climate disruption is just an unproven theory? Yes, there is a real danger that our rampaging technology will come back to bite us in a big way, and very soon. But is this inevitable? Maybe yes, but maybe no, if we can recognize and mitigate our penchant for denial.”
CHAPTER 10:
A Tale of Two Futures: Are You a Pessimist or an Optimist?
223 “Unfortunately, the focus remains mostly on “global warming” instead of the bigger concern—that we are disrupting the planet’s climate in completely unpredictable ways. Because climate prediction includes a significant degree of scientific uncertainty, this has allowed skeptics to gain the upper hand and even corner some expert scientists into difficult positions. A friend in the climate research field privately admits that he and most of his colleagues are afraid to stand up and speak out because of the vituperative attacks and massive smear campaigns that they would inevitably suffer”
228 – 229 “ While the public and politicians may choose to ignore climate change, the insurance industry cannot afford to do so. Using its comprehensive NatCatSERVICE database, which maintains data on natural catastrophes, Munich Re (one of the world’s largest reinsurance conglomerates) analyzes the frequency and loss trends of various events from an insurance perspective. In an October 2012 report, Munich Re published its analysis of all kinds of weather perils and trends. They study was prepared for underwriters and clients in North America, the world’s largest insurance and reinsurance market. Ironically, this region (also one of the world’s largest producers of greenhouse gases) has been most affected by extreme weather-related events in recent decades. The North American continent is already vulnerable to all types of weather hazards—hurricanes, winter storms, tornadoes, wildfires, drought, and floods (one reason is that there is no mountain range running from east to west that can separate hot from cold air). But the study shows a nearly fivefold increase in the number of weather-related loss events in North America for the period from 1980 to 2011, compared to a 400 percent increase in Asia, a 250 percent increase in Africa, a 200 percent increase in Europe, and a 150 percent increase in South America. The overall loss burden during this time frame from weather catastrophes in the United States was $1.06 trillion (in 2011 values), and some thirty thousand people lost their lives.”
236 DURWOOD ZAELKE and VEERABHADRAN RAMANATHAN “black carbon, a component of soot; methane, the main component of natural gas; lower-level ozone, a main ingredient of urban smog; and hydrofluorocarbons, or HFCs, which are used as coolants [.] account for as much as 40 percent of current warming. Unlike carbon dioxide, these pollutants are short-lived in the atmosphere. If we stop emitting them, they will disappear in a matter of weeks to a few decades. We have technologies to do this, and, in many cases, laws and institutions to support these cuts.”
242 ROBERT TRIVERS “Denial is [.] self-reinforcing—once you make the first denial, you tend to commit to it: you will deny, deny the denial, deny that and so on.”
243 “we can’t abandon denial any more than we can change our fundamental personality traits. What we can do is to recognize this trait and try to manage its deleterious effects […] Indeed, we don’t want to completely escape from our state of denial, even if we could—it’s the only thing that keeps us sane in the face of rational realization of mortality. We just need to recognize and manage its pathological consequences. […]
are we capable of controlling denial sufficiently to solve our current dilemmas? Can we create a spiritual construct (individually, or as a new formal religion) that can satisfy our acceptance of mortality without letting it drive our lives and society to oblivion? As always, the first step is recognition of the problem. The next step may require a process that is every bit as unlikely as the convergence of self-awareness and self-deception that allowed us to breath through the wall so many years ago.”
244 “reality is unpleasant for most people, and our built-in mechanisms for denial allow us to pick up whatever line of reasoning we find the most comforting in the face of competitive realities, however flawed that reasoning is.”
CHAPTER 11:
On the Positive Value of Human Reality Denial
250 “Tali Sharot has shown that distinct regions of the prefrontal cortex of the brain track “estimation errors,” and that highly optimistic individuals exhibit “reduced tracking of errors that call for a negative update.” She concludes that “optimism is tied to a selective update failure and diminished neural coding of undesirable information regarding the future.” And it is striking that the pathways in question (involving both the prefrontal cortex and the amygdala) are the very same ones involved in controlling fear and stress responses. In other words, the frontal lobes of your brain are much better at informing your stress pathways about good news than they are at informing you about bad news. This may well be one of the major neural mechanisms of reality denial.”
CHAPTER 12:
Explaining the Mysterious Origin of Us
261 IAN TATTERSALL “the earliest anatomical Homo sapiens appear right now to have been cognitively indistinguishable from the Neandertals and other contemporaries […] the archaelogical record seems to indicate a very late and essentially unheralded arrival of symbolic consciousness in just one lineage of large-brained hominid.”
EPILOGUE
284 STEPHEN HAWKING “our brains interpret the input from our sensory organs by making a model of the world. When such a model is successful at explaining events, we tend to attribute to it, and to the elements and concepts that constitute it, the quality of reality or absolute truth.”
CODA
288 DANIEL DENNETT “Any theory that makes progress is bound to be initially counterintuitive.”