The Meaning to Life? A Darwinian Existentialist has his Answers

human-lifespan

Michael Ruse | Aeon Ideas

I was raised as a Quaker, but around the age of 20 my faith faded. It would be easiest to say that this was because I took up philosophy – my lifelong occupation as a teacher and scholar. This is not true. More accurately, I joke that having had one headmaster in this life, I’ll be damned if I want another in the next. I was convinced back then that, by the age of 70, I would be getting back onside with the Powers That Be. But faith did not then return and, as I approach 80, is nowhere on the horizon. I feel more at peace with myself than ever before. It’s not that I don’t care about the meaning or purpose of life – I am a philosopher! Nor does my sense of peace mean that I am complacent or that I have delusions about my achievements and successes. Rather, I feel that deep contentment that religious people tell us is the gift or reward for proper living.

I come to my present state for two separate reasons. As a student of Charles Darwin, I am totally convinced – God or no God – that we are (as the 19th-century biologist Thomas Henry Huxley used to say) modified monkeys rather than modified mud. Culture is hugely important, but to ignore our biology is just wrong. Second, I am drawn, philosophically, to existentialism. A century after Darwin, Jean-Paul Sartre said that we are condemned to freedom, and I think he is right. Even if God does exist, He or She is irrelevant. The choices are ours.

Sartre denied such a thing as human nature. From this quintessential Frenchman, I take that with a pinch of salt: we are free, within the context of our Darwinian-created human nature. What am I talking about? A lot of philosophers today are uncomfortable even raising the idea of ‘human nature’. They feel that, too quickly, it is used against minorities – gay people, the disabled, and others – to suggest that they are not really human. This is a challenge not a refutation. If a definition of human nature cannot take account of the fact that up to 10 per cent of us have same-sex orientation, then the problem is not with human nature but with the definition.

What, then, is human nature? In the middle of the 20th century, it was popular to suggest that we are killer apes: we can and do make weapons, and we use them. But modern primatologists have little time for this. Their findings suggest that most apes would far rather fornicate than fight. In making war we are really not doing what comes naturally. I don’t deny that humans are violent, however our essence goes the other way. It is one of sociability. We are not that fast, we are not that strong, we are hopeless in bad weather; but we succeed because we work together. Indeed, our lack of natural weapons points that way. We cannot get all we want through violence. We must cooperate.

Darwinians did not discover this fact about our nature. Listen to the metaphysical poet John Donne in 1624:

No man is an island,
Entire of itself,
Every man is a piece of the continent,
A part of the main.
If a clod be washed away by the sea,
Europe is the less.
As well as if a promontory were.
As well as if a manor of thy friend’s
Or of thine own were:
Any man’s death diminishes me,
Because I am involved in mankind,
And therefore never send to know for whom the bell tolls;
It tolls for thee.

Darwinian evolutionary theory shows how this all came about, historically, through the forces of nature. It suggests that there is no eternal future or, if there is, it is not relevant for the here and now. Rather, we must live life to the full, within the context of – liberated by – our Darwinian-created human nature. I see three basic ways in which this occurs.

First, family. Humans are not like male orangutans whose home life is made up mainly of one-night stands. A male turns up, does his business, and then, sexually sated, vanishes. The impregnated female births and raises the children by herself. This is possible simply because she can. If she couldn’t then, biologically it would be in the interests of the males to lend a hand. Male birds help at the nest because, exposed as they are up trees, the chicks need to grow as quickly as possible. Humans face different challenges, but with the same end. We have big brains that need time to develop. Our young cannot fend for themselves within weeks or days. Therefore humans need lots of parental care, and our biology fits us for home life, as it were: spouses, offspring, parents, and more. Men don’t push the pram just by chance. Nor boast to their co-workers about their kid getting into Harvard.

Second, society. Co-workers, shop attendants, teachers, doctors, hotel clerks – the list is endless. Our evolutionary strength is that we work together, helping and expecting help. I am a teacher, not just of my children, but of yours (and others) too. You are a doctor: you give medical care not just to your children, but to mine (and others) too. In this way, we all benefit. As Adam Smith pointed out in 1776, none of this happens by chance or because nature has suddenly become soft: ‘It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own self-interest.’ Smith invoked the ‘invisible hand’. The Darwinian puts it down to evolution through natural selection.

Though life can be a drag sometimes, biology ensures that we generally get on with the job, and do it as part of our fulfilled lives. John Stuart Mill had it exactly right in 1863: ‘When people who are fairly fortunate in their material circumstances don’t find sufficient enjoyment to make life valuable to them, this is usually because they care for nobody but themselves.’

Third, culture. Works of art and entertainment, TV, movies, plays, novels, paintings and sport. Note how social it all is. Romeo and Juliet, about two kids in ill-fated love. The Sopranos, about a mob family. A Roy Lichtenstein faux-comic painting; a girl on the phone: ‘Oh, Jeff… I love you, too… but…’ England beating Australia at cricket. There are evolutionists who doubt that culture is so tightly bound to biology, and who are inclined to see it as a side-product of evolution, what Stephen Jay Gould in 1982 called an ‘exaptation’. This is surely true in part. But probably only in part. Darwin thought that culture might have something to do with sexual selection: protohumans using songs and melodies, say, to attract mates. Sherlock Holmes agreed; in A Study in Scarlet (1887), he tells Watson that musical ability predates speech, according to Darwin: ‘Perhaps that is why we are so subtly influenced by it. There are vague memories in our souls of those misty centuries when the world was in its childhood.’

Draw it together. I have had a full family life, a loving spouse and children. I even liked teenagers. I have been a college professor for 55 years. I have not always done the job as well as I could, but I am not lying when I say that Monday morning is my favourite time of the week. I’m not much of a creative artist, and I’m hopeless at sports. But I have done my scholarship and shared with others. Why else am I writing this? And I have enjoyed the work of fellow humans. A great performance of Mozart’s opera The Marriage of Figaro is heaven. I speak literally.

This is my meaning to life. When I meet my nonexistent God, I shall say to Him: ‘God, you gave me talents and it’s been a hell of a lot of fun using them. Thank you.’ I need no more. As George Meredith wrote in his poem ‘In the Woods’ (1870):

The lover of life knows his labour divine,
And therein is at peace.


A Meaning to Life (2019) by Michael Ruse is published via Princeton University Press.Aeon counter – do not remove

Michael Ruse is the Lucyle T Werkmeister Professor of Philosophy and director of the history and philosophy of science at Florida State University. He has written or edited more than 50 books, including most recently On Purpose (2017), Darwinism as Religion (2016), The Problem of War (2018) and A Meaning to Life (2019).

This article was originally published at Aeon and has been republished under Creative Commons. Read the original article here.

Richard Feynman was Wrong about Beauty and Truth in Science

Tuva

Spaceborne Imaging Radar photo of the autonomous republic of Tuva, the subject of Richard Feynmann’s intense interest during the latter part of his life and documented in Tuva or Bust! by Ralph Leighton. Photo taken from Space Shuttle Endeavour in 1994. Photo courtesy NASA/JPL

Massimo Pigliucci | Aeon Ideas

Edited by Nigel Warburton

The American physicist Richard Feynman is often quoted as saying: ‘You can recognise truth by its beauty and simplicity.’ The phrase appears in the work of the American science writer K C Cole – in her Sympathetic Vibrations: Reflections on Physics as a Way of Life (1985) – although I could not find other records of Feynman writing or saying it. We do know, however, that Feynman had great respect for the English physicist Paul Dirac, who believed that theories in physics should be both simple and beautiful.

Feynman was unquestionably one of the outstanding physicists of the 20th century. To his contributions to the Manhattan Project and the solution of the mystery surrounding the explosion of the Space Shuttle Challenger in 1986, add a Nobel Prize in 1965 shared with Julian Schwinger and Shin’ichirō Tomonaga ‘for their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles’. And he played the bongos too!

In the area of philosophy of science, though, like many physicists of his and the subsequent generation (and unlike those belonging to the previous one, including Albert Einstein and Niels Bohr), Feynman didn’t really shine – to put it mildly. He might have said that philosophy of science is as helpful to science as ornithology is to birds (a lot of quotations attributed to him are next to impossible to source). This has prompted countless responses from philosophers of science, including that birds are too stupid to do ornithology, or that without ornithology many birds species would be extinct.

The problem is that it’s difficult to defend the notion that the truth is recognisable by its beauty and simplicity, and it’s an idea that has contributed to getting fundamental physics into its current mess; for more on the latter topic, check out The Trouble with Physics (2006) by Lee Smolin, or Farewell to Reality (2013) by Jim Baggott, or subscribe to Peter Woit’s blog. To be clear, when discussing the simplicity and beauty of theories, we are not talking about Ockham’s razor (about which my colleague Elliott Sober has written for Aeon). Ockham’s razor is a prudent heuristic, providing us with an intuitive guide to the comparisons of different hypotheses. Other things being equal, we should prefer simpler ones. More specifically, the English monk William of Ockham (1287-1347) meant that ‘[hypothetical] entities are not to be multiplied without necessity’ (a phrase by the 17th-century Irish Franciscan philosopher John Punch). Thus, Ockham’s razor is an epistemological, not a metaphysical principle. It’s about how we know things, whereas Feynman’s and Dirac’s statements seem to be about the fundamental nature of reality.

But as the German theoretical physicist Sabine Hossenfelder has pointed out (also in Aeon), there is absolutely no reason to think that simplicity and beauty are reliable guides to physical reality. She is right for a number of reasons.

To begin with, the history of physics (alas, seldom studied by physicists) clearly shows that many simple theories have had to be abandoned in favour of more complex and ‘ugly’ ones. The notion that the Universe is in a steady state is simpler than one requiring an ongoing expansion; and yet scientists do now think that the Universe has been expanding for almost 14 billion years. In the 17th century Johannes Kepler realised that Copernicus’ theory was too beautiful to be true, since, as it turns out, planets don’t go around the Sun in perfect (according to human aesthetics!) circles, but rather following somewhat uglier ellipses.

And of course, beauty is, notoriously, in the eye of the beholder. What struck Feynman as beautiful might not be beautiful to other physicists or mathematicians. Beauty is a human value, not something out there in the cosmos. Biologists here know better. The capacity for aesthetic appreciation in our species is the result of a process of biological evolution, possibly involving natural selection. And there is absolutely no reason to think that we evolved an aesthetic sense that somehow happens to be tailored for the discovery of the ultimate theory of everything.

The moral of the story is that physicists should leave philosophy of science to the pros, and stick to what they know best. Better yet: this is an area where fruitful interdisciplinary dialogue is not just a possibility, but arguably a necessity. As Einstein wrote in a letter to his fellow physicist Robert Thornton in 1944:

I fully agree with you about the significance and educational value of methodology as well as history and philosophy of science. So many people today – and even professional scientists – seem to me like someone who has seen thousands of trees but has never seen a forest. A knowledge of the historic and philosophical background gives that kind of independence from prejudices of his generation from which most scientists are suffering. This independence created by philosophical insight is – in my opinion – the mark of distinction between a mere artisan or specialist and a real seeker after truth.

Ironically, it was Plato – a philosopher – who argued that beauty is a guide to truth (and goodness), apparently never having met an untruthful member of the opposite (or same, as the case might be) sex. He wrote about that in the Symposium, the dialogue featuring, among other things, sex education from Socrates. But philosophy has made much progress since Plato, and so has science. It is therefore a good idea for scientists and philosophers alike to check with each other before uttering notions that might be hard to defend, especially when it comes to figures who are influential with the public. To quote another philosopher, Ludwig Wittgenstein, in a different context: ‘Whereof one cannot speak, thereof one must be silent.’Aeon counter – do not remove


Massimo Pigliucci is professor of philosophy at City College and at the Graduate Center of the City University of New York. He is the author of How to Be a Stoic: Ancient Wisdom for Modern Living (2017) and his most recent book is A Handbook for New Stoics: How to Thrive in a World Out of Your Control (2019), co-authored with Gregory Lopez.

This article was originally published at Aeon and has been republished under Creative Commons. Read the original article here.

How the Dualism of Descartes Ruined our Mental Health

goya-lunatics

Yard with Lunatics 1794, (detail) by Francisco José de Goya y Lucientes. Courtesy Wikimedia/Meadows Museum, Dallas

James Barnes | Aeon Ideas

Toward the end of the Renaissance period, a radical epistemological and metaphysical shift overcame the Western psyche. The advances of Nicolaus Copernicus, Galileo Galilei and Francis Bacon posed a serious problem for Christian dogma and its dominion over the natural world. Following Bacon’s arguments, the natural world was now to be understood solely in terms of efficient causes (ie, external effects). Any inherent meaning or purpose to the natural world (ie, its ‘formal’ or ‘final’ causes) was deemed surplus to requirements. Insofar as it could be predicted and controlled in terms of efficient causes, not only was any notion of nature beyond this conception redundant, but God too could be effectively dispensed with.

In the 17th century, René Descartes’s dualism of matter and mind was an ingenious solution to the problem this created. ‘The ideas’ that had hitherto been understood as inhering in nature as ‘God’s thoughts’ were rescued from the advancing army of empirical science and withdrawn into the safety of a separate domain, ‘the mind’. On the one hand, this maintained a dimension proper to God, and on the other, served to ‘make the intellectual world safe for Copernicus and Galileo’, as the American philosopher Richard Rorty put it in Philosophy and the Mirror of Nature (1979). In one fell swoop, God’s substance-divinity was protected, while empirical science was given reign over nature-as-mechanism – something ungodly and therefore free game.

Nature was thereby drained of her inner life, rendered a deaf and blind apparatus of indifferent and value-free law, and humankind was faced with a world of inanimate, meaningless matter, upon which it projected its psyche – its aliveness, meaning and purpose – only in fantasy. It was this disenchanted vision of the world, at the dawn of the industrial revolution that followed, that the Romantics found so revolting, and feverishly revolted against.

The French philosopher Michel Foucault in The Order of Things (1966) termed it a shift in ‘episteme’ (roughly, a system of knowledge). The Western psyche, Foucault argued, had once been typified by ‘resemblance and similitude’. In this episteme, knowledge of the world was derived from participation and analogy (the ‘prose of the world’, as he called it), and the psyche was essentially extroverted and world-involved. But after the bifurcation of mind and nature, an episteme structured around ‘identity and difference’ came to possess the Western psyche. The episteme that now prevailed was, in Rorty’s terms, solely concerned with ‘truth as correspondence’ and ‘knowledge as accuracy of representations’. Psyche, as such, became essentially introverted and untangled from the world.

Foucault argued, however, that this move was not a supersession per se, but rather constituted an ‘othering’ of the prior experiential mode. As a result, its experiential and epistemological dimensions were not only denied validity as an experience, but became the ‘occasion of error’. Irrational experience (ie, experience inaccurately corresponding to the ‘objective’ world) then became a meaningless mistake – and disorder the perpetuation of that mistake. This is where Foucault located the beginning of the modern conception of ‘madness’.

Although Descartes’s dualism did not win the philosophical day, we in the West are still very much the children of the disenchanted bifurcation it ushered in. Our experience remains characterised by the separation of ‘mind’ and ‘nature’ instantiated by Descartes. Its present incarnation  – what we might call the empiricist-materialist position  –  not only predominates in academia, but in our everyday assumptions about ourselves and the world. This is particularly clear in the case of mental disorder.

Common notions of mental disorder remain only elaborations of ‘error’, conceived of in the language of ‘internal dysfunction’ relative to a mechanistic world devoid of any meaning and influence. These dysfunctions are either to be cured by psychopharmacology, or remedied by therapy meant to lead the patient to rediscover ‘objective truth’ of the world. To conceive of it in this way is not only simplistic, but highly biased.

While it is true that there is value in ‘normalising’ irrational experiences like this, it comes at a great cost. These interventions work (to the extent that they do) by emptying our irrational experiences of their intrinsic value or meaning. In doing so, not only are these experiences cut off from any world-meaning they might harbour, but so too from any agency and responsibility we or those around us have – they are only errors to be corrected.

In the previous episteme, before the bifurcation of mind and nature, irrational experiences were not just ‘error’ – they were speaking a language as meaningful as rational experiences, perhaps even more so. Imbued with the meaning and rhyme of nature herself, they were themselves pregnant with the amelioration of the suffering they brought. Within the world experienced this way, we had a ground, guide and container for our ‘irrationality’, but these crucial psychic presences vanished along with the withdrawal of nature’s inner life and the move to ‘identity and difference’.

In the face of an indifferent and unresponsive world that neglects to render our experience meaningful outside of our own minds  –  for nature-as-mechanism is powerless to do this  –  our minds have been left fixated on empty representations of a world that was once its source and being. All we have, if we are lucky to have them, are therapists and parents who try to take on what is, in reality, and given the magnitude of the loss, an impossible task.

But I’m not going to argue that we just need to ‘go back’ somehow. On the contrary, the bifurcation of mind and nature was at the root of immeasurable secular progress –  medical and technological advance, the rise of individual rights and social justice, to name just a few. It also protected us all from being bound up in the inherent uncertainty and flux of nature. It gave us a certain omnipotence – just as it gave science empirical control over nature – and most of us readily accept, and willingly spend, the inheritance bequeathed by it, and rightly so.

It cannot be emphasised enough, however, that this history is much less a ‘linear progress’ and much more a dialectic. Just as unified psyche-nature stunted material progress, material progress has now degenerated psyche. Perhaps, then, we might argue for a new swing in this pendulum. Given the dramatic increase in substance-use issues and recent reports of a teenage ‘mental health crisis’ and teen suicide rates rising in the US, the UK and elsewhere to name only the most conspicuous, perhaps the time is in fact overripe.

However, one might ask, by what means? There has been a resurgence of ‘pan-experiential’ and idealist-leaning theories in several disciplines, largely concerned with undoing the very knot of bifurcation and the excommunication of a living nature, and creating in its wake something afresh. This is because attempts at explaining subjective experience in empiricist-materialist terms have all but failed (principally due to what the Australian philosopher David Chalmers in 1995 termed the ‘the hard problem’ of consciousness). The notion that metaphysics is ‘dead’ would in fact be met with very significant qualification in certain quarters – indeed, the Canadian philosopher Evan Thompson et al argued along the same lines in a recent essay in Aeon.

It must be remembered that mental disorder as ‘error’ rises and falls with the empiricist-materialist metaphysics and the episteme it is a product of. Therefore, we might also think it justified to begin to reconceptualise the notion of mental disorder in the same terms as these theories. There has been a decisive shift in psychotherapeutic theory and practice away from the changing of parts or structures of the individual, and towards the idea that it is the very process of the therapeutic encounter itself that is ameliorative. Here, correct or incorrect judgments about ‘objective reality’ start to lose meaning, and psyche as open and organic starts to come back into focus, but the metaphysics remains. We ultimately need to be thinking about mental disorder on a metaphysical level, and not just within the confines of the status quo.Aeon counter – do not remove

James Barnes

This article was originally published at Aeon and has been republished under Creative Commons. Read the original article here.

To Boost your Self-esteem, Write about Chapters of your Life

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New car, 1980s. Photo by Don Pugh/Flickr

Christian Jarrett | Aeon Ideas

In truth, so much of what happens to us in life is random – we are pawns at the mercy of Lady Luck. To take ownership of our experiences and exert a feeling of control over our future, we tell stories about ourselves that weave meaning and continuity into our personal identity. Writing in the 1950s, the psychologist Erik Erikson put it this way:

To be adult means among other things to see one’s own life in continuous perspective, both in retrospect and in prospect … to selectively reconstruct his past in such a way that, step for step, it seems to have planned him, or better, he seems to have planned it.

Alongside your chosen values and goals in life, and your personality traits – how sociable you are, how much of a worrier and so on – your life story as you tell it makes up the final part of what in 2015 the personality psychologist Dan P McAdams at Northwestern University in Illinois called the ‘personological trinity’.

Of course, some of us tell these stories more explicitly than others – one person’s narrative identity might be a barely formed story at the edge of their consciousness, whereas another person might literally write out their past and future in a diary or memoir.

Intriguingly, there’s some evidence that prompting people to reflect on and tell their life stories – a process called ‘life review therapy’ – could be psychologically beneficial. However, most of this work has been on older adults and people with pre-existing problems such as depression or chronic physical illnesses. It remains to be established through careful experimentation whether prompting otherwise healthy people to reflect on their lives will have any immediate benefits.

A relevant factor in this regard is the tone, complexity and mood of the stories that people tell themselves. For instance, it’s been shown that people who tell more positive stories, including referring to more instances of personal redemption, tend to enjoy higher self-esteem and greater ‘self-concept clarity’ (the confidence and lucidity in how you see yourself). Perhaps engaging in writing or talking about one’s past will have immediate benefits only for people whose stories are more positive.

In a recent paper in the Journal of Personality, Kristina L Steiner at Denison University in Ohio and her colleagues looked into these questions and reported that writing about chapters in your life does indeed lead to a modest, temporary self-esteem boost, and that in fact this benefit arises regardless of how positive your stories are. However, there were no effects on self-concept clarity, and many questions on this topic remain for future study.

Steiner’s team tested three groups of healthy American participants across three studies. The first two groups – involving more than 300 people between them – were young undergraduates, most of them female. The final group, a balanced mix of 101 men and women, was recruited from the community, and they were older, with an average age of 62.

The format was essentially the same for each study. The participants were asked to complete various questionnaires measuring their mood, self-esteem and self-concept clarity, among other things. Then half of them were allocated to write about four chapters in their lives, spending 10 minutes on each. They were instructed to be as specific and detailed as possible, and to reflect on main themes, how each chapter related to their lives as a whole, and to think about any causes and effects of the chapter on them and their lives. The other half of the participants, who acted as a control group, spent the same time writing about four famous Americans of their choosing (to make this task more intellectually comparable, they were also instructed to reflect on the links between the individuals they chose, how they became famous, and other similar questions). After the writing tasks, all the participants retook the same psychological measures they’d completed at the start.

The participants who wrote about chapters in their lives displayed small, but statistically significant, increases to their self-esteem, whereas the control-group participants did not. This self-esteem boost wasn’t explained by any changes to their mood, and – to the researchers’ surprise – it didn’t matter whether the participants rated their chapters as mostly positive or negative, nor did it depend on whether they featured themes of agency (that is, being in control) and communion (pertaining to meaningful relationships). Disappointingly, there was no effect of the life-chapter task on self-concept clarity, nor on meaning and identity.

How long do the self-esteem benefits of the life-chapter task last, and might they accumulate by repeating the exercise? Clues come from the second of the studies, which involved two life chapter-writing tasks (and two tasks writing about famous Americans for the control group), with the second task coming 48 hours after the first. The researchers wanted to see if the self-esteem boost arising from the first life-chapter task would still be apparent at the start of the second task two days later – but it wasn’t. They also wanted to see if the self-esteem benefits might accumulate over the two tasks – they didn’t (the second life-chapter task had its own self-esteem benefit, but it wasn’t cumulative with the benefits of the first).

It remains unclear exactly why the life-chapter task had the self-esteem benefits that it did. It’s possible that the task led participants to consider how they had changed in positive ways. They might also have benefited from expressing and confronting their emotional reactions to these periods of their lives – this would certainly be consistent with the well-documented benefits of expressive writing and ‘affect labelling’ (the calming effect of putting our emotions into words). Future research will need to compare different life chapter-writing instructions to tease apart these different potential beneficial mechanisms. It would also be helpful to test more diverse groups of participants and different ‘dosages’ of the writing task to see if it is at all possible for the benefits to accrue over time.

The researchers said: ‘Our findings suggest that the experience of systematically reviewing one’s life and identifying, describing and conceptually linking life chapters may serve to enhance the self, even in the absence of increased self-concept clarity and meaning.’ If you are currently lacking much confidence and feel like you could benefit from an ego boost, it could be worth giving the life-chapter task a go. It’s true that the self-esteem benefits of the exercise were small, but as Steiner’s team noted, ‘the costs are low’ too.Aeon counter – do not remove

Christian Jarrett

This article was originally published at Aeon and has been republished under Creative Commons. Read the original article here.

Is Consciousness a Battle between your Beliefs and Perceptions?

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Now you see it… Magician Harry Houdini moments before ‘disappearing’ Jennie the 10,000lb elephant at the Hippodrome, New York, in 1918. Photo courtesy Library of Congress

Hakwan Lau | Aeon Ideas

Imagine you’re at a magic show, in which the performer suddenly vanishes. Of course, you ultimately know that the person is probably just hiding somewhere. Yet it continues to look as if the person has disappeared. We can’t reason away that appearance, no matter what logic dictates. Why are our conscious experiences so stubborn?

The fact that our perception of the world appears to be so intransigent, however much we might reflect on it, tells us something unique about how our brains are wired. Compare the magician scenario with how we usually process information. Say you have five friends who tell you it’s raining outside, and one weather website indicating that it isn’t. You’d probably just consider the website to be wrong and write it off. But when it comes to conscious perception, there seems to be something strangely persistent about what we see, hear and feel. Even when a perceptual experience is clearly ‘wrong’, we can’t just mute it.

Why is that so? Recent advances in artificial intelligence (AI) shed new light on this puzzle. In computer science, we know that neural networks for pattern-recognition – so-called deep learning models – can benefit from a process known as predictive coding. Instead of just taking in information passively, from the bottom up, networks can make top-down hypotheses about the world, to be tested against observations. They generally work better this way. When a neural network identifies a cat, for example, it first develops a model that allows it to predict or imagine what a cat looks like. It can then examine any incoming data that arrives to see whether or not it fits that expectation.

The trouble is, while these generative models can be super efficient once they’re up and running, they usually demand huge amounts of time and information to train. One solution is to use generative adversarial networks (GANs) – hailed as the ‘coolest idea in deep learning in the last 20 years’ by Facebook’s head of AI research Yann LeCun. In GANs, we might train one network (the generator) to create pictures of cats, mimicking real cats as closely as it can. And we train another network (the discriminator) to distinguish between the manufactured cat images and the real ones. We can then pit the two networks against each other, such that the discriminator is rewarded for catching fakes, while the generator is rewarded for getting away with them. When they are set up to compete, the networks grow together in prowess, not unlike an arch art-forger trying to outwit an art expert. This makes learning very efficient for each of them.

As well as a handy engineering trick, GANs are a potentially useful analogy for understanding the human brain. In mammalian brains, the neurons responsible for encoding perceptual information serve multiple purposes. For example, the neurons that fire when you see a cat also fire when you imagine or remember a cat; they can also activate more or less at random. So whenever there’s activity in our neural circuitry, the brain needs to be able to figure out the cause of the signals, whether internal or external.

We can call this exercise perceptual reality monitoring. John Locke, the 17th-century British philosopher, believed that we had some sort of inner organ that performed the job of sensory self-monitoring. But critics of Locke wondered why Mother Nature would take the trouble to grow a whole separate organ, on top of a system that’s already set up to detect the world via the senses. You have to be able to smell something before you can go about deciding whether or not the perception is real or fake; so why not just build in a check to the detecting mechanism itself?

In light of what we now know about GANs, though, Locke’s idea makes a certain amount of sense. Because our perceptual system takes up neural resources, parts of it get recycled for different uses. So imagining a cat draws on the same neuronal patterns as actually seeing one. But this overlap muddies the water regarding the meaning of the signals. Therefore, for the recycling scheme to work well, we need a discriminator to decide when we are seeing something versus when we’re merely thinking about it. This GAN-like inner sense organ – or something like it – needs to be there to act as an adversarial rival, to stimulate the growth of a well-honed predictive coding mechanism.

If this account is right, it’s fair to say that conscious experience is probably akin to a kind of logical inference. That is, if the perceptual signal from the generator says there is a cat, and the discriminator decides that this signal truthfully reflects the state of the world right now, we naturally see a cat. The same goes for raw feelings: pain can feel sharp, even when we know full well that nothing is poking at us, and patients can report feeling pain in limbs that have already been amputated. To the extent that the discriminator gets things right most of the time, we tend to trust it. No wonder that when there’s a conflict between subjective impressions and rational beliefs, it seems to make sense to believe what we consciously experience.

This perceptual stubbornness is not just a feature of humans. Some primates have it too, as shown by their capacity to be amazed and amused by magic tricks. That is, they seem to understand that there’s a tension between what they’re seeing and what they know to be true. Given what we understand about their brains – specifically, that their perceptual neurons are also ‘recyclable’ for top-down functioning – the GAN theory suggests that these nonhuman animals probably have conscious experiences not dissimilar to ours.

The future of AI is more challenging. If we built a robot with a very complex GAN-style architecture, would it be conscious? On the basis of our theory, it would probably be capable of predictive coding, exercising the same machinery for perception as it deploys for top-down prediction or imagination. Perhaps like some current generative networks, it could ‘dream’. Like us, it probably couldn’t reason away its pain – and it might even be able to appreciate stage magic.

Theorising about consciousness is notoriously hard, and we don’t yet know what it really consists in. So we wouldn’t be in a position to establish if our robot was truly conscious. Then again, we can’t do this with any certainty with respect to other animals either. At least by fleshing out some conjectures about the machinery of consciousness, we can begin
to test them against our intuitions – and, more importantly, in experiments. What we do know is that a model of the mind involving an inner mechanism of doubt – a nit-picking system that’s constantly on the lookout for fakes and forgeries in perception – is one of the most promising ideas we’ve come up with so far.

Hakwan Lau

This article was originally published at Aeon and has been republished under Creative Commons. Read the original article here.

The Matrix 20 Years On: How a Sci-fi Film Tackled Big Philosophical Questions

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The Matrix was a box office hit, but it also explored some of western philosophy’s most interesting themes.
HD Wallpapers Desktop/Warner Bros

Richard Colledge, Australian Catholic University

Incredible as it may seem, the end of March marks 20 years since the release of the first film in the Matrix franchise directed by The Wachowski siblings. This “cyberpunk” sci-fi movie was a box office hit with its dystopian futuristic vision, distinctive fashion sense, and slick, innovative action sequences. But it was also a catalyst for popular discussion around some very big philosophical themes.

The film centres on a computer hacker, “Neo” (played by Keanu Reeves), who learns that his whole life has been lived within an elaborate, simulated reality. This computer-generated dream world was designed by an artificial intelligence of human creation, which industrially farms human bodies for energy while distracting them via a relatively pleasant parallel reality called the “matrix”.

‘Have you ever had a dream, Neo, that you were so sure was real?’

This scenario recalls one of western philosophy’s most enduring thought experiments. In a famous passage from Plato’s Republic (ca 380 BCE), Plato has us imagine the human condition as being like a group of prisoners who have lived their lives underground and shackled, so that their experience of reality is limited to shadows projected onto their cave wall.


Read more:
The great movie scenes: The Matrix and bullet-time


A freed prisoner, Plato suggests, would be startled to discover the truth about reality, and blinded by the brilliance of the sun. Should he return below, his companions would have no means to understand what he has experienced and surely think him mad. Leaving the captivity of ignorance is difficult.

In The Matrix, Neo is freed by rebel leader Morpheus (ironically, the name of the Greek God of sleep) by being awoken to real life for the first time. But unlike Plato’s prisoner, who discovers the “higher” reality beyond his cave, the world that awaits Neo is both desolate and horrifying.

Our Fallible Senses

The Matrix also trades on more recent philosophical questions famously posed by the 17th century Frenchman René Descartes, concerning our inability to be certain about the evidence of our senses, and our capacity to know anything definite about the world as it really is.

Descartes even noted the difficulty of being certain that human experience is not the result of either a dream or a malevolent systematic deception.

The latter scenario was updated in philosopher Hilary Putnam’s 1981 “brain in a vat” thought experiment, which imagines a scientist electrically manipulating a brain to induce sensations of normal life.


Read more:
How do you know you’re not living in a computer simulation?


So ultimately, then, what is reality? The late 20th century French thinker Jean Baudrillard, whose book appears briefly (with an ironic touch) early in the film, wrote extensively on the ways in which contemporary mass society generates sophisticated imitations of reality that become so realistic they are mistaken for reality itself (like mistaking the map for the landscape, or the portrait for the person).

Of course, there is no need for a matrix-like AI conspiracy to achieve this. We see it now, perhaps even more intensely than 20 years ago, in the dominance of “reality TV” and curated identities of social media.

In some respects, the film appears to be reaching for a view close to that of the 18th century German philosopher, Immanuel Kant, who insisted that our senses do not simply copy the world; rather, reality conforms to the terms of our perception. We only ever experience the world as it is available through the partial spectrum of our senses.

The Ethics of Freedom

Ultimately, the Matrix trilogy proclaims that free individuals can change the future. But how should that freedom be exercised?

This dilemma is unfolded in the first film’s increasingly notorious red/blue pill scene, which raises the ethics of belief. Neo’s choice is to embrace either the “really real” (as exemplified by the red pill he is offered by Morpheus) or to return to his more normal “reality” (via the blue one).

This quandary was captured in a 1974 thought experiment by American philosopher, Robert Nozick. Given an “experience machine” capable of providing whatever experiences we desire, in a way indistinguishable from “real” ones, should we stubbornly prefer the truth of reality? Or can we feel free to reside within comfortable illusion?


Read more:
Why virtual reality cannot match the real thing


In The Matrix we see the rebels resolutely rejecting the comforts of the matrix, preferring grim reality. But we also see the rebel traitor Cypher (Joe Pantoliano) desperately seeking reinsertion into pleasant simulated reality. “Ignorance is bliss,” he affirms.

The film’s chief villain, Agent Smith (Hugo Weaving), darkly notes that unlike other mammals, (western) humanity insatiably consumes natural resources. The matrix, he suggests, is a “cure” for this human “contagion”.

We have heard much about the potential perils of AI, but perhaps there is something in Agent Smith’s accusation. In raising this tension, The Matrix still strikes a nerve – especially after 20 further years of insatiable consumption.The Conversation

Richard Colledge, Senior Lecturer & Head of School of Philosophy, Australian Catholic University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Climate Strikes: Researcher explains how Young People can Keep up the Momentum

Harriet Thew, University of Leeds

As part of one of the largest environmental protests ever seen, over a million young people went on strike on Friday March 15 2019, calling for more ambitious action on climate change. Inspired by Greta Thunberg, a Swedish school girl who protested outside the Swedish parliament every Friday throughout 2018, young people in over 100 countries left their classrooms and took to the streets.

The previous #YouthStrike4Climate on February 15 2019 mobilised over 10,000 young people in over 40 locations in the UK alone. Their marches, chants and signs captured attention and prompted debates regarding the motivations and methods of young strikers. Many were criticised by those in the government and the media for simply wanting an opportunity to miss school.

My PhD research explores youth participation in climate change governance, focusing on the UN climate negotiations. Between 2015 and 2018 I closely studied the Youth Climate Coalition (UKYCC) – a UK based, voluntary, youth-led group of 18 to 29 year olds – which attends the international negotiations and coordinates local and national climate change campaigns.

Members of the UK Youth Climate Coalition protest in London.
Harriet Thew, Author provided

My research shows that young people are mobilised by concern for people and wildlife, fears for the future and anger that climate action is neither sufficiently rapid nor ambitious. Young people need to feel as though they are “doing something” about climate change while politicians dither and scientists release increasingly alarming projections of future climate conditions.

The strikes have helped young activists find like-minded peers and new opportunities to engage. They articulate a collective youth voice, wielding the moral power of young people – a group which society agrees it is supposed to protect. All the same, there are threats to sustaining the movement’s momentum which need to be recognised now.

Challenge misplaced paternalism

The paternalism that gives youth a moral platform is a double-edged sword. Patronising responses from adults in positions of authority, from head teachers to the prime minister, dismiss their scientifically informed concerns and attack the messenger, rather than dealing with the message itself.

You’re too young to understand the complexity of this.

You’ll grow out of these beliefs.

You just want to skip school.

Stay in school and wait your turn to make a difference.

Striking may hurt your future job prospects.

The list goes on …

This frightens some children and young people into silence, but doesn’t address the factors which mobilised them in the first place. These threats are also largely unfounded.


Read more:
Climate change: a climate scientist answers questions from teenagers


To any young person reading this, I want to reassure you, as a university educator, that critical thinking, proactivity and an interest in current affairs are qualities that universities encourage. Over 200 academics signed this open letter – myself included – showing our support for the school strikes.

Don’t ‘grow up’

Growing up is inevitable, but it can cause problems for youth movements. As young people gain experience of climate action and expand their professional networks, they “grow out of” being able to represent youth, often getting jobs to advocate for other groups or causes. While this can be positive for individuals, institutional memory is lost when experienced advocates move on to do other things. This puts youth at a disadvantage in relation to other groups who are better resourced and don’t have a “time limit” in how long they can represent their cause.

Well-established youth organisations, such as Guides and Scouts, whom I have worked with in the past, can use their large networks and professional experience to sustain youth advocacy on climate change, though they lack the resources to do so alone. It would also help for other campaigners to show solidarity with the young strikers, and to recognise youth as an important group in climate change debates. This will give people more opportunity to keep supporting the youth climate movement as they get older.

Grow the climate justice movement

Researching the same group of young people for three years, I have identified a shift in their attitudes over time. As young participants become more involved in the movement, they encounter different types of injustices voiced by other groups. They hear activists sharing stories of the devastating climate impacts already experienced by communities, in places where sea level rise is inundating homes and droughts are killing livestock and causing starvation.

The climate justice movement emphasises how climate change exacerbates racial and economic inequality but frequently overlooks the ways these inequalities intersect with age-based disadvantages. Forgetting that frontline communities contain young people, youth movements in developed countries like the UK begin to question the validity of their intergenerational injustice claims.

Indigenous people often inhabit the frontline of impacts from pollution and climate change.
Rainforest Action Network/Flickr, CC BY-NC

Many feel ashamed for having claimed vulnerability, given their relatively privileged position. Over time, they lose faith in their right to be heard. It would strengthen the entire climate movement if other climate justice campaigners more vocally acknowledged young people as a vulnerable group and shared their platform so that these important voices could better amplify one another.

With my own platform, I would like to say this to the thousands who went on strike. You matter. You have a right to be heard and you shouldn’t be embarrassed to speak out. Have confidence in your message, engage with others but stay true to your principles. Stick together and remember that even when you leave school and enter work – you’re never too old to be a youth advocate.

Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.The Conversation

Harriet Thew, PhD Researcher in Climate Change Governance, University of Leeds

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Concept of Probability is not as Simple as You Think

probability

Phil Long/Flickr

Nevin Climenhaga | Aeon Ideas

The gambler, the quantum physicist and the juror all reason about probabilities: the probability of winning, of a radioactive atom decaying, of a defendant’s guilt. But despite their ubiquity, experts dispute just what probabilities are. This leads to disagreements on how to reason about, and with, probabilities – disagreements that our cognitive biases can exacerbate, such as our tendency to ignore evidence that runs counter to a hypothesis we favour. Clarifying the nature of probability, then, can help to improve our reasoning.

Three popular theories analyse probabilities as either frequencies, propensities or degrees of belief. Suppose I tell you that a coin has a 50 per cent probability of landing heads up. These theories, respectively, say that this is:

  • The frequency with which that coin lands heads;
  • The propensity, or tendency, that the coin’s physical characteristics give it to land heads;
  • How confident I am that it lands heads.

But each of these interpretations faces problems. Consider the following case:

Adam flips a fair coin that self-destructs after being tossed four times. Adam’s friends Beth, Charles and Dave are present, but blindfolded. After the fourth flip, Beth says: ‘The probability that the coin landed heads the first time is 50 per cent.’

Adam then tells his friends that the coin landed heads three times out of four. Charles says: ‘The probability that the coin landed heads the first time is 75 per cent.’

Dave, despite having the same information as Charles, says: ‘I disagree. The probability that the coin landed heads the first time is 60 per cent.’

The frequency interpretation struggles with Beth’s assertion. The frequency with which the coin lands heads is three out of four, and it can never be tossed again. Still, it seems that Beth was right: the probability that the coin landed heads the first time is 50 per cent.

Meanwhile, the propensity interpretation falters on Charles’s assertion. Since the coin is fair, it had an equal propensity to land heads or tails. Yet Charles also seems right to say that the probability that the coin landed heads the first time is 75 per cent.

The confidence interpretation makes sense of the first two assertions, holding that they express Beth and Charles’s confidence that the coin landed heads. But consider Dave’s assertion. When Dave says that the probability that the coin landed heads is 60 per cent, he says something false. But if Dave really is 60 per cent confident that the coin landed heads, then on the confidence interpretation, he has said something true – he has truly reported how certain he is.

Some philosophers think that such cases support a pluralistic approach in which there are multiple kinds of probabilities. My own view is that we should adopt a fourth interpretation – a degree-of-support interpretation.

Here, probabilities are understood as relations of evidential support between propositions. ‘The probability of X given Y’ is the degree to which Y supports the truth of X. When we speak of ‘the probability of X’ on its own, this is shorthand for the probability of X conditional on any background information we have. When Beth says that there is a 50 per cent probability that the coin landed heads, she means that this is the probability that it lands heads conditional on the information that it was tossed and some information about its construction (for example, it being symmetrical).

Relative to different information, however, the proposition that the coin landed heads has a different probability. When Charles says that there is a 75 per cent probability that the coin landed heads, he means this is the probability that it landed heads relative to the information that three of four tosses landed heads. Meanwhile, Dave says there is a 60 per cent probability that the coin landed heads, relative to this same information – but since this information in fact supports heads more strongly than 60 per cent, what Dave says is false.

The degree-of-support interpretation incorporates what’s right about each of our first three approaches while correcting their problems. It captures the connection between probabilities and degrees of confidence. It does this not by identifying them – instead, it takes degrees of belief to be rationally constrained by degrees of support. The reason I should be 50 per cent confident that a coin lands heads, if all I know about it is that it is symmetrical, is because this is the degree to which my evidence supports this hypothesis.

Similarly, the degree-of-support interpretation allows the information that the coin landed heads with a 75 per cent frequency to make it 75 per cent probable that it landed heads on any particular toss. It captures the connection between frequencies and probabilities but, unlike the frequency interpretation, it denies that frequencies and probabilities are the same thing. Instead, probabilities sometimes relate claims about frequencies to claims about specific individuals.

Finally, the degree-of-support interpretation analyses the propensity of the coin to land heads as a relation between, on the one hand, propositions about the construction of the coin and, on the other, the proposition that it lands heads. That is, it concerns the degree to which the coin’s construction predicts the coin’s behaviour. More generally, propensities link claims about causes and claims about effects – eg, a description of an atom’s intrinsic characteristics and the hypothesis that it decays.

Because they turn probabilities into different kinds of entities, our four theories offer divergent advice on how to figure out the values of probabilities. The first three interpretations (frequency, propensity and confidence) try to make probabilities things we can observe – through counting, experimentation or introspection. By contrast, degrees of support seem to be what philosophers call ‘abstract entities’ – neither in the world nor in our minds. While we know that a coin is symmetrical by observation, we know that the proposition ‘this coin is symmetrical’ supports the propositions ‘this coin lands heads’ and ‘this coin lands tails’ to equal degrees in the same way we know that ‘this coin lands heads’ entails ‘this coin lands heads or tails’: by thinking.

But a skeptic might point out that coin tosses are easy. Suppose we’re on a jury. How are we supposed to figure out the probability that the defendant committed the murder, so as to see whether there can be reasonable doubt about his guilt?

Answer: think more. First, ask: what is our evidence? What we want to figure out is how strongly this evidence supports the hypothesis that the defendant is guilty. Perhaps our salient evidence is that the defendant’s fingerprints are on the gun used to kill the victim.

Then, ask: can we use the mathematical rules of probability to break down the probability of our hypothesis in light of the evidence into more tractable probabilities? Here we are concerned with the probability of a cause (the defendant committing the murder) given an effect (his fingerprints being on the murder weapon). Bayes’s theorem lets us calculate this as a function of three further probabilities: the prior probability of the cause, the probability of the effect given this cause, and the probability of the effect without this cause.

Since this is all relative to any background information we have, the first probability (of the cause) is informed by what we know about the defendant’s motives, means and opportunity. We can get a handle on the third probability (of the effect without the cause) by breaking down the possibility that the defendant is innocent into other possible causes of the victim’s death, and asking how probable each is, and how probable they make it that the defendant’s fingerprints would be on the gun. We will eventually reach probabilities that we cannot break down any further. At this point, we might search for general principles to guide our assignments of probabilities, or we might rely on intuitive judgments, as we do in the coin cases.

When we are reasoning about criminals rather than coins, this process is unlikely to lead to convergence on precise probabilities. But there’s no alternative. We can’t resolve disagreements about how much the information we possess supports a hypothesis just by gathering more information. Instead, we can make progress only by way of philosophical reflection on the space of possibilities, the information we have, and how strongly it supports some possibilities over others.Aeon counter – do not remove

Nevin Climenhaga

This article was originally published at Aeon and has been republished under Creative Commons. Read the original article here.

Does Microdosing Improve your Mood and Performance? Here’s what the Research Says

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Microdosers take such small quantities of psychedelic substances that there are no noticeable effects.
By AppleZoomZoom

Vince Polito, Macquarie University

Microdosing means regularly taking very small doses of psychedelic substances such as LSD or psilocybin (magic mushrooms) over a period of weeks or months. The practice has made countless headlines over the past couple of years, with claims it can improve health, strengthen relationships, and increase productivity.

These claims are surprising because microdosers take doses so small there are no noticeable effects. These can be just 1/20th of a typical recreational dose, often every three or four days. With such small amounts, microdosers go about their daily business, including going to work, without experiencing any typical drug effects.

Previous research suggests microdosing may lead to better mood and energy levels, improved creativity, increased wisdom, and changes to how we perceive time.


Read more:
LSD ‘microdosing’ is trending in Silicon Valley – but can it actually make you more creative?


But these previous studies have mainly involved asking people to complete ratings or behavioural tasks as one-off measures.

Our study, published today in PLOS One, tracked the experience of 98 users over a longer period – six weeks – to systematically measure any psychological changes.

Overall, the participants reported both positive and negative effects from microdosing, including improved attention and mental health; but also more neuroticism.

What we did

As you would expect, there are many legal and bureaucratic barriers to psychedelic research. It wasn’t possible for us to run a study where we actually provided participants with psychedelic substances. Instead, we tried to come up with the most rigorous design possible in the current restrictive legal climate.

Our solution was to recruit people who were already experimenting with microdosing and to track their experiences carefully over time, using well validated and reliable psychometric measures.

Microdosers go about their lives without any typical drug effects.
Parker Byrd

Each day we asked participants to complete some brief ratings, telling us whether they had microdosed that day and describing their overall experience. This let us track the immediate effects of microdosing.

At the beginning and end of the study participants completed a detailed battery of psychological measures. This let us track the longer-term effects of microdosing.

In a separate sample, we explored the beliefs and expectations of people who are interested in microdosing. This let us track whether any changes in our main sample were aligned with what people generally predict will happen when microdosing.

What we found

There are five key findings from our study.

1. A general positive boost on microdosing days, but limited residual effects of each dose.

Many online accounts of microdosing suggest people microdose every three or four days. The thinking is that each microdose supposedly has a residual effect that lasts for a few days.

The daily ratings from participants in our study do not support this idea. Participants reported an immediate boost in all measures (connectedness, contemplation, creativity, focus, happiness, productiveness and wellness) on dosing days. But this was mostly not maintained on the following days.

However, there was some indication of a slight rebound in feelings of focus and productivity two days after dosing.

Microdosers experienced increased focus.
Rawpixel

2. Some indications of improvements in mental health

We also looked at cumulative effects of longer term microdosing. We found that after six weeks, participants reported lower levels of depression and stress.

We recruited people who were not experiencing any kind of mental illness for the study, so levels of depression and stress were relatively low to begin with. Nevertheless, ratings on these measures did drop.

This is an intriguing finding but it’s not clear from this result whether microdosing would have any effect on more significant levels of mood disturbance.

3. Shifts in attention

The microdosers in our study reported reduced mind wandering, meaning they were less likely to be distracted by unwanted thoughts.

They also reported an increase in absorption, meaning they were more likely to experience intense focused attention on imaginative experiences. Absorption has been linked to strong engagement with art and nature.

4. Increases in neuroticism and some challenging experiences

Not everyone had a good time microdosing. Some participants reported unpleasant and difficult experiences. In some cases, participants tried microdosing just once or twice, then didn’t want to continue.

Overall, participants reported a small increase in neuroticism after six weeks of microdosing, indicating an increase in the frequency of unpleasant emotions.

5. Changes do not entirely match people’s expectations

People have strong expectations about the effects of microdosing. But when we looked at the specific variables participants most expected would change, these didn’t match up with the changes actually reported by our microdosers.

Two of the biggest changes microdosers expected were increases in creativity and life satisfaction, but we found no evidence of shifts in these areas. This suggests the changes we found were not simply due to people’s expectations.

What does it all mean?

This complex set of findings is not what’s typically reported in media stories and online discussions of microdosing. There are promising indications of possible benefits of microdosing here, but also indications of some potential negative impacts, which should be taken seriously.


Read more:
Opening up the future of psychedelic science


It’s important to remember this was an observational study that relied heavily on the accuracy and honesty of participants in their reports. As such, these results need to be treated cautiously.

It’s early days for microdosing research and this work shows that we need to look more carefully at the effects of low dose psychedelics on mental health, attention, and neuroticism.The Conversation

Vince Polito, Postdoctoral Research Fellow in Cognitive Science, Macquarie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How Seeing Snakes in the Grass Helped Primates to Evolve

snake

Phrynonax poecilonotus, Wikipedia


Lynne A Isbell | Aeon Ideas

Evolution has favoured the modification and expansion of primate vision. Compared with other mammals, primates have, for example, greater depth perception from having forward-facing eyes with extensively overlapping visual fields, sharper visual acuity, more areas in the brain that are involved with vision, and, in some primates, trichromatic colour vision, which enables them to distinguish red from green hues. In fact, what separates primates from other mammals most is their much greater reliance on vision as the main sensory interface with the environment.

Vision is a window onto the world, its qualities determined by natural selection and the constraints of both animals’ bodies and the environments in which they live. Despite their long, shared evolutionary history, mammals don’t all see the world in the same way because they inhabit a variety of niches with different selective pressures. What were those selective pressures for primates, our lineage, that led to their having visual systems more expansive and more complex than those of other mammals?

In 2006, I published a new idea that could answer that question and more: the ‘snake detection theory’. I hypothesised that when large-gaped constricting snakes appeared about 100 million years ago and began eating mammals, their predatory behaviour favoured the evolution of changes in the vision of one kind of prey, the lineage that was to become primates. In other words, the ability to see immobile predatory snakes before getting too close became a highly beneficial trait for them to have and pass on to their descendants. Then, about 60 million years ago, venomous snakes appeared in Africa or Asia, adding more pressure on primates to detect and avoid them. This has also had repercussions on their visual systems.

There is a consistency between the degree of complexity in primate visual systems and the length of evolutionary time that primates have spent with venomous snakes. At one extreme, the lineage that comprises Old World monkeys, apes and humans has the best vision of all primates, including excellent visual acuity and fully trichromatic colour vision. Having evolved roughly at the same time and in the same place as venomous snakes, these primates have had continuous coexistence with them. They are also uniformly wary of snakes.

At the opposite end of the spectrum, Malagasy primates have the simplest visual systems. Among other things, they have low visual acuity because the fovea, a depression in the retina that is responsible for our visual acuity wherever we focus our eyes, is poorly developed (when it’s present at all). Although Madagascar has constricting snakes, it has no venomous snakes, so primates on that island never had to face that particular selective pressure. Behavioural evidence also reveals that they don’t all react fearfully toward snakes. Some can even walk on snakes or snake models, treating them as if they’re just another branch.

The visual systems of New World monkeys are in the middle. They have better visual acuity than Malagasy primates but more variability in their visual systems than Old World monkeys. For example, New World howler monkeys are all trichromatic, but in other New World primate species, only some individuals are able to distinguish red from green hues. New World primates were originally part of the anthropoid primate lineage in Africa that also includes Old World monkeys and apes, and so had to deal with venomous snakes for about 20-25 million years, but then, some 36 million years ago, they left Africa and arrived in South America where venomous snakes were not present until roughly 15 million years later. By then, New World monkeys had begun to diversify into different genera, and so each genus evolved separate solutions to the renewed problem caused by the arrival again of venomous snakes. As far as I know, no other explanation for the variation in their visual systems exists.

Since I proposed the snake detection theory, several studies have shown that nonhuman and human primates, including young children and snake-naive infants, have a visual bias toward snakes compared with other animate objects, such as lizards, spiders, worms, birds and flowers. Psychologists have discovered that we pick out images of snakes faster or more accurately than other objects, especially under cluttered or obscuring conditions that resemble the sorts of environments in which snakes are typically found. Snakes also distract us from finding other objects as quickly. Our ability to detect snakes faster is also more pronounced when we have less time to detect them and when they are in our periphery. Moreover, our ‘primary visual area’ in the back of the brain shows stronger electrophysiological responses to images of snakes than of lizards 150-300 milliseconds after people see the images, providing a measurable physical correlate of our greater visual bias toward them.

Since vision is mostly in the brain, we need to turn to neuroscience to understand the mechanisms for our visual bias toward snakes. All vertebrates have a visual system that allows them to distinguish potential predators from potential prey. This is a nonconscious visual system that involves only subcortical structures, including those that in mammals are called the superior colliculus and the pulvinar, and it allows for very fast visual detection and response. When an animal sees a predator, this nonconscious visual system also taps directly into motor responses such as freezing and darting.

As vertebrates, mammals have this nonconscious visual system, but they have also incorporated vision into the neocortex. No other animals have a neocortex. This somewhat slower, conscious visual system allows mammals to become cognizant of objects for what they really are. The first neocortical stop is the primary visual area, which is particularly sensitive to edges and lines of different orientations.

In a breakthrough study, a team of neuroscientists probed the responses of individual neurons in the pulvinar of Japanese macaques as they were shown images of snakes, faces of monkeys, hands of monkeys, and simple geometric shapes. Sure enough, many pulvinar neurons responded more strongly and more quickly to snakes than to the other images. The snake-sensitive neurons were found in a subsection of the pulvinar that is connected to a part of the superior colliculus involved in defensive motor behaviour such as freezing and darting, and to the amygdala, a subcortical structure involved in mediating fear responses. Among all mammals, the lineage with the greatest evolutionary exposure to venomous snakes, the anthropoid monkeys, apes and humans, also have the largest pulvinar. This makes perfect sense in the context of the snake detection theory.

What is it about snakes that makes them so attention-grabbing to us? Naturally, we use all the cues available (such as body shape and leglessness) but it’s their scales that should be the most reliable, because a little patch of snake might be all we have to go on. Indeed, wild vervet monkeys in Africa, for instance, are able with their superb visual acuity to detect just an inch of snake skin within a minute of coming near it. In people, electrophysiological responses in the primary visual area reveal greater early visual attention to snake scales compared with lizard skins and bird feathers. Again, the primary visual area is highly sensitive to edges and lines of different orientations, and snake skins with their spades offer these visual cues in spades.

The snake detection theory takes our seemingly contradictory attitudes about snakes and makes sense of them as a cohesive whole. Our long evolutionary exposure to snakes explains why ophiophobia is humanity’s most-reported phobia but also why our attraction and attention to snakes is so strong that we have even included them prominently in our religions and folklore. Most importantly, by recognising that our vision and our behaviour have been shaped by millions of years of interactions with another type of animal, we admit our close relationship with nature. We have not been above or outside nature as we might like to think, but have always been fully a part of it.Aeon counter – do not remove


Lynne A Isbell is professor of anthropology at the University of California, Davis. She is the author of The Fruit, the Tree, and the Serpent: Why We See So Well (2009). She is interested in primate behaviour and ecology.

This article was originally published at Aeon and has been republished under Creative Commons. Visit the original article here.