Two Americas

I've been trying to dial down MindBlog's mention of our current domestic turmoil and debate, but I can't resist passing on this clip from Krugman's recent piece that gives one succinct summary of our quandry:

Since the 1980s America has experienced growing regional divergence. We have become a knowledge economy driven by industries that rely on a highly educated work force, and firms in those industries, it turns out, want to be located in places where there are a lot of highly educated workers already — places like the Bay Area.

Unfortunately, most of these rising knowledge-industry hubs also severely limit housing construction; this is true even of greater New York, which is much denser than any other U.S. metropolitan area but could and should be even denser. As a result, housing prices in these metros have soared, and working-class families, instead of sharing in regional success, are being driven out.

The result is that there are now, in effect, two Americas: the America of high-tech, high-income enclaves that are unaffordable for the less affluent, and the rest of the country.

And this economic divergence goes along with political divergence, mainly because education has become a prime driver of political affiliation.

It may seem hard to believe now, but as recently as the early 2000s college graduates leaned Republican. Since then, however, highly educated voters — who have presumably been turned off by the G.O.P.’s embrace of culture wars and its growing anti-intellectualism — have become overwhelmingly Democratic, while non-college-educated whites have gone the other way.

As a result, the two Americas created by the collision of the knowledge economy and NIMBYism correspond fairly closely to the blue-red division: Democratic-voting districts have seen a big rise in incomes, while G.O.P. districts have been left behind:

 

NPR's "Joy Generator"

Try this antidote if you have the Sunday blahs.

Douthat's Guide to Finding Faith

I recommend that you read through Douthat's elegant exposition of the continuing relevance of some form of religious faith. I paste in below a few clips that particularly struck me.....

The great project of modern physics...has repeatedly confirmed the strange fittedness of our universe to human life. If science has discredited certain specific ideas about how God structured the natural world, it has also made the mathematical beauty of physical laws, as well as their seeming calibration for the emergence of life, much clearer to us than they were to people 500 years ago.

...The remarkable advances of neuroscience have only sharpened...the difficulty of figuring out how physical processes alone could create the lived reality of conscious life...So notable is the failure to discover consciousness in our dissected tissue that certain materialists, like Dennett, have fastened onto the idea that both conscious experience and selfhood must be essentially illusions...This idea, no less than the belief in a multiverse of infinite realities, requires a leap of faith. Both seem less parsimonious, less immediately reasonable, than a traditional religious assumption that mind precedes matter, as the mind of God precedes the universe — that the precise calibrations of physical reality and the irreducibility of personal experience are proof that consciousness came first.

..the God hypothesis is constantly vindicated by the comprehensibility of the universe, and the capacity of our reason to unlock its many secrets. Indeed, there’s a quietly theistic assumption to the whole scientific project. As David Bentley Hart puts it in his book “The Experience of God,” “We assume that the human mind can be a true mirror of objective reality because we assume that objective reality is already a mirror of mind.”

...when today’s evolutionary theorists go searching for a reason people believe so readily in spiritual powers and nonhuman minds, they are also making a concession to religion’s plausibility — because most of our evolved impulses and appetites correspond directly to something in reality itself...Of course, religion could be the exception: a desire with no real object, a set of experiences with no correlate outside the mind, sustained by a combination of wishful thinking, the desire of mortal creatures to believe in the imperishable and the inevitability of what debunkers of supernatural fraud sometimes call “residua,” the slice of strange events that lie outside our current scope of explanation.

...the world in 2021, no less than the world in 1521 or 321, presents considerable evidence of an originating intelligence presiding over a law-bound world well made for our minds to understand, and at the same time a panoply of spiritual forces that seem to intervene unpredictably in our existence.

That combination corresponds reasonably well to the cosmology on offer in many major world religions, from Christianity with its creator God who exists outside of space and time and its ministering angels and interceding saints, to Hinduism with its singular divinity finding embodiment in a pantheon of gods. Almost as if the old faiths had a somewhat plausible grasp on reality all along.

But wait, you might say: Given that Hinduism and Christianity are actually pretty different, maybe this attempted spell-breaking doesn’t get us very far. Postulating an uncreated divine intelligence or ultimate reality doesn’t tell us much about what God wants from us. Presupposing an active spiritual realm doesn’t prove that we should all go back to church, especially if these experiences show up cross-culturally, which means they don’t confirm any specific dogma. And you haven’t touched all the important problems with religion — what about the problem of evil? What about the way that institutional faith is used to oppress and shame people? Why not deism instead of theism, or pantheism instead of either?

These are fair questions, but this essay isn’t titled “How to Become a Presbyterian” or “How to Know Which Faith Is True.” The spell-breaking I’m offering here is a beginning, not an end. It creates an obligation without telling you how exactly to fulfill it. It opens onto further arguments, between religious traditions and within them, that aren’t easily resolved.

The difficulties of those ancient arguments — along with the challenge of dealing with religion as it’s actually embodied, in flawed people and institutions — are a big part of what keeps the spell of materialism intact. For finite and suffering creatures, religious belief offers important kinds of hope and consolation. But unbelief has its own comforts: It takes a whole vast zone of ideas and arguments, practices and demands, supernatural perils and metaphysical complexities, and whispers, well, at least you don’t have to spend time thinking about that.

But actually you do. So if you are standing uncertainly on the threshold of whatever faith tradition you feel closest to, you don’t have to heed the inner voice insisting that it’s necessarily more reasonable and sensible and modern to take a step backward. You can recognize instead that reality is probably not as materialism describes it, and take up the obligation of a serious human being preparing for life and death alike — to move forward, to step through.

Well-being of the aging brain - from the Univ.of Wisc. Center for Healty Minds

I am a supporter of the Center for Healthy Minds  at the University of Wisconsin, Madison, which was established and is lead by one of my former colleagues, Richie Davidson, The Center has recently released the transcript  (PDF here) of an August 16 live online seminar titled "The Aging Brain: Developing Well-Being for your future," that features three researchers talking about their work on aging. Melissa Rosenkranz describes work on bi-directional mind-brain-immune pathways through which emotion and inflammation are mutually influential, Ozioma Okokwe's work is on factors influencing resilience to Alzheimer's disease, and Stacey Schaefer, who leads the neuroscience project of the midlife in the US study (MIDUS), describes work on the time course and duration of emotional response and how they relate to long term cognitive and health outcomes. At the end of the transcript graphics used in the presentations as well as sources mentioned in the lectures are given. I am finding a number of the sources quite interesting, so I paste them in below:

OPPS!  NOTE ADDED.  A READER REPORTS THE LINKS BELOW DID NOT SURVIVE MY CUT AND PASTE.  SORRY ABOUT THAT....BUT, IT YOU CLICK THE "PDF HERE" LINK ABOVE, TO GET THE TRANSCRIPT OF THE SESSION, YOU GET THE REFERENCES AT THE END AND THOSE LINKS DO WORK.    

LINKS MENTIONED:

Learn more about MIDUS here: http://midus.wisc.edu/index.php
A paper on the topic of Dementia linked to Rumination is nicely summarized here: Rumination and Worry

Linked to Increased Dementia Risk

Here's a link from the American Federation for Aging Research (AFAR) to webinars related to aging on sleep, exercise, nutrition, gaming, cognition, as well as COVID: https://www.afar.org/afar-webinars

See the long list of aging-related links on this page from the Institute on Aging:

https://aging.wisc.edu/resources/

Here’s the paper about purpose in life, loneliness, and protective health behaviors during the COVID-19 pandemic: https://academic.oup.com/gerontologist/article/61

The paper on the exercise study can be found here: https://pubmed.ncbi.nlm.nih.gov/31970... The NIAWebsite for Physical Activity can be accessed at this link: https://go4life.nia.nih.gov

Find small moments of delight to boost happiness. Check out the Joy Generator:

https://apps.npr.org/joy-generator
Visit https://hminnovations.org/meditation-app or explore Healthy Minds Innovations other well-being

tools at https://hminnovations.org/well-being-...
Here's information about the MIND diet that Dr. Schaefer referenced: (Mediterranean-DASH Intervention

for Neurodegenerative Delay diet): https://www.rush.edu/news/brain-healt...
This link has information about aging and sleep: https://www.sleepfoundation.org/aging...

Research experiences and social justice

In the Editor's Choice section of the July 23 issue of Science Magazine Melissa McCarntney does a brief description of a biomedical research training program rooted in Critical Race Theory (CRT). Trying to overcome my initial knee jerk response of 'this is total Woke bullshit' (after all, I am an old school college professor) I forced myself to actually read through the article in question - a really tough slog through a long jargon laden (intersectionality, etc) slew of words - to find a few sentences that gave some notion of what the experimenters actually did. Here is a clip from the Camacho et al. paper:

In summer training and throughout the academic year, training modules and discussions on racism, sexism, and other forms of discrimination occur in BUILD PODER. We introduce students to the importance of cultural diversity in the sciences, implicit biases and prejudice in the forms of gender and racial microaggressions (Solórzano et al., 2000) and macroaggressions (Jones et al., 2010; van Ryn et al., 2015), impostor phenomenon (Cokley et al., 2013, 2015; Peteet et al., 2015), and stereotype threat (Steele, 1995, 1997; Jones et al., 2010). Students also learn strategies to deal with, overcome, and cope with these potential barriers and prejudices. Each module and workshop contains references to literature that highlights the intersection between racism and the sciences (e.g., van Ryn et al., 2015). These modules also include discussions about recognizing and highlighting what students can do when experiencing a micro-aggression.

This makes good sense, and appears to have helped the "URM" (underrepresented racial minority students). Here is McCartney's summary (the link to the article gets you its longer abstract):

Past diversity training initiatives have not yet led to equity in the STEM field. Camacho et al. propose a new tool to help approach that goal. BUILD PODER is an undergraduate biomedical research training program rooted in Critical Race Theory (CRT). The program unites students and faculty around biomedical research questions while contextualizing these questions around issues of social justice. The integration of research and social justice allows for a curriculum directed at transparency, respect, and correcting the historical abuses in science. Analysis of outcomes among a sample of undergraduate Latinx seniors revealed that BUILD PODER participants reported higher levels of science personal identity and science social identity upon graduation, demonstrating a positive effect of CRT-informed research experiences on Latinx students' science identity.

YouTube algorithms do not appear to drive attention to radical content.

From Hosseinmardi et al.;  

Significance

Daily share of news consumption on YouTube, a social media platform with more than 2 billion monthly users, has increased in the last few years. Constructing a large dataset of users’ trajectories across the full political spectrum during 2016–2019, we identify several distinct communities of news consumers, including “far-right” and “anti-woke.” Far right is small and not increasing in size over the observation period, while anti-woke is growing, and both grow in consumption per user. We find little evidence that the YouTube recommendation algorithm is driving attention to this content. Our results indicate that trends in video-based political news consumption are determined by a complicated combination of user preferences, platform features, and the supply-and-demand dynamics of the broader web.

Abstract

Although it is under-studied relative to other social media platforms, YouTube is arguably the largest and most engaging online media consumption platform in the world. Recently, YouTube’s scale has fueled concerns that YouTube users are being radicalized via a combination of biased recommendations and ostensibly apolitical “anti-woke” channels, both of which have been claimed to direct attention to radical political content. Here we test this hypothesis using a representative panel of more than 300,000 Americans and their individual-level browsing behavior, on and off YouTube, from January 2016 through December 2019. Using a labeled set of political news channels, we find that news consumption on YouTube is dominated by mainstream and largely centrist sources. Consumers of far-right content, while more engaged than average, represent a small and stable percentage of news consumers. However, consumption of “anti-woke” content, defined in terms of its opposition to progressive intellectual and political agendas, grew steadily in popularity and is correlated with consumption of far-right content off-platform. We find no evidence that engagement with far-right content is caused by YouTube recommendations systematically, nor do we find clear evidence that anti-woke channels serve as a gateway to the far right. Rather, consumption of political content on YouTube appears to reflect individual preferences that extend across the web as a whole.

Castration delays aging

I pass on this nugget by Beverly Purnell in the Editor's Choice section of this week's Science Magazine noting an interesting paper by Sugrue et al. First her summary, then the abstract of the Sugrue et al. paper.  

The summary:

As we age, our genetic material changes, not only through DNA mutation but also by epigenetic modification. Indeed, chronological age can be estimated based on analysis of DNA methylation. Male and female mammals display different average life spans, and a role for sex hormones is expected in this effect. Sugrue et al. established an epigenetic clock in sheep by examining methylated DNA in samples from blood and ears. They show that castration extends an animal's life span and feminizes the epigenome at specific androgen-regulated loci during aging.

The Abstract:

In mammals, females generally live longer than males. Nevertheless, the mechanisms underpinning sex-dependent longevity are currently unclear. Epigenetic clocks are powerful biological biomarkers capable of precisely estimating chronological age and identifying novel factors influencing the aging rate using only DNA methylation data. In this study, we developed the first epigenetic clock for domesticated sheep (Ovis aries), which can predict chronological age with a median absolute error of 5.1 months. We have discovered that castrated male sheep have a decelerated aging rate compared to intact males, mediated at least in part by the removal of androgens. Furthermore, we identified several androgen-sensitive CpG dinucleotides that become progressively hypomethylated with age in intact males, but remain stable in castrated males and females. Comparable sex-specific methylation differences in MKLN1 also exist in bat skin and a range of mouse tissues that have high androgen receptor expression, indicating that it may drive androgen-dependent hypomethylation in divergent mammalian species. In characterizing these sites, we identify biologically plausible mechanisms explaining how androgens drive male-accelerated aging.

What is our brain's spontaneous activity for?

Continuing in MindBlog's recent thread on the predictive brain (see here and here), I pass on highlights of an opinion piece by Pezzulo et al., who suggest that all that background brain noise has a very specific purpose - figuring out what to expect next:

Spontaneous brain dynamics are manifestations of top-down dynamics of generative models detached from action–perception cycles.

Generative models constantly produce top-down dynamics, but we call them expectations and attention during task engagement and spontaneous activity at rest.

Spontaneous brain dynamics during resting periods optimize generative models for future interactions by maximizing the entropy of explanations in the absence of specific data and reducing model complexity.

Low-frequency brain fluctuations during spontaneous activity reflect transitions between generic priors consisting of low-dimensional representations and connectivity patterns of the most frequent behavioral states.

High-frequency fluctuations during spontaneous activity in the hippocampus and other regions may support generative replay and model learning.

Brains at rest generate dynamical activity that is highly structured in space and time. We suggest that spontaneous activity, as in rest or dreaming, underlies top-down dynamics of generative models. During active tasks, generative models provide top-down predictive signals for perception, cognition, and action. When the brain is at rest and stimuli are weak or absent, top-down dynamics optimize the generative models for future interactions by maximizing the entropy of explanations and minimizing model complexity. Spontaneous fluctuations of correlated activity within and across brain regions may reflect transitions between ‘generic priors’ of the generative model: low dimensional latent variables and connectivity patterns of the most common perceptual, motor, cognitive, and interoceptive states. Even at rest, brains are proactive and predictive.

The connections between two brain regions that are required for consciousness are regulated by dopamine.

Important work from Spindler et al.:  

Significance

Understanding the neural bases of consciousness is of basic scientific and clinical importance. Human neuroimaging has established that a network of interconnected brain regions known as the default mode network disintegrates in anesthesia and after brain damage that causes disorders of consciousness. However, the neurochemical underpinnings of this network change remain largely unknown. Motivated by preclinical animal work and clinical observations, we found that across pharmacological (sedation) and pathological (disorders of consciousness) consciousness perturbation, the dopaminergic source nucleus, the ventral tegmental area, disconnects from the main nodes of the default mode network. As the severity of this dopaminergic disconnection was associated with default mode network disintegration, we propose that dopaminergic modulation may be a central mechanism for consciousness maintenance.

Abstract

Clinical research into consciousness has long focused on cortical macroscopic networks and their disruption in pathological or pharmacological consciousness perturbation. Despite demonstrating diagnostic utility in disorders of consciousness (DoC) and monitoring anesthetic depth, these cortico-centric approaches have been unable to characterize which neurochemical systems may underpin consciousness alterations. Instead, preclinical experiments have long implicated the dopaminergic ventral tegmental area (VTA) in the brainstem. Despite dopaminergic agonist efficacy in DoC patients equally pointing to dopamine, the VTA has not been studied in human perturbed consciousness. To bridge this translational gap between preclinical subcortical and clinical cortico-centric perspectives, we assessed functional connectivity changes of a histologically characterized VTA using functional MRI recordings of pharmacologically (propofol sedation) and pathologically perturbed consciousness (DoC patients). Both cohorts demonstrated VTA disconnection from the precuneus and posterior cingulate (PCu/PCC), a main default mode network node widely implicated in consciousness. Strikingly, the stronger VTA–PCu/PCC connectivity was, the more the PCu/PCC functional connectome resembled its awake configuration, suggesting a possible neuromodulatory relationship. VTA-PCu/PCC connectivity increased toward healthy control levels only in DoC patients who behaviorally improved at follow-up assessment. To test whether VTA–PCu/PCC connectivity can be affected by a dopaminergic agonist, we demonstrated in a separate set of traumatic brain injury patients without DoC that methylphenidate significantly increased this connectivity. Together, our results characterize an in vivo dopaminergic connectivity deficit common to reversible and chronic consciousness perturbation. This noninvasive assessment of the dopaminergic system bridges preclinical and clinical work, associating dopaminergic VTA function with macroscopic network alterations, thereby elucidating a critical aspect of brainstem–cortical interplay for consciousness.

How the insiders win - Philanthropy, advocacy, and profit.

From Bertrand et al., a study showing how U.S. Federal rulemaking based on considering "independent viewpoints" is corrupted:

Information is central to designing effective policy, and policymakers often rely on competing interests to separate useful from biased information. We show how this logic of virtuous competition can break down, using a new and comprehensive dataset on U.S. federal regulatory rulemaking for 2003–2016. For-profit corporations and nonprofit entities are active in the rulemaking process and are arguably expected to provide independent viewpoints. Policymakers, however, may not be fully aware of the financial ties between some firms and nonprofits – grants that are legal and tax-exempt, but hard to trace. We document three patterns which suggest that these grants may distort policy. First, we show that, shortly after a firm donates to a nonprofit, that nonprofit is more likely to comment on rules on which the firm has also commented. Second, when a firm comments on a rule, the comments by nonprofits that recently received grants from the firm’s foundation are systematically closer in content to the firm’s own comments, relative to comments submitted by other nonprofits. Third, the final rule’s discussion by a regulator is more similar to the firm’s comments on that rule when the firm’s recent grantees also commented on it.

Electromagnetic radiation in the wireless signal range increases wakefulness in mice

Liu et al. (open source) find that electromagnetic radiation (EMR) in the wireless signal range used by our cell phones, laptops, and Wi-Fi routers can increase wakefulness in mice, but only if the signal is pulsed and at much higher levels than are present in our homes.  

Significance

The steady increase of electromagnetic radiation (EMR) in the environment, particularly the wireless signal, causes serious public concern over its potential negative impact on health. However, it is challenging to examine such impact on human subjects due to associated complex issues. In this study, we establish an experimental system for the investigation of EMR impact on mice. Using this system, we uncovered a causal relationship between 2.4-GHz EMR modulated by 100-Hz square pulses and increased wakefulness in mice. This result identifies sleep alteration as a potential consequence of exposure to excessive wireless signals.

Abstract

Electromagnetic radiation (EMR) in the environment has increased sharply in recent decades. The effect of environmental EMR on living organisms remains poorly characterized. Here, we report the impact of wireless-range EMR on the sleep architecture of mouse. Prolonged exposure to 2.4-GHz EMR modulated by 100-Hz square pulses at a nonthermal output level results in markedly increased time of wakefulness in mice. These mice display corresponding decreased time of nonrapid eye movement (NREM) and rapid eye movement (REM). In contrast, prolonged exposure to unmodulated 2.4-GHz EMR at the same time-averaged output level has little impact on mouse sleep. These observations identify alteration of sleep architecture in mice as a specific physiological response to prolonged wireless-range EMR exposure.

The final two paragraphs of the paper make clear that the effects on mouse sleep require much higher power densities for the 2.4-GHz EMR signals than are emitted by smartphones, laptops, or Wi-Fi routers.

....the average power density at close proximity is about 0.037 W/m2 for a smartphone, 0.013 W/m2 for a laptop, and 0.13 W/m2 near the Wi-Fi router (1). These values are considerably lower than the time- and whole-body–averaged general public exposure limit of 10 W/m2 or occupational exposure limit of 50 W/m2 for 2–300 GHz suggested by International Commission on Non-Ionizing Radiation Protection (43). In our experiments, the measured spatial averaged power density for Conti8W is 36.80 ± 0.92 W/m2. Pulse64W is expected to have the same power density. Importantly, the effective EMR dose for inducing a biological response in mice is likely to be different from that in humans. Therefore, the relatively high EMR dose of the Pulse64W regimen that causes increased wakefulness in mice could be markedly reduced in humans. An epidemiological survey among those who work under either very high or very low doses of wireless radiation may reveal some clues.

In this study, 2.4-GHz EMR is modulated by 100-Hz square pulses, which have sharp edges and thus might have some unanticipated impact on neural activity in the brain. Additional experiments should be performed to examine whether other modulation functions such as sinusoidal modulation can induce similar increase of wakefulness in mice. In addition, other modulation frequencies such as 10 and 1,000 Hz should be investigated to answer the question of whether increased wakefulness is specific to certain modulation frequencies. Finally, both the intensity and the frequency of the carrier EMR (2.4 GHz in this study) should be scrutinized.

Seeing others react to threats triggers our own internal threat responses.

From Haaker et al. (open source): 

Significance

Social transmission of threat information by observation is effective in humans and other animals. However, it is unknown if such observation of others’ reacting to threats can retrieve memories that have been previously learned through direct, firsthand aversive experiences. Here, we show concordantly in humans and rats that observing a conspecific’s reactions to a threat is sufficient to recover associative memories of direct, firsthand aversive experiences, measured as conditioned threat responses (physiological responses and defensive behavior) in the observer. The reinstatement of threat responses by observation of others is specific to the context that is observed as being dangerous. Our findings provide cross-species evidence that observation of others’ threat reactions can recover associative memories of direct, firsthand aversive experiences.

Abstract

Information about dangers can spread effectively by observation of others’ threat responses. Yet, it is unclear if such observational threat information interacts with associative memories that are shaped by the individual’s direct, firsthand experiences. Here, we show in humans and rats that the mere observation of a conspecific’s threat reactions reinstates previously learned and extinguished threat responses in the observer. In two experiments, human participants displayed elevated physiological responses to threat-conditioned cues after observational reinstatement in a context-specific manner. The elevation of physiological responses (arousal) was further specific to the context that was observed as dangerous. An analogous experiment in rats provided converging results by demonstrating reinstatement of defensive behavior after observing another rat’s threat reactions. Taken together, our findings provide cross-species evidence that observation of others’ threat reactions can recover associations previously shaped by direct, firsthand aversive experiences. Our study offers a perspective on how retrieval of threat memories draws from associative mechanisms that might underlie both observations of others’ and firsthand experiences.

Historical language records reveal societal depression and anxiety in past two decades higher than during 20th century.

Fascinating work from Bollen et al. (open source):  

Significance

Can entire societies become more or less depressed over time? Here, we look for the historical traces of cognitive distortions, thinking patterns that are strongly associated with internalizing disorders such as depression and anxiety, in millions of books published over the course of the last two centuries in English, Spanish, and German. We find a pronounced “hockey stick” pattern: Over the past two decades the textual analogs of cognitive distortions surged well above historical levels, including those of World War I and II, after declining or stabilizing for most of the 20th century. Our results point to the possibility that recent socioeconomic changes, new technology, and social media are associated with a surge of cognitive distortions.

Abstract

Individuals with depression are prone to maladaptive patterns of thinking, known as cognitive distortions, whereby they think about themselves, the world, and the future in overly negative and inaccurate ways. These distortions are associated with marked changes in an individual’s mood, behavior, and language. We hypothesize that societies can undergo similar changes in their collective psychology that are reflected in historical records of language use. Here, we investigate the prevalence of textual markers of cognitive distortions in over 14 million books for the past 125 y and observe a surge of their prevalence since the 1980s, to levels exceeding those of the Great Depression and both World Wars. This pattern does not seem to be driven by changes in word meaning, publishing and writing standards, or the Google Books sample. Our results suggest a recent societal shift toward language associated with cognitive distortions and internalizing disorders.

Our gut microbiome pattern reflects healthy aging and survival

Interesting analysis by Wilmanski et al.:

The gut microbiome has important effects on human health, yet its importance in human ageing remains unclear. In the present study, we demonstrate that, starting in mid-to-late adulthood, gut microbiomes become increasingly unique to individuals with age. We leverage three independent cohorts comprising over 9,000 individuals and find that compositional uniqueness is strongly associated with microbially produced amino acid derivatives circulating in the bloodstream. In older age (over ~80 years), healthy individuals show continued microbial drift towards a unique compositional state, whereas this drift is absent in less healthy individuals. The identified microbiome pattern of healthy ageing is characterized by a depletion of core genera found across most humans, primarily Bacteroides. Retaining a high Bacteroides dominance into older age, or having a low gut microbiome uniqueness measure, predicts decreased survival in a 4-year follow-up. Our analysis identifies increasing compositional uniqueness of the gut microbiome as a component of healthy ageing, which is characterized by distinct microbial metabolic outputs in the blood.