Skeptic

“Fashion” and “Style” typically refer to products and practices that are valued in specific cultures and time periods. In the contemporary U.S., vintage clothing, athleisure, and oversize water bottles are in style, whereas cigarettes, neckties, fur coats, wood paneling, shag carpets, and white wall tires are out.

Ideas also vary in their popularity and prestige across cultures and times. These days, mindfulness, sustainability, plant-based diets, and pet parenting are fashionable, while eugenics, homophobia, hierarchical work environments, and colonialism are not.

Perhaps the most fashionable current idea is that the binary distinction of females and males—and girls and boys, and women and men—is scientifically incorrect and harmful. Instead, leading social scientists, activists, and even professional journals and organizations, have adopted the view that sex should be considered a nonbinary variable, either a continuous spectrum or something with more than two categories.

Yet, the traditional, binary view of sex, despite being unpopular, is basically correct. Crucially, I am confident that holding this view is in no way at odds with being fully respectful to individuals who are transgender or intersex. Here are eight reasons for affirming that biological sex is binary.

Let’s review each of them in more detail.

1. Evolutionary biologists define sex based on gametes, a binary framework. Although scientifically fruitful, this doesn’t work for many individuals.

Reproduction is fundamental to life. Although there are many ways of reproducing, one basic distinction is that of asexual reproduction versus sexual reproduction. In asexual reproduction, sometimes called cloning, an organism reproduces without the participation of another organism. Although asexual reproduction occurs in some vertebrate animals, including reptiles as large as Komodo dragons, it is rare. Instead, most vertebrates, including humans, only reproduce sexually, meaning that two organisms combine their genetic material to produce offspring.

In all vertebrate species, including humans, there are two kinds of sexual reproducers: females and males. Females contribute an egg, which is a gamete (i.e., sex cell) package with a large nutrient bundle and no ability to move. Males contribute sperm, which is a gamete package with no nutrients, but excellent mobility, usually because of a flagellum, a miniature tail. In humans, a single egg is roughly 100,000 times larger than a single sperm.

In all vertebrate species, including humans, there are two kinds of sexual reproducers: females and males.

Most evolutionary biologists, including Richard Dawkins and Jerry Coyne, define sex according to gametes, whether the individual produces eggs (female) or sperm (male).1, 2, 3, 4, 5 This gametes framework undergirds our understanding of reproduction across all sexually reproducing animal species. For instance, in terms of parental responsibility, producing eggs is a high investment strategy whereas producing sperm is a low investment strategy. Building on this initial pattern, in all placental mammals, females, but not males, gestate offspring and provide milk once they are born.

Although the gametes framework has proven highly fruitful for evolutionary biology, it has two key drawbacks when applied to humans. One is that gametes in mammals can’t be observed easily—we don’t lay eggs as do all birds and most reptiles. A second drawback is that, although this framework works well for species or populations, it doesn’t work for many individuals. Postmenopausal women generally don’t produce eggs and neither do women who have had their ovaries removed. Boys don’t produce sperm, and neither do men who have had their testes removed.

2. People in all societies define sex based on reproductive traits, another binary framework. This framework builds on the gametes definition and is far more practical.

Because of the limitations of the gametes framework, I propose the following two “new definitions” of sex based on reproductive traits that are related to gametes.

In humans, a female should be defined as an individual who possesses, or is on a trajectory to possess, or previously possessed, the traits necessary for reproduction as an egg producer; these traits include ovaries, fallopian tubes, uterus, cervix, and vagina. These traits are often referred to as the primary sex characteristics.In humans, a male should be defined as an individual who possesses, or is on a trajectory to possess, or previously possessed, the traits necessary for reproduction as a sperm producer; these traits include the testes, penis, and scrotum.

I put “new definitions” in quotes to make the point that, although I am arguing we should use this pair of definitions, it is more accurate to say that we should acknowledge our traditional use of them, rather than thinking of them as new. This is because people in all human societies distinguish between males and females, and, historically, they must have done this by observing a newborn’s external genitals. What other option could they have had?

Even in modern industrial societies, where blood and tissue tests are often available, genital inspection is still the main method of sex categorization, although that often now occurs by looking at ultrasound images months prior to birth.6

Of course, outside of the birthing room, most of us rarely examine anyone’s genitals to learn their sex. Instead, we use various traits that typically, but not always, co-occur with the primary reproductive traits. These include secondary sex characteristics, which are physical traits that are not necessary for reproduction but that usually accompany the respective set of reproductive traits, particularly after puberty. In women, these include enlarged breasts and widened hips; in men, they include facial hair and Adam’s apples. There are other relevant traits, including men’s generally lower vocal pitch and their greater height and upper body musculature. Even facial shape is extremely helpful: adults can, with high accuracy, correctly determine another adult’s sex from pictures alone.7, 8

In addition, many components of fashion and style serve, in part, to signal the wearer’s sex. For example, women typically have fuller lips than men, and the current popularity of lip filler procedures can be understood as means of amplifying femininity. Many other products and practices work similarly, including jewelry, piercings, tattoos, hairstyles, makeup, and clothing. Thanks to all this biological and cultural information, most of us interact with many people each day and rarely have doubts about whether a person is female or male.

Even in modern industrial societies, genital inspection is still the main method of sex categorization.

Nonetheless, it bears stressing that the initial assignment of a newborn’s sex, apparently in all societies, is based on external genitalia. In fact, this assignment can be considered part of our universal folk knowledge, “common sense” that sometimes turns out to be correct. Moreover, this universal folk knowledge about sex isn’t limited to knowing that sex is assigned based on external genitalia; it also includes recognizing that there are two, and only two, kinds of human reproducers, that only females bear children, and that females can only reproduce if they have had sexual intercourse with males.

Is this folk knowledge about sex universal, meaning that it has occurred in all human societies that ever existed? Logically, of course, nobody can prove that any belief or behavior is universal; there could always be some exceptional society that has never been studied.9 Nonetheless, we can be highly confident that these patterns are universal or nearly so. The reason is that, for the past few hundred years, cultural anthropologists, ethnographers, missionaries, and explorers have traveled the world documenting exotic beliefs and practices, such as taboos against eating nutritious foods or body modification that involves painful procedures. This attention to describe cultural beliefs extends to sexuality. We know, for example, that in some traditional societies, people believe (incorrectly) that a woman can only get pregnant if she is inseminated repeatedly;10 in other societies, people believe (incorrectly) in partible paternity, meaning that a child can have two biological fathers;11 in others, people believe (incorrectly) that a woman becomes impregnated by a spirit but that a penis must first open the vagina to allow the spirit’s entrance.12 If there were a society where people believed in a third manner or mode of reproduction or were unaware that penile-vaginal intercourse is, with very few exceptions, necessary for conception, we can be confident anthropologists would have studied it and described it by now.

3. Sex is consequential for many reasons, including that it is women who have babies, not men.

In addition to the ones just noted, humans hold other universal beliefs and practices. A fundamental practice in all societies is that there are distinct words for girls and boys, women and men, mother and father, and daughter and son.13 These words exist everywhere because they indicate reproductive roles, and reproduction is always potentially consequential. Even in contemporary countries with sub-replacement level fertility, a substantial portion of women bear children, an event with major consequences for education, work, recreation, family life, and, indeed, survival.

Healthcare is a particularly notable sphere where sex, based on reproductive traits, is consequential. Practitioners aiming to provide the best care frequently must consider if their patient is female or male. Diseases that differ substantially in prevalence, manifestation, or treatment, include Alzheimer’s, COVID-19, depression, diabetes, influenza, pneumonia, and several kinds of cancer.14

Some have asked whether our society would be better off if we simply ignored sex. Although this seems desirable in some situations, it is not practical in many others.15

4. Third genders are nonbinary, but they do not challenge the biological sex binary, reproductive traits framework.

Another frequent question is whether societies with so-called third genders pose a problem for the binary, reproductive traits framework. For example, in Samoa, there is a third gender kind of person called Fa’afafine, which roughly translates to “in the manner of a woman.” Fa’afafine are biological males who often dress in female-typical clothing, adopt feminine names, and do female-typical, people-oriented jobs such as teaching and nursing; they are exclusively attracted to male-typical, masculine men as sexual partners.16

Third gender individuals either do not reproduce or they reproduce in the typical male or female manner.

Fa’afafine are accepted in Samoa as a third kind of person, neither a typical male nor a typical female. However, everyone there recognizes that Fa’afafine do not reproduce in a third way; they rarely or never reproduce, and, if they do, they do so as men. In other societies, there are other kinds of third gender individuals, including biological females who adopt male-typical roles and, in other societies, individuals who do not conform to either a male-typical or female-typical role.17 However, the story is essentially the same everywhere: everyone knows that third gender individuals either do not reproduce or they reproduce in the typical male or female manner.

Many people, even educators and policymakers, express confusion about third gender individuals and claim they challenge the idea that sex is binary. However, this is attributable to many scholars and activists using the terms “sex” and “gender” interchangeably. They will say things such as, “The Fa’afafine embody a third gender and sex.”

Gender has a rich and broad web of meanings, but we don’t need to unpack them all to address the confusion. We only need to remember that what we can call gender roles associated with biological sex—that is, doing male-typical or female-typical things—can be nonbinary. That is, there can be three or more genders or gender roles, and there can be intermediate genders. Further, there are many other traits that are associated with biological sex that are nonbinary; these include skeletal traits, hormones, and personality. None of this, however, contradicts the binary reproductive traits framework discussed above. Again, there are exactly two kinds of sexual reproducers, male and female, and people in all societies—even societies with third genders—recognize this binary distinction, and they recognize it as consequential.

5. Intersex individuals challenge the binary, reproductive traits framework, but they don’t invalidate it because they do not reproduce in a third way.

A more substantial challenge to the binary, reproductive traits framework comes from intersex individuals, who are sometimes described as having DSDs (Disorders or Differences of Sexual Development). These individuals are born with genetic, hormonal, or physical characteristics that are unusual for males or females. For example, a person might have male-typical chromosomes (e.g., XY) yet their phenotype or appearance may be female. A critical point is that, unlike most third gender individuals, intersex individuals typically do not possess a full set of traits necessary for reproduction, and often they are unable to reproduce. Frequently discussed intersex conditions include complete androgen insensitivity syndrome (CAIS), congenital adrenal hyperplasia (CAH), 5-alpha reductase deficiency (5-ARD), and ovotesticular disorder (also called true hermaphroditism). In some communities, some intersex conditions occur fairly commonly (e.g., 5-ARD), and people with this condition may be described as embodying a third gender.18

Source

There is debate about the frequency of intersex conditions with some writers claiming that 1 in 60 live births is intersex and others suggesting the true frequency is roughly 1 in 5,000. The debate largely centers on what counts as a true intersex condition. Using a very broad definition,19, 20 anyone who doesn’t fit their “exacting criteria” for being a typical male or female should be considered intersex, making the prevalence relatively high. In this perspective, a man with a short but functional penis could be called intersex, as could a boy with hypospadias (i.e., their urethra opens on the underside of their penis instead of at the tip) or a woman who bore three children but learned later in life that her androgenic hormones were unusually high.

The binary nature of human reproduction is about as complete a binary distinction as one can find in the natural world.

However, if we reserve the label intersex for individuals who do not possess all traits necessary for successful reproduction, whose chromosomal sex does not match their phenotypic sex (e.g., XY female), or for whom there was genuine uncertainty about their birth sex—all of which might be called classic intersex conditions—the more accurate estimate is roughly 1 in 5,000.21 This estimate is not particularly controversial; it was cited without challenge in 2020 in a progressive editorial in the New England Journal of Medicine advocating for the removal of sex designations on birth certificates.22

Regardless of whether they are fairly common (1 in 60) or truly rare (1 in 5,000), some intersex individuals do not fit neatly into the binary, reproductive traits framework. Nevertheless, they don’t invalidate the framework for two reasons.

First, many definitions of real-world phenomena— including of species, vegetables, or games—become fuzzy or must admit exceptions if scrutinized.23 This is true even of binaries that we usually take for granted:

• Nearly all of the earth’s water can be classified as freshwater or saltwater, yet there are transitional, intermediate areas, which are sometimes called brackish.
• When coins are flipped, they land on one side or the other, heads or tails, however, coins occasionally land on their edge.
• In all societies, people are considered dead or alive, yet, with modern medicine, some individuals may exist in intermediate states, including comas and brain death.

A second, and more crucial, reason that intersex individuals don’t invalidate this framework is that this framework is based on female and male modes of reproduction, and intersex individuals do not reproduce in a third way. All intersex individuals who reproduce, reproduce in either the male or the female manner. To summarize: the binary framework accommodates all modes of sexual reproduction in humans, but it does not (quite) accommodate all humans.

It’s worth stressing that, as Dawkins has eloquently explained,24 the binary nature of human reproduction is about as complete a binary distinction as one can find in the natural world.

6. Hyde and colleagues’ (2019) popular nonbinary definition of sex is indefensible.

What about the nonbinary definitions of sex? Because these have become influential, one might assume that they are better than the binary definitions. I want to note that there is apparently no nonbinary definition of sex that has been recognized as being the best. Nevertheless, a good place to start is with a review article by Hyde and colleagues entitled, “The Future of Sex and Gender in Psychology: Five Challenges to the Gender Binary.”25 This article was published in 2019 in the American Psychologist, a leading journal of the American Psychological Association, the largest psychological society in the world. Hyde is one of the most influential sex and gender scholars, and this article has already been cited more than 1,100 times—a very high number for any academic article, particularly one published so recently. Hyde et al. offer this definition of sex: “The term sex is used here to refer to biological systems involving the X and Y chromosomes, pre- and postnatal sexual differentiation, and hormones that influence sexual differentiation of the external genitals, which, in turn, serve as the basis for sex assignment at birth.”

This is a terrible definition, on several counts. The first issue is that it fails to acknowledge the unifying or organizing feature of the properties included in the definition—that unifying feature being, of course, reproduction. Imagine someone defined a door as: “A human-created object, situated in a house, dwelling, or vehicle, that can be comprised of various materials, that can be decorative, and that can have other objects affixed to it.” These stated properties of doors are all true, yet this is an inadequate definition because it doesn’t state that the chief purpose of a door is to serve as a movable barrier. Similarly, it would be a poor definition of an eye if someone listed many of its components (e.g., cornea, lens, retina) but failed to mention that the eye’s function is to see (that is, to transduce some property of some portion of the electromagnetic spectrum into neural impulses).

A second issue is that Hyde et al. have not explained why a new definition of sex is needed. A basic principle of communication is that if there is an established definition, one should not alter it, or introduce a new one, without justification. Of relevance here is that the gametes definitions of sex developed by biologists is well established—it has been used for more than 100 years and has proven extremely fruitful. (Yes, it’s true that earlier in this article I proposed defining sex based on reproductive traits, however, I explained why this is a sensible extension of the gametes definitions and that it is best viewed as an acknowledgment of our intuitive, universal folk knowledge.)

A third problem is that Hyde et al. have not provided a constructive, practical definition of sex. To make this clear, recall that according to the reproductive traits framework, an individual is female if they possess (or did possess or will possess) the traits necessary for reproduction as an egg producer, and they are male if they possess (or did possess or will possess) the traits necessary for reproduction as a sperm producer, or they are outside the binary if they don’t possess traits for either of these modes of reproduction. There will always be a few edge cases requiring further careful consideration. That said, the vast majority of people can be categorized easily by the reproductive traits framework.

Hyde et al. don’t offer anything similarly useful. They do not state what, according to their definition, the various kinds or categories of sex are—whether it be three, four, five, or more categories. Or, if they consider sex a gradient or spectrum, rather than a categorical variable, they do not specify what concepts or variables that gradient represents. This is worth emphasizing: Based on those very definitions, one cannot categorize a single person as female, male, a third sex, or some intermediate sex. Practically speaking, a 99.9 percent easy classification (i.e., the reproductive traits framework) is preferable to a 0 percent classification!

What issues do Hyde et al. address in their article? One emphasis is defining additional terms, such as “gender,” “transgender,” “cisgender,” “nonbinary,” “agender,” and “genderfluid.” This creates the impression that sex is mixed up with these other terms. The other approach Hyde et al. take—and this comprises most of the article—is to argue that most traits that typically differ between women and men are affected by many factors that can be placed on a gradient or spectrum. These traits include the amounts of various hormones, the size of various brain structures, and the amount or frequency of cognitive abilities, social behaviors, romantic attraction, and feeling like a man or a woman. Although it’s true that these traits are nonbinary, that is not at odds with the reproductive traits framework. The take-home message of that framework is not that all sex-differentiated traits are binary; it’s that the two modes of reproduction—and the reproductive traits that support them—are binary.

So, how does the review by Hyde et al. deal with the fact that reproduction is binary? It doesn’t—it simply ignores the issue. In particular, although it is more than 20 journal pages and over 14,000 words, the words “gamete,” “baby,” “child,” “pregnancy,” “mother,” or “parent,” do not appear, except in parentheses or in the references section. There are a few mentions of “reproductive phases” and “reproductive structures,” but there is no acknowledgment that people bear and raise children, that these events are important, or that reproduction should be considered when defining sex.

Of course, Hyde et al. might argue that ignoring reproduction is a feature, not a bug—indeed, one that justifies their new definition of sex. Perhaps so, but this then raises the question of what trait should serve as the foundation for defining sex. Since they do not provide any answer, I submit the reason is that no nonbinary definition is defensible.

Without a theoretically defensible definition of sex to provide the endpoints of a gradient or spectrum, no individual could be placed on any female-male spectrum for any trait.

Imagine that someone proposed that the amount of testosterone a person is exposed to prior to birth should be the foundation for defining sex, an idea that seems reasonable given that such exposure is known to correlate with variation in several typically sex-differentiated important areas, including play preferences, work preferences, cognitive abilities, and sexual orientation. Although apparently reasonable, one might argue that it is in fact an adult’s current level of circulating testosterone, not their prenatal exposure, that is the more salient measure; another might suggest that prenatal estrogen exposure as the key measure; a fourth might posit that yet another hormone is critical.

The resulting situation is actually more nebulous because other scholars might just as reasonably claim that hormones are no more important than brain shape, skeletal anatomy, personality, or other areas, and each area has many possible measures. There is simply no single area or measure that is more defensible than the others.

In addition, a more fundamental problem is that any scoring system requires a reference point, and scholars who do not accept a binary definition of sex have committed themselves to abandoning the reference point of binary sex. This issue is relevant to every kind of trait—behavioral, anatomical, physiological—that might be considered a candidate for characterizing sex along a spectrum. Without a theoretically defensible definition of sex to provide the endpoints of a gradient or spectrum, no individual could be placed on any female-male spectrum for any trait.

7. No better nonbinary definition has been offered.

If the definitions and ideas proposed by Hyde et al. in 2019 are unworkable, then perhaps there is some other framework that works better? Though I follow the scholarship and discussions in this area closely, I’ve yet to encounter one.

In debates and essays, scholars arguing against the “sex is binary” position, including Alice Dreger26 and Steven Novella,27 invariably echo the points made by Hyde et al., including that some intersex individuals do not fit the binary and that most traits related to sex are not binary. However, these scholars never cite nor develop a viable nonbinary alternative framework, and they fail to acknowledge the fact that all humans who reproduce do so in either the male or female mode, never in a third or intermediate way.

I’ve long taught the course, “Psychology of Sex Differences,” and so am familiar with the leading textbooks in this field, and have participated in a content analysis of the leading textbooks.28 These books also deny that sex is binary yet fail to offer any constructive nonbinary alternative. Furthermore, although they invariably address reproduction and childrearing in later chapters, when they first introduce and define the terms sex and gender in their opening chapters, they do not acknowledge either that reproduction exists or that it should be incorporated into a definition of sex.

8. Nonbinary definitions of sex are popular because they are viewed as being progressive. However, one can hold progressive political views while still retaining the traditional binary view of sex.

If the binary framework of sex based on reproduction is solid and the nonbinary alternatives are so weak, why have the nonbinary alternatives gained so much traction? Why is the nonbinary view presented not only in texts but especially in the media?

The short answer is that scholars, especially evolutionary biologists, haven’t done an adequate job in making the binary basics accessible. While concentrating on the logical and heuristic power of the gametes framework, including its applicability to species where individuals can alter their sexual strategies or reproduce asexually, evolutionary biologists have neglected to provide intuitive and practical definitions for nonspecialists. I hope this article has made the case for how and why a reproductive traits framework—which builds on the gametes framework and makes explicit humans’ universal folk knowledge—remedies this problem.

Those with intersex conditions don’t fully fit the traditional binary pattern, and neither do gay people, or third gender individuals.

A second reason nonbinary definitions of sex have become popular is that they seem to accommodate better the diverse and varied biologies, psychologies, and experiences of individuals who do not conform to the traditional binary pattern, i.e., that most people have male or female reproductive traits, and this difference is accompanied by a corresponding package of female-typical or male-typical nonreproductive traits.29 Among many others, these include secondary sex traits (e.g., enlarged breasts, facial hair), normative social roles and interests (e.g., homemaker, breadwinner), heterosexual orientation, and identifying with one’s biological sex (cisgender). Those with intersex conditions don’t fully fit the traditional binary pattern, and neither do gay people, or third gender individuals. Further, in the U.S. and other Western societies, traditionally there has not been any third gender category or categories, but this is changing as increasing numbers, especially of younger people, identify as transgender.

Although there have always been people who don’t fit the traditional binary pattern, in recent years the visibility of these individuals—and the respect and legal rights afforded to them—has increased tremendously. A major contributor to this change has involved rejecting the presumed practical and moral superiority of the traditional binary pattern. Some scholars call this the cisgender heteronormative pattern. Whatever the nomenclature, the critical point is that more and more individuals have recognized that it is fine and safe to be, for example, a biological woman who is sexually attracted to women, a biological man who identifies as a woman, a biological woman who prefers fixing cars rather than crocheting baby blankets, or an intersex person whose reproductive traits do not allow categorization as being strictly male or female.

For many, myself included, such rejection of the superiority and dominance of the traditional binary pattern represents true ethical and political progress. However, doing this does not require abandoning the scientifically accurate view that sex is binary.30, 31

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I am fascinated by the technologies that live largely behind the scenes. These are not generally consumer devices, but they may be components of consumer products, or may largely have a role in industry – but they make our modern world possible, or make it much better. In addition I think that material science is largely underrated in terms of popular appeal, but it is material science that often make all other technologies possible or feasible. There is another aspect of technology that I have been increasingly interested in – solid state technology. These are, generally speaking, devices that use electricity rather than moving parts. You are likely familiar with solid state drives, that do not have spinning discs and therefore are smaller, use less power, and last longer. One big advantage of electric vehicles is that they are largely solid state, without the moving parts of an engine.

There is a technology that combines all three of these features – it is a component technology, dependent on material science, and solid state: thermoelectric devices. This may not sound sexy, but bear with me, this is cool (pun intended) technology. Thermoelectric materials are those that convert electricity into a temperature difference across a material, or convert a temperature difference into electricity. In reality, everything is a thermoelectric material, but most materials have insignificant thermoelectric effects (so are functionally not thermoelectric).

Thermoelectric devices can be used to harvest energy, from any temperature difference. These are generally not large amounts of energy – we don’t have thermoelectric power plants connected to the grid – and they are currently not practical and cost effective enough for a large scale. This may be possible in the future, but not today. However, for applications that require small amounts of energy, harvesting that energy from ambient sources like small temperature differences is feasible.

There are likely many more applications for the reverse – using electricity to cause temperature changes. This is basically a refrigerator, and in fact y0u can buy small solid state thermoelectric refrigerators. A traditional refrigerator uses a compressor and a refrigerant. This is a liquid that turns into a gas at low temperature, absorbing heat when it transitions to gas and then letting off heat when it transitions back to liquid. But this requires a compressor with moving parts and pipes to carry the refrigerant. Refrigerants are also not good for the environment or the ozone. Thermoelectric coolers can be smaller, use less electricity, are quiet, and have more precise temperature control. But their size is limited because they are not powerful enough for full-sized refrigerators.

As an aside, I see that Samsung is coming out this year with a hybrid full-size refrigerator. I still uses a compressor, but also has a thermoelectric cooler to reduce temperature variation throughout the refrigerator.

Thermoelectric cooling is also useful for electronics, which having an increasing problem with heat dissipation as we make them smaller, more compact, and more powerful. Heat management is now a major limiting factor for high end computer chips. This is also a major limiting factor for bio-electronics – implanting chips in people for various potential applications. Having a small and efficient solid state cooling device that just requires electricity would enable this technology.

But – the current state of the art for thermoelectric cooling is limited. Devices have low overall efficiency, and their manufacture is expensive and generates a lot of waste.  In other words – there is a huge opportunity to improve this technology with massive and far ranging potential benefits. This is an area ripe for investment with clear benefits. This can also be a significant component of our current overall goal to electrify our technology – to accomplish with electricity what currently requires moving parts and fossil fuels.

All this is why I was very interested in this latest advance – Interfacial bonding enhances thermoelectric cooling in 3D-printed materials. This incorporates yet another technology that has my interest – 3D printing, or additive manufacturing. This does not represent an improvement in the thermoelectric devices themselves, but an improvement in the cost and efficiency of making them (again, and often neglected by very important aspect of any technology). As one of the authors says:

“With our present work, we can 3D print exactly the needed shape of thermoelectric materials. In addition, the resulting devices exhibit a net cooling effect of 50 degrees in the air. This means that our 3D-printed materials perform similarly to ones that are significantly more expensive to manufacture,” says Xu.”

The innovation has to do with the molecular bonding of the materials in the 3D printing process. As Xu says, the performance is the same as existing materials, but with much lower cost to manufacture. As always, shifting to a new technology often means that there is room for further incremental advances to make the advantages even better over time. It may take years for this technology to translate to the market, but it is very possible it may lead directly to a slew of new products and applications.

It may seem like a small thing, but I am looking forward to a future (hopefully not too distant) with full-sized thermoelectric refrigerators, and with computers that don’t need fans or water cooling. Having a silent computer without fans is nice for podcasting, which I know is a particular interest of mine, but is also increasingly common.

In general, quality of life will be better if we are surrounded by technology that is silent, small, efficient, cost-effective, and long-lasting. Thermoelectric cooling can make all of that increasingly possible.

The post Thermoelectric Cooling – It’s Cooler Than You Think first appeared on NeuroLogica Blog.

The evolution of the human brain is a fascinating subject. The brain is arguably the most complex structure in the known (to us) universe, and is the feature that makes humanity unique and has allowed us to dominate (for good or ill) the fate of this planet. But of course we are but a twig on a vast evolutionary tree, replete with complex brains. From a human-centric perspective, the closer groups are to humans evolutionarily, the more complex their brains (generally speaking). Apes are the most “encephalized” among primates, as are the primates among mammals, and the mammals among vertebrates. This makes evolutionary sense – that the biggest and most complex brains would evolve from the group with the biggest and most complex brains.

But this evolutionary perspective can be tricky. We can’t confuse looking back through evolutionary time with looking across the landscape of extant species. Any species alive today has just as much evolutionary history behind them as humans. Their brains did not stop evolving once their branch split off from the one that lead to humans. There are therefore some groups which have complex brains because they are evolutionarily close to humans, and their brains have a lot of homology with humans. But there are also other groups that have complex brains because they evolved them completely independently, after their group split from ours. Cetaceans such as whales and dolphins come to mind. They have big brains, but their brains are organized somewhat differently from primates.

Another group that is often considered to be highly intelligent, independent from primates, is birds. Birds are still vertebrates, and in fact they are amniotes, the group that contains reptiles, birds, and mammals. It is still an open question as to exactly how much of the human brain architecture was present at the last common ancestor of all amniotes (and is therefore homologous) and how much evolved later independently. To explore this question we need to look at not only the anatomy of brains and the networks within them, but brain cell types and their genetic origins. For example, even structures that currently look very different can retain evidence of common ancestry if they are built with the same genes. Or – structures that look similar may be built with different genes, and are therefore evolutionarily independent, or analogous.

With that background, we now have a publication of several research projects examining the brain of various amniotes – Evolutionary convergence of sensory circuits in the pallium of amniotes. The pallium is basically the cerebral cortex – the layers of gray and white matter that sit on top of the cerebrum. This is the “advanced” part of the brain in vertebrates, which include the neocortex in humans. When comparing the  pallium of reptiles, birds, and mammals, what did they find?

 “Their neurons are born in different locations and developmental times in each species,” explains Dr. García-Moreno, head of the Brain Development and Evolution laboratory, “indicating that they are not comparable neurons derived from a common ancestor.”

Time and location during development is a big clue as to the evolutionary source of different cells and structure. Genes are another way to determine evolutionary source, so a separate analysis looked at the genes that are activated when forming the pallium of these different groups. It turns out – they use very different assemblages of genes in developing the neurons of the pallium. All this strongly suggests that extant reptiles, birds, and mammals evolved similar brain structures independently after they split apart as groups. They use different neuron type derived from different genes, which means those neurons evolved from different ancestor cell types.

To do this analysis they looked at hundreds of genes and cell types across species, creating an atlas of brain cells, and then did (of course) a computer analysis:

“We were able to describe the hundreds of genes that each type of neuron uses in these brains, cell by cell, and compare them with bioinformatics tools.” The results show that birds have retained most inhibitory neurons present in all other vertebrates for hundreds of millions of years. However, their excitatory neurons, responsible for transmitting information in the pallium, have evolved in a unique way. Only a few neuronal types in the avian brain were identified with genetic profiles similar to those found in mammals, such as the claustrum and the hippocampus, suggesting that some neurons are very ancient and shared across species. “However, most excitatory neurons have evolved in new and different ways in each species,” details Dr. García-Moreno.

Convergent evolution like this occurs because nature finds similar solutions to the same problem. But if they evolved independently, the tiny details (like the genes they are built from) will differ. But also, a similar solution is not an identical solution. This means that bird brains are likely to be different in important ways from mammalian brains. They have a different type of intelligence that mammals, primates, and humans do (just like dolphins have a different type of intelligence).

This is the aspect of this research that fascinates me the most – how is our view of reality affected by the quirky of our neurological evolution? Our view of reality is mostly a constructed neurological illusion (albeit a useful illusion). It is probable that chimpanzees see the world in a very similar way to humans, as their brains diverged only recently from our own. But the reality that dolphin or crow brains construct might be vastly different than our own.

There are “intelligent” creatures on Earth that diverge even more from the human model. Octopuses have a doughnut shaped brain that wraps around their esophagus, with many of the neurons also distributed in their tentacles. They have as many neurons as a dog, but they are far more distributed. Their tentacles have some capacity for independent neurological function (if you want to call that “thought”). It is highly likely that the experience of reality of an octopus is extremely different than any mammal.

This line of thinking always leads me to ponder – what might the intelligence of an alien species be like? In science fiction it is a common story-telling contrivance that aliens are remarkably humanoid, not just in their body plan but in their intelligence. They mostly have not only human-level intelligence, but a recognizably human type of intelligence. I think it is far more likely that any alien intelligence, even one capable of technology, would be different from human intelligence in ways difficult (and perhaps impossible) for us to contemplate.

There are some sci fi stories that explore this idea, like Arrival, and I usually find them very good. But still I think fiction is just scratching the surface of this idea. I understand why this is – it’s hard to tell a story with aliens when we cannot even interface with them intellectually – unless that fact is part of the story itself. But still, there is a lot of space to explore aliens that are human enough to have a meaningful interaction, but different enough to feel neurologically alien. There are likely some constants to hold onto, such as pleasure and pain, and self-preservation. But even exploring that idea – what would be the constants, and what can vary, is fascinating.

This all relates to another idea I try to emphasize whenever relevant – we are our neurology. Our identity and experience is the firing of patterns of neurons in our brains, and it is a uniquely constructed experience.

The post Birds Separately Evolved Complex Brains first appeared on NeuroLogica Blog.

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My younger self, seeing that title – AI Powered Bionic Arm – would definitely feel as if the future had arrived, and in many ways it has. This is not the bionic arm of the 1970s TV show, however. That level of tech is probably closer to the 2070s than the 1970s. But we are still making impressive advances in brain-machine interface technology and robotics, to the point that we can replace missing limbs with serviceable robotic replacements.

In this video Sarah De Lagarde discusses her experience as the first person with an AI powered bionic arm. This represents a nice advance in this technology, and we are just scratching the surface. Let’s review where we are with this technology and how artificial intelligence can play an important role.

There are different ways to control robotics – you can have preprogrammed movements (with or without sensory feedback), AI can control the movements in real time, you can have a human operator, through some kind of interface including motion capture, or you can use a brain-machine interface of some sort. For robotic prosthetic limbs obviously the user needs to be able to control them in real time, and we want that experience to feel as natural as possible.

The options for robotic prosthetics include direct connection to the brain, which can be from a variety of electrodes. They can be deep brain electrodes, brain surface, scalp surface, or even stents inside the veins of the brain (stentrodes). All have their advantages and disadvantages. Brain surface and deep brain have the best resolution, but they are the most invasive. Scalp surface is the least invasive, but has the lowest resolution. Stentrodes may, for now, be the best compromise, until we develop more biocompatible and durable brain electrodes.

You can also control a robotic prosthetic without a direct brain connection, using surviving muscles as the interface. That is the method used in De Lagarde’s prosthetic. The advantage here is that you don’t need wires in the brain. Electrodes from the robotic limb connect to existing muscles which the user can contract voluntarily. The muscles themselves are not moving anything, but they generate a sizable electrical impulse which can activate the robotic limb. The user then has to learn to control the robotic limb by activating different sequences of muscle contractions.

At first this method of control requires a lot of concentration. I think a good analogy, one used by De Lagarde, is to think of controlling a virtual character in a video game. At first, you need to concentrate on the correct sequence of keys to hit to get the character to do what you want. But after a while you don’t have to think about the keystrokes. You just think about what you want the character to do and your fingers automatically (it seems) go to the correct keys or manipulate the mouse appropriately. The cognitive burden decreases and your control increases. This is the learning phase of controlling any robotic prosthetic.

As the technology develops researchers learned that providing sensory feedback is a huge help to this process. When the user uses the limb it can provide haptic feedback, such as vibrations, that correspond to the movement. Users report this is an extremely helpful feature. It allows for superior and more natural control, and allows them to control the limb without having to look directly at it. Sensory feedback closes the usual feedback loop of natural motor control.

And that is where the technology has gotten to, with continued incremental advances. But now we can add AI to the mix. What roll does that potentially play? As the user learns to contract the correct muscles in order to get the robotic limb to do what they want, AI connected to the limb itself can learn to recognize the user behavior and better predict what movements they want. The learning curve is now bidirectional.

De Lagarde reports that the primary benefit of the AI learning to interpret her movements better is a decrease in the lag time between her wanting to move and the robotic limb moving. At first the delay could be 10 seconds, which is forever if all you want to do is close your fist. But now the delay is imperceptible, with the limb moving essentially in real time. The limb does not feel like her natural limb. She still feels like it is a tool that she can use. But that tool is getting more and more useful and easy to use.

AI may be the perfect tool for brain-machine interface in general, and again in a bidirectional way. What AI is very good at is looking at tons of noisy data and finding patterns. This can help us interpret brain signals, even from low-res scalp electrodes, meaning that by training on the brain waves from one user an AI can learn to interpret what the brain waves mean in terms of brain activity and user intention. Further, AI can help interpret the user’s attempts at controlling a device or communicating with a BMI. This can dramatically reduce the extensive training period that BMIs often require, getting months of user training down to days. It can also improve the quality of the ultimate control achieved, and reduce the cognitive burden of the user.

We are already past the point of having usable robotic prosthetic limbs controlled by the user. The technology is also advancing nicely and quite rapidly, and AI is just providing another layer to the tech that fuels more incremental advances. It’s still hard to say how long it will take to get to the Bionic Man level of technology, but it’s easy to predict better and better artificial limbs.

The post AI Powered Bionic Arm first appeared on NeuroLogica Blog.

A few of your favorite experts weigh in on how you can make sure your information comes from the very best sources.

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It’s probably not a surprise that a blog author dedicated to critical thinking and neuroscience feels that misinformation is one of the most significant threats to society, but I really to think this. Misinformation (false, misleading, or erroneous information) and disinformation (deliberately misleading information) have the ability to cause a disconnect between the public and reality. In a democracy this severs the feedback loop between voters and their representatives. In an authoritarian government it a tool of control and repression. In either case citizens cannot freely choose their representatives. This is also the problem with extreme jerrymandering – in which politicians choose their voters rather than the other way around.

Misinformation and disinformation have always existed in human society, and it is an interesting question whether or not they have increased recently and to what extent social media has amplified them. Regardless, it is useful to understand what factors contribute to susceptibility to misinformation in order to make people more resilient to it. We all benefit if the typical citizen has the ability to discern reality and identify fake news when they see it.

There has been a lot of research on this question over the years, and I have discussed it often, but it’s always useful to try to gather together years of research into a single systematic review and/or meta-analysis. It’s possible I and others may be selectively choosing or remembering parts of the research to reinforce a particular view – a problem that can be solved with a thorough analysis of all existing data. And of course I must point out that such reviews are subject to their own selection bias, but if properly done such bias should be minimal. The best case scenario is for there to be multiple systematic reviews, so I can get a sense of the consensus of those reviews, spreading out bias as much as possible in the hopes it will average out in the end.

With that in mind, there is a recent meta-analysis of studies looking at the demographics of susceptibility to misinformation.  The results mostly confirm what I recall from looking at the individual studies over the years, but there are some interesting wrinkles. They looked at studies which used the news headline paradigm – having subjects answer if they think a headline is true or not, “totaling 256,337 unique choices made by 11,561 participants across 31 experiments.” That’s a good chunk of data. First, people were significantly better than chance at determining which headlines were true (68.51%) or false 67.24%). That’s better than it being a coin flip, but still, about a third of the time subjects in these studies could not tell real from fake headlines. Given the potential number of false headlines people encounter daily, this can result in massive misinformation.

What factors contributed to susceptibility to misinformation, or protected against it? One factor that many people may find surprising, but which I have seen many times over the years, is that education level alone conveyed essentially no benefit. This also aligns with the pseudoscience literature – education level (until you get to advanced science degrees) does not protect against believing pseudoscience. You might also (and I do) view this as a failure of the education system, which is supposed to be teaching critical thinking. This does not appear to be happening to any significant degree.

There were some strong predictors. People who have an analytical thinking style were more accurate on both counts – identifying true and false headlines, but with a bit of a false headline bias. This factor comes up often in the literature. An analytical thinking style also correlates with lower belief in conspiracy theories, for example. Can we teach an analytical thinking style? Yes, absolutely. People have a different inherent tendency to rely on analytical vs intuitive thinking, but almost by definition analytical thinking is a conscious deliberate act and is a skill that can be taught. Perhaps analytical thinking is the thing that schools are not teaching students but should be.

Older age also was associated with higher overall discrimination, and also with a false headline bias, meaning that their default was to be skeptical rather than believing. It’s interesting to think about the interplay between these two things – in a world with mostly false headlines, having a strong skeptical bias will lead to greater accuracy. Disbelieving becomes a good first approximation of reality. The research, as far as I can see, did not attempt to replicate reality in terms of the proportion of true to false headlines. This means that the false bias may be more or less useful in the real world than in the studies, depending on the misinformation ecosystem.

Also being a self-identified Democrat correlated with greater accuracy and also a false bias, while self-identifying as a Republican was associated with lower accuracy and a truth bias (tending to believe headlines were true). Deeply exploring why this is the case is beyond the scope of this article (this is a complex question), but let me just throw out there a couple of the main theories. One is that Republicans are already self-selected for some cognitive features, such as intuitive thinking. Another is that the current information landscape is not uniform from a partisan perspective, and is essentially selecting for people who tend to believe headlines.

Some other important factors emerged from this data. One is that a strong predictor of believing headlines was partisan alignment – people tended to believe headlines that aligned with their self-identified partisan label. This is due to “motivated reflection” (what I generally refer to as motivated reasoning).  The study also confirmed something I have also encountered previously – that those with higher analytical thinking skills actually displayed more motivated reasoning when combined with partisan bias. Essentially smarter people have the potential to be better and more confident at their motivated reasoning. This is a huge reason for caution and humility – motivated reasoning is a powerful force, and being smart not only does not necessarily protect us from it, but may make it worse.

Finally, the single strongest predictor of accepting false headlines as true was familiarity. If a subject had encountered the claim previously, they were much more likely to believe it. This is perhaps the most concerning factor to come out of this review, because it means that mere repetition may be enough to get most people to accept a false reality. This has big implications for the “echochamber” effect on both mainstream and social media. If you get most of your news from one or a few ideologically aligned outlets, you essentially are allowing them to craft your perception of reality.

From all this data, what (individually and as a society) should we do about this, if anything?

First, I think we need to seriously consider how critical thinking is taught (or not taught) in schools. Real critical thinking skills need to be taught at every level and in almost every subject, but also as a separate dedicated course (perhaps combined with some basic scientific literacy and media savvy). Hey, one can dream.

The probability of doing something meaningful in terms of regulating media seems close to zero. That ship has sailed. The fairness doctrine is gone. We live in the proverbial wild west of misinformation, and this is not likely to change anytime soon. Therefore, individually, we can protect ourselves by being skeptical, working our analytical thinking skills, checking our own biases and motivated reasoning, and not relying on a few ideologically aligned sources of news. One good rule of thumb is to be especially skeptical of any news that reinforces your existing biases. But dealing with a societal problem on an individual level is always a tricky proposition.

The post Who Believes Misinformation first appeared on NeuroLogica Blog.

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Designing research studies to determine what is going on inside the minds of animals is extremely challenging. The literature is littered with past studies that failed to properly control for all variables and thereby overinterpreted the results. The challenge is that we cannot read the minds of animals, and they cannot communicate directly to us using language. We have to infer what is going on in their minds from their behavior, and inference can be tricky.

One specific question is whether or not our closest ancestors have a “theory of mind”. This is the ability to think about what other creatures are thinking and feeling. Typical humans do this naturally – we know that other people have minds like our own and we can think strategically about the implications of what other people think, how to predict their behavior based upon this, and how to manipulate the thoughts of other people in order to achieve our ends.

Animal research over the last century or so has been characterized by assumptions that some cognitive ability is unique to humans, only to find that this ability exists in some animals, at least in a precursor form. This makes sense, as we have evolved from other animals, most of our abilities likely did not come out of nowhere but evolved from more basic precursors.

But it is still undeniably true that humans are unique in the animal kingdom for our sophisticated cognitive abilities. Our language, abstraction, problem solving, and technological ability is significantly advanced beyond any other animal. We therefore cannot just assume that even our closest relatives possess any specific cognitive ability that humans have, and therefore this is a rich target of research.

The specific question of whether or not our ape relatives have a theory of mind remains an open research controversy. Previous research has suggested that they might, but all of this research was designed around the question of whether or not another individual had some specific piece of knowledge. Does the subject ape know that another ape or a human knows a piece of information? This research suggests that they might, but there remains a controversy over how to interpret the results – again, what can we infer from the animal’s behavior?

A new study seeks to inform this discussion by adding another type of research – looking at whether or not a subject ape, in this case a bonobo, understands that a human researcher lacks information. This is exploring the theory of mind from the perspective of another creatures ignorance rather than their knowledge. The advantage here, from a research perspective, is that such a theory of mind would require that the bonobo simultaneously knows the relevant piece of information and that a human researcher does not know this information – that their mental map of reality is different from another creature’s mental map of reality.

The setup is relatively simple. The bonobo sits across from a human researcher, and at a 90 degree angle from a “game master”. The game master places a treat under one of several cups in full view of the bonobo and the human researcher. They then wait 5 seconds and then the researcher reveals the treat and gives it to the bonobo. This is the training phase – letting the bonobo know that there is a treat there and they will be given the treat by the human researcher after a delay.

In the test phase an opaque barrier is placed between the human researcher and the cups, and this barrier either has a window or it doesn’t. So in some conditions the human researcher knows where the treat is and in others they don’t. The research question is – will the bonobo point to the cup more often and more quickly when the human researcher does not know where the treat is?

The results were pretty solid – the bonobos in multiple tests pointed to the cup with the treat far more often, quickly, and insistently when the human researcher did not know where the treat was. They also ran the experiment with no researcher, to make sure the bonobo was not just reaching for the treat, and again they did not point to the cup when there was no human researcher to communicate to.

No one experiment like this is ever definitive, and it’s the job of researchers to think of other and more simple ways to explain the results. But the behavior of the bonobos in this experimental setup matched what was predicted if they indeed have at least a rudimentary theory of mind. They seem to know when the human researcher knew where the treat was, independent of the bonobo’s own knowledge of where the treat was.

This kind of behavior makes sense for an intensely social animal, like bonobos. Having a theory of mind about other members of your community is a huge advantage on cooperative behavior. Hunting in particular is an obvious scenario where coordination ads to success (bonobos do, in fact, hunt).

This will not be the final word on this contentious question, but does move the needle one click in the direction of concluding that apes likely have a theory of mind. We will see if these results replicate, and what other research designs have to say about this question.

The post Do Apes Have a Theory of Mind first appeared on NeuroLogica Blog.

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Everything, apparently, has a second life on TikTok. At least this keeps us skeptics busy – we have to redebunk everything we have debunked over the last century because it is popping up again on social media, confusing and misinforming another generation. This video is a great example – a short video discussing the “incorruptibility’ of St. Teresa of Avila. This is mainly a Catholic thing (but also the Eastern Orthodox Church) – the notion that the bodies of saints do not decompose, but remain in a pristine state after death, by divine intervention. This is considered a miracle, and for a time was a criterion for sainthood.

The video features Carlos Eire, a Yale professor of history focusing on medieval religious history. You may notice that the video does not include any shots of the actual body of St. Teresa. I could not find any online. Her body is not on display like some incorruptibles, but has been exhumed in 1914 and again recently. So we only have the reports of the examiners. This is where much of the confusion is generated – the church defines incorruptible very differently than the believers who then misrepresent the actual evidence. Essentially, if the soft tissues are preserved in any way (so the corpse has not completely skeletonized) and remains somewhat flexible, that’s good enough.

The case of Teresa is typical – one of the recent examiners said, “There is no color, there is no skin color, because the skin is mummified, but you can see it, especially the middle of the face.” So the body is mummified and you can only partly make out the face. That is probably not what most believers imagine when the think of miraculous incorruptibility.

This is the same story over and over – first hand accounts of actual examiners describe a desiccated corpse, in some state of mummification. Whenever they are put on display, that is exactly what you see. Sometimes body parts (like feet or hands) are cut off and preserved separately as relics. Often a wax or metal mask is placed over the face because the appearance may be upsetting to some of the public. The wax masks can be made to look very lifelike, and some viewers may think they are looking at the actual corpse. But the narrative among believers is often very different.

It has also been found that there are many very natural factors that correlate with the state of the allegedly incorruptible bodies. A team of researchers from the University of Pisa explored the microenvironments of the tombs:

“They discovered that small differences in temperature, moisture, and construction techniques lead to some tombs producing naturally preserved bodies while others in the same church didn’t. Now you can debate God’s role in choosing which bodies went into which tombs before these differences were known, but I’m going to stick with the corpses. Once the incorrupt bodies were removed from these climates or if the climates changed, they deteriorated.”

The condition of the bodies seems to be an effect of the environment, not the saintliness of the person in life.

It is also not a secret – though not advertised by promoters of miraculous incorruptibility – that the bodies are often treated in order to preserve them. This goes beyond controlling the environment. Some corpses are treated with acid as a preservative, or oils or sealed with wax.

When you examine each case in detail, or the phenomenon as a whole, what you find is completely consistent with what naturally happens to bodies after death. Most decay completely to skeletons. However, in the right environment, some may be naturally mummified and may partly or completely not go through putrefaction. But if their environment is changed they may then proceed to full decay. And bodies are often treated to help preserve them. There is simply no need for anything miraculous to explain any of these cases.

There is also a good rule of thumb for any such miraculous or supernatural claim – if there were actually cases of supernatural preservation, we would all have seen it. This would be huge news, and you would not have to travel to some church in Italy to get a few of an encased corpse covered by a wax mask.

As a side note, and at the risk of sounding irreverent, I wonder if any maker of a zombie film considered having the corpse of an incorruptible animate. If done well, that could be a truly horrific scene.

The post Incorruptible Skepticism first appeared on NeuroLogica Blog.

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On January 20th a Chinese tech company released the free version of their chatbot called DeepSeek. The AI chatbot, by all accounts, is about on par with existing widely available chatbots, like ChatGPT. It does not represent any new abilities or breakthrough in quality. And yet the release shocked the industry causing the tech-heavy stock market Nasdaq to fall 3%. Let’s review why that is, and then I will give some thoughts on what this means for AI in general.

What was apparently innovative about DeepSeek is that, the company claims, it was trained for only $8 million. Meanwhile ChatGPT 4 training cost over $100. The AI tech industry is of the belief that further advances in LLMs (large language models – a type of AI) requires greater investments, with ChatGPT-5 estimated to cost over a billion dollars. Being able to accomplish similar results at a fraction of the cost is a big deal. It may also mean that existing AI companies are overvalued (which is why their stocks tumbled).

Further, the company that made DeepSeek used mainly lower power graphics chips. Apparently they did have a horde of high end chips (the export of which are banned to China) but was able to combine them with more basic graphics chips to create DeepSeek. Again, this is what is disruptive – they are able to get similar results with lower cost components and cheaper training. Finally, this innovation represents a change for the balance of AI tech between the US and China. Up until now China has mainly been following the US, copying its technology and trailing by a couple of years. But now a Chinese company has innovated something new, not just copied US technology. This is what has China hawks freaking out. (Mr. President, we cannot allow an AI gap!)

There is potentially some good and some bad to the DeepSeek phenomenon. From a purely industry and market perspective, this could ultimately be a good thing. Competition is healthy. And it is also good to flip the script a bit and show that innovation does not always mean bigger and more expensive. Low cost AI will likely have the effect of lowering the bar for entry so that not only the tech giants are playing. I would also like to see innovation that allows for the operation of AI data centers requiring less energy. Energy efficiency is going to have to be a priority.

But what are the doomsayers saying? There are basically two layers to the concerns – fear over AI in general, and fears over China. Cheaper more efficient AIs might be good for the market, but this will also likely accelerate the development and deployment of AI applications, something which is already happening so fast that many experts fear we cannot manage security risks and avoid unintended consequences.

For example, LLMs can write code, and in some cases they can even alter their own code, even unexpectedly. Recently an AI demonstrated the ability to clone itself. This has often been considered a tipping point where we potentially lose control over AI – AI that an iterate and duplicate itself without human intervention, leading to code no one fully understands. This will make it increasingly difficult to know how an AI app is working and what it is capable of. Cheaper LLMs leading to proliferation obviously makes all this more likely to happen and therefore more concerning. It’s a bit like CRISPR – cheap genetic manipulation is great for research and medical applications, but at some point we begin to get concerned about cheap and easy genetic engineering.

What about the China angle? I wrote recently about the TikTok hubbub, and concerns about an authoritarian rival country having access to large amounts of data on US citizens as well as the ability to put their thumb on the scale of our internal political discourse (not to mention deliberate dumbing down our citizenry). If China takes the lead in AI this will give them another powerful platform to do the same. At the very least it subjects people outside of China to Chinese government censorship. DeepSeek, for example, will not discuss any details of Tiananmen Square, because that topic is taboo by the Chinese government.

It is difficult to know, while we are in the middle of all of this happening, how it will ultimately play out. In 20 years or so will we look back at this time as a period of naive AI panic, with fears of AI largely coming to nothing? Or will we look back and realize we were all watching a train wreck in slow motion while doing nothing about it? There is a third possibility – the YdK pathway. Perhaps we pass some reasonable regulations that allow for the industry to develop and innovate, while protecting the public from the worst risks and preventing authoritarian governments from getting their hands on a tool of ultimate oppression (at least outside their own countries). Then we can endlessly debate what would have happened if we did not take steps to prevent disaster.

The post The Skinny on DeepSeek first appeared on NeuroLogica Blog.

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There really is a significant mystery in the world of cosmology. This, in my opinion, is a good thing. Such mysteries point in the direction of new physics, or at least a new understanding of the universe. Resolving this mystery – called the Hubble Tension – is a major goal of cosmology. This is a scientific cliffhanger, one which will unfortunately take years or even decades to sort out. Recent studies have now made the Hubble Tension even more dramatic.

The Hubble Tension refers to discrepancies in measuring the rate of expansion of the universe using different models or techniques. We have known since 1929 that the universe is not static, but it is expanding. This was the famous discovery of Edwin Hubble who notice

d that galaxies further from Earth have a greater red-shift, meaning they are moving away from us faster. This can only be explained as an expanding universe – everything (not gravitationally bound) is moving away from everything else. This became known as Hubble’s Law, and the rate of expansion as the Hubble Constant.

Then in 1998 two teams, the Supernova Cosmology Project and the High-Z Supernova Search Team, analyzing data from Type 1a supernovae, found that the expansion rate of the universe is actually accelerating – it is faster now than in the distant past. This discovery won the Nobel Prize in physics in 2011 for  Adam Riess, Saul Perlmutter, and Brian Schmidt. The problem remains, however, that we have no idea what is causing this acceleration, or even any theory about what might have the necessary properties to cause it. This mysterious force was called “dark energy”, and instantly became the dominant form of mass-energy in the universe, making up 68-70% of the universe.

I have seen the Hubble Tension framed in two ways – it is a disconnect between our models of cosmology (what they predict) and measurements of the rate of expansion, or it is a disagreement between different methods of measuring that expansion rate. The two main methods of measuring the expansion rate are using Type 1a supernovae and by measuring the cosmic background radiation. Type 1a supernovae are considered standard candle because they have roughly the same absolute magnitude (brightness). The are white dwarf stars in a binary system that are siphoning off mass from their partner. When they reach a critical point of mass, they go supernova. So every Type 1a goes supernova with the same mass, and therefore the same brightness. If we know an object’s absolute magnitude of brightness, then we can calculate its distance. It was this data that lead to the discovery that the universe is accelerating.

But using our models of physics, we can also calculate the expansion of the universe by looking at the cosmic microwave background (CMB) radiation, which is the glow left over after the Big Bang. This gets cooler as the universe expands, and so we can calculate that expansion by looking at the CMB close to us and farther away. Here is where the Hubble Tension comes in. Using Type 1a supernovae, we calculate the Hubble Constant to be 73 km/s per megaparsec. Using the CMB the calculation is 67 km/s/Mpc. These numbers are not close enough – they are very different.

At first it was thought that perhaps the difference is due to imprecision in our measurements. As we gather more and better data (such as building a more complete sample of Type 1a supernovae), using newer and better instruments, some hoped that perhaps these two numbers would come into alignment. The opposite has happened – newer data has solidified the Hubble Tension.

A recent study, for example, uses the Dark Energy Spectroscopic Instrument (DESI) to make more precise measurements of Type 1a’s in the nearby Coma cluster. This is used to make a more precise calibration of our overall measurements of distance in the universe. With this more precise data, the authors argue that the Hubble Tension should now be considered a “Hubble Crisis” (a term which then metastasized throughout reporting headlines). The bottom line is that there really is a disconnect between theory and measurements.

Even more interesting, another group has used updated Type 1a supernovae data to argue that perhaps dark energy does not have to exist at all. This is their argument: The calculation of the Hubble Constant throughout the universe used to establish an accelerating universe is based on the assumption of isotropy and homogeneity at the scale we are observing. Isotropy means that the universe is essentially the same density no matter which direction you look in, while homogeneity means that every piece of the universe is the same as every other piece. So no matter where you are and which direction you look in, you will observe about the same density of mass and energy. This is obviously not true at small scales, like within a galaxy, so the real question is – at what scale does the universe become isotropic and homogenous? Essentially cosmologists have used the assumption of isotropy and homogeneity at the scale of the observable universe to make their calculations regarding expansion. This is called the lambda CDM model (ΛCDM), where lambda is the cosmological constant and CDM is cold dark matter.

This group, however, argues that this is not true. There are vast gaps with little matter, and matter tends to clump along filaments in the universe. If instead you take into account these variations in the density of matter throughout the universe, you get different results for the Hubble Constant. The primary reason for this is General Relativity. This is part of Einstein’s (highly verified) theory that matter affects spacetime. Where matter is dense, time relatively slows down. This means as we look out into the universe, the light that we see is travelling faster through empty space than it is through space with lots of matter, because that matter is causing time to slow down. So if you measure the expansion rate of the universes it will appear faster in gaps and slower in galaxy clusters. As the universe expands, the gaps expand, meaning the later universe will have more gaps and therefore measure a faster acceleration, while the older universe has smaller gaps and therefore measures a slower expansion. They call this the timescape model.

If the timescape model is true, then the expansion of the universe is not accelerating (it’s just an illusion of our observations and assumptions), and therefore there is no need for dark energy. They further argue that their model is a better fit for the data than ΛCDM (but not by much). We need more and better data to definitively determine which model is correct. They are also not mutually exclusive – timescape may explain some but not all of the observed acceleration, still leaving room for some dark energy.

I find this all fascinating. I will admit I am rooting for timescape. I never liked the concept of dark energy. It was always a placeholder, but also just has properties that are really counter-intuitive. For example, dark energy does not dilute as spacetime expands. This does not mean it is false – the universe can be really counterintuitive to us apes with our very narrow perspectives. I will also follow whatever the data says. But wouldn’t it be exciting if an underdog like timescape overturned a Nobel Prize winning discovery, and for at least a second time in my lifetime radically changed how we think about cosmology. Timescape may also resolve the Hubble Tension to boot.

Whatever the answer turns out to be – clearly there is something wrong with our current cosmology. Resolving this “crisis” will expand our knowledge of the universe.

The post The Hubble Tension Hubbub first appeared on NeuroLogica Blog.