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Here is a question that keeps me awake at nights: how do you define right versus left without referring to something, like the placement of our heart, an organ that is already tilted toward one side of the body (the left except in rare cases of situs inversus)?

For example, have a look at a bilaterally symmetrical organism below, in this case one of my favorites (Merriam-Webster defines bilateral symmetry as “symmetry in which similar anatomical parts are arranged on opposite sides of a median axis so that only one plane can divide the individual into essentially identical halves”.) We know left from right because we define them consistently, and that’s because humans are NOT bilaterally symmetrical so we can all agree on which side is which.

But now I’ll ask you to answer this. (i.e., by pointing) Assume you’re talking to a person (a Martian?) who has never heard about right vs. left sides.  Tell them, using the diagram of one of my favorite organisms below, standing upright, which side is the right and which the left without referring to your own body, to any minute differences in the diagram, or to asymmetries in the environment (e.g. the world or the solar system).  Since both sides are identical, how do you know which one is right without referring to how we’ve already defined it, presumably based on our own bodies?  Explain to a Martian who is bilaterally symmetrical which side is its right and which its left, and how they would know it.

Partial image by Charl Hutchings, CC BY 4.0, via Wikimedia Commons

 

I’m not sure if I’m making myself clear here, so I looked in the Oxford English Dictyion for the definition of “right”. There are of course many definitions that don’t refer to the direction, but here’s what it gives for the direction:

a.  of, relating to, situated on, or being the side of the body which is away from the side on which the heart is mostly located b.  located nearer to the right hand than to the left c. located to the right of an observer facing the object specified or directed as the right arm would point when raised out to the side d. located on the right of an observer facing in the same direction as the object specified

This didn’t help, because it all comes down to how humans have defined the sides based on our own asymmetries.

This problem is connected with something that’s always intrigued me: how do directional asymmetries evolve, in which an animals is predictably asymmetrical, like our hearts being more on one side or the others?  (There are some creatures with “fluctuating asymmetry”, in which right is different from left, but it’s not consistent, like lobsters in which one claw is a crusher and the other a slicer, or flatfish that develop to lie randomly on its left or right side sides as adults.  Evolving these doesn’t pose the problem I describe below.)

If we evolved from a bilaterally symmetrical (or radially symmetrical) organism, then even if front and back are genetically specified, as they are, how can you evolve from such a creature into an organism that has features consistently on the right (or left) sides?  The chemical gradients in a bilaterally symmetrical ancestor are presumably the same on both sides, so how can a gene mutation arise that consistently recognizes a given side to give rise to a feature on that side? In other words, how can a mutation KNOW whether it is on the left or right side of the body? (Of course once an initial directional asymmetry has evolved, it creates a directional cue that can be used to evolve further directional asymmetries. It’s the evolution of the first directional feature that is the difficulty.)

I’ve discussed this more clearly in two old posts on this site (here and here), which gives some partial answers residing in how asymmetrical molecules or asymmetrical beating of cilia could lead to the evolution of directional asymmetry from bilateral asymmetry.

But the problem above still nags at me: how do you tell a bilaterally symmetrical Martian which side is right and which is left without referring to our own bodies? Can it be done?

Again, this may be a non-problem, but I’ve seen no definition of “right” or “left” independent of our own bodily asymmetries.

Analysis of DNA from a Neanderthal fossil found in a French cave indicates that it belonged to a group that was isolated for more than 50,000 years

DNA analysis shows that people from Easter Island had contact with Indigenous Americans around the 1300s, and finds there was no population crash before the arrival of Europeans

Gas bubbles on the surface of a star have been observed for the first time in detail outside our solar system, and they are 75 times the size of our sun

We're finally pinning down the mechanisms that drive obsessive-compulsive disorder, revealing a complex combination of imbalanced brain networks, the immune system and even gut microbes

Physicists have created the first two-dimensional version of the Bose glass, a novel phase of matter that challenges statistical mechanics.

Researchers have succeeded in combining two major research fields in photonics by creating a nano-object with unique optical qualities. Since the object is a thousand times thinner than the human hair, yet very powerful, the breakthrough has great potential in the development of efficient and compact nonlinear optical devices.

Researchers have succeeded in combining two major research fields in photonics by creating a nano-object with unique optical qualities. Since the object is a thousand times thinner than the human hair, yet very powerful, the breakthrough has great potential in the development of efficient and compact nonlinear optical devices.

For the design of reliable power grounding systems for critical electrical infrastructure, soil resistivity investigation is crucial. However, soil resistivity depends on various geotechnical properties, necessitating the need for robust assessment methods. In a new study, researchers conducted a comprehensive investigation into the behavior and relationships between soil resistivity and key geotechnical parameters and developed a predictive model based on their findings. This model can lead to cost-effective and more reliable design of grounding systems.

Water polluted with heavy metals can pose a threat when consumed by humans and aquatic life. Sugar-derived polymers from plants remove these metals but often require other substances to adjust their stability or solubility in water. Now, researchers report a sugar-like polymer that traps heavy metals within insoluble clumps for easy removal. In proof-of-concept tests, the polymer removed ionic cadmium and lead from river water spiked with these persistent contaminants.

Most atoms are made from positively charged protons, neutral neutrons and negatively charged electrons. Positronium is an exotic atom composed of a single negative electron and a positively charged antimatter positron. It is naturally very short-lived, but researchers have now successfully cooled and slowed down samples of positronium using carefully tuned lasers. They hope this research will help others explore exotic forms of matter, and that such research might unlock the secrets of antimatter.

Astronomers have captured images of a star other than the Sun in enough detail to track the motion of bubbling gas on its surface. The images of the star, R Doradus, were obtained in July and August 2023. They show giant, hot bubbles of gas, 75 times the size of the Sun, appearing on the surface and sinking back into the star's interior faster than expected.

Neuroscientists have revealed how sensory input is transformed into motor action across multiple brain regions in mice. The research shows that decision-making is a global process across the brain that is coordinated by learning. The findings could aid artificial intelligence research by providing insights into how to design more distributed neural networks.

With maps of the connections between neurons and artificial intelligence methods, researchers can now do what they never thought possible: predict the activity of individual neurons without making a single measurement in a living brain.

There were at least two op-eds in the New York Times in the last few days arguing that if Harris was to win last night’s debate, she could not spend her time attacking Trump but had to show that she had tangible policy proposals for the American people.  Well, Harris did win the debate (I’m not aware of anybody who disagrees with this, including conservative websites like the National Review), but it was not because of her policy proposals. (Fortunately, I managed to stay awake to watch the whole thing.)

The NYT was wrong: Harris won the debate hands down, not by presenting tangible policies (she did mention a few), but by doing what she was told not to do: baiting and attacking Trump. She did it calmly but persistently, to the point where Trump became so baffled and enraged that he simply lost it, becoming unhinged and yes, almost deranged. And when that happened, his narcissism and lying became uncontrollable. In fact, at some points I thought that, like Biden, he had simply lost his ability to think. It seems to me now that Trump is showing signs of age, in a manner different in degree but not in kind from the kind of fogginess that brought down Biden in his last debate with Trump.

If you didn’t see the debate, it’s below.

I suspect that some of Harris’s debate practice involved confecting statements that would unsettle Trump, and, sure enough, they worked, like a red cape shown to a bull.  Perhaps the most effective was Harris’s assertion that people got bored at Trump rallies, which were insubstantial and full of pop culture, and simply left them early.

That was enough to unsettle Trump, who claims that his rallies were, like everything else he does, the greatest in the history of America. And he never recovered his equilibrium.  The lies and misstatements spouted forth like water from a fountain.  There was the statement that Haitians were eating pets in Ohio, the claim that Harris met both Putin and Zelensky and failed to secure a peace (she never met Putin), the false claim that tariffs on foreign goods wouldn’t result in higher prices for consumers, that if was elected he could settle the Ukraine/Russia war before he took office, that Harris was a Marxist, that some Democrats support the execution of children after birth, and so on. None of that is true. When Harris said that world leaders were laughing at Trump’s ineptitude (another statement guaranteed to bait him), his response was to quote Hungarian President Viktor Orbán, a minor figure who admires Trump but also admires Putin. Was that the best he could do?

The WaPo and other sites have compiled a list of Trump’s lies and exaggerations, and it’s long.  Now Harris wasn’t immune to misstatements, either, but they were far fewer, and included her statement that “And as of today, there is not one member of the United States military who is in active duty in a combat zone, in any war zone around the world, the first time this century,”, which isn’t true. She claimed that the Biden administration created over 800,000 manufacturing jobs (the true number is close to 625,00).  But these are trivial compared to Trump’s fulminating and arrant lying.

I don’t know how many undecided voters would have been swayed by Trump’s performance to vote for him, but I doubt that it’s anywhere close to half.  The debate was really a contrast in likability and personality, and Harris’s cool demeanor and failure to get flustered made her look far better than Trump, whom I’ve always said suffers from a form of personality disorder.  And voters want to like the person whose box they check on the Presidential ballot.

Both candidates evaded some questions, including Trump’s denial of any responsibility for Project 2025, his failure to own up to the “fine people on both sides” statements he said after the far-right rally in Charlottesville, and his failure to specify how he’d rid the country of 11 million illegal immigrants. For her part, Harris didn’t really explain how her policies could change if her values didn’t, and she didn’t own up to her change of policy on fracking nor admit the seriousness of the immigration issue. This was balanced by two statements by Harris that were eloquent and, at least to me, somewhat moving: her defense of abortion rights for women and her rebuke of Trump for failing to stand for America’s democratic values by not supporting Ukraine.

No, Harris wasn’t strong on presenting policies (she did outline some, like her $6,000 tax credit to parents with newborns and a reduction in tax credits, and her website now outlines specific plans, including giving $25,000 to first-time home buyers). Whether her plans are financially viable is another question, but neither she nor Trump were asked that. (Note that, according to the New Republic, many of Harris’s policies were lifted directly from Biden’s campaign website).

The one issue on which I strongly disagree with Harris is the stand on Israel she espoused. While she said she strongly supported Israel and its right to defend itself, she also argued that the death toll of civilians in Gaza (something that’s been lifted from Hamas’s figures) is too high, and that we need both an immediate cease-fire and especially a two-state solution.  Both of those policies explicitly deny Israel the right to defend itself: a cease-fire now is a loss for Israel and a victory for Hamas, and we simply cannot have a two-state solution now. There are not honest brokers on either side, and of course neither Israel nor the Palestinians really want a two-state “solution”, which won’t solve any problems. (Israel now has no faith that a Palestinian state will be peaceful, and the Palestinians want the erasure of the state of Israel far more than they want their own state alongside Israel.)  I have little faith that Harris will conduct an israeli policy to my liking, but of course many Americans are far less pro-Israel than I.

As for the moderators, they were pretty good, though David Muir dominated the questions over Linsey Davis, which seems to me a bit sexist. However, the questions were generally good, and I thought the policy of fact-checking false claims during the live debate was a good one (and probably threw Trump off even more).

I believe that the Democrats, flush with victory, are now calling for a second debate, but I’m not sure there will be one. If the polls show that voters (and the electoral college) have moved towards Harris, Trump will surely not agree to a second debate.

When I discussed this with Luana today, she came to a conclusion that is hers. And here it comes. There is one good outcome of this debate: whichever side loses will have to recalibrate. If Trump loses, then MAGA is gone and Trump has lost most of his influence in the GOP. If Harris loses, then the Democrats have to become yet more centrist (though I have to add that Harris has deliberately become more centrist recently as a pragmatic issue to win).

We don’t know who will win the election, and the next few days will show how much Trump’s embarrassing performance will cost the GOP. (Remember, he’s always been an awful debater but has nevertheless come out on top twice.)  But regardless of that, there’s no question that the winner of the debate was Kamala Harris. I’m still not a big fan of hers, but was reminded last night why I’ve always regarded Trump as a joke—but a very dangerous joke.

Now, of course, it’s your turn to weigh in, and I ask you to do so in the comments. (There was some weighing in after my livestream post on the debate last night.)

And we’re back, with a batch of insect and spider photos from regular Mark Sturtevant. Mark’s comments are indented, and you can enlarge his photos by clicking on them.

Here are more pictures of arthropods that were taken last summer from eastern Michigan, which is where I live. They include both pictures from the field along with staged shots from the ‘ol dining room table.

First up are two bee- or wasp-mimicking Syrphid flies. The first one is Somula decora and the second is Temnostoma alternans. An issue that Syrphid flies will have when mimicking Hymenopterans is that because they are descended from flies with shortened antennae, they lack the long antennae of their models. The first one tries to fix that with antennae that are placed out on a stalk on the head.

The second one (which is doing a great job looking like a Yellowjacket, btw), instead tends to wave its darked front legs up and down as wasps will do with their antennae. The provided link is worth viewing, as it shows one of these flies using its legs. It really sells it! We often see that mimics not only take on the appearance of their models, but they will also imitate some of their identifying behaviors as well.

Next up is a simple Asian Lady Beetle larva Harmonia axyridis. This predatory larva will graze on aphids and then pupate to later become the ubiquitous Lady Beetle that everyone sees everywhere. In case anyone is wondering, the terms Lady Beetle, Ladybird Beetle, and Ladybug (one word) are all widely used, but it is technically more correct to use a reference that they are beetles (Coleoptera), and not bugs (Hemiptera). I will try to remember that.

It has been many years since I’ve seen the beetle shown in the next picture. This is an Elm Borer, Saperda tridentata. The common name of course tells you something about the biology of this insect.

Let’s wrap up this set with some Jumping Spiders, which belong to the family Salticidae (referring to their habit of jumping, or saltating). I am lucky in that many species from this charming family are commonly seen in and around the house. There quite a few more besides the three shown here.

First up is a male Tan or Familiar Jumping Spider, Platycryptus undatus. These are our largest Salticid, and I can always find a few out on the shed. They are distinctly flatter than many members of this family, and they use that to quickly hide inside crevices on the shed. One has to be fast when trying to catch them.

Next is a female Dimorphic jumping spider, Maevia inclemens. They have this name since males come in two color morphs that look completely different. I showed one here a couple posts back. Jumping spiders are usually fidgety to photograph, but a common trick is to calm them down with a little snack.

Last, here is a female Zebra Jumping Spider, Salticus scenicus. These are one of our smallest Salticids. Males sport very large chelicerae and fangs, and I have not managed to get WEIT-worthy pictures of one since (for me) they are always dialed up to eleven. Save it for next season, I always say. Anyway, the last Zebra picture shows a new post-processing trick where I add Dramatic Lighting by using layer masks to apply darkened gradients above and below. This is to add greater depth to the surroundings and to emphasize the subject.

It seems there is an endless stream of artificial intelligence (AI) news coming out, and this includes the field of medicine. There also continues to be a debate about the true impact of AI – how much is hype, and how much is a genuine advance that can transform our technology? As with many technological advances, it’s both. New tech, perhaps especially […]

The post Update on AI in the Clinic first appeared on Science-Based Medicine.

In between two spacecraft visiting Jupiter’s moon Io, a volcano spreading material over hundreds of kilometres has appeared

Cleaner wrasse use their reflection to build a mental image of their body size, which they use to compare themselves to rivals before picking a fight

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