brains – Greg Laden's Blog

Brain microbiome

Greg Laden — Mon, 06 Aug 2018 20:16:24 +0000

Human brains, presumably mammal brains in general, do not have microbiomes. If they did, they would look like Donald Sutherland in that movie.

Also, a microbiome is not the same thing as an infection. A microbiome is a mutualistic (or similar) ecology of multi-celled organisms or part thereof (like, your gut or your eyeballs or something) and microbes, probably including multiple species or varieties. Brains do not have that. If there are microbes in the brain it is an infection.

There is some interesting research out there possibly linking infections and Alzheimers. It is unfortunately being couched in terms of microbiomes. Why? Mainly because science reporters are generally not scientists, so they don’t bump on errors like that? Maybe. But in this case, there seems to be an actual project that claims to be actually mapping out the brain’s microbiome, including “helpful” organisms.

Here is the article from the Harvard Gazette

And here is a Twitter Feed confirming what I say above.

Compelling evidence for a human brain microbiome is non-existent (see also placenta microbiome) https://t.co/aFZc1hiQji

— Nick Loman (@pathogenomenick) August 5, 2018

If you have evidence to the contrary please post it below.

How ants navigate homeward – forward, backward, or sideward

Greg Laden — Thu, 19 Jan 2017 20:00:41 +0000

I’ve got this press release that will be of interest to many:

An international team including researchers at the university of Edinburgh and Antoine Wystrach of the Research Centre on Animal Cognition (CNRS/Université Toulouse III—Paul Sabatier) has shown that ants can get their bearings whatever the orientation of their body. Their brains may be smaller than the head of a pin, but ants are excellent navigators that use celestial and terrestrial cues to memorize their paths. To do so, they use several regions of the brain simultaneously, proving once again that the brain of insects is more complex than thought. The researchers’ findings were published in Current Biology on January 19, 2017.

Until now, ethological research suggested that ants memorized the scenery perceived along their route as it is projected on their multifaceted retinas—thus using a body-centered, or egocentric, frame of reference. By this hypothesis, to recognize memorized surroundings and follow a path formerly traveled, ants would need to orient their bodies in the same way each time. But they sometimes need to walk backwards as well, and this doesn’t prevent them from finding their way back to their nest. Could it be that ants can recognize a route when facing the opposite direction? Are they able to create a visual model of their environment that is independent of their body orientation?

To answer these questions, the researchers studied Cataglyphis velox, an Andalusian desert ant known for its solo navigation ability. First they let the insects familiarize themselves with a route that included a 90° turn. After a day of training, ants that received a cookie crumb light enough to carry while walking forward handled the turn without the slightest difficulty. However, those given large cookie crumbs had to move backward, and unlike the others, they maintained their bearing instead of turning.

They also exhibited unexpected behavior: After walking backward a bit, they would occasionally drop their crumb, turn around, observe the scenery while pointing their bodies in the right direction, return to the crumb, and resume towing it backward – but this time in the correct direction. For these ants, body alignment thus seems necessary for recognition of scenery perceived by their retinas, but they are then able to memorize the new bearing and follow it backward. This behavior also shows that they can recall the existence of the dropped cookie crumb, and its location, in order to return to it after updating their bearing. These observations imply that at least 3 kinds of memory are working in unison: the visual memory of the route, the memory of the new direction to follow, and the memory of the crumb to retrieve.

Through another experiment using a mirror to reflect the sun1, the team demonstrated that the ants used celestial cues to maintain their bearing while walking backwards. Furthermore, ants were able to move in straight paths, whether walking forward, backward, or sideways. Once a bearing is memorized, they stay on it no matter how their bodies are oriented. Together these observations suggest that ants register direction using an external – or allocentric – frame of reference.

These new findings show that the ants’ spatial orientation relies on multiple mental representations and memories woven together through a flow of information between several areas of their brain. This offers a whole new perspective on the world of insects, which is much more complex than previously believed.

The Brain: An Illustrated History of Neuroscience

Greg Laden — Thu, 19 Nov 2015 18:01:24 +0000

In 1817, Karl August Weinhold had a go at a real-life Frankenstein’s monster — only in his version he uses a cat. The German scooped out the brain and spinal cord of a recently dead cat. He then pured a molten mixture of zinc and silver into the skull and spinal cavity. He was attempting to make the two metals work like an electric pile, or battery, inside the unfortunate cate, replacing the electrical of the nerves. Weinhold reported that the cat was revived momentarily by the currents and stood up and stretched in a rather robotic fashion!

It’s Alive!!!!

Weinhold’s reanimated cat was just the tip of the iceberg. In those days, the same days during which Mary Shelley wrote Frankenstein, the forerunners of modern neuroscience were reanimating all sorts of animals (it started, of course, with frogs) including humans, with suitably horrifying results, using primitive electricity generating machines and ingeniously placed probes.

The Brain: An Illustrated History of Neuroscience (Ponderables 100 Ideas That Changed Histoy Who Did What When) (Ponderables 100 Discoveries That Changed Histoy Who Did What When) by the prolific Tom Jackson (see list below) mentions the cat story in a small sidebar, but several of the 100 moments in neuroscience relate to this sort of early scientific activity. The idea of the book is to put a large topic, in this case the history of neuroscience, into 100 bite sized pieces (with a 101st item at the end, a sort of technical summary) in chronological order. The result is a very browsable and fascinating book, an educational and entertaining coffee table item, even a good gift idea.

I know something about neuroscience and brain evolution, and even a bit about the history of this research, and I found most of the entries to be reasonable, well researched, and accurate. There is sufficient debunking of some of the bad ideas (about race, IQ, etc.), though I would like to have seen Jackson’s treatment of lateralization to have been a bit more probing and nuanced, since that is one of the areas where pop culture has overstayed its welcome. Still, the book is scientifically accurate, not to deep yet not a gloss.

One of the neat features of the book is a giant pull out unfoldable wall poster that is a timeline of the history of neuroscience. I’ll probably give that to my wife for her to hang in her biology classroom, especially since she teaches a fair amount about brains and intends to expand on that teaching over the next couple of years.

The other side of the foldout timeline is a set of optical illusions, including the blind spot test, the arrows affecting the apparent length of the line test, and a lot of the other usual illusions, all very well done with quality presentation and printing.

There are bits at the beginning and end of the book (including item 101, mentioned above) that serve as reference material. There is an index, though it is not dense (for example, having noted the cat story I use above, I tried to look it up in the Index but couldn’t find it). Also as an appendix is a explication of several key open questions in neurobiology (the “Imponderables”). Also, references are supplied.

The illustrations are excellent throughout.

This book is for anyone interested in science, especially neuro. If you cover this topic in your High School or Middle School classes, it is a good book to have in your library. It would make an excellent gift for the science-oriented person you know, especially since it is just out and they won’t have it yet.

This is part of the Ponderables series of illustrated books published by Shelter Harbor Press.

Other books by Tom Jackson:

Mathematics An Illustrated History of Numbers (100 Ponderables)


The Elements: An Illustrated History of the Periodic Table (100 Ponderables)



The Universe An Illustrated History of Astronomy (Ponderables)



Physics: An Illustrated History of the Foundations of Science (Ponderables 100 Breakthroughs That Changed History Who Did What When)



Philosophy: An Illustrated History of Thought  (Ponderables 100 Ideas That Changed History Who Did What When)



Chilled: How Refrigeration Changed the World and Might Do So Again



Magic School Bus Presents: Insects: A Nonfiction Companion to the Original Magic School Bus Series



Exploring Nature: Monkeys: Baboons, Macaques, Mandrills, Lemurs And Other Primates, All Shown In More Than 180 Enticing Photographs (Exploring Nature (Armadillo))

Two Journeys Through the Human Past

Greg Laden — Thu, 15 Dec 2011 20:35:08 +0000

Recently, I mentioned two new books on human evolution, and I told you I had a print review of them coming up. Well, it’s here, in American Scientist! Yes, I know, that’s an internet thing, but it is the internet version of the print thing. Please have a look, and leave a nice comment! Or … Continue reading →

Dawkins…. On Purpose

Greg Laden — Thu, 05 Mar 2009 08:52:48 +0000

Dawkins gave a talk that could be criticized as not particularly new, in that his main idea is that human brains are too powerful and adaptable to continue to function primarily within an adaptive program serving as a proper adaptive organ. Instead, human brains think up all sorts of other, rather non-Darwinian things to do. This idea has been explored and talked about in many ways by many people. Kurt Vonegut Jr.’s character in Galapagos repeatedly, in a state of lament, quips “Thanks, Big Brain…” as evidence accumulates that our inevitable march towards extinction is primarily a function of that particular organ’s activities. People have talked about the brain as the outcome of runaway sexual selection. Evolutionary psychologists have talked about the evolution of strong preferences and desires, which in turn play out i a rather Frankensteinian fashion in a world where those desires can be met with ease instead of hard work and much time. Thus, we have evolved a yearning for rare nutrients such as salt and fat, and then we invented the ability to have unlimited access to salt and fat. So now, in a ‘civilized world’, it is the salt and fat that kills us incited of the predator or the con-specific competitor over access to some food or some sexual opportunity. (Thanks, Big Brain….)

But the talk was not old stuff. (See this important commentary by PZ Myers.) There was some important new stuff here as well. I had the sense that there was a fairly elaborate theory running below the surface and we were seeing bits and pieces of it, chosen for the audience and embedded in necessary contextual explanation which takes time to do. Thus, in an hours time, we got a taste which probably engorged the average intelligent audience member, but left the specialist chomping at the bit.

Dawkins made a number of points in his talk, and I’ll focus on what I see as the central thread. This thread addressed the concept of ‘purpose’ in relation to design, the differentiation of purpose into two types (archeo and neo, also potentially thought of as “natural” and “human-mad”), the potential complexity and (most importantly) adaptability of purpose-imbued systems, and the potential of subversion of this adaptability. This subversion is the crux of the talk, and it is unfortunate that this could not have been a two part talk where everything but subversion was covered in Part I, and the subversion question (which is really a major revision or extension of the memetic hypothesis, I think) in Part II.

As hinted above, subversion of adaptable purpose is, according to Dawkins, the expiation for the crazy stuff humans do, including things like skydiving and things like the rise of a Nazi state. Dawkins did not explore the ways in which this idea works (or not) differently at proximate (“how”) levels vs. ultimate (“why”) levels, but I’m sure he’d have some interesting things to say about it.

Purpose in relation to design was in part explicated by looking at both natural and artificial selection. He started with a very clear differentiation of where purpose can exist and not exist, where something like Ayers Rock, a lump of clay, or a rock may not really have a “purpose” while an adaptive function of a designed thing (like the culturally selected huge udder of a cow) may (to make a farmer rich). He used examples from both artificial selection and natural selection, as well as human engineering, and made clear the distinction between selection as a process (you’all know how that works) vs. intentional design or selection by humans. (But that distinction, while important, is not key to this thread, so we’ll leave that off).

Neo-purpose vs. archaeo-purpose (or maybe it’s “archeo-pupose”) are two terms that Dawkins introduced to differentiate between natural and human-engineered ‘purposeful’ things. Archaeo-purpose = adaptive functionality, maybe even non adaptive but naturalistic functionality, in nature. Neo-purpose is stuff humans make to do stuff, including artificial selection. The use of these terms in the talk seemed post-hoc and unnecessary, telling me that he’s got more to say about this but did not go into it at the time. (I mean, if you are going to design a couple of neologisms, they’ve got to have a purpose, right!?!??)

As an aside, with these terms we may have (primarily within the concept of archaeo-purpose) the possibility of a new way of talking about a definition of life. A living thing or feature of a living thing may have latent archaeo-purpose, but a non-living thing does not. However, abiotic action can have archaeo-purpose. Water (water just sitting there being observed) does not have “purpose.” But, the purpose of the falling of the water down a running stream or water fall can be described in thermodynamic terms, elemental bonding in partial physical or electromagnetic terms, etc. The purpose of the water is undefined or null, the purpose of the water fall is as a means of water answering the call of gravity. In nature, only life and verbs can have (archaeo) purpose. In a cultural context, anything can have (neo-) purpose. Like a rock. A rock in a sculpture garden can have the purpose of causing a visitor to the sculpture garden to wonder “what is the purpose of this rock…”

But I digresses…

A certain kind, category, subset, maybe level (not well described by Dawkins in the talk) of purpose can be complex and highly adaptive in how it plays out, like a guided missile which can adjust its trajectory to find its target, or a bat flying after an insect. The link between everything noted above about purpose and this complexity is accretetive. You’ve got to lay out the framework of purpose before you talk about the nature of purpose, but it is really the nature of purpose that we want to be talking about. If there is a link between the fundamentals of purpose and this property of complexity and/or adaptability, Dawkins did not explicate. But I suspect he is thinking about it.

Complex adaptive purpose (I’ll call it that for now, though I don’t really like the “complex” part … there can be adaptive purpose, and I can think of many examples can be and is often subverted. Dawkins gave some examples. This is particularly interesting to me, because I think a lot of important evolutoinary shifts have been exactly this, and indeed, almost all examples of co-evolution are just this, and everything is co-evolution.

But Dawkins point is simply that the brain is a complex adaptive system with a purpose that emerges from its developmental history, and if this developmental history is altered one way or another, you can get different syndromes of purpose. Thus Nazi’s, thus skydivers, thus people filing into a huge theatre to listen to some guy talk about purpose.

I have in mind a number of criticisms of the idea, but I can’t really be sure that they are valid criticisms because, as I suggest above, there are important parts of this idea that were not developed in the talk. thus, these critiques would be unfair and probably, even worse, misdirected. I would just be showing off my knowledge of things and possibly my vocabulary and writing abilities. Which is, of course, my primary adaptive methodology for obtaining food and sex. Which, at the moment, I have plenty of, so what would be the purpose of that!?!?!??

Male vs. Female Brains

Greg Laden — Wed, 25 Feb 2009 20:48:38 +0000

The male and female human brains are different. Some of the better documented differences are similar to differences seen in other mammals. They are hard to find, very small, and may or may not be of great significance. Obviously, some are very important because they probably relate to such things as the ability … or lack thereof … to bear offspring. But this is hardly ever considered in the parodies we see of these differences.

[Repost from Gregladen.com]

You have all seen the sometimes funny, sometimes not cartoon depictions of these differences, for example this one:

Obviously, this is in part a joke: If you looked at someone’s brain, you would not find it to be structured in this way at all. These vastly different “regions” are meant to lampoon culturally widespread perceptions of male-female differences in overall behavior, attitude, etc. by showing huge corresponding brain differences in the cartoon. It is interesting to consider that the differences purported in this sort of cartoon are huge, but the actual neurological differences we see in the real brains are small.

But what about these differences? It is often said that behind every stereotype there is some reality, or that everything no matter how fanciful has a grain of truth, etc. These are utterly idiotic things to say. If you were just now thinking that you kinda agree with these statements, please reconsider. Consider the possibility that people can habitually say or believe something and it is nothing close to, and not remotely based on, any kind of truth. Like that the stars are jewels stuck to the inside of an overturned bowl. That is not even close to the truth.

In almost all cartoon comparative neuroanatomy, males brains have large “sex” regions while female brains have large “don’t want sex” regions (such as a headache generator). This probably means that the person who drew the cartoon is either a teenage male or an older male who is too geeked-out to get dates. That is why he has time to draw these cartoons.

Other differences shown in the cartoons relate to language. These usually denigrate the female half of the equation (the “talk, talk, and more talk” region). It is interesting to note that in real life females have fewer language-related deficits than males, and can often engage in two conversations simultaneously, which most men can not do. It is possible that the language related differences, or some of them, relate to the difference between males and females in the number of connections between the left and right hemispheres (females have way more).

Other differences shown in many cartoons are obviously generation and subculture dependent. For instance, the ability to program a VCR and the fixation on the remote. I live with two females, and one of them is the only person in the house who can program the VCR. I can do it if I need to, but I threw out the directions and it will take me a while to figure out, and blood will be spilled and profanities uttered. Both of my female house mates are about as fixated on the remote as I am. They tend to be able to find it more easily than I can, because their ancestors were gatherers and finding the remote is roughly the same thing as finding nuts, berries, and most importantly, plant underground storage organs. I, on the other hand, descend from a long line of hunters, so I tend to hunt the remote. Hunting, as is well known, tends to yield a more inconsistent return. So most of the time I don’t find any remote at all, and now and then, I find three or four of them in one episode of searching.

In any event, I think the cartoon depictions of male vs. female brains have two functions. One is as a means of examining cultural attitudes towards sex differences. Cultural distinctions, cultural activities, enculturated values, beliefs, and abilities tend to be both much more dramatic and much less controllable or adjustable than so-called “biological” differences. (Which is the opposite of what most people believe.) The cartoons tell us more about the cartoonist than about the object of the cartoon’s message. Also, it is interesting to note that some of the sex differences shown in the cartoons … which are presumably always of heterosexual cartoon brains … are part of the widely enculturated beliefs about homosexuality. A gay man understands, appreciates, and is generally into shoes (men or women’s shoes). Gay men understand the difference between wants and needs. And so on. However, we rarely if ever see the gay vs. straight brain cartoon. Off hand, I can think of no examples.

Which reminds me, if you are interested, please post a comment pointing to any brain difference cartoons you think are interesting or at least (from some perspective or another) funny. If I get enough, and they are sufficiently interesting, I’ll make a post that has them all as a kind of Web Museum of Brain Difference Cartoons. I could use it in class.

The other, closely related, function of these cartoons is as a touchstone to beliefs about how the brain works regardless of sex differences. For instance, the brain seems to function, according to these cartoons, to regulate sexual behavior, linguistic activities, and grooming or household activities. I find it interesting that these cartoons rarely reference thermoregulation, which absolutely counts as a perceived sex differences, and is definitely regulated in the brain.

Evolution of Language: Deacon vs. Pinker

Greg Laden — Fri, 15 Dec 2006 02:31:14 +0000

In considering the evolution of human language, I think it is helpful to contrast these two books, and the ideas presented in them:

Terrence Deacon’s “<The Symbolic Species: The Co-evolution of Language and the Brain”

and

Stephen Pinker’s “The Language Instinct: How the Mind Creates Language (P.S.)”

Neither book is exceptionally new, and in fact, Pinker has cranked out a number of books since The Language Instinct. However, I think The Language Instinct is the best of Pinker’s volumes for this discussion. In it, he lays out the basic evolutionary psychology argument in a way that is most directly contrasted with the ideas in Deacon’s. Also, The Language Instinct has a great chapter called (if memory serves) “The Language Mavens” which is worth reading whether or not you agree with or even like the rest of Pinker’s book.

Pinker’s argument, first laid out in a paper with Bloom in Cosmides, Toobey and Barkow’s volume “The Adapted Mind: Evolutionary Psychology and the Generation of Culture,” is that there is strong evidence that language is an adaptation (i.e., it is costly, complex, etc.) and thus, as an adaptation, is something subject to natural selection. Since language is mainly a cerebral brain function, we can assume that there are brain structures (mainly in the cerebrum) that facilitate language, and that these structures (language “modules,” in the parlance of evolutionary psychologists) are the actual traits under selection. Furthermore, we can assume that these traits are just like any other traits shaped by evolutionary forces, in that there are sets of genes that code for them. In essence, it is these genes that are actually under selection.

Pinker strengthens his argument by citing interesting aspects of language. Most compelling is probably Pinker’s discussion of pidgins and creoles, which he uses to argue that young children seem to be linguistic geniuses.

A pidgin is a partially formed derivative semi-language made of two or more languages brought together n one community by historical events such as slavery. The children who are exposed to the pidgin, as they grow up, turn the pidgin into a full blown language (a “creole”) with all the usual linguistic bells and whistles, including a reasonably extensive lexicon. This is an argument for the “built in” nature of language function because how could this happen were it not deeply encoded by genetic programs?

Deacon presents a very different argument. The main problem that Deacon has with Pinker is that Pinker’s model (and this applies broadly to evolutionary psychology in general) is biologically impossible. Neural systems, especially in the cerebrum, are not coded for at any important level of detail by sets of genes. Rather, they develop as the brain develops in response to the context in which they are growing. There is abundant evidence to support this view of neurological development. In fact, this view of neural development is pretty much the established central dogma for neurobiology. Deacon was speaking of this sort of thing before this had become so well established, and in areas such as anthropology and evolutionary psychology, where there appears to be a decade or so time lag between thinking about how brains have evolved and knowing about how brains actually develop and function. The point is, Pinker’s model can’t be true, as great as it sounds, because it relies on biological systems that don’t exist.

The fact that brains don’t work the way Pinker requires them to work is a sufficiently powerfully killer fact to derail the Pinker/Bloom/Cosmides/Toobey/Barkow paradigm that we need look no further. However, Deacon’s work offers more. It turns out that there are Darwinian processes working at the neurological level, in that the development of the brain systems that we see in adults involves overproduction followed by culling, which is precisely a Darwinian process. Even more interesting (but not, I think, as clear or well established) is Deacon’s assertion that languages themselves, due to the process of Darwinian selection in the symbolic realm, are adapted to be learned by children. Deacon asserts that a language ideal for use by adults may be very different than the language system we actually end up with.

So, children are not really linguistic geniuses. Rather, languages are shaped to be learned by children who are in some ways incredible learning machines, but with roughly the same limitations as adults.

An excellent discussion of Deacon and Pinker can be found on John Hawks’ blog: http://www.johnhawks.net/weblog/topics/minds/deacon.html John mentions that Chomsky’s view of language requires no intermediate forms, which seems implausible yet “is supported by some prominent evolutionists, such as Stephen Jay Gould, who views it as likely that other brain functions requiring symbolic logic were the targets of selection, and that language later arose as an artifact of culture.” Maybe, but I would like to add that in my view, the “fully blown or nothing” view of language is politically motivated and not necessarily well founded by evolutionary biology. Why political? John explains: “[the possibility of intermediate languages] makes it possible that today’s people still vary in their biological capabilities with respect to language, and that selection may still be happening.”

My interpretation of Deacon vs. Pinker leads me to support Deacon’s view over Pinkers in most respects, while John is more equivocal. This may be in part because I have had hours of conversation with Deacon about this, and I share his view of the symbolic/semiotic side of the argument.

However, John Hawks also points out differences between Deacon’s model and current paleo-neurobiology, based on research done more recently than the publication of The Symbolic Species, with which he (Hawks) is very familiar. So I strongly recommend that the reader visit his site and put some of that stuff in your brain as well.