News from the front (and back) of evolutionary theory. Lots of bitching about Darwin.
A very clear, 5 minute “explain it like I was 13” introduction to Epigenetics. This is the most important new topic in the science of evolution. The implications are much deeper and broader than suggested here.
If you’d like to hear more about these implications, click this link to the Epigenetics category. This will be the first post, with the others just below.
This is one hellacious science fact; it’s absolutely Metal. A question about the evolutionary point of menstruation leads to revealing the surprising life and death struggle between Mother and Fetus. It turns out their interests overlap only to a point. Beyond that point, it’s all cold-blooded competition; a no holds barred cage match. Suddenly, a third player appears.
Suzanne Sadedin, Ph.D. Evolutionary Biology
“…In many mammals, the placenta, which is part of the fetus, just interfaces with the surface of the mother’s blood vessels, allowing nutrients to cross to the little darling. Marsupials don’t even let their fetuses get to the blood: they merely secrete a sort of milk through the uterine wall. However, other mammal groups, including the higher primates, have retained a more direct connection, termed a hemochorial placenta. Among humans, chimpanzees, and gorillas, its development is especially invasive.
Inside the uterus, we have a thick layer of endometrial tissue, which contains only tiny blood vessels. The endometrium seals off our main blood supply from the newly implanted embryo. The growing placenta literally burrows through this layer, rips into arterial walls and re-wires them to channel blood straight to the hungry embryo. It delves deep into the surrounding tissues, razes them and pumps the arteries full of hormones so they expand into the space created. It paralyzes these arteries so the mother cannot even constrict them.
What this means is that the growing fetus now has direct, unrestricted access to its mother’s blood supply. It can manufacture hormones and use them to manipulate her. It can, for instance, increase her blood sugar, dilate her arteries, and inflate her blood pressure to provide itself with more nutrients. And it does. Some fetal cells find their way through the placenta and into the mother’s bloodstream. They will grow in her blood and organs, and even in her brain, for the rest of her life, making her a genetic chimera.
This might seem rather disrespectful. In fact, it’s sibling rivalry at its evolutionary best. You see, mother and fetus have quite distinct evolutionary interests. The mother ‘wants’ to dedicate approximately equal resources to all her surviving children, including possible future children, and none to those who will die. The fetus ‘wants’ to survive, and take as much as it can get. (The quotes are to indicate that this isn’t about what they consciously want, but about what evolution tends to optimize.)
There’s also a third player here – the father, whose interests align still less with the mother’s because her other offspring may not be his. Through a process called genomic imprinting, certain fetal genes inherited from the father can activate in the placenta. These genes ruthlessly promote the welfare of the offspring at the mother’s expense.”
Humans are in a symbiotic relationship with another species. Without this relationship, modern people would not exist.
The only thing that really separates us from other species is our shapeshifting survival strategy. Most animals have a survival strategy that sets like concrete into a virtual job description. The job description includes what food you eat, how you acquire it, how you shelter, mate, and raise young: A strategy.
Survival strategies are like an idea that grows into an organism. The organism fully commits to the idea by adapting; physically becoming the technology (the claws, teeth, running muscles, etc.) needed for the job. These adaptations improve success within the strategy but it’s like evolving into a corner. It’s like gambling the house on your betting system.
Humanity substitutes tools for adaptations, we don’t morph into a specialized form and narrow down. Tool use isn’t exactly what separates us though. There are numerous “generalist” species such as birds and other primates that cleverly use tools. The difference is that these species are elegantly solving problems posed by tasks in their job description and surviving better as a result, but never innovating to the extent of “leveling up” to a different job.
We have a sort of default simple job of walking around in a group picking up food. We have a second sense for noticing useful stuff and trying it. It’s as simple as understanding that that stick will help us knock down more fruit. When faced with more complicated problems like catching fish, we try all sorts of half-assed ideas before getting a flash of insight like damming up the far end of the pool in the stream to trap the fish for easier capture. Continue reading
This scientific initiative fucking THRILLS me.
“Logic of Life is an initiative that unifies world-leading quantitative research in the life and life-inspired sciences in Switzerland with a bold aim: To identify the rules of life that drive emergence and self-organization at all biological scales, such as the appearance of variation, the formation of spatial patterns, the division of labor, and the creation of robustness. This will address one of the biggest missing links in our current understanding of life, namely how scales are connected. Knowing these rules will revolutionize the translation of biological findings into products, services, and treatments that benefit our society”. https://www.logicoflife.ch/
Hal Whitehead, Kevin N. Laland, Luke Rendell, Rose Thorogood & Andrew Whiten Nature Communications volume 10, Article number: 2405 (2019)
Culture (behaviour based on socially transmitted information) is present in diverse animal species, yet how it interacts with genetic evolution remains largely unexplored. Here, we review the evidence for gene-culture coevolution in animals, especially birds, cetaceans and primates. We describe how culture can relax or intensify selection under different circumstances, create new selection pressures by changing ecology or behaviour, and favour adaptations, including in other species. Finally, we illustrate how, through culturally mediated migration and assortative mating, culture can shape population genetic structure and diversity. This evidence suggests strongly that animal culture plays an important evolutionary role, and we encourage explicit analyses of gene-culture coevolution in nature.
July 1st is 161 years since Darwin’s “Natural Selection” theory was accepted by the Linnean society of scientists as the correct explanation and Evolution became Darwinian Evolution.
I find most people think Darwin was a lovely and rather enlightened man, and that his theory rose to prominence on merit alone.
Those people can’t complete a dichotomous key test between asses and elbows, scientifically speaking. If you’ve never read my stuff before, you might worry I’m a closet creationist. Nope.
Another example of life experience heredity via an unknown process.
Excerpts from Scientific American
A stressed-out and traumatized father can leave scars in his children. New research suggests this happens because sperm “learn” paternal experiences via a mysterious mode of intercellular communication…
The findings are “novel and of very high impact, especially when we consider the impact of military service or other work environments that can confer high stress,” says Robert Rissman, a neuroscientist at the University of California, San Diego, who was not involved with the research. “I think it would be important to better understand the specificity of the effect and how different types of stressors or strength of stressors can modulate this system.”
Every organism has a survival strategy. Survival strategies are species and subspecies templates for living. They describe a specialized role within an ecological niche. Their roles are defined by exploiting a particular angle on making a living and by the adaptations of their bodies toward this goal. The amazing anteater for example makes a living…anyone? Anyone? Correct, eating ants. And has adapted in an amusingly specialized way with powerful claws for ripping into nests and long sticky tongue.
That is a deep, deep commitment to eating ants. But not really any deeper a commitment than most other species: The overall species strategy is a highly specialized job with a body increasingly adapted as a tool to do that job.
But not us. We are constantly looking for new angles to play and new ways to play them. In pursuit of that goal we may vary our focus, lifestyle, and ecological niche. But except for phenotypic variations based on local weather our bodies don’t adapt. We don’t specialize via our bodies, we specialize via technology: A spear is a 7 foot long claw that can fly. Well sewn clothing is a thick warm pelt, opening our way toward the ice caps. Horses turn us into ten foot tall monsters moving at the speed of antelopes. Farming is a “Game of Life” survival cheat code the levels us up. Sufficient change in technology equals a virtual shift of species with an altered template for life.
Our technology transforms us personally and as social animals. The rules for hunter gatherers are not the rules for farming villages. We reorganize ourselves in a bottom up that unpacks itself through the individual daily actions of each human playing the new game. Pyramids and kings pop into being from the right tools and population sizes. Each shift redefines the group size that we consider to be: Us. Ourselves. Are we 50 people, a thousand people, a million people? Ask the tools, they make the rules.
When the human community becomes large enough and complex enough it becomes a virtual ecosystem unto itself. The specialized work of individuals mirrors the variety of organisms in a wild ecosystem. Enough complexity makes a self sustaining virtual ecology. AT least until the robots throw us all out of work.
Cultural Variation as a strategy
Every human group that can define as “US” creates culture. That culture expresses local traits with one unique voice. Varieties of approaches to mating, religious dogma, openness to outsiders, etc. equals a real time experiment in how successful these traits are as a human survival strategy. The values for these different traits emerge from the tension force within the community. Authoritarianism is a strategy, so is liberal democracy, so is theocracy. Winning could mean stability or expansion. I call this expansionist trait “Virality”. One culture may make it’s people happy and healthy but virally dominant cultures can take them over.
(That’s draft one. As usual, if you found this intriguing check back once in awhile. I do update and re-write.)
Scientists taught white mice to fear the smell of cherry blossoms.
(“So Bob, what line of work are you in?” “I frighten mice, like my Father and Grandfather before me..”)
The offspring of these frightened mice were never subjected to this cherry blossom trauma but mysteriously, they also feared the smell. More amazing still, the grandchild generation of the original trauma mice, also never subjected to the treatment, reacted with fear.
This is the classic cited example of Epigenetics or Soft Inheritance. The traumatic experience memory is passed along not by DNA, but by methylation changes on the DNA. It’s the DNA equivalent of working memory between generations.
In the old synthetic theory, without soft inheritance:
Two squirrels are living at the same time, in the way, way back when. Along comes a saber-tooth cat. Both squirrels run but the faster one survives and the slower one doesn’t.
Ergo->Faster squirrel genes move one step forward and thanks for playing, slower squirrel genes!
And now, with epigenetics:
Same time, way, way back when. Two squirrels again, different scenario. One squirrel has a close encounter with the saber-tooth cat and gets away, badly shaken but alive. The other squirrel was obliviously examining his nuts in a tree nearby. He never saw the cat, and he is unaffected. Squirrel number 1 has babies and they are born with a fear of cats or at least an extra sensitivity to “something moved!” Squirrel number 1 has enhanced his reproductive status by communicating a mission-critical message to the next generation and the one after. They are literally BORN with more “street smarts” than squirrel number 2’s offspring.
What does it mean if a creature inherits some of the important EXPERIENCES of at least two generations of its ancestors and possibly more? This breakthrough model is fascinating because it describes a form of parental teaching of life lessons to the young in species that can’t archive data or tell stories. Instead, they attach a little chemical post-it note to their genes saying “Beware of Cat”.
If asked “how could the genes know “Cat”? I’d answer “The same way they knew about cherry blossoms.” It’s staggering to think of the sophisticated mechanisms involved and questions rise like mountains in the near distance. Actually, it’s one question, repeated.
1. Something terrifying happens and a sort of snapshot of the event is taken within the organism. How?
2. Which captures details of the experience. How?
3. Ranking some as meaningful. How?
4. And retaining them. How?
5. Ultimately initiating a process that hands this information off to the sex cells for the next generation. How?
6. This new generation “knows” this life lesson as if they’d lived it themselves. But How?
We have now reached the “Talking out of my ass” section.
The thing that gives me shivers (of excitement) is the list of things that must take place for this to work.
- There’s got to be a threshold of some kind. How intense does the experience need to be to “make the cut”?
- There must be a mechanism that takes these “Must know” memories out from all the other memories and decides to engrave them on gametes.
- There must be some crazy-ass coding that allows methylation changes on DNA to communicate details like the smell of cherry blossoms. That would be a highly specific molecule banging into the olfactory brain possibly for the first time ever, and setting off the fire alarm…through code.
- Also, the code is obviously not a complete memory falsifying the experience of the animal receiving it, but close enough that when the real world and this knowledge construct line up, it causes an autonomic emergency deja vu.
I think the “Camera” that could take that memory snapshot is perception/working-memory and the developing chemicals would be concentrations of fight or flight stress hormones that “develop and burn-in” the image. It could also be triggered by something less obvious, like the moment of relief at reaching safety, with the adrenaline fading and your little squirrel heart going like mad. That could prompt a rewind and transcription of the last minute of memory. Who the hell knows?
2, 3 & 4. I imagine the salient details are the Bold and Italic sensations of that experience, the ones that loom and glow in memory as you look back on it, momentarily experienced again. Long term memory is the most economical way to retain this information and would occur naturally. Perhaps mentally reliving the event (including within dreams) a critical number of times prioritizes passing it forward.
5. I got nothing.
It seems certain to me that many classic human knee-jerk fears like spiders, toadstools and snakes are among our deeply reinforced examples of this process. And that brings up some issues closer to home. Presumably, every human baby is born with some of these “presets”. It seems like the nearly global ones must become default elements of our standard inheritance. Is there some process that triggers the elevation of a methylation memory to DNA proper? Is there some tipping point of reinforcement that causes that? Like if PARENT has a trauma experience coded and CHILD does too, (as their own direct experience, not passively) would the two copies being present in CHILD pass on the message to GRANDCHILD with more urgency? For example, could two doubly reinforced people merging their four copies at the moment of conception cause a crossover to DNA inheritance? That question is kind of rhetorical, I’m just shaking my head at the amazing possibilities of this system.
Other random questions:
- Could that kind of double reinforcement play a part in paralyzing phobias?
- How long does it take from trauma to rewritten gametes? If the survivor conceived the next day would the information be ready?
- Men replenish sperm at a rate that shows tremendous optimism, and a woman’s eggs are more or less archived, or at least they travel like a slow and stately parade in comparison to sperm. Does this mean these memories are sex-linked?
- Since our gametes are so different would there have to be separate mechanisms to do the encoding? Do eggs get these “critical updates”?
- Are there equivalent positive messages about life success, not just skin-of-our-teeth escapes? It makes some sense to me that success heuristics belong in the system too, but would be harder for us to demonstrate experimentally. Perhaps that’s more of a learn by observation thing. Animal parents can demonstrate life skills but can’t demonstrate how to avoid a monster attack.
- Can these messages be annotated in the trip from say, a grandparent to a grandchild?
- Could separate, different messages from different parents ever blend and synthesize into something unique?
- Is there a decay time for these messages? Do they fade across generations if not reinforced? Is there a mechanism protecting normal healthy species behavior from being dangerously rewritten or overridden by these alerts?
In summary, we are talking about an evolutionary mechanism which fills a couple of the gaping holes in Darwinian theory.
A Tautology for a Theory: “Survival of the fittest” is a fugue idea, chasing its tail. The fittest can only be described by their survival. The Darwinian mechanism is really about the elimination of gene-pool competitors leaving “the fittest” still standing and reproducing. Kinky!
Time: There is no mechanism for the fittest to develop their adaptive advantage except endless friggin’ time and lucky mutations. Evolution has happened much faster in reality than jives with Darwin’s crawlingly slow “change through random accident and mutation” story. Instantly this makes much more sense than calling upon eternity to explain your mechanism.
Random Changes: Random mutations have been studied constantly since the theory launched. In an experiment replicated many times, random mutations have been generated in thousands of generations of fruit flies in the lab by radiation. Not a single lucky mutation resulted. No change in that population resulted.
Galapagos finches have fitness-enhancing beaks but no practical way to acquire them. Deprived of support from randomness and eternity, Darwin is an empty lab coat. We have reached a happy upgrade to our thinking.
Evolution is sophisticated, multilayered and complex. It stacks the deck in any way it can. It behaves at the very least, as if strategic. We are arriving at theories that mirror the subtlety of reality. We are finally getting better at this.
Drones aren’t irrelevant in bee society they just aren’t really the kind of people you want to be seen with.
Drones develop from unfertilized eggs and are haploid. Queens and workers develop from fertilized eggs and are diploid.
Virtually all organisms are diploid, an original genetic mix based on sexual reproduction with a mix of genes from mom (xx) and dad (xy). The only males in a beehive are the drones and they do not participate in gathering nectar and other bee jobs, they are there purely to inseminate the queen (queen being a strange word for ovary, apparently) and drones are the offspring of unfertilized eggs.
So drones are haploid, containing no recombination of the previous generation, it is basically a flying gamete and all its sperm are identical. All those identical sperm have only source of genetic information, the unfertilized egg it hatched from. A drone is basically a clever workaround for an egg to make sperm that makes more eggs. But to bees it’s critical that there is as little genetic drift as possible. As a result, the sister bees who do all the work are more closely related than ordinary sisters, instead of sharing 50 % of genes they share 75 %. More reinforcement for the idea that a hive is a quasi individual. And get this (pulling from wikipedia below) …
Because the male bee technically has only a mother, and no father, it’s genealogical tree is rather interesting. In the first generation there is one member (the male). One generation back there is also one member (the mother). Two generations back there are two members (the mother and father of the mother). Three generations back there are three members. Four back there are five members. That is, the numbers in each generation going back are 1, 1, 2, 3, 5, 8, … —the Fibonacci Sequence.