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Darwin Was Wrong…
…and Lamarck was right.
Well, maybe. Of the two major theories of human evolution developed in the 19th century, Darwin believed in natural selection — that human traits are passed along through DNA and not through environmental factors — and Lamarck believed that parents can transmit environmentally acquired traits.
Darwin won the sweepstakes, but Lamarck may not have been entirely wrong. From ArsTechnica:
…scientists exposed male mice to six weeks of alternating stressors like 36 hours of constant light, a 15-minute exposure to fox odor, exposure to a novel object (marbles) overnight, 15 minutes of restraint in a 50 mL conical tube, multiple cage changes, white noise all night long, or saturated bedding.
Poor little guys.
Then the scientists allowed the mice to breed. Adult offspring of these chronically stressed dads had reduced hypothalamic-pituitary-adrenal stress axis reactivity; when they themselves were restrained for 15 minutes, they did not make as much corticosterone as mice sired by relaxed dads. This is relevant, and problematic, because blunted stress responses in humans are associated with neuropsychiatric disorders like depression, schizophrenia, and autism.
In other words, dads better learn to relax a bit:
The researchers found that stressed dads have increased levels of nine microRNAs in their sperm. The scientists obviously hypothesized that these miRNAs were responsible for the reduced corticosterone response in the kids, and they set out to test it by injecting a similar cocktail of RNA into single-cell mouse zygotes. After these zygotes divided into two cells, one of the cells was allowed to develop into a full-grown mouse and the other was taken for genetic analysis. The mice that got these miRNAs looked exactly the same as those born to the stressed dads; as adults, they had the same blunted stress response and transcriptional changes in their brains. So the miRNAs are responsible for transmitting this effect.
On the other hand, let me ask the dads out there: seeing the world the way it is these days, isn’t being totally stressed out the most rational way to be?
Published in Science & Technology
Makes sense. To believe otherwise is to assume that semen production is independent and isolated/resistant to hormonal changes in the body produced by living in a particular environment. The ability to measure and manage the impact is not a given. It simply is one of the ways that random events drive evolutionary change.
Indeed.
I prefer the story Rob of the co-founder with Darwin of the theory of evolution by natural selection – Alfred Wallace. He came up with the theory at about the same time as Darwin but after it was published he began to have serious doubts about the theory.
In particular he had problems reconciling the ideas that certain traits could not have remained in human evolution program as they did not offer at the time an evolutionary advantage – music, drawings etc.
He had also issues with certain physical human features and the soul if I remember right.
Being stressed out is a response to stimuli which makes it a choice IMHO. I cannot fully control my circumstances but I always control my response to circumstance. I choose to be more mellow. It does help to also choose not to over load my schedule as so many do today. The world may be a wreck but I can choose not to be.
I only worry when it is productive to do so.
I work hard, do all that I can, and leave the rest in G-d’s hands. As a result, I am actually a pretty relaxed workaholic.
Doesn’t explain my kids, though.
Ah! Welcome to the world of epigentics Rob. The effects upon offspring can be propagated for several generations after as well. In mice fed a high methyl diet while pregnant produced mice with a darker coat color. This darkened color persisted in subsequent generations even when maintained on a normal diet. Though over time the trait did disappear. The cause of this was that a high methyl diet led to the an alteration in the expression of the coat color genes. This alteration was heritable though not preserved in the DNA sequence but rather in the chemical modifications to the DNA sequence, which are also heritable, yet more easily mutable.
Micro RNAs are know to be important in targeting protein complexes to regions of Chromosomes to alter these chemical modifications. These modifications are not only limited to the DNA strand but also the associated histone proteins around which DNA is wrapped. Really the levels of information stored in our chromosomes goes well beyond the mere DNA sequence.
In fact one of the most famous cases of Scientific fraud, which involved the claims of an Austrina biologist named Paul Kammerer, might be explained by our understanding of epigenetics, though at the time the work was dismissed as fraudulent due to the discovery of tampering with the samples. Sadly much of Kammerer’s work was lost in WWI and and he committed suicide, shortly after his work was discredited.
If that’s the case, then, cool, I’m the product of “peak evolution.”
When My Mom told My Dad that She was pregnant, He was so
^finger quote^ rational ^finger quote^
that He fled before I was born.
You say that now, OS, but how’s about we tuck you into a 50ml conical tube for 15 minutes?
You’ll be singing a different tune then.
I’m not sure about acquired traits, but if my son inherits my acquired tastes he’s going to look a bottle of Tito’s vodka.
Trofim Lysenko, call your office…
Stress is part of the survival instinct managing same by studying mice to explain the process is over thinking from those too afraid to live.
Was Darwin wrong ? Try the current effect of thinking and science to Pavlovs or Gobels experiments in determining outcomes. Prove that wrong –
Got any links about epigenetics?
If fascinates me when science gets turned on its head.
When I was schooled pre-2000, we were taught that some traits are heritable (height, looks, eye color) and others are not (work ethic, intelligence, musical ability, etc.).
I don’t think we have a complete answer even now on what is heritable or how it works, except to question everything.
Epigenetics also means science fiction is wrong when vats of clones all produce the same identical figure. Environmental stimuli result in different LOOKING beings as well, as we found with modern day clones such as Dolly the sheep.
link time:
All personality traits are heavily heritable. Put almost any qualified mainstream psychometrician under oath and he will tell you that IQ is only slightly less heritable than height at adulthood.
Here is an interesting link from Richard Dawkins’ old student Matt Ridley on epigenetics.
Er, no.
DNA turns out to be more complicated than originally thought: genes can be turned on and off, and traits can be activated or deactivated. But the traits were already there, waiting to be turned on.
The ability to activate traits already in the genome based on environmental conditions and pass them on to offspring offers a clear survival benefit, so it’s hardly surprising that it evolved.
Lamarck is still wrong, as “He argued that organisms thus moved from simple to complex in a steady, predictable way based on the fundamental physical principles of alchemy.”
Yeah, Newton liked alchemy too. It was wrong.
Lamarck was simply an example of a theory that seemed to fit the evidence at the time, but was disproved by subsequent observations.
But the more modern notion of DNA as a hard-coded program that runs and succeeds or fails based on the success of reproduction may also prove to be too simple.
It seems the program can modify itself, leading to new traits that appear to be, but are not, Lamarkian.
That would explain Mr Obama Jr.
No, no, Rob.
To the extent that Darwin was wrong, he was wrong because he had no access to modern genetics — not until the late 1880s-90s did Mendel do his work on pea plants and become the ‘father of genetics.’ Nor did Darwin appreciate the significance of DNA, which would subsequently become the foundation of modern microevolutionary theory; nor had the branch of developmental biology called Evo-Devo been developed; nor had he access to parts of the fossil record that have since been discovered.
Darwin was quite right, as far as we know, in providing an explanation for the micro-evolution of the finch. His work on microevolution stands: random mutation and cumulative selection answers many questions about it, so long as there is an empirically known or plausible functional continuum — at the morphological or genetic level — leading from an ancestral species or structure to a descendent species.
Had he left it at that, there would have been no problem. Darwin’s mistake — or rather, his ambitious hypothesis that hasn’t stood up well to subsequent discovery — was the suggestion that the origin of life and the evolution of all the novelties in the history of life could be explained by extending, over long periods of time, the mechanism of cumulative selection that fashioned the different species of finches.
As it turns out, since Darwin’s time, there’s been a massive increase in our understanding of developmental genetics. I won’t go into the details here, but the impression one gets is that nature is often stubbornly discontinuous, resistant to every attempt to reduce it to a Darwinian functional continuum. The great divisions in the natural order are still profound. The empirical or hypothetical series of adaptive transformations are lacking.
So yes, Darwin was wrong, in his grander claims, but not because Lamarck was right, at least not in so far as he was trying to answer the same claims. Lamarck is of no more use to us if we’re trying to explain the origin of life and the evolution of all the novelties in the history of life. Epigeneticists, as Valiuth points out, have been observing these kinds of phenomena at least since the 50s and 60s, and there’s not much doubt about them; e.g., 9/11 babies inherit stress from mothers, etc.
But the main point remains: Neither Darwin nor Lamarck were able to answer the big questions, the ones we really want to know: What is the origin of life? What is the origin of species? Darwin posited that entirely random mutation and natural selection were the creative demiurge; Lamarck likewise proposed that mutation — albeit not wholly random, because in his view an organism passed on characteristics it acquired during its lifetime to its offspring — plus natural selection would do the trick. Darwin was not initially inclined to reject that idea, either. When he published On the Origin of Species, he gave credence to what he called “use and disuse inheritance,” although he rejected other aspects of Lamarck’s theories. It was only later that Mendelian genetics supplanted the notion of inheritance of acquired traits, eventually leading to the development of the modern evolutionary synthesis and the general abandonment of Lamarckian theory.
So in a limited sense, Darwin was right — about microevolution. And Lamarck was right — about the possibility that the environment can tinker with the building-blocks and that offspring can thereby inherit the mutations.
But we’re still left in the dark about the big questions, and it’s growing darker every day: Now that we know so much more about the details of biology, we’re coming up with baffling results like this:
If you feel demystified by that, I congratulate you, but I sure don’t. Seems to me what they’re saying is, “We can imagine a process by which every now and again, for reasons we can’t begin to understand, a miracle occurs … which can be thought of as missing links to help to demystify the the alchemist’s sorcery, otherwise known as, “a miracle.”
Or at least, “Something we don’t remotely understand.”
Perhaps “yet,” perhaps “ever,” depending on your temperament.
I’ve long been a skeptic of Darwin. Rightly so, it seems.
I’m sure I wouldn’t like being treated like those mice were, but I’d still be choosing how I reacted, just as much as I choose how I react to my wife’s great cooking, or any positive circumstance. Realizing that, when I do have problems, I choose not to let any one of them ruin a whole day. I can either dwell on the bad stuff or move on. It doesn’t mean I don’t notice it, just that I choose to not let circumstance control my emotions. I do get angry, of course, but my responses are under my control so I try (and sometimes fail) to choose a response that is good for me, long-term.
All I can say is that the kids were lucky to be born when I was a carpenter, and not later, when I was a project manager.
Excessive rationality is a symptom of insanity. Being a bit crazy, like my husband, is the most reasonable response to life.
It’s been a long time since chimps and humans diverged. New DNA would be required to explain that divergence, however it got there.
Here’s a better example of how little we know about the pace and process of evolution:
So here’s an example of rapid physical change (including new organ structures) in just a few decades!
I haven’t seen a DNA analysis (just mitochondrial DNA) that would explain how such rapid change occurred, but this is from the original study:
Is it epigenetics? It sure as shooting looks Lamarckian, whatever the mechanism of it.
But evidently evolution doesn’t have to be a slow, stately process—it’s clearly more complicated that we’d thought.
For great enlightenment on this topic, see:
“Signature in the Cell” reviewed by anonymous
and
“Darwin’s Doubt” both by Stephen C. Meyer
I cannot recommend these books strongly enough. They make a compelling, valid, scientific case for intelligent design without invoking a deity.
Indeed. I find that the more you know about the actual mechanisms of the cell, the more you’re driven towards intelligent design.
Of course, opinions on intelligent design have always been driven more by philosophical priors than by scientific evidence. Either way you slice it.
On Socratesinthecity.com, Eric Metaxas interviews Stephen Meyer.
As far as SF goes, Orphan Black gets this right–variation within a theme.
I think it is pretty obvious if one is a lover of dogs that hard-coded DNA as the only determinant of biological expression is wrong.
It also blurs the line between learned and inherited traits.
My dog was bred to hunt moose. He was whelped in Tennessee, where there are no moose. I got him as a small puppy, and never made any effort to train him about moose, as there are none where I live, in Connecticut.
He’d seen plenty of deer, and really had no unique reaction to them, different from other dogs.
But the first time he saw a moose, he went bananas—he was in the car, so it was very apparent. When he comes across deer tracks, he has no interest. When he comes across moose tracks, off he goes to track it down, as he was bred to.
I don’t know that we have any explanation for how a trait like that is acquired and transmitted across generations.
Well here is some links that might be of interest to people these are actual literature reviews by scientists. I believe they are all open source. Hopefully they aren’t too filled with unexplained technical terms for people. But if you have any questions about them I am always glad to try to help you sort it all out.
Transgenerational epigenetic inheritance in plants
Epigenetic memory in plants
I would also recommend Wikipidiea. It actually has very good articles on all of this.
In response to Claire’s lengthy post on the subject of Darwin and macro-evolution. If I understand her complaint it is that Darwin and modern biology while having proposed a good mechanisms for micro-evolution find themselves on uncertain footing in the macro field. I though do really see why her objections arise to the extrapolation from micro to macro.
The mechanisms for genetic change are well established on the micro level. Furthermore what other mechanisms are there to facilitate the macro changes other than the same mechanisms observed on the micro level. The difference between macro and micro evolution is the distance between the last common ancestor, and therefore it is only time that distinguishes one species from another. Because the mechanisms of creating diversity are the same, at all time points. Either that or we must assume the existence of a novel mechanism of change present in the past absent in the present.
Simply, put the vast morphological differences we observe between insects and mammals today which we ascribe as macro-evolution have their origin in a distant past micro-evolutionary event. It has to be. What other physical method is there?
So Darwin was right about the nature of the mechanism of change, everything else with respect to evolution has just been filling in the details.
Slightly OT, but one thing my high school biology teacher said that has stuck with me is that an amoeba has as much evolution behind it as we do.