Acquired Characteristics May Be Inheritable 242
A story from a week or so back in Technology Review describes research coming to the surprising conclusion that Jean-Baptiste Lamarck may have been right — that acquired characteristics can be passed on to offspring, at least in rodents. Lamarck's ideas have been controversial for 200 years, and dismissed in mainstream scientific thinking for nearly that long. "In Feig's study, mice genetically engineered to have memory problems were raised in an enriched environment — given toys, exercise, and social interaction — for two weeks during adolescence. The animals' memory improved... The mice were then returned to normal conditions, where they grew up and had offspring. This next generation of mice also had better memory, despite having the genetic defect and never having been exposed to the enriched environment."
Interesting... (Score:5, Informative)
Lamarck is one of those guys who's name is generally synonymous with bad science (he's about as villified as Darwin is deified). I'm actually a bit (pleasantly) surprised that someone would invest the time into this sort of study.
That being said, the article is rather short in one important area: a suggested mechanism for this sort of inheritance. Without that, it's bound to be mired in controversy for some time.
Actual article (Score:5, Informative)
Here's the actual article [jneurosci.org].
Histone modifications (Score:5, Informative)
We're just learning that Histone/DNA modifications can be inherited.
Histones (the spools around which DNA is stored) tell when the DNA source code should be 'active' vs 'inactive'. And these histones have a huge data space in the form of possible modifications (methylation, acetylation, etc.).
When DNA is replicated, these histones too are replicated at the same time. And they seem to be replicated in a semiconserved manner similar to DNA (half go to 'old' strand, half go to 'new' strand). And that there is a whole series of touring-like proteins that can 'read' 'write' or 'erase' these modifications.
If these modifications are made during an organism's life, they can be inherited by offspring.
Not only is the code being copied, but the 'marks' that tell which/when/where to read the code at any given time/condition too can be passed down. And that these marks can be written in real time rather than waiting for mutations in the code itself.
There was a recent study that XO females who inherited the X from their father had markedly different dispositions than those who inherited the X from their mother. DNA modification that is unique to how the male or female deal with their own X chromosome could be being passed down to offspring.
Re:Interesting... (Score:5, Informative)
What? I've heard Larmarck's evolutionary ideas ridiculed but villified?
He wasn't that unscientific. He was just wrong.
Or are you thinking of Lysenko? Now that particular advocate of inherited-acquired-characteristics was indeed a villain, a lousy scientist and a political tool.
Re:Interesting... (Score:5, Informative)
Actually, I've just taken a peek at the original article in J. Neuroscience, as posted in the comments below.
The interesting thing is that this seems to be passed on at embryogenesis - so it's quite distinct from learning. It's also quite distinct from other epigenetic inheritance studies, which have demonstrated that some of mom's behaviour can result in changes in the offspring's tissues. If this is in fact happening at the embryo stage, it is a whole different pathway.
Re:Interesting... (Score:5, Informative)
Yes, it does. The article says that the changes are still evident even when the pups are raised by control rats, NOT their mother.
It also says the change is not permanent - it only lasts a few months. I didn't notice any mention of whether the mother rat still functions at a high level when she's pregnant. If she does, the change could be due to the environment in utero, which would be consistent with the effect fading over time.
Re:Lack of control? (Score:2, Informative)
There was certainly no shortage of control groups (they did several controls, apparently following standard protocol for this type of research, according to the original journal article).
As for the "healthy womb" hypothesis, I think that the interesting thing is the specificity of the effect - the offspring show the same changes in a specific biochemical pathway (that compensated for a genetic defect) that the mother had as a result of the enriched environment. Not to say that it couldn't be just a healthy womb effect, but the specificity of the whole thing seems to point elsewhere.
Re:Interesting... (Score:4, Informative)
a suggested mechanism for this sort of inheritance
Epigenetics? [wikipedia.org]
Re:Interesting... (Score:4, Informative)
There is a mechanism for this kind of inheritance and it is part of a growing field called epigenetics. Whether genes are present are not as important as how they are expressed. Are they switched on or off? Experiments show that gene expression can be altered by environment and that epigentic information can be passed down to the next generation. There was a great Nova episode about it.
http://www.pbs.org/wgbh/nova/sciencenow/3411/02.html
I'm not sure if this is the exact mechanism involved in this study, but it is a possibility.
Re:Not a surprising result ..... (Score:2, Informative)
Really, this is hardly a surprising result.
o.O
There are many possible mechanisms that suggest themselves, operating either on the embryo or on the newborn - parents who are more intelligent are likely to be able to pass on more of what they've learned and/or provide a "richer" environment for their offspring, even if we're only talking about mice.
"The findings held true even when pups were raised by memory-deficient mice that had never had the benefits of toys and social interaction."
So, tell us, how are the more intelligent parents passing this on to their children when their children are being raised by the less intelligent "control mothers"? Are you suggesting some sort of psychic connection of between these mice and their real, more intelligent mothers? Or did you just not read the article in question, and are basing the criticism on the summary alone? I know, it's /., but still...
Re:Interesting... (Score:3, Informative)
Actually, if you read his wikipedia entry, it turns out that Lamarck wasn't extraordinary in the view of inheriting features. Darwins opinion was similar.
Only the next generation (Neolamarckism) extremed the point of view (giraffes, etc) and Lamarck got held responsible. Luckily he died first :-)
http://en.wikipedia.org/wiki/Lamarckism#Neo-Lamarckism [wikipedia.org]
Re:Interesting... (Score:3, Informative)
One can hypothesize that certain actions lead to genomic changes that will be replicated in the germ line (oocytes or spermatocytes).
We already know that mutations can introduce genomic changes that are propagated to the offspring. It could be as simple as a replication error in the spermatocyte.
We also know that hormones activate parts of the genome that may be inactive. Depending on the type of hormone, they enter the cell or effect a change in the cell that causes activation of a segment of DNA in the nucleus that will induce the production of a protein or enzyme. It's possible (but I am not sure--perhaps a biologist here can confirm) that some of the activation mechanisms are actual mutations rather than the removal of inhibitory substances on the chain.
Given the huge amount of stuff we don't know, it's reasonable to suppose that mutations that propagate to the offspring might be caused by the development of traits in the parent such as enhanced learning. After studying some genetics, I have come to believe that almost any of these things is possible, and we have a ton left to learn.
The theory some are offering here that behavior is passed on via non-genetic pathways is of course also plausible but would not be necessarily a permanent alteration in the population. Have they looked at the 3rd and 4th generations yet?
Obviously, an improvement in intellectual abilities that results in a permanent germline change would have huge ramifications for humans. Yet, smart people don't necessarily have smart offspring. A mediocre person who manages to uplift themselves to a high level of intellectual achievement might be expected to have smarter kids, but this doesn't seem to be a trend. Then again, a massive study might confirm or disconfirm this.
Luckily, we have a more science-friendly administration and hopefully they will start throwing more money at this kind of basic research, our general national bankruptcy notwithstanding. Friends at NIH and NIST have told me their budgets are going up, so something new is happening, at least. I'm not a fan of big government, but (depoliticized) science funding is definitely a good thing that benefits the country and the entire world.
Re:Wait, how does it get passed? (Score:4, Informative)
Many genes are only activated in the presence of certain helper chemicals. Similarly, some proteins can only fold properly with the assistance of helper enzymes. Some of these helper systems form a loop and are kickstarted by the uterine environment.
If you disrupt one of those loops by injecting hormones or other methods of altering body chemistry, like scaring the living shit of a mouse at an early age, the cycle will break and thus affect the uterine environment and not kickstart the next mouse's production of those chemicals.
I could've sworn it had already been shown that pumping adrenaline into young female mice caused them to be adrenaline-sensitive and their progeny to be maternal inheritably adrenaline sensitive, but I can't find a link for it.
Re:Interesting... (Score:3, Informative)
Individuals adapt, populations evolve.
Re:Does it need one? (Score:3, Informative)
You're confusing a model with a mechanism.
We have no mechanism to explain gravity, but a wonderful model that handles it well enough to land us on mars. Mendel didn't have DNA and was able to make predictions and conduct his experiments just fine.
Re:Interesting... (Score:4, Informative)
First, no one "deifies Darwin".
Some people do, actually. Some people claim he's the greatest thinker ever, launched the most revolutionary idea ever entirely on his own, etc.
Of course those people are wrong. Darwin didn't work in a vaccuum. Darwin's grandfather had already published the idea that all animals might have a common ancestor. Several others were working towards the exact same theory that Darwin ended up publishing. When Alfred Russell Wallace wrote Darwin about this new theory he was working on, Darwin suddenly got in a hurry to get his published first. If he hadn't we could have been celebrating a Wallace-year instead of a Darwin-year.
Darwin was merely a good scientist who was the first to publish an important theory that turned out to be true. But a lot of people make more out of him than that.
Females aren't born with all their eggs (Score:5, Informative)
Re:Interesting... (Score:3, Informative)
I don't know about the study but this effect can be readily observed in cannabis plants. Cannabis plants have a differentiated gender, unlike most plants there is a distinct male and distinct female.
Under stress a female plant can become a hermaphrodite by producing one or more male flowers (there are chemicals to induce this or erratic light patterns or keeping the plant alive under artificial lighting for extreme lengths of time without fertilization). That plant can self pollinate or pollinate another female.
In the cannabis world the seeds from such a union are prized because they grow all female plants (unfertilized female flowers are the only part of the plant that is smoked)but there is a well known side effect of this process. The seeds have a significant chance of being hermaphrodites without any of the stresses that caused the condition in the mother plant.
Re:Interesting... (Score:2, Informative)
When Alfred Russell Wallace wrote Darwin about this new theory he was working on, Darwin suddenly got in a hurry to get his published first. If he hadn't we could have been celebrating a Wallace-year instead of a Darwin-year
not exactly.
the story goes (at least for what i remember of "the origin of the species" that i recently read)
that darwin were working to his theory for some forty-fifty years, when he received this mail about practically identical ideas from wallace, then some friend of him insisted that he pubblish his theory before wallace do, but he insisted to clarify with wallace first, and wallace insisted that darwin pubblish his work (that contain some thousand of pages, cases and example to support his theory).
the final result is "the origin of the species" a quick exposition of his theory with some reference to the tons of material he collected and a thoroughly detailed introductory chapter with names and ideas of all who contributed to the ideas on the field, his grand father, lamark and wallace for example.
Re:Interesting... (Score:5, Informative)
So does he work for the discovery institute?
Close, he was employed by Joseph Stalin