I'm currently involved in research regarding DNA methylation in mice. Epigenetic modification is really interesting and still not very well understood insofar as how the response occurs. These methylation changes may also occur as a response to other environmental stresses later in life as well as childhood, and other epigenetic modifications may be passed to offspring. We should see some very interesting discoveries that change our current ideas of heritability and response to environmental stimuli in the next few years as we're able to better detect the epigenetic factors in a cost effective manner.
The recent advancements in DNA research absolutely fascinate me. What really intrigues me is how easy/difficult it is for our environment and current mentality affect our DNA.
I have always thought that the random-mutation factor in Darwin's evolutionary theory was a rather poor explanation to the highly specialized organisms we see today. In that specific account I've, personally, always favored Lamarquism as the simplest, most plausible theory.
Of course such an opinion might be considered 'heretic' among the scientific society, which I found to be way too dogmatic on most aspects.
>Of course such an opinion might be considered 'heretic' >which I found to be way too dogmatic on most aspects.
Go ahead and design some falsifiable and testable experiments to prove this. You can whine about dogmatism or you can challenge it. I suspect like more Lamarckian ideas its quickly refuted, but you are welcome to try. That's how science works.
As far as I, any many others, can tell, random mutation and natural selection works really, really well, but would love to be proved wrong. Please note "proven" isn't flowerly speech about how some ideas "feel" righter than others.
Sorry, I didn't mean to sound like a dismissive asshole, but epigenetics is still a young science. We can't even tell if this stuff in inheritable or if it even makes any difference if it was. Epigenetic inheritance even if real doesn't change genes it just changes expression. Its really not like Lamarck at all (if you are fat and like rap music, you will have fat children who like rap music because magic, that's why!).
>In fact, from a quick glance in history we see science prove itself wrong over and over again,
That's a feature, not a bug. Think something is wrong? Prove it. Then it becomes the status quo. Then that gets either refined or dismissed by a better theory. You may say this process is evolutionary...(oh, I love puns).
Are there egos and politics involved? Yes, just like in any human endeavor.
I don't think science should work on dogmatism at all... leave dogma to the church.
I have seen more than a share of people that call themselves scientists literally laugh at an argument and dismiss it without analysis or a counter-argument.
In fact, from a quick glance in history we see science prove itself wrong over and over again, which is natural, but it's very common to contemporary scientists think they are just right.
All I'm saying is that sometimes, not all times, scientists appear more like cult-followers than researchers.
What I find fascinating is whether or not the genes altered by our environment would send those altered genes through the reproductive system. It would seem like the answer no; otherwise each successive generation would just get weaker and weaker as a simple function of genetic damage carrying over decades, centuries, across multiple generations.
What would need to be shown in order to support Lamarkianism is that the methylation patterns are passed on to offspring (and showing that the methylation patterns in childhood were different from those at birth, would probably be helpful as well).
It is fallacious to extrapolate from patterns of reproduction at the cellular level of amino acids to reproduction patterns at the organism level of sperm and egg. It is akin to applying quantum mechanics to billiard balls.
What the study does show is that there are long term effects of childhood living conditions which manifest themselves at the celluar level. Given that we are readily able to observe some effects of childhood living conditions at the macro level of the human organism (e.g. physiological manifestations of diet or altitude), finding their biochemical mode of expression should not be entirely unexpected.
We actually have flys in our lab that have been selected for living in low oxygen environments (4% O2 vs ~21% O2 in room air) over the course of 32 generations. While that by itself is not particularly impressive, the really interesting part is that these flies can be put back in room air for several generations, and then re-introduced to the 4% O2 environment and still survive, which wild type flys cannot do.
After studying the issue, I'd be willing to bet a friend a lot of money that natural selection alone will be proven insufficient to fully explain evolution.
I would argue that it (sort of) is because most people tend to stay at the socioeconomic level they were raised in. In other words, the mechanism for carrying this forward is not in the DNA but the culture.
There was a facinating Nova show on epigenetics back in 2007 called "The Ghost in Your Genes" about the discovery that epigenetics could have intergenerational effects.
I couldn't find a link to the video just to a transcript:
http://www.pbs.org/wgbh/nova/transcripts/3413_genes.html
Essentially in some cancers the cells lose their ability to uptake cannabinoids because those receptors get methylated, and so by unmethylating them (and adding extra cannabinoids) you can attack the cancer.
I always thought that the scientific community accepted Darwin's random-mutation factor way too easily and without challenge. It never seemed very credible to me. The more I watched wild life documentaries the more Larmackism grew on me.
Actually Darwin didn't know anything about random mutations, as in fact he didn't know about DNA or even genes. The Origin of Species is about observed results: "descent with modification" rather than about mechanism.
In any case, I'm not too sure about the scientific community being so easily accepting of Darwin. It's true that evolution (that is, the gradual changes in the characteristics of populations) was nearly universally accepted relatively quickly, but natural selection as a mechanism was not. In fact, for some decades in the late 19th and early 20th centuries natural selection was widely regarded as a minor contributor to evolution.
This was not a matter of anyone believing that natural selection didn't occur, but simply an argument over the relative magnitudes of different forces. Alternative drivers of evolution included neo-Lamarckism. Notably, estimates of the age of the Earth at the time were very much lower than our current ones and many scientists believed (correctly) that natural selection was too slow a process to have produced the variety of life observed over a 10-100 million year timespan.
It wasn't accepted so easily at all. Multiple evolutionary studies concluded mutation is sufficient to explain the majority (if not all) of variation seen in a species.
This is further supported by historical studies showing consistent mutation rates overtime. There are different mechanisms that result in population wide changes, but that doesn't exclude random mutations (in the general sense, be it point mutations or transpositions) from being the progenitor of all new genetic information.
I can't tell if you're joking or not, but just to be clear: traditional genetics' utility for explaining natural variation among individuals represents an enormous increase in scientific understanding, and is supported by tens of thousands of scientific papers and countless benefits to society.
It's somewhat absurd to compare the credibility of genetics as a field to what is still almost entirely conjecture.
I never said genetics as a whole is not credible, it's the random part that I think is off, just to clarify.
From our brief history of mankind, I don't think there's enough information and hard fact to either prove or refute the random factor, as far as I know it is just accepted. I could also be wrong since I'm not all that up to date in this matter.
The mechanisms of traditional genetics, which include (at a simplified level) random variation at the base-pair level, are extremely well understood.
The impact of this potential new mechanism of inheritance is unknown, but it will only add to our current understanding of how things work. It will not tear down our understanding.
Yes. You are right on the money with Lamarckism. There was a separate study showing people who lived through a famine passed on its effects lasting several generations.
This particular study wasn't designed to answer that question, as is stated at the end of the article. It's possible but based on this set of evidence we can't really draw any conclusions about that. I imagine there's already work being done to address that question though because it's an important thing to understand especially in the context of DNA methylation having an impact on quality of life.
Based on how meiosis works, I can see how methylation could be passed down to offspring. But these changes in methylation would have to occur within the specialized cells which produce sperm and egg. If the methylation pattern changes in your liver or heart cells, it doesn't matter since these somatic cells don't get to pass this information on to offspring.
Females are born with all their eggs, so any changes in methylation that occur to these eggs will persist into adulthood (I assume). But is it possible that these eggs are somehow protected from this alteration? As for sperm, these are produced within the testes following puberty, and are generated continuously. Therefore, in order to pass down altered methylation, the original gamete cells responsible for generating sperm would have to be altered. But if you wanted to do this successfully, you'd have to make sure to alter ALL the gamete cells. Otherwise you're gambling as to which sperm cell hits the pay load. Again, I'm curious if these cells are more or less prone to altered methylation.
I find this whole concept fascinating! Imagine...your dad gets bullied as a kid, results in altered methylation pattern, and this gets passed to you! Wow.
What I also find fascinating is the number of individuals with this sort of background reading/commenting on HN. I think it's great! Are many of you into Bioinformatics?
One thing I have observed, particularly with Africans, is that if they grow up in Europe or if they grow up in Africa, there is a clear difference in the way they look when they are older, no matter their socio-economic status at that point.
I think you are confusing African ethnicities (since only using the word Africans is quite superfluous anyway).
Africa is the most diverse continent in terms of phenotype and genetics. For example: a West African, an Ethiopian and a San person have very little in common, physically speaking. It is a bit like saying African Americans are 'African' while most have admixtures with non-Africans.
Studies showed that Ethiopians (toward 50-55%) and Kushites (towards 35% for Bejas) have an important western asian input so they tend to look like transitional people.
All of them look very Nigerian to my eyes. Maybe if that blogger looked past his own cultural bias, he would notice there is variation amongst themselves.
It's not clear without further scientifically designed testing whether there is more "cultural bias" in grouping people by saying "All of them look very Nigerian to my eyes" or by saying that it is easy to see which of the varied individuals grow up in the West and which grew up in Nigeria. (It's an empirical question, first of all, whether observer identifications of that kind can be verified by controlled experiments with unfamiliar individuals in either case.) There are definitely different cultural biases among human beings about whether environment of development matters most or ancestral lineage group matters most in making distinct human individuals more or less alike for the social purpose of grouping them by some commonality. One refreshingly interesting fact I learned from the book The History of White People by Nell Irvin Painter
is that the ancient Greek authors were overwhelmingly of the opinion that what made different people groups different from one another was different living environments (climate and topography), with the Greeks of course thinking that their living environment tended to produce superior people.
Differences in early childhood diet (and also in patterns of early childhood exercise and sunlight exposure) bring about substantial differences in appearance among cousins or even siblings in the same family lineage among persons of recent east Asian genetic heritage too. I can observe some of those differences in my own extended family. I have seen many other examples over the years of "Asian" people having different growth patterns depending on whether they spent early childhood in Taiwan or in the United States.
When I lived it HK I noticed it was generally very easy to tell locals from mainland Chinese from ABCs from internationally-schooled locals. I think I've noticed the same thing with people of African descent - however, in both cases I thought it was more to do with subtle differences in mannerisms and dress than in the way they actually look.
It can also be seen, but to a different extent. An african that grows up in a city in a wealthy household seems to end up with a different sort of facial structure and skin than those who grow up in rural areas...and it never goes. However, the effect is far more pronounced among those who grow up abroad.
You can see this clearly in london - it's pretty easy to observe which Africans migrated to England at perhaps age 10, vs those who were born and grew up in England.
It could just be the signs of malnutrition. 200 years ago there was about 1 foot difference between English nobles and Welch coal miners, because the nobles were better fed as children. It would probably show in a different facial structure too.
I too work in biology, and while this is interesting, that there are differences between people is not that surprising, and attempting to link socio-economic conditions to such widely different methylation patterns when you've got a sample size of 40 isn't very convincing. That said, nice work!
DNA is expressed in RNA synthesizing proteins that in turn feedback to RNA, which feeds back to DNA, right? And this happens over multiple generations, and sometimes in a single person, depending on what aspects of which combination of the system we're talking about?
Maybe someone could explain the downvotes?
This is a serious question.
There have been stories about for instance heart transplantations where the new owner experiences dreams and desires of the first owner although the persons never met.
These stories were always marked as 'not possible' but now it seems a bit more 'plausible'.
This research is not stating that memory is stored in DNA. The headline uses the word 'memory' as in 'influence'. The living conditions of a particular in childhood influences their DNA post-childhood.
