Hacker News Reader

Comment by calibas | Hacker News Reader

I assume most people were taught the same things I was, namely that Lamarckism is ridiculous nonsense, and now we're finding it has elements of truth.

View on HN

I can corroborate that. I think most people intuitively know that what they were being taught wasn't quite true though. I certainly did.

It’s worth noting that this has been mainstream science for over a decade. It’s important to know, but honestly not new.

If you were taught that Lamarck was wrong in every conceivable way, then your instructor(s) didn't understand very much about the subject. I certainly wasn't told that every aspect of Lamarck's proposals were false, nor were any of my colleagues.

It has elements of truth. But the elements of truth that it has could not have been discovered had we not gone through thinking that it was false.

I like the attitude, that we can't throw anything out completely if we're to be open to new learning...but let's categorize these effects as "epigenetics" broadly and leave Lamarckism at rest :)

But even epigenetics does not cover all of the ways that derived traits can be passed. For instance, prenatal testosterone levels affect the baby [0], yet those same levels may be affected by the mother's environment. Hence the environment may have effect on lifespring through means other than just epigenetics.

[0] http://www.abc.net.au/news/science/2015-09-23/masculine-face...

Prenatal testosterone can alter the baby's phenotype, but can it alter the baby's genotype?

Something has to alter the baby's genotype (more specifically, the genes in germ line cells, which are the only cells whose genetic material gets passed on to offspring) in order to count as a method of heritability. Otherwise prenatal testosterone is the same as any other thing in the environment which can alter an organism's phenotype.

Part of the problem is that it hasn't been laid to rest, it's still being taught as an example of an outdated and mistaken scientific theory, which has lead to a bias against epigenetics.

I feel like the term "epigenetics" takes on different definitions depending on context.

The term can have two meanings depending which part of the term you emphasize. I think it is important to be pedantic here.

EPI-genetics with an emphasis on "epi" really describes any mechanism that happens above the genotype level. Transcription factor binding is technically "epigenetic". It is a really broad term.

Epi-GENETICS with an emphasis on "genetics" describes inheritance of information outside of the genetic information. This is probably the more interesting use of the term.

It seems like most biologist use it as a catch-all term for methylation/histone modifications/polycomb-type mechanisms. All of these mechanisms are EPI-genetic, but not all have really been proven to be epi-GENETIC.

Reply on news.ycombinator.com