Genetic inheritance, as we might all know, is inheriting genes from our parents.
Then theres epigenome which are genes that are changed by the environment and our experiences therefore the genes that we inherit or are passed on.
What we know less of is how traits that are related to our experiences are passed on to the next generations.
So... once you finish this article, will you be able to pass it down to your next of kin purely on memory? *Fingers crossed*
Lets find out.
But first
What is the genome? What is DNA?
Genome is the genetic material in an organism comprised of DNA present in every cell of your body. They are the set of instructions that run our body. Different cells have different function. To give you an anology, imagine your DNA is an IKEA book for furniture with instructions. Every cell uses a page from those instructions specifically for it and these pages are called RNA.
Somatic Vs Germ cells
The intructions come from germ cells which are the egg and sperm. They fuse giving you half of your mothers instructions and the other half from you father creating you.
Somatic cells are every other cell you own but do not contribute to genetic inheritance. Why do you need to know this? Anything that affects your germ cells can be passed on but the same doesn’t hold for your somatic cells.
Inheritance of aquired traits. Is there such a thing?
Lamarck was the first to address this stating: If an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring.
A person who tried to justify this theory was Paul kammer with his experiment on mid wife toads. Mid wife toads generally mate on land but his experiment intended on them to mate underwater by developing nuptial pads, which are black swellings between the forearm and the thumb of male toads. Nuptial pads help male toads grasp the female toads when they mate in water. By increasing the temperature in the laboratory to between sixty-seven and eighty-six degrees Fahrenheit, Kammerer induced the toads to move to the water and mate there, as it was cooler. Female midwife toads deposited their eggs directly in the water, as opposed to on land. Kammerer published his work as a success with absolutely no proof. It was later found that he faked the experiment injecting blue dye into the toads to induce the naptial pads.
Then
James McConnell did an experiment in the 70s with worms. Quite gruesome things actually. Trained flatworms, cut them up, put them in a blender and feed them to other untrained worms to see if memory could be inherited through feeding. Just to prove that memory can be reduced to a molecule and transfered. As a result, McConnell claimed, the untrained flatworms performed behaviors that the trained flatworms had previously learned. In short, the dead flatworms' memories had found a new home.
Thanks for the memories, I guess?
■ Now, for aquired traits to be inherited, there are barriers to be breeched; walls that need to be torn down them to pass down.
1) Wisemans barrier theory: The idea that there is an impenetrable barrier that separates the germline and somatic cells. Germ cells are the prime transport pods while all other cells play no role in inheritance as we said.
This has shaped much thinking in evolutionary biology and in many other disciplines. However, recent research has revealed that the so-called 'Weismann Barrier' is leaky, and that information is transferred from soma to germline.
2) Epigenetic reprogramming:
Epigenetics is the process by which an organism’s genotype interacts with the environment to produce its phenotype and provides a framework for explaining individual variations and the uniqueness of cells, tissues, or organs despite identical genetic information.
Reprogramming is the erasure of these aqcuired epigenetic information.
To put it simply, say using the IKEA anology, you have cells that have instructions to build a coffee table. But due to your environment, YOUR coffee table comes with a drawer because why not? So, theres a slight modification to the instructions right? Now, when you are transferring your genes to your offsprings, these slight modifications are erased and so your child has the instructions of the original coffee table only.
In mammals, about 1% of genes escape epigenetic reprogramming through a process called Imprinting.
So yes, your kid can inherit that drawer if you are part of the 1%.
To understand how we've investigated the inheritance of memory lets first identify the Model Organism.
Model organisms:
Organisms that have been worked on by grand communities of people that represent the biology of humans to some extent and have led to blockbusters and groudbreaking discoveries in medicine.
Eg. E. Coli bacteria, flies, worms C. Elegans nematodes, fish (zebrafish) and of course mice
Learning about our memory was first largely studied in snails because of their large and relatively easy to work with neurons. In fact, a team at ULCA reported they have transferred a memory from one marine snail to another, creating an artificial memory, by injecting RNA from one to another. This research could lead to new ways to lessen the trauma of painful memories with RNA and to restore lost memories.
Clear cut proof of the existent of inheritance of aquired traits was first found in C. Elegans.
C. Elegans are the first organism to be sequenced before humans. mostly found in rotten fruits and leaves. They are 1mm long so need to be seen through a microscope.
They have 959 cells in total which 302 are neurons. Generation time is 3 days unlike in mice which take 21 days to produce the next generation.
Dr Oded Rechavi, a researcher in biogenetics underwent an experiment to test virus resistance in these worms. This would later prove the theory of inhertance of aqcuired traits.
The experiment was on resistance to viruses
The worms are naturally resistant to viruses due to small RNA.
In 2006, double strands of RNA were inserted into the worms replacing the original strands
An analogy: taking the specific instruction of a coffee table from IKEA handbook and insert a copy of that into the book erasing the original page.
This leads to gene silencing preventing them from being expressed.
It was shown that these double strands spread throught the whole body and gets replicated into the next generation of worms.
The same goes when the worms were fed these double stranded RNA through bacteria that produce it, the same effect happened.
This experiment was used to silence the virus resistant gene then injecting a virus into them. They found that the worms produced their own RNA genes corresponding to the viruses passing it down to the next generation.
Read more about it here
Can worms transmit brain activity?
Can memory transfer between generations?
Lets see what memory initially is:
A change of behaviour because of what happened in the past.
So, can we planning the fate of the next generation using your brain without speaking to the them?
Like inserting an instruction manual into your brain based on your experiences to be passed on.
When transfering information it needs to be embedded within the DNA while memory is synaptic in nature connecting part of the brain (like electricity)
Can that be translated into heritable information or molecular form inserted in DNA?
This is close to impossible so to answer our question in the beginning, will you be able to pass on this article to your kids on memory alone? I regrettably say, possibly not.
Yet, some specific pieces of information can.
As an example, pairing an odour with something thats disliked, like famine for example. The receptor for that particular odour would disappear or regress and this would be passed on. This has been shown not in worms but in mammals. Learning a certain thing and a particular receptor in your body would adjust getting passed on to the next generation.
So there you have it, memories COULD be passed on but have limitation especially since not much has been published on this particular topic and research is still ongoing but its definitely something to watch out for.
Heres an interesting story from a commentor that could spark a debate.
If I have added if only a bit to your world of knowledge, make sure to follow for more☆
