It鈥檚 a story that would make the publishers of the Kama Sutra blush with envy. A 25-year-old graduate student鈥檚 sex drive suddenly surged and his technique apparently improved overnight. 鈥淚 make love like I know exactly how the woman鈥檚 body feels and responds,鈥� he told researchers, 鈥渁lmost as if it is my body.鈥� His girlfriend concurred: 鈥淗e鈥檚 a much better lover now.鈥� She also noticed other changes. Her boyfriend was now a hugger, and he loved to go shopping, and he carried a purse with him. And going to museums? 鈥淗e would never, absolutely never do that,鈥� she said. 鈥淣ow, he would go every week.鈥�
What strange potion did her boyfriend drink? No potion at all, it turns out. He had cystic fibrosis and received a heart-and-lung transplant. The donor? A young lesbian woman who did landscape paintings. Did her vital organs remember who she was at a cellular level and did that essence transform the young man?
This story is one of ten cases reported in which may just be the wildest and most entertaining paper I have read in a long time. It is an attempt to document real-life cases of a trope common enough in movies: that organs contain the personality of their donors, and this personality can transform their recipient. Hollywood tends to prefer darker storylines than the student whose sex life improved post-surgery, portraying instead innocent people receiving the hand of a serial killer and experiencing the compulsion to murder.
We know that memories reside in the brain. But do other cells in our body also retain a memory of who we are?
Immunological memory and habituated trumpets
Living things are made of cells. Let鈥檚 take the body as a whole. We can see that a human is made up of discreet organs. These organs are made up of tissues, and each tissue is made up of cells. Like babies, cells begin life with the potential to be many different things, but they eventually specialize, becoming neurons, heart cells, muscle cells, bone cells, etc.
Our brain, which is made up of many different types of cells including neurons, clearly has memory. This is what cognitive neuroscientists study: how our neurons are capable of encoding information and remembering it.
Memory also exists outside of the brain and is the reason why vaccines work in the first place. Some of our white blood cells become memory cells after encountering a disease-causing microorganism鈥攐r a harmless fragment of it, such as in a vaccine. These memory cells settle into different parts of the body and scan what they see. If they are presented with the microbe again, they can mount a very quick and effective response. The reason why these white blood cells have a memory of their early encounter is not because they have a literal brain. Human brains are made up of billions of cells; an individual cell does not have a brain. Rather, they confer our immune system with a type of memory simply by existing.
When a virus against which we have been vaccinated infects us, some of our white blood cells will ingest it and break it down to pieces, regurgitating these chunks and displaying them on their surface. And when our memory cells make contact with these chunks, they get activated. 鈥淭hat recognition and activation occurs rapidly,鈥� Andrea Love tells me. She has a doctorate in microbiology and immunology and is the author of aimed at a general audience interested in science and health. Because these memory cells exist, our immune response, driven by the activation of specific genes and the production of chemical messengers, occurs within hours to days instead of the delay of days to weeks we see when first encountering a disease-causing microorganism. This sped-up immune response, due to the existence of memory cells, is what we refer to as the immunological memory.
There is also some interesting research that provides evidence for non-brain and non-immune cells exhibiting some form of memory in very specific circumstances.
We can look, for example, at the trumpet animalcule, a tiny organism also known as Stentor. Unlike us, it has no brain, no organs, no tissues; the entire animalcule is a single cell, often microscopic, shaped like a trumpet. And yet, despite this lack of complexity, it can learn, and learning requires a form of memory. When something touches it, it contracts into a ball to protect itself, but this burns energy. Stentor can鈥檛 afford to do this if it鈥檚 simply being bumped repeatedly by some algae. So, it has learned to habituate to a repeated touch that uses the same level of force. When it is bumped again and again, it is . It remembers the previous bumps and adjusts accordingly. How it does this remains to be elucidated, to the best of my knowledge, and it probably involves the complex molecular dance of DNA, RNA, and proteins inside the animalcule. But surprisingly enough, this single-celled organism has a type of memory, and similar properties have been observed in, for example, giant amoebas.
It is thus possible for individual cells to have some primitive form of memory. But an organ transferring its donor鈥檚 essence onto a recipient?
Not letting your heart rule your head
When we return to that old transplantation trope, there is a lot to unpack before we should even contemplate that the cells remember who they belonged to.
These incredible stories can easily arise because of selection bias. If a transplant patient suddenly matches their donor by sheer coincidence, their story will be shared a lot because it is interesting and it fits a certain type of magical thinking. If a transplant patient does not experience these changes in personality, that story is unlikely to travel far. Sexy stories sell, and a patient with better lovemaking skills after a heart transplant is a story people will love to tell.
A recruited transplant recipients to know if personality changes could be seen after a graft of any organ, not just the heart, and although its authors report that nearly 9 in 10 of their participants told them their personality had changed, I don鈥檛 think we should blindly trust this result. They asked the members of Facebook groups dedicated to supporting people who had received an organ transplant, and 鈥減ersonality changes鈥� was right in the title of their survey. Participation is likely to be skewed in favour of those who think their personality has changed.
Some of the reported changes can also be explained in much more banal ways. A teenage girl who received the heart of an 18-year-old boy who wrote songs that, upon listening to the boy鈥檚 music, 鈥淚 could finish the phrases of his songs.鈥� I experienced the very same thing when first listening to Jekyll & Hyde: The Musical. The music is great, but the rhyming lyrics are so predictable, I found myself guessing many of them correctly, no organ transplantation required. At 18 years of age, the organ donor in this case was probably not writing incredibly complex lyrics.
In another case reported by the same researchers, a teenage girl with no prior interest in medicine decides to go to medical school following her successful surgery. We are told the donor wanted to be an actress, but her father wanted her to go into medicine. Hence, somehow, the recipient鈥檚 newfound love of medicine has nothing to do with the life-saving surgery she received as a teenager, but everything to do with the donor鈥檚 father鈥檚 wishes. We are a far cry from Occam鈥檚 razor.
Another big explanation for personality changes is the immunosuppressant medications that patients have to take for the transplantation. Prednisone, for example, makes you hungry. The stress of the surgery and its life-saving quality can also change someone鈥檚 outlook on life and result in changes in terms of life goals, preferences, and values, and these can coincidentally align with the donor鈥檚 sometimes.
There鈥檚 also what the patient brings to the operation in terms of beliefs and expectations. Doctors have written about their donor鈥檚 hypothetical sexual behaviour and preference will be transferred onto them. Others fret that they will become suicidal because that is how their donor died. Some bring a lot of racism to the table. A 47-year-old white man received the heart of a 17-year-old Black student. He that he thought a particular organ of his might grow in the process to match the donor鈥檚, and that he sometimes felt guilty (but not seriously) after intercourse 鈥渂ecause a Black man made love to my wife.鈥� All of these irrational beliefs can lead to personality changes without the need to invoke a hypothetical cellular memory.
This whole topic seems to encourage non-scientific thinking, where ancient ideas of devouring an enemy鈥檚 heart to gain his courage are now used to explain the changes a person goes through after nearly dying. The popular therapy service Better Help has an on its website about cellular memory that is pretty bad. Its author waxes lyrical about d茅j脿 vu and birthmarks representing memories from past lives and about karmic debt. There is no scientific evidence behind any of this, the article points out, but isn鈥檛 it 鈥渋nteresting to entertain?鈥�
No, I don鈥檛 think it鈥檚 interesting to entertain. In fact, it鈥檚 potentially damaging. Feeding people鈥檚 imagination in this way can make them unnecessarily wary of donating their organs or accepting a transplant, believing some magical cellular memory will infect them and alter their identity. Yes, there is some interesting evidence that some cells can remember certain things in certain contexts, and I look forward to more studies better elucidating the cell biology of living things. But if you fear that 鈥渉aving a woman鈥檚 heart would make [you] gay鈥濃�攚hich the 25-year-old heart recipient with improved bedroom skills quoted at the beginning admitted to thinking prior to the surgery鈥攖here is a lot more to unpack than the claim that cells can remember things.
Take-home message:
- Some people believe that after receiving an organ transplant (usually the heart), they will take on the personality of the donor because the organ remembers who it belonged to
- Cells can display memory, such as in brain cells, certain cells of our immune system, and even single-celled organisms that can habituate to certain stimuli, but beyond that, claims of cellular memory are speculative
- Stories of personality changes post-transplantation can much better be explained by coincidence, selection bias, the effect of immunosuppressant medication, the life-changing experience of undergoing a heart transplant, and the prior beliefs and expectations of the recipient
