Will Humans Ever Regenerate Like Time Lords?

How Bioengineers are Catching Up to Gallifrey

Wouldn’t it be great if our bodies had a CTRL-Z function? Imagine being able to heal minor injuries, chronic conditions and fatal wounds in seconds. In Doctor Who, time lords can do just that. On the verge of death, they’re able to regenerate their bodies and become new versions of themselves. This trick allows time lords to live thousands of years and offers a last-minute solution in life-threatening situations. Surprisingly, the way time lords regenerate shares attributes with the way real organisms do, and our accelerating understanding of how organisms regenerate may make it possible for us to do the same.

Side Note: Regeneration means the Doctor’s whole body, their personality and their gender can and do change. For that reason, I’ll be using they-them pronouns to describe the Doctor generally, but I’ll use he-him or she-her pronouns to describe the Doctor when discussing specific points in the show’s history.

Let’s go over what exactly happens when a time lord regenerates. First, they begin to glow a bright yellow. Then, they release a large amount of energy, sometimes even creating an explosion. During this process, every single cell in their body is replaced. They take on a new appearance, new personality and sometimes a new gender. It appears that all they retain after regeneration is their memory. Time lords can also store regeneration energy to use between regenerations. That energy can be used to heal minor injuries.

Since regeneration energy is such a vital part of how the Doctor regenerates, understanding regeneration means figuring out what that energy is.

Energy seems like a very tangible thing. We can gain it by eating and lose it by working, but fundamentally, energy is a concept. The video above does a great job of defining energy as the simple measure of a physical system’s ability to do things. However, the energy of a system alone doesn’t tell you what things that system will do. For that, you also need information about the system and its environment. For time lords to regenerate, they need to provide both energy to reconstruct their bodies and information that tells their bodies how to use said energy. Decades of research suggest that that’s exactly how real organisms control cell growth. They use chemical energy in the form of ATP to drive regenerative biochemistry, and they use electric signals to instruct their cells on how to grow and organize themselves.

Finding out how regeneration works requires us to understand bioelectricity and morphogenesis. Bioelectricity is the study of voltages and electric fields produced naturally within living things. Morphogenesis is the organization of cells and cell structures within living things. This ranges from the organelles within a cell to the cells within organ tissues. Morphogenesis includes processes like the formation of embryos and the regeneration of various organ tissues. Around the 1930s, a professor of anatomy at Yale, Harold Burr, began researching whether these two fields were related. His hypothesis was that bioelectric signals guide the formation of living things. In recent years, advanced methods of examination have revealed that bioelectricity does indeed play a major role in morphogenesis.

In a nutshell, a cell creates electricity by pumping ions from one side of the cell membrane to the other. The resulting distribution of charges creates an electric voltage across the cell membrane. Neurotransmitters from the brain can open up channels for these ions to diffuse across the membrane and eliminate the charge gradient. This changes the voltage of the cell and affects its behavior.

As it turns out, these changes in voltage act as a sort of blueprint for how an organism should form. Michael Levin, a software engineer turned developmental biologist, studies the relationship between bioelectric signaling and morphogenesis. According to an article from Quanta Magazine:

Levin likens the ion channel’s effect to a sharpening filter in photo-editing software, in that “it can strengthen voltage differences between adjacent tissues that help you maintain correct boundaries.”

In layman’s terms, voltage differences between cells are created to draw lines between where one type of cell forms versus another. This discovery helps explain how a developing organism knows where to grow certain types of cells instead of others. For the longest time, scientists assumed that genetic expression alone dictates how organisms develop, but that idea fails to consider the necessary spatial and temporal cues an organism needs to form properly. Bioelectric signals fill in those gaps.

Levin and his team also found that many different species share an ancient gene that codes for a proton-transporting ring protein. This structure is vital for regeneration and embryogenesis because it is implicated in the gap junctions and ion pumps that electrically polarize cells. Evolutionary history suggests this gene and its corresponding structures are the one common factor for regeneration across multiple kingdoms of life. It also seems to have independently evolved at least twice.

The networks of ion channels, protein pumps and gap junctions throughout living tissues guide both the development of organisms from embryos and the regeneration of damaged organs. These structures can even resemble computational circuits. In case you’re not convinced, Levin’s team was actually able to induce bioelectric cues in organisms by injecting them with messenger RNA that encodes for HCN2, an ion channel that produces bioelectricity. They found that brainless tadpole embryos developed abnormalities when left to grow on their own, but developed normally when artificially given the correct bioelectric cues.

The same article from Quanta Magazine talks about how these findings shine a light on the role the nervous system plays in bodily development:

Levin’s research demonstrates that the nervous system plays a much more important role in how organisms build themselves than previously thought, said Min Zhao, a biologist at the University of California, Davis, and an expert on the biomedical application and molecular biophysics of electric-field effects in living tissues.

Levin’s team also found that they could use bioelectricity to cause flatworms to grow two heads and extra tails in unexpected places. They could even make frogs with extra legs and turn their gut tissue into eyes. All of this was done simply by hacking the bioelectric activity responsible for planning out the organisms’ growth and development. And bioelectricity doesn’t just offer insights into the development of complex organisms. Single-celled organisms like bacteria also seem to depend on bioelectric signals when they develop.

So what is regeneration energy? It’s likely bioelectrical energy that time lords use to guide the regeneration of their cells. There’s even evidence in the show to support this. In the episode The Magician’s Apprentice, the time lord Missy states that she’d be unable to regenerate if her brain stem was severed. From that, we can infer that the brain is an essential part of regeneration. As we discussed, the bioelectric signals in many organisms are triggered by neurotransmitters sent by the brain. These transmitters diffuse between cells and activate their ion channels. So time lords not being able to regenerate without a brain lines up with the processes behind real-life regeneration. Their brains are what trigger their regenerations.

Missy’s statement also suggests that a time lord’s brain must not be completely replaced during regeneration, which could explain how they preserve their memories as they morph between bodies. However, even if their brains are fully replaced, it’s possible memories from each region of the brain get moved to separate regions before being re-imprinted onto the old regions once they’ve regenerated. A powerful feature of neurons is their ability to hold multiple pieces of electrochemical information simultaneously, and based on how much of their long lives time lords can remember, their neurons likely possess superhuman information density.

The research of Michael Levin and others also suggests that certain memories can be stored using RNA. This is a proposed explanation for how flatworms can retain memories after regrowing their heads. Perhaps time lords utilize a similar trick where they move RNA around in their brains and bodies as they regenerate.

An important question remains: why do time lords glow when they regenerate? I think what we’re seeing is a corona discharge. Corona discharge occurs when a stream of charged particles like electrons or ions are accelerated through the air by an electric field. As the particles move through the air, they collide with atoms and rip electrons from their nuclei. Those electrons do the same to more atoms in what’s known as an electron avalanche. The ionized air becomes a plasma and produces light as electrons recombine with their atoms. The color of this light depends on the chemical composition of the air.

As you can see above, corona discharge in regular air(left) glows violet, while corona discharge through sodium vapor(right) glows yellow, just like the substance released by time lords. This leads me to suspect that time lords must have a high sodium content in their bodies, which makes sense given that sodium ions play a large part in the production of bioelectricity. When time lords regenerate, the sodium contained in their old cells is blasted away as those cells are shed. The electricity running through the time lord’s body creates a corona discharge that appears yellow due to the sodium vapor ejected into the air. For more information on corona discharges, I recommend this fun video from Kyle Hill:

Corona discharges typically occur in air at voltages of tens of kilovolts or higher. That’s much more than the millivolts involved in most bioelectric phenomena. This isn’t a problem for the time lords though because they are naturally resilient under high amounts of electricity and electromagnetic radiation. In the episode World War Three, we see the Doctor survive an electrocution that kills the humans around him. There’s even enough electricity present to create visible discharges in the air.

If the Doctor can survive this electrical onslaught, it stands to reason their body could perform many more bioelectric interactions per second than humans without having to worry about the damaging effects that generating that much electricity would usually have on an organism. This increased rate of bioelectric activity in the Doctor’s body may explain, in part, why they’re able to reconfigure their body so quickly. They’d also need large stores of metabolic energy and considerable heat resistance. The rapid cascade of metabolic reactions that occurred as they reconfigured their bodies would produce a lot of heat. These factors could also explain why the Doctor can sometimes release enough energy during regeneration to create large explosions.

So now we know how the Doctor likely regenerates using bioelectric signaling. What about us? Can we use our knowledge of bioelectricity and morphogenesis to rebuild our own bodies?

While I doubt we’ll be letting off corona discharges and changing our faces anytime soon, research is promising to change the way we think about our bodies. Hacking our own bioelectric activity could allow us to heal ourselves better than ever. Bioelectric manipulation may even be able to help us battle cancer, since cancer cells have been found to have irregular bioelectric activity which keeps them from properly communicating with neighboring cells. Burr’s original idea that electricity is involved in growth and healing has led to discoveries that may forever transform regenerative medicine.

In conclusion, the process of regeneration in Doctor Who lines up surprisingly well with the actual biophysics of living things. Regeneration energy may actually be the precise application of bioelectric signals. And like in real organisms, these signals can tell cells how to reform themselves when healing damaged parts of a body. Research is already being done on how to use these types of signals in the real-life regeneration of human tissues, and I for one am incredibly excited to see where the science takes us.

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