By Urvashi Balasubramaniam
Ever since humans have been alive, they have wanted to keep it that way. Evading death has filled the pages of our legends and our literature, but with science rapidly advancing, could immortality one day become a reality? To discuss how we can prevent death, we have to start by understanding why we die.
Our bodies consist of over 200 million billion cells all working together to create us. Your cells divide to replace older ones. Every time they divide, they copy their DNA, which is a set of instructions that tells the cells what they are and what to do.
But if I asked you to copy a long list of letters over and over again, you're bound to make a mistake somewhere. Cells behave the same way. Every time they copy their DNA, they produce glitches. These glitches, or genetic mutations, eventually lead to evolution. So your abilities are actually the results of billions of mistakes!
When the number of newly-formed cells is less than the old ones, you start to die, which occurs as early as the age of twenty-five. What a great excuse for not turning in your college term paper.
To prevent too many glitches, cells have to stop dividing after about 50 times through a process called apoptosis. So what would happen if your cells divided indefinitely?
Strategy #1: Infinite Cell Division
At first glance, it seems like a good deal. After all, if your cells keep dividing, you never run out of you! Immortality achieved? Not quite. Remember those copying glitches during cell division? If cells keep mutating like that unchecked, they multiply to form tumours. You might know these by a different name: cancer.
Cancer is a huge problem because the body isn't designed to detect when its own body cells go haywire. Luckily, synthetic biologists have created a method called CAR-T cell therapy or biohacking, allowing us to edit the DNA of white blood cells and help them recognise and destroy tumours.
We should also consider telomeres, which are structured at the end of your chromosomes that shorten as the cell divides (and as you age). When it can't get any shorter, you die. If we could find a way to keep them nice and long, infinite cell division could make us truly immortal.
How telomeres shorten as cells repeatedly divide
The hydra uses enzyme telomerase to prevent the shortening of telomeres and thus it doesn’t show senescence (or signs of deterioration as it ages).
Strategy #2: Become a Jellyfish
The secret to immortality may also lie in a small aquatic creature: the immortal jellyfish. Yep, that's right! The Turritopsis dohrnii (right) is the only known organism to have completely escaped death.
These creatures transdifferentiate their cells, which means they can convert one kind of cell that has already been assigned a function, to another kind of cell. Transdifferentiation of cells allows jellyfish to return to a younger state in their life cycle, which lets them live forever.
Its tentacles deteriorate and it eventually becomes a cyst that can reactivate genetic instructions from earlier in its life! Anytime it gets stressed, it simply turns back the clock and enjoys its time as a baby jellyfish. But transdifferentiation isn't limited to jellyfish. If you remove a chicken's lens in their eye, the iris cells of a chicken will transform into lens cells (even though chickens can't restart their life cycle).
We don't yet know what signals are sent to these cells and how they change their type, or whether it's even possible in mammals. But studying the process further could help us understand how to regenerate tissue without stem cells and even help switch cells off to treat cancer.
Humans have always wondered what technology they could develop to achieve immortality. Jellyfish prove it's a no-brainer.
Strategy #3: Upload your Mind
The idea of cyborgs and humans becoming machines sound like they belong in a science-fiction novel, but let's consider it in reality. You are a conscious human being (or so I hope) which enables you to read this article, wonder about immortality and go about your life. So could computers take the place of where your biology fails you?
To do this, you'd have to map your entire brain and somehow convert it into a computer-readable form that could capture the entirety of your consciousness. The human brain has 86 billion neurons connected by at least a hundred trillion synapses that form the connectome. Here's where the problems arise.
We haven't yet mapped the connectome, and we don't understand the brain's workings as well as we need to properly map it. After all, if we map it wrongly, who knows what could happen?
We'd also have to map it with technology that doesn't currently exist. While MRI scans resolutions of about half a millimetre, we would require a resolution of a micron (or a thousandth of a millimetre) to capture the synapses. To do this, you'd need a field strength so strong that you'd fry the brain, which isn't exactly ideal.
What we are getting better at, though, is computing power and storage space. So all we have to do now is solve the ethical concerns, develop better scanning technology, find the source of our consciousness in the brain and build a virtual existence that mirrors our own. Whew! Though it's unlikely we'll achieve mind uploading anytime soon, it's an interesting prospect. And humanity has managed to achieve some pretty unthinkable things in the past, so who knows what the future holds?
Strategy #4: Escape Velocity
Every year, we improve our life expectancy by 0.3 years. If we improve it by one year every year, we become immortal. This is a hypothetical situation called 'longevity escape velocity'.
As humanity pushes its medical, technological and imaginative limits, we live longer and longer in this incredible world. Immortality has long been a central idea of our mortal lives, and perhaps one day it will be a simple reality for all of us.
References:
Immortal Jellyfish – The creature that defies death (picture source)
Building the Human Brain Network (picture source)
Special thanks to Dr. Debamita Chatterjee and Malathi Anantha for their inputs on telomeres and aging.