Immortality is Real!
Immortality is great. Who wouldn't want to live forever? However we try to prevent it, aging is inevitable. For humans, at least. There are some organisms that can indeed live forever due to their genetics and the environment around them. So, let's explore what makes these organisms live forever or, at least, for a very long time!
Eastern California has a true time machine near its White Mountain range - the bristlecone pine tree called Methuselah, which is the oldest living tree in the world (4765 years old!). It is not just this tree, it is the whole species of bristlecone pine trees that live for a very long time. The reason lies in the harsh environment they live in such as cold temperatures, strong winds, and usually dry soil. These conditions with the trees' natural ability to grow slow make their wood very dense. It is so dense that fungi and pests cannot penetrate it, and the trees stay mostly unaffected. Sometimes bristlecone pines grow so slowly that this time doesn't even add a ring of growth to their trunk.
*Hydra* is a small insect-looking organism that lives in freshwaters. It does not undergo senescence or, in other words, biological aging. The reason lies in specific genes called FoxO (humans and other animals have it, too!). Normal cells slowly deteriorate over time while *Hydra* is capable of renewing them over and over again due to the abundance of FoxO genes. However, when scientists prevented them to perform their function, *Hydra*'s cells slowly started aging.
There is only one species that is considered biologically immortal - the jellyfish *Turritopsis dohrnii.* The reason why it is called the only true immortal organism is that it has no maximum lifespan. Just like any other species, these jellyfish have a life cycle. However, the difference is when they are about to die. When they are faced with stressful situations like injury, an abundance of predators, or starvation, they turn themselves into a small blob of tissue. This blob follows all life cycles of the jellyfish until the fully developed adult form is capable of reproduction and then converts itself into a blob again.
Perhaps, someday humans will achieve immortality or at least figure out all scientific processes behind it. Right now we can only observe other species and make our guesses!
