 Our bodies are like clocks, and one day we're going to stop ticking. But why? Everything in our body, right down to our cells, is constantly aging. But why does this happen? To answer this question, we're going to have to take a look at it on the cellular level. One potential cause of aging is the mitochondria. As you can see, not all of the DNA in a cell is found in a nucleus. Some can be found in the mitochondria, since it is theorized that mitochondria was once a small, free living creature. Mitochondrial DNA mutates much faster than nucleic DNA. As mitochondrial DNA takes more damage, the mitochondria gradually declines in its ability to produce energy, which can lead to cell death. However, that's just only one piece of the puzzle. Aging could also be caused by something fishy going on in the nucleus. In the nucleus, our genes are twisted into double strands called chromosomes. At the end of the chromosomes are telomeres, which are repetitive strands of DNA. Telomeres protect our genetic information and keep chromosome ends from sticking to each other, which can seriously mess up an organism's genetic information. Each time a cell divides, the telomere shortens. When the telomeres get too short, the cell ceases to divide and either becomes inactive or dies. It is believed the shortening of telomeres is what causes aging. However, aging isn't just caused by genetics alone. External factors can also play a role in aging. For example, our body metabolizes glucose from the food we eat along with oxygen in the air we breathe for energy. This metabolic process takes place in the mitochondria, where oxygen is used to convert food into energy. The mitochondria is extremely efficient with this process, but they produce chemically reactive molecules containing oxygen called oxygen-free radicals, which attack your DNA strands affecting its function and structure severely. This is why this process is believed to be one of the causes of aging. Also, let's not forget exposure to harmful substances such as smoking tobacco, which can destroy your skin's elastic fibers, giving your skin a wrinkly look, can also be a cause of aging too. Even the sun, which is the ultimate source of energy, contributes to aging by releasing harmful ultraviolet rays, which can damage our skin and give it wrinkles, freckles, and red patches, and even skin cancer. It's scary how the things which we need for survival are also the things which are slowly killing us. Even more scarier than the external factors of aging are the internal factors. Yes, your rate of aging is also influenced by your psychological state as well. Numerous studies have shown stress from things like depression, social isolation, anxiety attacks, and even stuff like unemployment can result in shortened DNA strands thus speeding up the process of aging. For example, in 2014, scientists in Austria examined telomere lengths of socially isolated African gray parrots and compared it to the telomere lengths of African gray parrots with a partner. And it wasn't a surprise at all that the single parrots had shorter telomere lengths than those with the mate. So now the question is, how do we stop aging? The best answer at the moment is, we don't know how to yet. And even if we could halt aging, you would still probably die from external threats like asteroids, wild animals, diseases, you get the idea. However, while we can't stop aging, we can slow it down. How? Well, it's simple, sort of. Just eat a healthy diet, limit UV exposure, exercise in healthy amounts, and try to wind down and be stress free as possible. That's pretty much the best you can do to slow down aging naturally for now. But in the future, aging may no longer be a problem. I hope you enjoyed this video. If you did, then subscribe for new science videos each month. And don't forget to leave a like and share this video so others can learn too.