Well if you’re looking for scientific back ground, they already know what causes aging.
A VERY basic summary is as follows; Your DNA copies itself everytime it is multiplied into a new cell, which is literally millions and millions of times a day. Your DNA obviously contains all of the info that tells your body how to make different parts, how your skin should look, how an organ is designed, how a hormone is made, etc, etc (everything).
Well as you might expect, if you copy something a bunch of times, there will be small errors in the copies, that would accrue over time. Think of it like if you went and took a textbook page with a recipe on it, and you copied it in a copy machine, then copied the copy, and then copied that copy, and so on and so forth 100 times. By the time you got to 100, you probably wouldn’t be able to read the recipe, or at least parts of it would be faded and hard to read. This is basically what happens to your DNA.
As it multiplies, it ends up losing small parts, or being mutated by outside sources (for example radiation or carcinogens). Over time your DNA even gets shorter (the older you are, the shorter your DNA’s total length), and this begins to show as aging eventually. So THEORETICALLY, if you can find a way to prevent your DNA from being damaged/degraded, you could live forever (or at least not die from aging).
(Interesting side note, cancer is caused when a “stop” codon is mutated in your genome. This codon would normally tell a series of cells to stop multiplying when new copies are no longer needed, and they would also lead to the cell’s own “death” sequence [that’s not the actual name, but it’s been a while so I’m light on the specifics]... so in a sense, cancer has already accomplished the feat of eternal life, as it will never die so long as its continually supplied with nutrients…. going along with this, they still have live cancer scrapings they took in the 50’s, alive in a petri dish in a lab today).