I'm not sure which group this question really belongs to, so "general physics" sounds like a safe bet. This question was prompted by having listened to Neil deGrasse Tyson's more philosophical views about our nature and our connection to the universe, which are quite insightful. Most of the larger molecules in my body are probably relatively recent (as living organisms build and break things like protein chains all the time.) Many of the simpler molecules, such as water, are probably much, much older (although I do not know all that much about the formation of such molecules.) Some might be quite recent, but some may be really old. The atoms in my body are probably really, really old. Most of the heavier elements probably formed in the star or stars that were the ancestor(s) of our solar system, some may be even older than that. (If I have understood correctly, it's estimated that our sun is a third-generation star, meaning that it formed from the remnants of stars, which themselves formed from the remnants of the first stars in our universe.) It might be possible that some of the simpler atoms in my body were actually produced by the first-generation stars of our universe, so they are really, really old. But how about the individual particles in my body? The protons, electrons and neutrons? Are they as old as the universe itself? Did they form in the first moments of the Big Bang? (Can such particles form afterwards?) In other words, how old are the protons, electrons and neutrons (and possibly other particles) in my body?