Why do we change as we get old?

As we age, our bodies change due to various reasons. One main reason is related to our DNA. Over time, our DNA, which acts as the instructions for our bodies, can become damaged by things like chemicals, pollution, and sun exposure. This can lead to our bodies not functioning as well as they used to. Another theory suggests that a part of our DNA called telomeres gets shorter over time, and this can contribute to the aging process. Additionally, factors like lifestyle choices, such as exposure to harmful substances and lack of proper nutrition, can also affect how we age.