In an animistic world we can imagine spirits living past our deaths and eventually finding new forms. There is no evidence in favour or against this idea. Not being falsifiable, the hypothesis is beyond the realm of science. But there may be no need for such a thought when molecular reincarnation is as real as the ground on which we stand.

In fact, as we stand we shed skin cells, feeding dust mites; we exhale carbon dioxide and water; we sweat carboxylic acids and aqueous sulphurous concoctions. The cells, acids and other compounds eventually get degraded into gases, phosphates, sulphates and more water that join their respective chemical cycles, external veins of our living planet. Molecules that were once part of our flesh become part of new sap and blood.

We sit to eat molecules that were once part of fish and plants. We become the reincarnation of transient beings. When we drink ions and uncharged atoms, we borrow them and enrich them with nitrogenous compounds. Rivers then flow and oceans ebb with parts of our selves that will soon become parts of others.

As mammals we care for our young. Our offspring retain some of our macromolecules in the form of deoxyribonucleic acid. The mitochondrial varieties of DNA are rarely adulterated, being preserved from grandmother to mother to daughter for countless generations. Similarly, among men, Y chromosomes preserve genes as religiously as paternalistic societies maintain surnames.  

As thinking animals, our molecules orchestrate into neurons and neurotransmitters. Strongly interwoven assemblies of neurons known as ideas occasionally emerge. The best of these reincarnate themselves in the minds of others. And like the molecules that make them possible, they outlive the temporary shelters of individuals.

Death is simply the final and largest repayment of a molecular debt, but a fair amount of caring and weaving can be done before then.