If we were back in nature chances are, when we died or, if we were killed, a predator or scavenger would come along and eat us. Those who choose to be buried feed worms and insects. So- our 'energy' in the form of fats and nutrients would get transfered along to other creatures. When humans eat animals- do they take on part of their consciousness?
Do we still sense our waste material? Think of how many shits we've all done, teeth we've lost, nail and hair clippings we've thrown away. Are you aware of where they all are now? Or, where they went? Are you worried about what might be happening to them? It seems unlikely. They don't feel a part of you anymore. They could throw your nail clippings into molten lava and you wouldn't feel a thing.
I tend to believe our physical matter requires a working brain and consciousness to register that it's alive. Sure- particles of us will still exist after we die. Maybe for a long time but- I doubt we'll be aware of that.
Ever been under anaesthesia? Did things bother you during that period? If they did it right- no. They could have opened up your chest and you wouldn't have been aware of it. Personally, I'm not too worried about things I will never be aware of and, never feel.
I never quite understand why people are sure their own consciousness will reappear. I guess it does come down to belief ultimately. Plus, how you see consciousness. I tend to see it as simply a function of the brain, rather than a separate entity.
Like seeing is a function of the eye and brain combined. We all have eyes- does that mean we all see in the same way? We know we don't. Some people are colourblind. Some animals see in a completely different way to us. It surely depends on what genes they got. What species they are. I imagine the same goes for our brains. So, I tend to feel that only our own brain creates our consciousness in the particular configuration we have. How could 'you' be you if you were born 100 years in the future to different parents?
Another example is cloning. If they cloned you- would you share a consciousness with that person? Would you know their thoughts? After all- they do actually have a replica of your brain. It seems unlikely. More likely that you would be able to relate closely how to clone you might think or feel. But, even then, experiences change us. So, if your lives were very different- you may end up very different people.
Another consideration is- what is your earliest memory? What were you first few weeks of life like? You were obviously alive and conscious but, I doubt you can remember. You may not have many memories for a year or two. So- wouldn't that suggest that consciousness is something that grows and develops- as the brain inside the organism does? If it were a fully fledged entity inside a baby, wouldn't we be smarter at that age?
If our energies/ consciousness have always existed- what were we when humans didn't exist here? What will we become when they are destroyed? Would the consciousness of a dinosaur or amoeba fit inside a human? Why don't more of us have a bigger sense of all these other lives we must have lived? How does this recycling programme fit with changes in population numbers?
Can you remember your past lives? I doubt many of us can. Meaning that, either we don't have them. Or, we do have them but, don't remember them. So- even if a future 'you' does come back, presumably, they or, you will have no sense or memory of your current life. It will be as if they/ you are starting again- effectively a new entity.
So, that's another reason I don't worry so much about that element of it. I feel sorry for any new life coming here but for one, I don't believe any of it will be me again. And, if I'm wrong and it is me, it will be me will complete amnesia. Plus- born some time in the future to new parents. I hope they considered their situation more thoroughly before deciding to breed.