Very sad, when full fledged men talk about single-celled organism.
No single celled bacterium can became a human miltiple cellulare organism.
Without logical evidence I am always told about apes who shall be our forbears.
Nothing is alike human . Pigs donors us organs temporarely.
Because to donor organs will go in huge shortages . More and more can some honest surgerys and neuroscientists convince that the braindeath is not meaning to be dead and pains are feeling.
You get anesthasia and tied up for keep calm to cut out your organs.About anesthesia lying docs say , muscles have get paralized. Other ways would be more effective.
That is beyond the topic , but to belief scientists of space that makes us believe to other weird and dangerous scientist.
Go for looking sources about apnoe test , what means to choke patients who are like a state of coma or not be able any reactions.
Look up for lazarussyndrom.