You must of course be talking about the present human body, because the spirit is for all practical purposes so to speak ETERNAL and I say for all practical purposes, because just as the spirits were made they can also one day be unmade.
I as to the so called matterial earth body, it is said that in the future when things are remade some people will have NEW ETERNAL BODIES HERE ON THE NEW EARTH.
As to the present bodie(s), you might not belive in the old tales, but it is said that there were people, maybe survivors from the past flood or some very advanced and forgaten past civilization, that knew how to stay alive for hundred of years, but maybe no more than a 1000 years or so, read the books by Homer also read the book by Virgil and also read "The Epic of Gilgamesh", read the Vedic hindu sacred writings, The Vedas, Also read the Bible, The Old TestaMent, there were giants and mighty men of old not to mention Noah, Enoch, Matusa and all the others, read about the Danaans or De Danaans from the greeks the people fron Denmark (land of the De Danaans-founded by them) and last from the irish or Ireland, where the De Danaans were last seen, They where all over Europa, they founded Italy also.
You think that Zeus and Hercules are just an old wive's tale, think again, maybe you also think that Noah, Moses and Jesus are also an old wive's tale.
The so called god's, Zeus and his crowd and the De Danaans and others like them of course they were not gods and they did grow old, but very very slowly, but they were practically immortal (about 1000 years) they were either survivors from Atlantid or and from sons or grand sons of survivors of the sunked continent and or from before the flood.
Very hard to believe yes, but read all the books and tales and mythology from all the countries of the world and The Epic of Gilgamesh and the Bible.