When he was 84 years old Picasso dashed-off two autobiographical pictures that he called the Musketeers.
One art historian thought they were “incoherent scrawls done by a frantic old man in death’s antechamber”.
But zoologists knew that such recapitulation was a common feature in evolving systems. Natural processes often went back to the beginning and repeated their development with some slight change. The great Ernst Haeckel said that “ontogeny recapitulated phylogeny” – embryo development followed the path formerly hacked out by evolution.
That meant the patterns of the past were revealed in the species’ embryology. Perhaps some patterns were also revealed through the life of an individual? Returning to its early state would be part of a normal biography – nostalgia.