Last year on August 13, Fidel Castro was convalescing after botched intestinal surgery as his condition and prognosis, though clearly grave, remained shrouded in secrecy. It was his birthday, and two weeks earlier he had surrendered power to his brother Raul. His withdrawal, nearly coinciding with the birthday, generated a torrent of international media attention.

Soon the regime revealed that birthday observances would be postponed for four months, until December 2, Cuba’s revolutionary armed forces day. Expectations were high that he would reemerge, deliver a speech, watch a military parade with a phalanx of officials, and possibly announce he was returning to power. Camera crews, television and radio personalities, a host of reporters, and not a few celebrities and acolytes flocked to Havana hoping for a glimpse of the venerable Fidel. Many were cheering for his recovery and return.

Cuban officials hinted that he would be present, that there would be surprises that day. The official media were flooded with features lionizing the stricken leader, letters from well wishers around the world, and other unusually reverential treatment. The eightieth birthday had come to symbolize his longevity, durability in power, and possibly even his recovery. But on the morning of December 2, as crowds of Cubans and international media gathered, it was not until Raul rose to deliver the keynote address that it became clear Fidel would not be personally accepting birthday greetings.

None among the few of us who knew better were inclined to spoil all the fun. Fidel had not in fact turned eighty last year. On August 13, 2006 he marked his seventy-ninth birthday. His actual eightieth is now upon him.

That he has been lying about his age through most of his adult life has been known outside of Cuba to some of his biographers and other astute students of his life. Yet, despite the overwhelming evidence that he was born on August 13, 1927 in Biran, Oriente province, he has clung to the birth date, exactly one year earlier in 1926, that is inscribed in his birth certificate.

In my study of the Castro brothers, After Fidel, I revealed some previously undiscovered evidence that supports the later birth date. On different occasions in the late 1950’s Fidel’s mother Lina Ruz and three of his sisters publicly confirmed the 1927 date.

In April, 1957 his sisters Emma and Lidia were interviewed by a reporter for the New York Spanish language newspaper El Diario de Nueva York. They said Fidel had been born in 1927. Later, in January 1959, Lina and Fidel’s older sister Angela confirmed this to Gerardo Rodriguez Morejon, Fidel’s first Cuban biographer. In a letter to him they confirmed the accuracy of his study, based in part on information they had provided. On the first page of his book Rodriguez Morejon gives the 1927 birth date.

Fidel’s two known surviving brothers have no illusions about this either. Older brother Ramon informed one biographer that he is twenty-two months older than Fidel. Ramon is known to have been born in October, 1925. And, according to another of Fidel’s biographers, at the time of Fidel’s ostensible fiftieth birthday in 1976, Raul reminded him that it was actually his forty-ninth. Fidel is said to have responded, “I am the age that the documents indicate. If they say I am fifty, I am fifty.”

He said much the same on the one occasion when to my knowledge he was asked to comment on the record about his true age. During an extended interview in 1977 with broadcast journalist Barbara Walters, he was pressed on the matter, but was vague, refusing to insist on the earlier birth date. “I take the less favorable date,” he told Walters. It seemed like an implicit acknowledgment of the truth.

Through the decades he spent in power Fidel almost invariably was able to quickly calculate, even as he was delivering speeches or granting interviews, the age he supposedly was at some juncture in the past that he was describing. For example, he claimed to be thirty-two in January 1959 when his revolution triumphed, not his actual thirty-one. It has been rare for him to slip up when counting backwards. But he did that in January 1979 when he told another American interviewer that he had been eighteen when he began his studies at the University of Havana. That was correct, but on other occasions he does the retrospective math better to suit the false age, claiming he was nineteen at that time.

Several of his biographers, discounting Fidel’s and the official Cuban line, have described his actual age correctly. In addition to Rodriguez Morejon, Peter Bourne, Leycester Coltman, and Claudia Furiati express no doubts, arguing for the 1927 date. Others, Robert Quirk and Tad Szulc, for example, were reluctant to choose definitively between 1926 and 1927. Still others, the German Volker Skierka, French biographer Serge Raffy, and the much maligned Herbert Matthews, accept the erroneous 1926 date without comment.

But what has remained even more in doubt, and until now unresolved among Fidel’s multiple biographers, is precisely why and when his birth date was falsified. Some biographers have alleged that Angel bribed a local official to produce a falsified birth certificate. But if so, was that done, as I asserted in After Fidel, and quoting Coltman, at the time the young Fidel was seeking admission to Belen, the elite Jesuit prep school in Havana and needed to be a year older? Although that interpretation has been accepted by many, I now believe it is wrong.

Recently I have been persuaded by Mario L. Beira, a Miami psychologist and astute student of Fidel Castro, that the date change occurred in January, 1935 when the seven and a half year old Fidel was first baptized. He was a student at LaSalle, the Christian Brothers school in Santiago he attended before moving on to the Jesuit Dolores school. Dr. Beira concludes, I believe accurately, that this baptismal certificate, with the 1926 date, is the first official document that records Fidel’s age. It may have simply been a clerical error, or more likely orchestrated to make it possible for Fidel to skip a grade at La Salle. It was not long after the baptism that he advanced from the third to the fifth grade, which required that he be ten years of age.

So in a few days, Fidel Castro finally and truly will become on octogenarian. Perhaps this is the time for him --in one of his reflections?-- to finally admit the truth.