Since taking power, in 1959, his birthdays have been marked by mass celebrations in Communist-run Cuba and garnered an outpouring of greetings from across the globe. Each year also added another notch in power, until Mr. Castro became the world's longest-serving leader (a title he still holds, even though his brother is now the chief of staff).
On his 65th birthday, Castro received wishes from thousands of athletes participating in the Pan-American Games in Cuba in 1991. At age 77, he was more isolated, amid a mass jailing of critics in 2003 that drew world rebuke, but he was feted at home. In 2006, when he turned 80 and had just ceded power to his younger brother Raul Castro amid health concerns, crowds gathered to celebrate, and remind the globe, that he was still very much part of the political landscape.
But the celebrations that mark Aug. 13 each year also have become a tally of another type in Cuba: the increasing collective age of its population.
Cuba's National Office of Statistics says about 2 million of the island's 11 million inhabitants, or 17 percent, were over 60 years old last year. That's already high compared to Latin America as a whole, where the rate is somewhere north of 9 percent, extrapolating from UN figures from 2000.
The trend is accelerating, with the number of seniors projected to nearly double to 3.6 million, or a third of the population, by 2035. During the same period, working-age Cubans are expected to decline from 65 percent to 52 percent.
There are many reasons Cuba is a demographic outlier in Latin America, which includes its universal and universally lauded health-care system that has put life expectancy at 78, on par with that of the US. Birth rates are also much lower.
“The economy is tough,” says William LeoGrande, a Cuba expert at American University in Washington. “In some poor countries, agricultural ones, the more kids you have, the more hands you have to work. In the case of Cuba, which is not an agricultural society but by and large an urban society, more kids is more mouths to feed.”
Plus, he adds, women have access to education and opt not to mother large families, which means that, like in European countries, they only average about 1.5 children.
“Women have a lot of rights in Cuba. It is easy to get divorced, to obtain contraception,” says Mr. LeoGrande. “Women are not tied to child rearing in the way that they are in some societies.”
Most important, perhaps, is the outmigration of some 35,000 people a year, according to the AP, many of whom are the youngest and sturdiest Cubans.
Across Latin America, emigration has been an escape valve for countries that cannot create enough viable jobs for citizens. But as Cuba embarks on a major economic overhaul, taking Cubans off public payrolls in return for the right to open up small businesses in an attempt to revive the economy, it needs the manpower that it is losing each year, especially as the island ages.
The Cuban government has acknowledged the predicament. And behind the celebratory mood of the birthday of Cuba's revolutionary icon each year, it's something of which the country is painfully reminded.