Zhou Yongkang, formerly the Chinese Communist Party Politburo Standing Committee member in charge of security, sits in a courtroom at the the First Intermediate People's Court of Tianjin in Tianjin, China, on Thursday.  (AP Photo/CCTV via AP Video)

As Zhou Yongkang was sentenced to life in prison by a Chinese court on Thursday, the former domestic security chief became the highest-level official to be punished in President Xi Jinping's nationwide anticorruption campaign.

His fall from grace was a public spectacle. Chinese state television showed Zhou bowing his head and confessing his crimes. And while he appeared healthy, one change in his appearance was hard to miss: The 72-year-old Zhou's hair, once dark black, was now a shock of white.

Zhou Yongkang attends the closing ceremony of the National People's Congress at the Great Hall of the People in Beijing in March 2012. (Jason Lee/Reuters, file)

It made a dramatic impression on many members of the public. Before Zhou was expelled from the Communist Party and placed under arrest on Dec. 5, his hair was completely black. The proceedings of his trial were conducted in secret, meaning this is the first time that we've been able to see him in a while.

What changed? It's possible that seven months of imprisonment and his impending sentencing have been such a shock to the system that Zhou's hair   made this dramatic change naturally.

But another explanation is probably more likely: Zhou's imprisonment has deprived him of the hair dye that he was using to artificially color his hair black.

Senior Communist Party leaders in China are rarely seen with gray hair, despite the fact that many are of the age where some silver streaks might be expected. Experts say that many almost certainly die their hair darker in a desire to look younger and more virile, and also to not stand out from their Communist Party peers.

China sentenced its powerful former domestic security chief Zhou Yongkang to life in jail, after he was found guilty of bribery, leaking state secrets and abuse of power. (Reuters)

For disgraced Chinese officials, the banning of hair dye appears to have become a standard, if perhaps inadvertent, sign of punishment. The Beijing News recently published side-by-side comparisons of a number of disgraced politicians before their arrest and during their court appearances. Many appeared to have aged dramatically in a short space of time – at least partially due to grayer hair.

By 2013, the removal of hair dye had become an expected part of an official Chinese scandal. Awaiting the high-profile trial of Bo Xilai, the powerful former Communist Party head in Chongqing, writer Paul French was quoted in Foreign Policy as saying: "I’m looking forward to the grey hair — they always deny them the hair dye in prison and so the most shocking thing is the grey hair — publicly parading a senior Chinese politician with grey hair is tantamount to [making] him walk naked through town!!"

It's not quite that simple, however. When Bo appeared at trial, his hair was still black, though it's not clear if it was natural or dyed. And Zhu Rongji, the former Chinese premier who retired in 2003, surprised observers in 2012 by appearing at a meeting of the Communist Party Congress with natural, gray hair.

Steve Tsang, professor of contemporary Chinese studies at University of Nottingham, told  WorldViews that while Zhou's hair appears to have gone gray as a result of a lack of hair dye, he was hesitant to attribute any political meaning to it.

"One can always read something into any act or presentation that is open to interpretation," Tsang said. "One such interpretation is that he is no longer under the protection of the Party and thus not given hair dye to make him look like one of the Party leaders. I would not go further than that."

Even if Zhou's white hair was not a deliberate political message, some on the Chinese Internet appeared to interpret it as one. A number of social media users suggested ironically that Zhou's hair had turned white due to his dedication to the country; others cited the W.B. Yeats poem "When You Are Old," which recently became popular in China after being translated and set to music.

Zhou was found guilty of leaking state secrets, and Gu You, a columnist, suggested that his new hair color had also revealed a state secret. "Depriving Zhou the right to dye his hair has leaked the top secret of the Party and the government," Gu wrote on Weibo.

 Xu Jing contributed to this report

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