A youthful continent is run by old men. The average African leader is 63 years old; the oldest, President Paul Biya of Cameroon, is 90, a full 72 years older than the average Cameroonian. Under their grip, democracy has fallen to its lowest point in decades: Half of all Africans live in countries considered “not free” by Freedom House.

Five African heads of state, including Mr Biya, have held power for more than three decades; nearly all are grooming their sons as successors. “Sick old men,” said the Nigerian writer and Nobel laureate, Wole Soyinka, in an interview.

President Paul Kagame of Rwanda, in power since 1994, receives over $1 billion in Western aid annually, and has established his tiny country as a hub for sports and international conferences – even as he is accused of killing or kidnapping his critics, or purports to win elections by a margin of 99 per cent.

As the United States, China and Russia vie for position, an array of middle powers is crowding in too. About 400 new embassies have opened in African countries since 2012, according to the Diplometrics Program at the University of Denver. Turkey, Qatar, the United Arab Emirates and India top the list.

The number of embassies includes non-African countries with more than 20 embassies in Africa in 2021. Source: University of Denver Pardee Center Diplomatic Representation Database By Lauren Leatherby

Yet there is one key group that Africa’s gerontocrats have disastrously failed to win over: the alienated youth of their own nations.

“Our elites treat us like idiots,” Nourdine Aouadé, a lawyer and young political leader, said at his office in Niger’s capital, Niamey, after a military takeover in August. Like many young Nigeriens, Mr Awade, 32, supported the action.

“Coups are just the consequence of social injustice,” he said.

Three people standing upright in rubble next to a patched corrugated iron building. They are wearing uniforms with straps crossing in X’s over their chests and small potted trees balanced on their heads.

Youthful uprisings first flared in 2011, during the Arab Spring, when an uprising in Tunisia inspired others in Egypt and Libya. Later, powerful demonstrations erupted in Nigeria, Zimbabwe, Senegal and even Eswatini, a tiny kingdom of 1.2 million people in southern Africa.

This year, young people have channelled their anger into pro-military populism – cheering the new junta in Niger or, weeks later, Gabon, where they posted TikTok videos mocking their newly ousted president, Ali Bongo Ondimba. Other leaders, watching nervously, worry that they could be next.

The age gap between geriatric leaders and restless youth is “a major source of tension” in many African countries, said Simon Mulongo, a former African Union diplomat from Uganda. “It’s a powder keg, and it can explode anytime.”

One day last spring, Nuha Abdelgadir was hunched over her phone at a cafe in Sudan’s capital, Khartoum. Her thumb flicked restlessly through a gallery of smiling faces – friends who had been killed by Sudan’s security forces in pro-democracy demonstrations. Ms Abdelgadir, 18, had come to take their place.

“We’re equal with the boys,” she said, gesturing to another young woman. “We’ve got shields, we throw stones, we clash.”

Her group, “Anger Without Limits,” was at the fore of the street clashes that had occurred every week since Sudan’s military had seized power in a coup 18 months earlier. Ms Abdelgadir’s job was to pluck streaming tear-gas canisters from the ground and fling them back at the police. It was risky work, she admitted; over 100 protesters had been killed. But, she said, “I don’t care.”

Weeks later, Sudan tumbled into war. Fighting between rival military factions in mid-April rippled across Khartoum, then the country. On the third day of fighting, a stray shell punched through Ms Abdelgadir’s home, sending it up in flames. She fled with her family to the countryside. By September, she was planning to leave Sudan, and even the continent.

Even then, she insisted she would be back to finish what she had started. “We will take to the streets again,” she texted, the night before boarding a bus taking her over Sudan’s border into Ethiopia. “The democracy we dream of will come.”

While some take flight, others pick up a gun. In the Sahel, the semiarid region bordering the Sahara that runs across the African continent, tens of thousands of teenagers have joined militant groups linked to Al Qaeda and Islamic State. They bring havoc in their wake – thousands of civilians killed, five million forced from their homes and political destabilisation that has led to a string of military coups.

But the main driver of this powerful insurgency is not an extremist ideology or religious belief, according to a UN study of 1,000 former fighters from eight countries. Instead, researchers found, the single biggest reason for joining a militant group was the simple desire to have a job.

Modu Ali, from a poor family with 10 children in northern Nigeria, had barely finished primary school when he joined the extremist group Boko Haram, over a decade ago. His goal was to “fight for the rights of the deprived,” he said. “Instead it ruined my life.” He surrendered and joined a rehabilitation program for former fighters.

The Sahel leads the world in two ways. It is the global centre of extremist violence, accounting for 43 per cent of all such deaths in 2022, according to the Global Terrorism Index. And it has the highest birthrates – on average seven children per woman in Niger and northern Nigeria, six in Mali and Chad, and five in Sudan and Burkina Faso.

Like many in Zaria, a Muslim-majority city in northern Nigeria, Ms Saidu expected to be married by 14 and to have her first child soon after. “My uncle was hellbent on finding me a husband,” she recalled.

Instead, she enrolled at the Centre for Girls Education, an American-funded programme that has helped as many as 70,000 girls to stay in school, and ultimately to have smaller families.

Educating girls has an unusually large effect on family size in Africa because it delays the age of marriage and helps young women to space out their children, researchers have found. “It’s a natural kind of birth control,” said Habiba Mohammed, the programme’s director.

Ms Saidu, now 17, recently applied for nursing school.

“I do want to get married,” she said. But first, she said, “I want to be independent and learn to support myself.”

It could be that Africa will undergo transformations that are hard to see now.

When the economist Ha-Joon Chang was growing up in South Korea in the 1960s, his country was subjected to the same condescension and racism levelled at many African nations today, he said. It was poor, had just emerged from war, and was seen by American officials as a basket case.

“Nobody took us seriously,” said Mr Chang, now a professor of economics at the School of Oriental and African Studies in London.

That South Korea has become one of the world’s largest economies shows how success can strike in the most unlikely places, Mr Chang added: “With time and effort, remarkable transformations are possible.”

A young population was a big part of South Korea’s success, Mr Chang said. But it took other ingredients, too: visionary leaders, wise policies and education, as well as intangibles like drive, innovation and sheer good fortune, he said. “A lot of things have to work together.”

This year’s surging turmoil – new crises, new wars and new economic slumps – would give pause to the greatest of optimists. Yet there are also reasons to hope.

“I tell my friends in England that the time will come when they will put out a red carpet for those guys now coming in boats,” said Mr Ibrahim, the philanthropist.

Some, like Nedye Astou Touré, are already reaching for the stars. Ms Touré, a 23-year-old student, stood over a pile of old aircraft parts at a university lab in Dakar, the capital of Senegal. Her eyes gleamed with anticipation. “It’s for a rocket,” she said of the pile.

She and another senior at the university hope to launch their projectile 100 metres into the air, a first step toward building a low-orbit satellite. It might take a while, Ms Touré admitted. But while others with such grand dreams have typically left Africa behind, she wanted to show it can be done at home.

“Just wait,” she said. “Three years from now you might be hearing about us.”

• The New York Tomes report