The popular scientific journal Nature has drawn up its annual list of the most important personalities in the world of science, but this year the list was not without controversy.
The decision to include the 16-year-old Swedish activist Greta Thunberg on the list has surprised some, given that she shares a position of importance with 9 scientists who have stood out in disciplines such as CRISPR, genetic editing technique; knowledge of our brain, quantum computing, space exploration, and even eminent figures such as the co-discoverer of Ebola.
Ecology has occupied a large part of the scientific agenda for 2019, which is why not only Greta but also two other personalities (in this case, scientists) related to her work in defence of the environment have been recognized in the famous list.
Ricardo Galvão, physicist: in defence of science in Brazil
The 72-year-old physicist Ricardo Galvão confronted Brazil's President Bolsonaro, who defends science. After Bolsonaro accused the scientists of lying about the data, Galvão produced a brilliant response that was applauded by civil society and his fellow scientists, making him a true hero.
Victoria Kaspi, the astronomer in search of the mysterious fast radio bursts
Astronomer Victoria Kaspi led the project to capture fast radio bursts from the CHIME telescope, which is now the best instrument we have for this work. Most surprisingly, the CHIME telescope was originally designed to map the hydrogen emission from distant galaxies, to answer questions about the origin of our universe. Kaspi realized that the sensitivity of the telescope and its large field of view could be ideal for capturing the FRBs. His role was key to finding funding for the project.
Nenad Sestan, the neuroscientist who 'revived' the brains of dead pigs
Nenad Sestan is famous for making a revolutionary discovery, which took place in 2016, that has allowed us to rethink the border between life and death: he found electrical activity in the brains of dead pigs.
Sestan's team removed the organs shortly after death and infused them with oxygen and an icy preservative. In doing so, the brains were at least partially brought back to life.
Does that mean that Sestan figured out how to create zombies? Not exactly. A neurologist would later confirm that the observed activity was not widespread and coordinated, so there's no sign of consciousness.
In addition to the ethical implications of this delicate discovery, Sestan's work may help reconsider the definition of brain death, as well as lay the groundwork for a technology capable of preserving organs for transplantation.
Sandra Díaz, defender of biodiversity
Nature has called it the 'guardian of biodiversity'. Argentina's Sandra Diaz is one of 144 researchers - the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) - who has produced the world's most comprehensive study on biodiversity: one million species are heading for extinction, due to human activities.
Their 1,500-page final report says that nations will not meet most of the global targets on biodiversity and sustainable development unless they make massive changes, such as abandoning the idea that economies must grow steadily. Diaz decided to be positive: he challenged the idea that ecosystems and their benefits for humans, such as food or climate regulation, are highly dependent on having a large number of species.
Jean-Jacques Muyembe Tamfum, the Ebola co-discoverer who continues to save lives
In 1976, Jean-Jacques Muyembe Tamfum travelled deep into the rainforests of what is now the Democratic Republic of Congo (DRC) to investigate an outbreak of an unidentified disease that was rapidly killing people: it was the virus later called Ebola.
Now, 43 years after the disease was discovered, Muyembe is leading the DRC's response to the most volatile Ebola outbreak yet. Since August 2018, the epidemic has killed more than 2,200 people in the northeast of the country.
In the last weeks of 2019, Muyembe led a clinical trial of 680 people, with a survival rate of 90 per cent. His contribution is proving critical in controlling a chaotic outbreak.
Yohannes Haile-Selassie, the palaeontologist who found the oldest hominid
Haile-Selassie's team found the remains of a complete skull of an early hominid, Australopithecus anamensis. But this was not just any hominid, but the oldest human relative of the Australopithecus anamensis, dating back 3.8 million years.
Some people say that this discovery only rivals Lucy, the 3.2 million-year-old fossil of the species Australopithecus afarensis. The team is still studying the skull for more clues about its place in prehistory.
Wendy Rogers, a transplant ethics advocate
Wendy Rogers, a bioethicist at Macquarie University in Sydney, Australia, is one of the people who have questioned China's origin of livers, hearts and kidneys in certain transplant practices. For two decades, scientists suspected that these organs came from prisoners, and were illegally obtained. When the government denied the facts, claiming that they came from volunteers, some people decided to get to the bottom of the matter.
Rogers, along with his team, brought to light more than 400 reports in which doctors could not prove that the donors had given their consent. Those documents, published between 2001 and 2017, reported more than 85,000 transplants.
Today, Rogers' list continues to grow, in one of the world's biggest bioethics scandals.
Hongkui Deng achieved promising results using CRISPR against the HIV virus
Hongkui Deng's laboratory at Peking University in Beijing demonstrated how gene editing through the CRISPR technique can create a potentially unlimited supply of cells that are immune to HIV infection.
In 2008, Timothy Ray Brown became the first known person to eliminate the virus, thanks to a bone marrow transplant; but this protective mutation found in the donor was very rare and practically non-existent in China, Deng's country of origin.
It was then that Deng decided to try to edit the gene: he took immunologically compatible stem cells from the bone marrow of a donor, edited them with CRISPR-Cas9 and then transplanted them into a person with leukaemia and HIV.
Did he achieve the same success story as Brown's Berlin patient? Unfortunately, no: for safety reasons, Deng used only 18% of modified cells, so the HIV infection remained in the patient. Deng hopes in the short term to transplant a higher proportion of genetically edited cells.
John Martinis, a pioneer in quantum computing
John Martinis stands out for leading the creation of a quantum computer capable of performing much faster calculations than the best of conventional computers.
Martins was influenced from the 1980s by the famous Richard Feynman, who first worked on the idea of using the quantum characteristics of particles to make superimposed computers.
The feat required the work of 70 scientists and engineers, and resulted in a surprising challenge: the machine, called Sycamore, could do in 200 seconds what they estimated would take 10,000 years for the best supercomputer at the time.
Greta Thunberg, the controversial climate activist
"I don't want you to listen to me, I want you to listen to the scientists." The recognition of 16-year-old Swedish activist Greta Thunberg on this list may be controversial. But it is undeniable that her role has mobilized hundreds of people around the planet with the aim of not only making her voice heard but also that of the members of the IPCC (the Intergovernmental Panel on Climate Change).
As Nature magazine itself acknowledges, "scientists have spent decades warning about climate change, but they have not been able to capture the world's attention as Thunberg has done this year, 2019.
According to Angela Ledford Anderson, director of the Climate and Energy Program of the Union of Concerned Scientists in Washington DC: "Their mobilization of young people shows that the younger generation expects science to inform policy, and can inspire many teenagers to become the scientists themselves.