 extinct. Victory in hand, countries around the world discontinued their vaccination programmes. That was a mistake. The smallpox vaccine also reduced the risk of contracting a related illness called monkeypox and without the vaccine, monkeypox is on the rise in Africa. In the Democratic Republic of Congo, the virus has become 20 times more common in the last 30 years. Resuming vaccination isn’t the answer for a politically unstable area; active surveillance is a better bet. Ironically, such a programme was set up in the 80s, and abandoned because the disease was deemed to be no threat to public health.
There are countless examples of people holding on to their beliefs in the face of overwhelming evidence to the contrary. That’s not unexpected. This year, three experiments showed that when people’s confidence in their beliefs is shaken, they become stronger advocates for those beliefs. Contrary evidence creates a sense of intense discomfort as people try to cope with conflicting ideas. People go to great lengths to reduce this “cognitive dissonance”; some try to do it by mustering support for their ideas.
This year, Archbishop Desmond Tutu and !Gubi, a tribal Bushman elder, became the second and third African people to have their entire genomes sequenced. !Gubi’s genes are vastly different to that of three other Bushmen from neighbouring areas. Pick any two and peer into their genomes and you’d see more variety than you would between a European and an Asian. This diversity reveals just how important it is to include African people in genome sequencing projects. The continent is the birthplace of humanity and its people are the most genetically diverse on the planet. To understand human genetics without understanding Africa is like trying to learn a language by only looking at words starting with z.
The ability to reset adult cells into a stem-like state was one of the biggest advances of the last decade. The reprogrammed cells have the potential to produce any of the various cells in the human body, with obvious implications for medicine. But there’s a catch. This year, Kitai Kim found that the cells retain a memory of their past specialities. A blood cell, for example, can be reverted back into a stem cell, but it carries a record of its history. It keeps molecular Post-it notes that annotate their DNA and affect how it’s used. This constrains its future, making it easier to turn this converted stem cell back into a blood cell than, say, a brain cell. A different technique for creating stem cells, which controversially involves destroying embryos, doesn’t share this problem.
A natural experiment in Nicaragua clearly shows that language has the ability to affect the way we think. In the 1970s, deaf Nicaraguan schoolchildren spontaneously invented a new sign language with its own grammar and vocabulary. The language has become more complex over time, and so have the thoughts of its users. Jennie Pyers found that people who learned NSL before it developed specific gestures for left and right perform more poorly on a spatial awareness test than children who grew up knowing how to sign those terms.
Imagine taking a course of antibiotics and suddenly finding that your sexual desires have changed. That’s exactly what happened to some Israeli fruit flies, which were raised on diets of either maltose or starch. They developed gut bacteria that specialised on these foods and as a result, they preferred to mate with other flies with similar food biases. A dose of antibiotics, and their mating preferences vanished. The study suggests that you can only understand an animal’s evolution by considering the genes of the bacteria and other passengers that live inside it. This is the hologenome – the combined genes of a host and all the microbes it contains.
Two studies this year showed that humans often have nothing to do with the diseases that plague us; we’re just collateral damage in an invisible war. When faced with predatory amoebas, E.coli (a mostly harmless gut bacteria) turns nasty, evolving into a resistant strain that kills the