This year may be best remembered for how quickly scientific triumph morphed into disappointment, and even tragedy: breakthroughs in stem-cell research and cosmology were quickly discredited; commercial spaceflight faced major setbacks. Yet landing a probe on a comet, tracing humanity’s origins and a concerted push to understand the brain provided reasons to celebrate.
Human origins decoded
Considering that they have been dead for around 30,000 years, Neanderthals had a hell of a year. Their DNA survives in non-African human genomes, thanks to ancient interbreeding, and two teams this year catalogued humans’ Neanderthal heritage. Scientists learnt more about the sexual encounters between Homo neanderthalensis and early humans after analysing the two oldest Homo sapiens genomes on record — from men who lived in southwest Siberia 45,000 years ago and in western Russia more than 36,000 years ago, respectively. The DNA revealed hitherto-unknown human groups and more precise dates for when H. sapiens coupled with Neanderthals, which probably occurred in the Middle East between 50,000 and 60,000 years ago. Radiocarbon dating of dozens of archaeological sites in Europe, meanwhile, showed that humans and Neanderthals coexisted there for much longer than was once thought — up to several thousand years in some places. Genomes old and new charted the emergence of agriculture. Contemporary Europeans carry DNA inherited from light-skinned, brown-eyed farmers who migrated from the Middle East beginning 7,000–8,000 years ago, in addition to more-ancient ancestry. The achievements of these early farmers — domestication of crops such as wheat and barley — are also being understood through genome sequencing. In July, a consortium reported a draft copy of the gargantuan wheat genome, which contains 124,000 genes and 17 billion nucleotides. Another group released the genomes of 3,000 rice varieties.