SVANTE PAABOA 40,000-year-old human carried 6-9 percent Neanderthal DNA in its genome, according to a study published this week (June 22) in Nature. This is about twice as much as all non-African humans harbor in their genomes today. Some of the Neanderthal DNA in the ancient human was found in three large chromosomal segments, suggesting an interbreeding event between modern humans and Neanderthals that occurred just four to six generations back.
“I think the conclusions are quite clear, and it’s really quite remarkable that they were lucky to find a hybrid that was so recent to be able to date it to a few generations back,” Rasmus Nielsen, a University of California Berkeley population geneticist who was not involved with the work, told The Scientist.
WIKIMEDIA, RAMAResearchers mapped the neural activity of mice exposed to an approaching object and found the nervous signal travels from the cells in the retina that perceive the threat to the superior colliculus of the midbrain. There, neurons expressing the calcium-binding protein parvalbumin (PV) relayed the signal to the parabigeminal nucleus (PBGN), which leads to the amygdala. Stimulation of the PV neurons in the superior colliculus or of the PBGN were sufficient to reduce a fear response—the mouse first attempted to escape but quickly froze. The researchers published their results in Science this week (June 25).
“To me that was a surprise—that [the neural signals] take so many stages to arrive at the fear place [the amygdala],” said Botond Roska of the Friedrich Meischer Institute for Biomedical Research in Basel, Switzerland, who was not involved in the study. “I thought that this ...
