Researchers have grown the first human-monkey hybrid embryos as well as mouse embryos in artificial wombs late into development. These biomedical breakthroughs raise different ethical quandaries.
Drivers with long commutes who rarely charge their plug-in hybrid car are likely to emit much more CO₂ than official test figures suggest.
At the moment, fuel taxes pay for most of the maintenance of US roads, bridges and highways. What happens when the majority of cars no longer run on gasoline?