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Extracts from unpublished papers on the methods used by a Chinese scientist to genetically modify the embryos of two girls reveal a series of potentially dangerous problems with the procedure and ethical shortcomings.

We look at the mechanism behind the formation of our facial features and how this is linked to our evolution, scrutinise the impact of current emissions on global climates and see why lithium, used in batteries and medicines, is now a potentially widespread pollutant.

66 million years ago, a huge asteroid hit the earth, wiping out most of the dinosaurs that roamed the land. It would still be tens of millions of years before the first humans appeared - but what if those dinosaurs hadn’t died out? Would we ever have evolved?

CrowdScience listener Sunil was struck by this thought as he passed a Jurassic fossil site: if dinosaurs were still around, would I be here now?
We dive back into the past to see how our distant mammal ancestors managed to live alongside huge, fierce dinosaurs; and why the disappearance of those dinosaurs was great news for mammals. They invaded the spaces left behind, biodiversity flourished, and that led – eventually – to humans evolving. It looks like our existence depends on that big dinosaur extinction.

But we explore a big ‘what if?’: if the asteroid hadn’t hit, could our primate ancestors still have found a niche – somewhere, somehow - to evolve into humans? Or would evolution have taken a radically different path: would dinosaurs have developed human levels of intelligence? Is highly intelligent life inevitable, if you give it long enough to develop? We look to modern day birds - descendants of certain small dinosaurs who survived the asteroid strike - to glean some clues.

(Photo: He Jiankui, Chinese scientist and professor at Southern University of Science and Technology in Shenzhen. Credit:Reuters)