Great women of science, and tuskless elephants

This week, Chris tells the stories of two great but under-appreciated women of science: Émilie du Châtelet, who brought Newton's work to Europe, and Mary Somerville, 19th century polymath and technically the world's first scientist. And Stu finds out how ivory poaching is putting selection pressure on African elephants causing them to evolve to be smaller in size and tuskless.