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An international team of researchers has discovered that an outbreak of Ebola in Guinea in February this year was the result of re-activated Ebola virus in someone who’d been infected at least five years ago during the earlier large Ebola epidemic that swept through Guinea, Sierra Leone and Liberia. This means the virus can remain dormant in some Ebola survivors for five years or more.

Virologists Alpha Kabinet Keita and Robert Garry talk to Roland Pease about the research and its implications. Also in the programme: The eruption of lavas from Iceland’s newest volcano Fagradalsfjall continues six months on. Geochemist Ed Marshall tells us how he gets up close to sample the molten rock with a long scoop and a bucket of water, and what he’s learning about this remarkable eruption. NASA’s Katie Stack Morgan updates Science in Action on the Perseverance rover’s successful sampling of rocks from Jezero crater on the planet Mars. When the specimens are eventually returned to Earth, she says they may turn out to contain tiny samples of Mars’ water and atmosphere from early in the Red Planet’s history.

Also...Look into my eyes. What do you see? Pupil, lens, retina… an intricate set of special tissues and mechanisms all working seamlessly together, so that I can see the world around me. Charles Darwin called the eye an ‘organ of extreme perfection’ and he’s not wrong!

But if the eye is so complex and intricate, how did it evolve? One listener, Aloyce from Tanzania, got in touch to pose this difficult question. It’s a question that taxed Darwin himself, but CrowdScience is always up for a challenge!

The problem is that eyes weren’t ever designed - they were cobbled together over millions and millions of years, formed gradually by the tweaks and adaptations of evolution. How do you get from the basic detection of light to the wonderful complexity - and diversity – of visual systems we find throughout the animal kingdom?

CrowdScience sent Marnie Chesterton on an 800 million year journey to trace how the different elements that make up the human eye gradually came into being; from the emergence of the first light-sensitive proteins to crude eye-cups, from deep sea creatures with simple pinhole eyes to the first light-focusing lenses, all the way to the technicolour detail of the present day.

(Image credit: Getty Images)