It’s easy to think of dogs as our natural companions, yet only about a quarter of the world’s dogs are actually pets – most are free-ranging village or street animals. As nations like India rapidly urbanise, millions of dogs are being forced to adapt, shifting from passive rural scavengers to aggressive defenders of city territories.

That’s according to Nishant Kumar at the University of Oxford and India’s National Centre for Biological Science, who researches how humans and animals co-exist in shared spaces. He explains a legal battle over the future of street dogs, which pits scared residents against animal lovers, and has made it all the way to India’s supreme court. The country’s ancient pact of co-existence with village dogs, he says, may not survive in a more urban future.

Britain’s youngest dementia sufferer recently passed away at the age of 24. Following his diagnosis at 22 – when his brain resembled that of a 70 year old – his family made the decision to donate his brain to science. Rahul Sidhu, a neuroscientist at the University of Sheffield, says this “extraordinary gift” is a rare opportunity to study exactly what went wrong inside the young man’s brain – and could accelerate the search for a cure for dementia.

We now know of more than 6,000 “exoplanets” in other solar systems, and there will be billions more still undiscovered. The next big challenge for scientists is to figure out which of these planets could support life. Carole Haswell, an astrophysicist at the Open University, reports on efforts to detect signs of life by analysing the atmospheres of these distant worlds.