Mastodon tusk reveals life of roaming

Chemical signatures inscribed in an ancient tusk tell a mastodon’s life story — from his adolescent years to his premature death around 13,200 years ago. Researchers matched the chemical signatures in the tusks of an American mastodon (Mammut americanum) with those from his home range in what is now Indiana. They found that, as an adult, he travelled to mastodon mating grounds every year in the spring and summer. It was there, at 34 years of age, that he met his end, probably from a skull puncture during a battle with another bull.

How the giraffe got its neck

A newly described species of giraffoid that lived millions of years ago in China suggests how the giraffe might have got its long neck. Discokeryx xiezhi, named after a mythical unicorn-like creature, had a thick headpiece optimised for high-speed, head-bashing fights. Its discovery adds more weight to the theory that giraffes evolved longer necks for sexual competition, with male giraffes engaging in violent neck-swinging fights and longer necks attracting mates.

How a special immune system protects grey matter

Researchers once thought that the brain was walled off from the rest of the body’s immune system, but an exciting picture is emerging of the brain as a unique immunological ecosystem. The brain’s border control actually does allow immune cells from the body into the fluid-filled membranes that surround the organ. Special immune cells produced in the skull’s bone marrow could be gentler than normal immune cells. Researchers are exploring how these and other kinds of immune cells in the brain play a role in fighting diseases and could be harnessed in treatments.