• Geology

SCIENTISTS have discovered that ancient Welshmen helped build Stonehenge.

How and why the stone monument was built over 5,000 years ago has received much attention from scientists over the years; who did the grafting has been overlooked until now.

While Stonehenge’s bluestones came from the Preseli Mountains, who constructed the ring of standing stones, which weighed up to 25 tons, remained unknown. Read more.

• Radioisotopes

Radioactive residue from Cold War nuclear tests has given scientists a cipher to decode the ages of whale sharks, written on the animals’ vertebrae.

Whale sharks (Rhincodon typus) accumulate alternating stripes of opaque and translucent tissue on their vertebrae as they age, similar to the way tree trunks grow rings. But until now, scientists haven’t known whether whale shark vertebrae gain a new growth band each year or every six months — making it difficult to gauge just how fast these sharks grow or how long they live. Read more.

• Astronomy

Seeing this strontium supports the idea that these smashups create many elements heavier than iron

Astronomers have for the first time definitively ID’d the birth of a specific heavy element during a neutron-star smashup. They found strontium. And it showed up in the wavelengths of light — or spectra — making up this collision’s afterglow. Read more.

• Biology

“The change we observed in tuna, which are near the top of the marine food web, reflects profound changes in physiology or species composition occurring at the bottom of the food web,” said Nicolas Cassar, professor of biogeochemistry at Duke University’s Nicholas School of the Environment. Read more.