Hello Nature readers,
Today, we meet a new contender for the heaviest animal ever, learn about the 'twinkle' of massive stars and consider key questions on the new wave of anti-obesity drugs.

Ancient whale could be heaviest animal ever

The blue whale (Balaenoptera musculus) is no longer indisputably the heaviest animal to have ever lived. Fossilized vertebrae, ribs and part of a pelvis from a Perucetus colossus, dating from 38 million years ago, suggest that it was a whale of a whale, even though it is thought to have looked more like a manatee. Most blue whales weigh around 100–150 tonnes; the researchers' best guess is that P. colossus weighed around 180 tonnes. It probably looked "like a giant sausage", says palaeontologist Eli Amson.

Alzheimer's drug trials lack diversity

Black and Hispanic people are up to twice as likely as white people to develop Alzheimer's disease, yet they made up no more than 20% of participants in trials for new monoclonal antibody drugs against the disease. This under-representation is partly because the trials selected participants with high levels of Alzheimer's-associated proteins in the brain — in people of colour, these levels tend to be lower. The lack of diversity is both an equity and a scientific problem, researchers say. There are concerns over the safety and efficacy of the drugs in diverse populations, and questions as to whether these trials fully address the causes of dementia.

Why some massive stars twinkle

The turbulent cores of massive stars could cause fluctuations in their brightness. Unlike the twinkling of stars seen from Earth, this isn't caused by atmospheric disturbances. Researchers hypothesize that gravity waves are behind the subtle changes in how some massive stars shine. Gravity waves (not to be confused with gravitational waves) are created when huge waves of plasma bubble out of the star's core and crash into its perimeter.

New weight-loss drugs bring new questions

A wave of anti-obesity drugs is coming, following the breakthrough popularity of semaglutide (marketed as Wegovy) — and with them comes a fresh set of questions. The weight-loss drugs, including tirzepatide and retatrutide, mimic hunger-related hormones, but exactly how they reduce appetite is still being worked out. Researchers are keen to understand why not everyone experiences the impressive weight losses seen in clinical trials. There are concerns about long-term risks, as researchers think that most people who start taking these drugs could stay on them for life. And there's the question of whether the medications will change our views on obesity. Some hope that they will show that obesity has a biological basis, whereas others fear that they could exacerbate weight stigma.

How power companies can weather change

Utility companies and regulators need to prepare the power grid for the wildfires, droughts, floods and landslides that will become more frequent with climate change, says systems engineer Juliet Homer. Preparation can come in many forms, such as building new infrastructure outside flood plains or moving power lines underground in fire-prone areas. Climate researchers can and must play their part in this, Homer says. "There is a huge need for local, regularly updated and user-friendly data."