Daily briefing: The limit of human endurance

Ultramarathon runners, arctic explorers and pregnant women reveal how hard humans can go. Plus, new restrictions on fetal-tissue research in the US and a flood of research ethics violations at a Japanese hospital.

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Coloured scanning electron micrograph of a foetal vein

Fetal tissue, such as the red-blood cells shown here, is the centre of a US political battle.Credit: Steve Gschmeissner/Science Photo Library

New restrictions on fetal-tissue research

The US government is ending fetal-tissue research by scientists at its agencies. It will also require proposals from academic researchers seeking National Institutes of Health (NIH) funding for fetal-tissue studies to be reviewed by an ethics board. The change could effectively end most fetal-tissue research in the United States.

The government has already decided against renewing its contract with a lab at the University of California, San Francisco, that uses fetal tissue. “Today’s action ends a 30-year partnership with the NIH to use specially designed models that could be developed only through the use of fetal tissue to find a cure for HIV,” said UCSF chancellor Sam Hawgood in a statement. At issue is the fact that fetal tissue is collected from elective abortions.

Nature | 4 min read

Hospital uncovers flood of ethics violations

A brain and heart hospital and research centre in Japan says an internal investigation found 158 cases in which studies had violated ethics standards since 2013. Two cardiac studies at the National Cerebral and Cardiovascular Center in Suita were done without approval from an ethics review board. In the other 156 cases, participants weren’t given the option to opt out of a study once they had left hospital.

Nature | 2 min read

Why Pfizer didn’t test a possible Alzheimer’s drug

Some researchers are frustrated that Pfizer never published findings that hinted its rheumatoid arthritis drug, Enbrel, could have potential as a treatment for Alzheimer’s disease — and chose not to investigate the drug further itself. Pfizer had evidence from insurance records that people treated with Enbrel were less likely to develop Alzheimer’s than were those who hadn’t taken the drug, according to a 2018 company document seen by The Washington Post. Critics say that Pfizer might have turned away from doing an expensive trial to confirm any benefit from Enbrel because the drug’s patent was soon to expire. Pfizer says that doubts about the drug’s efficacy, not its money-earning potential, were the reason the company didn’t move forward.

The Washington Post | 9 min read

The limit of human endurance

Researchers studying ultramarathon runners, arctic explorers and Tour de France bike racers have determined the maximum amount of energy a person can expend for a sustained period of time. It’s around 2.5 times your basal metabolic rate — the amount of energy your body uses while just chilling out. The limit seems to come down to how much food you can digest, rather than anything to do with your heart, lungs or muscles. The real champions: pregnant women, whose energy use peaks at 2.2 times their basal metabolic rate.

BBC | 4 min read

Reference: Science Advances paper

By the numbers

4,000 calories a day

The maximum energy output that an average person can maintain for more than a couple of days.


So you want to be a science writer

If you fancy being published in the popular press, you may find the writing skills you developed in academia are more of a hindrance than a help. Physiologist and freelance science writer Brittney Borowiec offers a clear-eyed view of the hurdles that stand between you and your first byline.

Nature | 5 min read

“I prefer ideas that are original over those that are just pleasing.”

At the age of 90, biologist E. O. Wilson says he wants to “settle the questions about group selection for once and for all” — and give altruism its due as a driver of human evolution. “You know, We’ve heard everything we can possibly hear about the destructive and negative aspects of human nature,” Wilson tells Quanta. “There’s a lot of evidence that we evolved because of qualities we consider unifying and propitious for the future.”

Quanta | 14 min read


“I am what a scientist looks like. And so are you.”

Astrobiologist Aomawa Shields, who also trained as an actor, describes learning to embrace your full self on the path to becoming a scientist. (TeenVogue)

I’m not sure if this is good news or bad news, but the US National Weather Service spotted a swarm of ladybugs/ladybirds/🐞s so big that it showed up on radar. Thanks for letting me swarm your inbox with this newsletter — let me know what you think of it all at

Thanks for reading!

Flora Graham, senior editor, Nature Briefing

Nature Briefing

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