But it can also go awry in disease, providing new targets for treatment: Cancer cells exploit these molecular switches to thrive, for example, and increasing cells' tolerance for low oxygen could offer a way to treat heart attacks and strokes.
He said while some promising drugs have been developed, including for kidney patients who don't get enough oxygen, it will be years before it's clear whether such discoveries are going to change the lives of tens of thousands.
Members of the Nobel Committee for Physics sit in front of a screen displaying the names of the winners of the 2019 Nobel Prize in Physics at the Royal Swedish Academy of Sciences in Stockholm on October 8, 2019.
Using theoretical tools and calculations, Peebles was able to interpret trace radiation from the infancy of the universe and so discover new physical processes, the academy said. Each field's award is administered by a different organisation - the Nobel Assembly at the Karolinska Institute, Stockholm, awards the medicine prize.
"It was just so surreal, and I sort of had this out-of-body feeling of just great appreciation", he said, adding he was accepting the prize partly on behalf of his late wife Carolyn, a cancer surgeon.
"You should enter it for the love of the science", he said. The work of the three new Nobel Laureates brought some of these answers to light.
"This year's Nobel laureates have painted a picture of our universe far stranger and more wonderful than we could ever have imagined", Ulf Danielsson, a professor and member of the Nobel Committee for Physics, told reporters as the prize was announced.
This year's Nobel winners will receive a gold medal and a diploma at a ceremony in Stockholm on December 10.
Good morning! I'm Emma Löfgren and I will be your slightly confused host as I guide you through the science behind this week's Nobel Prizes.
Past physics prize laureates include Albert Einstein, Niels Bohr and James Chadwick, the discoverer of the neutron.
Explaining why the scientists were being recognized for the award, which is officially known as the the Nobel Prize in Physiology or Medicine, this year, Johnson said their discoveries were now a "complete and clear story".
This year will see two literature prizes handed out because the one last year was suspended after a scandal rocked the Swedish Academy.