If we look across the whole of the mammal branch of the tree of life, we find there are many groups of mammals that have ...

This is because, although the liver did produce bile and albumin, “it is unlikely that the production…was enough to support the human body for a long period”, the study concluded.

The liver was transplanted last year into a person who was brain-dead, and it “functioned very well in the human body” for 10 days, the researchers said.

Weighing around 3 to 3.5 pounds (1.4 to 1.6 kg), the liver is the second heaviest organ in the human body, according to the American Liver Foundation.

Surgeons externally attached a pig liver to a brain-dead human body and watched it successfully filter blood, a step toward eventually trying the technique in patients with liver failure.