Biomedical law experts say changing technology may require a less stringent definition.

The pace of biotechnology research is blurring the bounds of humanity so rapidly that two US scholars are calling for a rethink on what it means to be legally human.

Writing in the journal Science biomedical law experts Bartha Knoppers, from McGill University in Canada, and Henry Greely, from Stanford University in the US, say technologies that mix non-human and human cells, such as CRISPRxenotransplantation and chimeras, mean a less stringent definition of “human” will be needed going forward.

For the purposes of ascribing all-important human rights, set out in the United Nations Universal Declaration of Human Rights, we should only require the organism to be “substantially” human, they argue.

One biotech prompting the taxonomy shift is the human-animal chimera.

Scientists have used DNA editing to make animal embryos that lack an organ, with the aim of inserting human stem cells into the embryo to grow a transplantable human organ in its place.

In July, Japanese scientists were funded, for the first time, to gestate mouse embryos containing human cells to term in a surrogate animal.

Another tech adding to the cellular traffic between species is xenotransplantation. US start-up EGenesis recently secured $100 million funding for its program to genetically modify pig organs to make them suitable for human transplant.

Such developments, write Knoppers and Greely, “challenge the animal-human species divide”, posing a headache for global legal systems whose pedigree traces back to the Roman axiom “Hominum causa omne jus constitutum est” – “All law is created for the sake of men”.

The advances raise the curly question of whether, and why, a person with pig parts can still claim membership of the “human family”. Knoppers and Greely think they can, with some rejigging of our jurisprudence.

Read the full story in Cosmos magazine here