Researchers are blurring the lines of what it means to be human, so do our laws need to change, asks Jessica Hamzelou

Enter the chimera
Savulescu, however, thinks the first legal cases will involve human-animal chimeras: animals that contain cells from two species.

Human-pig chimeras are already being grown. These contain cells that could allow them to develop human organs, although, so far, the resulting embryos have been destroyed

before this happens. The idea is that transplant organs could be made in pigs using a person’s cells, allowing them to circumvent lengthy waiting lists for humandonated organs. In theory, the organs should be human enough to avoid being rejected by the recipient’s immune system.

But at what point do the pigs themselves become too human to be used in this way? Mice with human brain cells are smarter than typical mice, and perform four times better on memory tests, for example. There is a concern that should these pigs accidentally develop human brain cells, they might also develop some of the “morally significant” characteristics of humans, such as self-consciousness. “We have to get off the fence and decide what it is about life that makes killing that being especially wrong,” says Savulescu.

Other potential legal cases will surround the physical and cognitive enhancement of humans, says Jennifer Chandler at the University of Ottawa. Technically, we humans have

been cognitively enhancing ourselves for as long as we have been around. Education improves our thinking, for instance. But newer approaches that involve stimulating the brain using implanted devices start to merge human and machine, she says. Brain implants are already being used to treat conditions like epilepsy and Parkinson’s disease, and are currently being investigated in a range of other conditions.

Some neuroscientists are attempting to tweak the way those implants work to enhance cognition. One team has already used a device originally implanted to treat epilepsy to improve memory in a group of volunteers.

A company called Kernel is working on a brain implant to boost human intelligence, while Neuralink, which Elon Musk co-founded, aims to connect people’s brains to computer-based artificial intelligence.

Because these devices target our brains, they have a greater potential to affect the characteristics that make us human, says Chandler. Hip replacements and insulin pumps

are one thing, but “it seems somehow a little different when you’re talking about an implant that’s meant to directly modify mental functioning”, she says.

In the future, the law may distinguish between “enhanced” and “unenhanced” humans,

says Chandler. “People fuss about cheating,” she says. “If people cognitively enhance in the context of a competition, does that break the rules or not?” Courts may eventually be forced to decide, she says.

Some futurists predict that we will one day be able to upload the contents of our brains onto a computer. Would such an upload be human? “I guess that would be a place to apply the substantially human test that we propose,” says Greely.