It identified some experiments that should not yet be done because of strong ethical objections.

It is for Japan to decide how to regulate this new work, but it is still worth asking how close it comes to crossing one of the UK report's red lines,

There's something undeniably creepy about an animal that is partly human. And the more human it gets, the creepier it becomes.

That is why the news that a Japanese team is well on its way to creating pigs with human organs has been described as something that will "ensure the employment of a generation of bioethicists".

Two years ago, the UK Academy of Medical Sciences released a groundbreaking report on "animals containing human material".

all of which leads to the unsurprising conclusion that the ultimate aim of this research -- to provide desperately needed human organs for transplantation can only be achieved if serious ethical and technical hurdles are surmounted. We are rapidly approaching those ethical hurdles.

One is to breed an animal that has human sperm or eggs. Another is to create a non-human primate with a humanised brain.

An entire generation of bioethicists may not be needed, but there is still plenty of work to be done. Thank you.

Of course, any ethical concerns must be weighed against the potential benefits for human health and life.