This is the Guardian. What makes us human? Does it matter how our biological lives begin? These are just

some of the huge ethical and philosophical questions raised by a groundbreaking scientific

advance announced last week.

Researchers in the US and the UK say they've made a leap forward.

They've created synthetic human embryo-like structures

from stem cells that are more advanced

than any similar structures made so far.

A group of scientists from the US and UK

teaming up to create what is being called the world's first synthetic human embryos made without eggs or sperm.

Researchers say these structures could revolutionize our understanding of the earliest stages of human development,

the impact of genetic disorders and the causes of recurrent miscarriage.

But as the science races ahead, it leaves in its wake fundamental legal and ethical

implications. So today we're asking, how could synthetic human embryos transform medical research?

And can the law keep up?

From the guardian, I'm Madeline Finley and this is Science Weekly.

Hannah Devlin, you're the Guardian's science correspondent and last week you broke this huge

exclusive for the paper about synthetic human embryos. It was based on the

work of Professor Magdalena Zernica Zernica Gertz of the University of Cambridge and the California

Institute of Technology.

Now, this hasn't been officially published, but she announced it at a plenary address at the International

Society for Stem Cell Research's annual meeting in Boston. Tell me more.

So what this team did was they created essentially lab-grown replicas of embryos, of natural

...