The Download: Embryo ethics, and reducing chatbot risks

Instead of relying on the same old recipe biology has followed for a billion years, give or take, stem-cell scientist Jacob Hanna is coaxing the beginnings of animal bodies directly from stem cells. 

Join these cells together in the right way, and they will spontaneously attempt to organize into an embryo—a feat that’s opening up the earliest phases of development to scientific scrutiny and may lead to a new source of tissue for transplant medicine.

Hanna is the vanguard of a wider movement that’s fusing advanced methods in genetics, stem-cell biology, and still-­primitive artificial wombs to create bodies where they’ve never grown before—outside the uterus. But exactly how far Hanna has taken his models of the human embryo is an open question. Read the full story.

—Antonio Regalado

This story is from our forthcoming print issue, which is all about the body. If you haven’t already, subscribe now to receive future issues once they land.

Why AI should be able to “hang up” on you

Chatbots today are everything machines. But the one thing that almost no chatbot will ever do is stop talking to you.

Why should a tech company build a feature that reduces the time people spend using its product? The answer is simple: AI’s ability to generate endless streams of humanlike, authoritative, and helpful text can facilitate delusional spirals, worsen mental-health crises, and otherwise harm vulnerable people. 

So, why aren’t companies using this obvious safeguard? Read the full story.