Fwd: Simply Science: Making eggs from skin cells

Nevertheless the race to revolutionise human reproduction once again is on. I, for one, can't wait to impress my own grandchild with stories of a neighbour who, as the most normal thing in the world, managed to have kids—using eggs made of skin.

Best regards,
Seetha Ram
—
KE Seetha Ram, Dr. Eng. | Fellow, Asian Development Bank Institute | Visiting Professor, University of Tokyo | Special Advisor to JR East for India High Speed Rail | The Club of Rome

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From: The Economist <noreply@e.economist.com>
Date: Thu, Oct 2, 2025 at 04:36
Subject: Simply Science: Making eggs from skin cells
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Also: A portent of death may have helped create life

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October 1st 2025

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Making eggs from skin cells

Emilie Steinmark Science correspondent

At a recent dinner with friends, we began talking about how much had changed since our grandparents were born. Consider the rise of commercial flights, the internet, mobile phones—even a toilet of one's own, inside the house! The discussion reminded me of a thing my grandmother used to say, in an awestruck tone, whenever her neighbour came up in conversation: "She had a test-tube baby, you know." In-vitro fertilisation (IVF) is undeniably one of the big technological advances of the past century. Humans spent hundreds of thousands of years with just one way to reproduce. Then, in 1978, the first child conceived through IVF was born and millions of couples around the world have since become parents this way. I'm not sure any other scientific leap has led to more human joy. But IVF is not perfect. It is expensive, hard on the woman's body and many never get to bring home a baby even after years of trying. In some cases, women don't have any usable eggs left to fertilise. As a result scientists have spent years working on making new eggs for infertile women—or indeed anyone without eggs wishing to have children, such as male gay couples. So far one approach, known as in-vitro gametogenesis, has dominated. It works by reprogramming a person's skin cells to become induced pluripotent stem cells and then nudging those stem cells to develop into eggs. It has succeeded in mice, even producing live pups. In humans, however, progress has been a lot slower. As I report in this week's Science section, another approach has appeared on the scene. Based on somatic-cell nuclear transfer, the cloning technique that made Dolly the sheep in the 1990s, American scientists have managed to get the DNA from a woman's skin cell into a donated egg cell (from which they had removed the nucleus). They also worked out a way to roughly halve the "new" egg's number of chromosomes, so that there is room for a sperm to fertilise the egg and contribute its genes. In this way they made a handful of early embryos. But the technique is still far from the clinic. All these embryos had chromosomal abnormalities because the researchers have yet to work out how to control exactly which chromosomes (and how many of them) are kept in the egg and which are removed from it. No babies will be born this way until they sort out that crucial step. Nevertheless the race to revolutionise human reproduction once again is on. I, for one, can't wait to impress my own grandchild with stories of a neighbour who, as the most normal thing in the world, managed to have kids—using eggs made of skin. I'm curious: which scientific advance do you think has brought the most joy to the most people? Write to us at sciencenewsletter@economist.com. Elsewhere at The Economist: The best tanks of all time A restaurant scandal sticks in China's throat The economics of self-driving taxis Last week we asked you what scares you most about AI. Thank you for your letters. Max, one reader, worries that humans overestimate the ability of the technology. "We get a good laugh when the large language model suggests putting glue on pizza," he wrote. "We won't be laughing when it gets something more subtle wrong and someone makes a lethal mistake." Meanwhile, Andrew in California doesn't think we have anything to fear. People tend to humanise AI by giving it human desires, such as money or power, he says. "None of which is applicable to a machine." If you don't fancy trying to understand the fundamental desires of AI, let me point you in the direction of our primers on a different topic. Biology can be bewildering: to help we have published six explainers covering everything from cells and DNA to evolution and planetary history. We hope you find them educational and rewarding. See you next week.

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