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A human embryo after seven days

LENNART NILSSON, TT/SCIENCE PHOTO LIBRARY

We now know how a developing embryo reverses signs of ageing and appears younger than the fertilised egg from which it arose. The finding suggests that embryos are able to rejuvenate, which could lead to ways of reversing age-related diseases.

One of life’s great mysteries is how aged parents produce youthful offspring. Our cells show signs of age as a result of the accumulation of damage wrought by the environment and the body’s metabolism, and yet the eggs and sperm our bodies make combine to produce a baby …