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Cosmic rays may have given right-handed genetic helixes an evolutionary edge at the beginning of life’s history.
Studies suggest that epigenetics allows some learned adaptive responses to be passed down to new generations. The question is how.
Origin-of-life researchers have usually studied the potential of pure starting materials, but messy mixtures of chemicals may kick-start life more effectively.
Modern humans and more ancient hominins interbred many times throughout Eurasia and Africa, and the genetic flow went both ways.
To avoid passing on new mutations to offspring, plants may minimize the number of divisions by the stem cells that make flowers and seeds.
Surviving fragments of genetic material preserved in sediments allow scientists to see the full diversity of past life — even microbes.