The world is a step closer to doing away with men.
Scientists in China have managed to produce healthy mice from two mothers, bypassing males entirely. They lived healthily into adulthood and had children of their own the normal way.
In contrast, mice produced using only genetic material from males died within two days of being born.
"We were interested in the question of why mammals can only undergo sexual reproduction," said study author Qi Zhou of the Chinese Academy of Sciences.
Many other animals can reproduce with just one parent, mammals can't. Past attempts to produce babies from parents of the same sex - not clones, but actual offspring - have failed to produce healthy young.
The Chinese scientists succeeded using a haploid embryonic stem cell taken from a female, rather than a normal stem cell. Haploid stem cells contain DNA from only one parent, not two, and the scientists believe this is why their method worked.
Before the haploid stem cell was implanted in another female's egg, some of its genome had to be deleted - particular genes which cause birth defects if DNA from both a mother and a father isn't present, a process known as genomic imprinting.
The 210 embryos created produced 29 babies, all of which lived to adulthood and produced more offspring.
Making mice from two dads was a little trickier - more genes had to be deleted, and the cells had to be inserted into an egg with all its female genetic material removed, along with sperm from another male. Surrogate mothers then had to carry the babies to term.
These babies only lived for 48 hours, but the scientists are sure they can improve on that.
"This research shows us what's possible," said co-author Wei Li. "We saw that the defects in bimaternal mice can be eliminated and that bipaternal reproduction barriers in mammals can also be crossed."
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Another method for creating mice with two fathers was tried in 2011, with similar results. In that experiment, a female created with stem cells from one father was mated with a second father.
"That method sidestepped the problem of genomic imprinting but presents ethical and practical hurdles if this technology were to ever be considered for humans," the scientists said.
The research was published in journal Cell Stem Cell.