The illustrious Dr. Frank clued me in on the story about the sheep/human chimera, a man-made creature with 15% human genes and 85% sheeply ones. These critters are an experimental stage in the production of an organ-donor pool for sickly humans.
Now from the journal Nature we find that genetic mixing isn’t just for the laboratory, as Mother Nature does it herself with cute little marmosets:
As a general rule, a man who learns that his children are genetically his brother’s offspring would have good cause for distress. But for one group of primates, that wouldn’t necessarily mean that mum has been unfaithful, a new study finds.
The reason, says Corinna Ross of the University of Texas Health Science Center in San Antonio, is that these primates are often genetic mosaics containing some cells that belonged to their siblings. And when those cells happen to be sperm, a male can sire offspring that are genetically nephews and nieces rather than sons and daughters.
This strange genetic mixing could be one of the reasons why these animals tend to raise their families in large collectives, with everyone lending a hand; animals are thought to generally give more parental attention to children with a strong genetic similarity to themselves.
Marmosets, you see, are typically born in pairs of non-identical twins who share a common blood supply in the womb. This leads to genetic migration and chimaerism. So any ideas you may have had about impenetrable walls between species and individuals in nature have to be set aside.
Humans can also, rarely, be mosaics.
There are about three known instances