Marmosets: who's who?

Now, this is something I had never heard of before that is just too weird/crazy/cool not to blog about. Apparently, female marmosets (small South American primates) normally give birth to fraternal twins. Kind of quirky, but nothing too shocking there. However, it turns out that during early fetal development, the twins swap lots of stem cells. Twin A gives some stem cells to Twin B; Twin B gives some stem cells to Twin A. These stem cells then go on to differentiate into various other types of cells, tissues, and organs. So, a single marmoset is actually a mixture of two different sets of DNA - a phenomenon known as chimerism (named after the mythological creature Chimera - a beast made up of multiple animal parts).

Scientists have also found that almost half of male marmosets actually carry two lineages of sperm, and in some rare cases, females can carry two lineages of eggs. This means that some of their gametes are genetically NOT THEIR OWN, but instead are genetically their sibling's. If you will allow a somewhat crude elaboration, this means that a male may fertilize an egg with his brother's sperm, thereby siring not his own child, but his niece or nephew. Likewise, it is possible that a female could give birth to her niece or nephew and not her son or daughter. Genetically speaking of course.

Told you it was wierd/crazy/cool.

Read more:
NY Times article