linkstream2 microblog

QT{{”
“Early on, the cells in an embryo can turn into any tissue. As these stem cells divide, they can lose this flexibility, committing to becoming one kind of cell or another. After that, cells typically shut down their viral genes.
Viral proteins appear to help keep stem cells from losing this potential. …
Viruses might have exploited embryos to make more copies of
themselves. By keeping their hosts as stem cells for longer, the viruses were able to invade more parts of the embryo’s body.” “}}

Ancient Viruses Are Buried in Your DNA, by @CarlZimmer
https://www.NYTimes.com/2017/10/04/science/ancient-viruses-dna-genome.html Nice #intuition on why they may promote the stem-cell state

Puzzler: Rock the Boat
http://www.slate.com/blogs/bad_astronomy/2016/06/26/if_you_throw_a_rock_off_a_boat_does_the_water_go_up_or_down.html Good illustration of Archimedes’ principle & using extreme cases for intuition, ie dense rock