Blurring Life’s Boundaries
Darwinian theory is based on the idea that heredity flows vertically, parent to offspring, and that life’s history has branched like a tree. Now we know otherwise: that the ‘tree’ of life isn’t that simple.
By David Quammen
Since the late 1970s, there have come three big surprises about what we humans are and about how life on our planet has evolved.
The first of those three surprises involves a whole category of life, previously unsuspected and now known as the archaea. (They look like bacteria through a microscope, but their DNA reveals they are shockingly different.) Another is a mode of hereditary change that was also unsuspected, now called horizontal gene transfer. (Heredity was supposed to move only vertically, from parents to offspring.) The third is a revelation, or anyway a strong likelihood, about our own deepest ancestry. (It seems now that our lineage traces to the archaea.) So we ourselves probably come from creatures that, as recently as forty years ago, were unknown to exist....
H/T on Twitter
No comments:
Post a Comment