Imagine the tree of life. The tip of every branch represents one species, whether you're talking about humans, E. coli, tardigrades, baker's yeast or giant kelp. If you follow any two branches ...

A version of this article appears in print on Dec. 17, 2024, Section D, Page 3 of the New York edition with the headline: A ‘Second Tree of Life’ Could Wreak Havoc.