![]() ![]() It may be a sphinx with a riddle that many biologists are reluctant to consider: What if the pattern of evolution is not actually a tree?įossils that resemble hoatzins have been found in Europe and Africa, but today the birds can be found only in the river basins of the Amazon and Orinoco of South America. The hoatzin may be more than a missing piece of the evolutionary puzzle. “Frankly, there is no one in the world who knows what hoatzins are,” Cracraft, who is now a member of B10K, said. Another, in 2020, concluded that this clumsy flier is a sister species to a group that includes tiny, hovering hummingbirds and high-speed swifts. One 2014 analysis suggested that the bird’s closest living relatives are cranes and shorebirds such as gulls and plovers. “I was completely amazed by this bird,” she said.ĭNA research has not solved the mysteries of the hoatzin it has deepened them. But, early in the process, she encountered an evolutionary enigma called Opisthocomus hoazin. “I think there was always this idea that, once we sequence full genomes, we will be able to solve it,” Stiller told me. ![]() With help from four supercomputers in three different countries, they began to compare each bird’s DNA to figure out how they were related. When Stiller joined the project, her colleagues were combing through museums and laboratories to sample three hundred and sixty-three bird species, chosen carefully to represent the diversity of living birds. ![]() By mapping a major branch on the tree of life, B10K aims to light the way. Its value to such fields as agriculture, conservation, and medicine would be incalculable evolutionary trees have already deepened our understanding of SARS-CoV-2, the virus that causes COVID-19. Wilson predicted that such a tree could unify biology. “It is now realistic to conceive of reconstructing the entire Tree of Life-eventually to include all of the living and extinct species,” Joel Cracraft, the curator of birds at the American Museum of Natural History, wrote, in 2004. The rise of genome sequencing, at the turn of the twenty-first century, seemed to bring Darwin’s dream within reach. “The time will come I believe, though I shall not live to see it, when we shall have fairly true genealogical trees of each great kingdom of nature,” Darwin wrote to a friend. The tree of life became for biology what the periodic table was for chemistry-both a foundation and an emblem for the field. “ On the Origin of Species,” published twenty-two years later, includes only one diagram: an evolutionary tree. Darwin wondered whether the finches might have shared a common ancestor from mainland South America-whether all of life might have evolved through a process of “descent with modification”-and he drew a rudimentary tree in his private notebook, beneath the words “I think.” The tree showed how a single ancestral population could branch into many species, each with its own evolutionary path. In 1837, a taxonomist in London told Charles Darwin that the finches he had shot and carelessly lumped together in the Galápagos Islands were, in fact, many different species. “Everything in biology has a history, and we can show this history as a bifurcating tree,” she said.īirds are the most diverse vertebrates on land, and they have always been central to ideas about the natural world. The amount of data and computing power required for this mission is almost unfathomable, but the final product should be as simple in principle as the diagram Stiller had assembled as a child. Then, in 2017, she moved to the University of Copenhagen and joined B10K, a scientific collaboration that aims to sequence the genome of every bird species-more than ten thousand in all-and to reveal their connections in a comprehensive tree. Years later, as a graduate student in biology, Stiller worked on an evolutionary tree for seahorses and their relatives, using DNA to understand the ancestry of different species. “I wonder if this experience of reconstructing a family tree primed me to appreciate trees and the powerful insights they hold,” Stiller told me in a recent e-mail. Sons killed fathers uncles kidnapped nieces siblings fell in love. As lineages became clear, so did family dramas. ![]() Frustrated, she wrote each name on a card and started to arrange children beneath parents on a desk in her bedroom. She often lost track of their relationships, however-their feuds, trysts, and betrayals-as she flipped among the entries. When Josefin Stiller was growing up in Berlin, she loved reading about Greek gods in an encyclopedia of mythology. ![]()
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