The chicken came from the dinosaur. You’ve probably seen that fact in every high school biology textbook, nestled under a “Did You Know?” side-margin that you skimmed because it wasn’t part of the assigned reading.
Until recently, however, we weren’t sure where that relationship began. What’s more, we haven’t even been confident what birds are related to, once they and dinosaurs parted ways on the evolutionary tree. Where have birds perched on our tree of life?
Just like humans continue to seek the long-lost relatives who would complete our family tree, scientists across the world have been combing the avian genome for answers. And partly thanks to researchers at the University of Florida, we finally have it.
Dr. Edward L. Braun, Associate Dean of the biology department at the University of Florida, headed the “Early Bird” project, which studied the relationship between animals like alligators, waterfowl, chickens and peacocks. This, along with the research of hundreds of evolutionary biologists across the world, finally mapped the genome of the 10,000-bird species, an accomplishment that landed on the cover of Science magazine this past December.
With his tie-dyed “EVOLUTION” T-shirt and tortoise-shell glasses, Braun looks like he would be as comfortable behind binoculars as he would a microscope. He has been studying the bird genome since graduate school, painstakingly piecing together the A’s, C’s, T’s, and G’s to give us a map of the bird genome.
What’s more, we haven’t even been confident what birds are related to, once they and dinosaurs parted ways on the evolutionary tree. Where have birds perched on our tree of life?
The four base chemicals of DNA — denoted by the letters A, C, T and G — can be sewn together into groups of three, called genes, to form unique traits. Different permutations like AUG, GTC, CTT, GGG, TAG, and so on create feathers, beaks, the tendency to poop on cars–essentially everything that makes a bird a bird and not, say, a human reader of The Fine Print.
Like many of the genetic researchers in the ‘80s, Braun said he spent much of his research interpreting DNA sequences one gene at a time, making a spool of only thousands in the span of months. For each letter recorded, he and others used a program which automatically repeated the letters punched into it: A A A T G C C T and so on, thousands and thousands of times in a synthesized voice, as if unhappy with its lot in life.
But genomic sequencing has come a long way. That old, cumbersome process has, like many things in science, become automated with new technology. Using strips of RNA, a strand of biological data that mirrors DNA, researchers can match the A’s, T’s, C’s and G’s. So, like teeth in a zipper, we are able to line up the different strands until we get a more complete picture. Computers allow for as many as 40 billion sequences of data to be processed in the span of a week, leaving human computation in the dust.
Researchers like Braun are only interested in 1 percent of that picture, however. The other 99 percent of the genome is the same for all vertebrae, ourselves included.
That 1 percent can provide a lot of information, though. From it, new branches grew from the tree of life, while others were trimmed away. Like an awkward family reunion, birds unaware they had any relationship to one another were shoved together as their genome was ordered. This reclassification put birds previously thought distant relatives, like doves and flamingos, next to one another. What an ancestor of both a flamingo and dove would look like is still up for debate.
Braun’s research delves further into the avian genome than just doves and flamingos, though. He studies “deep avian genomics,” which explores the ancestors of birds and their commonality with more exotic creatures like the alligator and turtle. Natural selection has been a strange boss, ordering some species to evolve while others remain the same as they have for millions of years.
Even within the avian tree, certain branches grew at accelerated rates while others — such as waterfowl and and large landfowl like the ostrich — fell by the wayside. Braun said that this may be due to factors like length of life: A zebra finch’s life is measured in years, while an alligator’s or ostrich’s is measured in decades. Such a quick turnover leads to remarkable shifts in evolution, producing everything from the fat, waddling chicken to the nimble hummingbird.
Such a quick turnover leads to remarkable shifts in evolution, producing everything from the fat, waddling chicken to the nimble hummingbird.
While most of this research seems like biological semantics, it provides us vital information. Millions of years ago, the world teetered on a precipice very similar to the one we lean over now. This event, aptly called a Great Extinction, wiped out the dinosaurs–and something similar is looming upon their distant relatives (us).
With things like man-made climate change and dwindling resources, our home is becoming much less hospitable. So inhospitable, in fact, that we could lose as much as 95 percent of species on our little blue planet. Like a Noah in a post-apocalyptic arc, we must choose which species will benefit the emerging world the most. By studying the branches that grow from the tree of life, we can better understand who can act as archives of life’s intricate history. We can better see the branches that lead to twigs and leaves, rather than those that stick out into the sky, barren.
And, unfortunately, we have to decide who we will save from the shears.