September 27, 2012
Seeing a hadrosaur alive would be a fantastic sight. Or any non-avian dinosaur, for that matter. As lovely as today’s avian dinosaurs are, it’s their distant, extinct cousins that fire my imagination. Sadly, despite the speculations of theoretical physicist Michio Kaku, I don’t think my dinosaur dreams are going to come true.
In a Big Think video posted last week, Kaku rhapsodized about the possibility of resurrecting extinct species through genetic techniques. I’m not as optimistic as he is, especially since Kaku glosses over some essential steps in his confused editorial.
Kaku spends most of the video talking about Neanderthals and woolly mammoths. These species went extinct so recently that, in some cases, researchers can extract DNA from their remains and go about reconstructing their genomes. Pretty cool science. Whether I’ll ever be able to cuddle a fuzzy baby woolly mammoth is another matter. (I’ve heard promises ever since I was a child. I’m still waiting.) But non-avian dinosaurs obviously present a different problem. They went extinct about 66 million years ago, and, given the circumstances required for genetic preservation, there’s no hope of ever obtaining Mesozoic dinosaur DNA.
But, Kaku says, “we have soft tissue from the dinosaurs.” He makes it sound as if dinosaur skeletons are saturated with bits of prehistoric flesh. “If you take a hadrosaur and crack open the thigh bones, bingo,” he says, “You find soft tissue right there in the bone marrow.”
Kaku’s going far afield from what science has actually revealed. Since 2007, paleontologists and molecular biologists have been tussling over the possibility that some non-avian dinosaur fossils might preserved the degraded remnants of soft tissue structures such as blood vessels. A Tyrannosaurus femur kicked off the debate, which has since extended to the hadrosaur Brachylophosaurus, as well.
Even though researchers Mary Schweitzer, John Asara and colleagues have hypothesized that they’ve detected preserved proteins from remnants of dinosaur soft tissues, their results have been heavily criticized. The supposed dinosaur leftovers may be microfossils created by bacterial biofilms that broke down the creature’s bodies, and the protein analysis–which placed the supposed T. rex protein close to bird protein–might have suffered from contamination. As yet, there’s no definitive proof that non-avian dinosaur soft tissues or proteins have actually been recovered, and the debate is set to go on for years to come. Contrary to what Kaku says, you can’t simply break open a dinosaur skeleton and start scooping out marrow.
Not that preserved protein would bring us closer to resurrecting Tyrannosaurus or Brachylophosaurus, anyway. The biomolecules could tell us a bit about dinosaur biology, and possibly become another way to test evolutionary relationships, but we’d still lack dinosaur DNA. And even if we could reconstruct a dinosaur’s genome, that doesn’t mean that we could easily clone one. Much like Michael Crichton before him, Kaku skips over an essential and complicated step–the development of the embryo inside the mother. How do you go from a genetic map to a viable embryo? And how can we account for interactions between the embryo and the surrogate mother–a member of a different, living species–that could influence the experimental animal’s development?
Studying the genetics and biomolecular makeup of prehistoric organisms is a fascinating area of research. And even though the dinosaur protein issue remains contentious, the debate has the potential to refine a new way to look at dinosaurs. That’s where the real value of this science is. Non-avian dinosaurs are long gone, and I don’t believe that we’ll ever be able to bring them back to life. But the more we understand about their biology, the better we can reconstruct dinosaurs in our scientific imagination.
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