Dr. Neil Shubin says we humans are walking fossil repositories.
“Written inside our bodies is the history that extends from the Big Bang over 13.7 billion years ago, to the formation of the Earth and the Earth-Moon system and the solar system,” Shubin said at a talk Thursday evening at Town Hall Seattle. “We have interactions with the solar system embedded within ourselves.”
Shubin, a University of Chicago paleontologist, is the author of The Universe Within: Discovering the Common History of Rocks, Planets, and People. He is best known for the discovery of Tiktaalik roseae, a so-called “fishapod” that was something of missing link, one of the first fish to sport limbs and start crawling around on land, bridging the gap between fish and other early tetrapods. Shubin began writing about science for popular audiences because he saw that many in the general public view as bizarre things that most scientists have accepted as fact for more than a century. He said it is important for us to understand science and history because it changes how we see the world.
“When you see history what you see is connections that exist among yourself and the rest of the living world and the physical world. Indeed, when you look at our own bodies with the lens of history, what you see is that in every organ, cell, and gene of our bodies we have history,” he said. “The point is seeing the history inside of us that begins with the shared history that we have with the rest of life on our planet, and then the history of the cosmos beyond.”
Shubin pointed to his own discovery as an example of our connection to other living creatures. He said Tiktaalik and the transition from fish to tetrapod wasn’t just some oddball event 375 million years ago.
“That wrist that appeared for the first time in Tiktaalik and its cousins is something that’s become our own wrist,” he said. “That neck that we see for the first time in Tiktaalik and its cousins is something that’s become our own neck. So every time you bend your wrist and every time you shake your head you can thank these guys and you can thank the fish-to-tetrapod transition.”
“We know that because we can trace this transition from individual bones all the way from fish to us,” Shubin continued. “We can do it with comparative anatomy with living creatures, we can do it genetically and developmentally with living creatures, and we have the fossils to bridge these gaps.”
Our connections to the universe are just as profound, Shubin said. The elements of which we are made were created during the Big Bang and heavier elements were fused in the cores of stars and spread by novae and supernovae.
“Our atoms are derived from shared connections and shared history with the cosmos, with the universe. Our molecules and proteins are derived from a shared history with the solar system and the planet, and the shaping and working of our organs come about from interactions with the biosphere, other living creatures, as well as the planet and solar system itself.”
The most fascinating connection between the solar system and us is the biological clock discovered in the early 1960s by French geologist Michel Siffre, who went deep into a cave for several months. He couldn’t see the Sun or feel the turning of the Earth. He had no sense of night or day. Yet his rest, activity, and biological functions all clicked along on a 24-hour cycle.
“DNA and protein activity rises and falls during the day, and it does so as a kind of a pendulum, like a clock has,” Shubin explained. “There’s a negative feedback loop of activities between genes and proteins that causes it to rise and fall in a set period.” Each of our two trillion cells is a little time clock, set to the spinning of the Earth.
It’s a wonder we’re ever late for anything.
The Earth’s climate also has left its mark, according to Shubin. Changes in our planet’s orbit and its wobble around its axis created a cycle of ice ages that had a profound impact. Ice changed East Africa from woodland into open savannah; it was in that habitat, Shubin noted, that our ancient ancestors really began to flourish as bipeds.
“Glaciation has been a major factor in human history, human evolution, and in much of the distribution and diversity of life that we have on the planet today,” Shubin said.
Shubin concluded his talk by noting that science, from Copernicus to Darwin, has blown up the human notion of itself as the center of the universe and shown us to be just another interconnected member in the tree of life.
“As science has removed us from this special perch, I believe it’s given us something different, it has connected us in the deepest ways,” he said. “It’s connected us to the rest of living creatures, its connected us to the planet, it’s connected us to the solar system, and it’s connected us to the universe beyond. I believe that’s a very profound gift.”