It's In Our Bones
By Eliza Stein; illustration by Charlie Theobald
Four and a half billion years ago, a camera began recording. It captured images of faces, footprints, fingernails. It saw the first proteins strung out piece-by-piece; it saw microscopic, single-celled masses absorbed by their neighboring blobs of life; it saw families trekking across grasslands in search of food. This camera ran for billions of years, from angles all over the planet, capturing the sky, the trees, predators, prey, insects and bacteria. And after each frame, the film was discarded on the ground, where it would be covered in mud, land and vegetation, maybe for the rest of time.
“The fossil record is like a film of evolution from which 999 out of every 1,000 frames have been lost on the cutting-room floor,” David Quammen writes in his National Geographic article “Was Darwin Wrong?.” That means that, over the course of all those billions of years, we only have a vague idea of what 0.1% of the entirety of Earth’s living history looks like. And that’s just a rough estimation.
Somehow, though, 0.1% is enough. A radio program based out of Charlotte, North Carolina covered a story earlier this year about an excavation project in South Africa that uncovered over 1,500 pieces of bone. The episode, “Homo Ndaledi and How We Think About Human Evolution,” sought to uncover the details of a new human ancestor, and explored how this discovery might change our understanding of where we come from.
“Let’s get it out of the way,” begins Mike Collins, the host of Charlotte Talks, “Dr. Marks, you’re both an anthropologist and a geneticist. Are most scientists convinced that Darwin was right?”
“No,” replies Dr. Marks, Professor of Anthropology at UNC Charlotte, “All scientists are convinced that Darwin was right.”
Then Collins asked the question that evolutionary scientists might never hear the end of: Did evolution really happen? And Dr. Marks answered the way that modern scientists will always answer this question: Yes. Evolution happened, and it continues to.
Dr. Krista Fish, a biological anthropologist and professor of Anthropology at Colorado College, tries to avoid the subject of evolution when she isn’t engaging with other scientists. “People have a lot of misconceptions about evolution,” she tells me. “They just don’t have the background in evolutionary theory. Part of that is from the public school system. Even though evolution is the foundation of all biology, teachers are afraid to even bring it up in class. It’s kind of like sex ed—if you don’t learn it in middle school, things can go wrong.”
Whether or not we can attribute it to a lack of “evolution ed” in middle school, our world is plagued by a general confusion of what evolutionary science really is and what it can tell us. A general mistrust of media, academics and almost all public figures—the resources that might actually be able to answer some of our questions—hurts our chances of understanding.
The late John H. Ogwyn was well-spoken in the word of God, and he wrote about finding the origins of humanity in religion. “Evolution requires a degree of ‘blind faith’ far beyond what is asked of those who believe in the Bible’s account of creation,” Ogwyn wrote in Tomorrow’s World, a magazine sponsored by the Living Church of God. Ogwyn’s article appears in “Evolution: Fact or Fiction?” which aims to convey a message that is widely accepted today: the theory of evolution is exactly that—a theory.
The first time I came across David Quammen’s article was in a copy of Tomorrow’s World, which depicts evolution as a film for which most frames have been lost. “While asserting that the fossil evidence proves Darwin’s theory correct,” Ogwyn wrote of Quammen’s National Geographic article, “evolutionary theory asks its believers to accept a premise for which 99.9 percent of the data are missing!” Though it’s hard to accept, he kind of has a point.
So what do we know about evolution, then?
On October 1., 2013, paleoanthropologist Lee Berger first laid eyes on photographs of the newest missing link: Homo naledi. Over the course of four weeks, more than 1,500 pieces of bone were removed from the Dinaledi Chamber in South Africa, revealing yet another puzzle for scientists to solve. The evidence, which includes bones from individuals of all ages, places Homo naledi somewhere in our family tree; less clear, however, is exactly where in our lineage this ancestor belongs.
Here’s what we know so far about Homo naledi, according to Anne Gibbons of Science magazine: “The skull was globular, like a member of our genus Homo, but the brain was small and primitive. The wrist suggested this species was an adept toolmaker, but its shoulder and fingers showed it still climbed in trees, like more primitive hominins.” Here’s what we don’t know about Homo naledi: what its discovery means.
Almost all scientists have their own interpretations. Stephanie Keep wrote an article in the academic journal Understanding Evolution discussing the implications of the Homo naledi discovery. In the article, “Is there anything truly surprising about Homo naledi?,” evolutionary biologist Francis Thackeray claims that Homo naledi is a distinct species of the Homo genus, dating back about two million years. Other scientists believe that Homo naledi isn’t a new species at all, but rather another variant of an already known species, Homo erectus. Still others reject the claim that the new specimen is of the Homo genus at all.
Here we confront one of the most prominent issues in evolutionary science: While all scientists agree that evolution absolutely, irrefutably explains the origins of humanity, few can agree on much more than that. “Put two scientists in a room and you’ll get 20 different opinions,” jokes Dr. Zachary Throckmorton, Lincoln Memorial University Professor of Anatomy, who was interviewed on Charlotte Talks with Dr. Marks. This isn’t an issue of modernity either—whether it was Ionian philosophers scoffing at Anaximander, devout religious figures shunning Zhuangzi or Darwin himself reviewing the errors of Jean-Baptiste Lamarck, we see disagreement among scientists, particularly around the subject of evolution, dating all the way to the beginning of history.
Charles Darwin laid a substantial foundation for evolutionary science with the publication of Origin of Species, but he still didn’t have all of the facts. He knew that certain traits were passed on from generation to generation, but it would be another decade-and-a-half before the scientific community recognized the validity of George Mendel’s discovery of “genes,” and almost a century before genetic material was identified as DNA. And for what it’s worth, while Mendel and Darwin were correct about many concepts of inheritance, each drew conclusions that were later refuted. Mendel had an overgeneralized interpretation of gene dominance and Darwin traced many ancestral lineages that later turned out to be false. Regardless, both made major discoveries that aided the progress of evolutionary science.
One of the most challenging aspects of science is the coexistence of discovery and error in research. Dr. Fish tells her students, “You never prove a hypothesis—you either accept or reject the hypothesis. There are just so many possible sources of error throughout the process.”
We see this not only in evolutionary science, but also across most other disciplines. “Out on the frontiers of physics,” writes Sharon Begley in the Wall Street Journal, “error and brilliance can seem joined at the hip…Even Einstein published a paper claiming that objects cannot be affected without being physically touched, which was later refuted.” Although he was wrong, Einstein’s paper led to great advancements in physics and math. “Research inspired by Einstein’s bold mistake led to the new field of quantum computing,” says Begley.
Although the scientific community constantly debates the details of evolution, there is a general consensus that it is a major mechanism of change in the living world. In 2002, Scientific American writer John Rennie attempted to clear up several misconceptions about evolution in his article, “Answers to Creationism.” “Pick up any issue of a peer-reviewed biological journal, and you will find articles that support and extend evolutionary studies or that embrace evolution as a fundamental concept,” Rennie writes. “Conversely, serious scientific publications disputing evolution are all but nonexistent.”
Evolutionary science attempts to answer one of the biggest questions humans have ever grappled with: Where do we come from? Unfortunately, there is no shortage of roadblocks on the way to uncovering the answer. We’re looking at a history of billions of years, and the evidence we have is damaged and scarce. We’re seeking to place a gigantic web of fragmented and interweaving ancestry into neat, segregated boxes.
When I asked if she thought we’d ever be able to collect the evidence we need to fully understand human origins, Dr. Fish laughed. “We’ll always have more information, but the process of what actually ends up in the fossil record is so happenstance. There’s always the possibility that we’re missing a piece of the complete picture.”
For now, Fish says, evolutionary science can help us understand more about who we are and our place in the natural world. It sheds light on patterns of disease exposure, migration and medicine. It gives us insight into how societies were constructed hundreds of thousands of years ago, what allowed for progress and what hindered it. Maybe someday we will be able to construct an evolutionary lineage that all scientists agree upon. Maybe not. For now, though, discoveries about who we are and where we come from contribute to social, political and economic progress, helping us not only understand where we come from, but also where we’re going.