How science works: New ideas upend old ones through a burden of proof
How science works: New ideas upend old ones through a burden of proof
By Wendy Kirschner  

When scientists want to share their brilliant ideas with the world, the process is pretty transparent. They write an article and send it to a journal for peer review. Experts in the field review the merits of the work and determine whether or not it deserves to be published. 

Peer review is a form of "quality control" in the scientific community and getting published can be extremely competitive. 

The journal Science publishes fewer than eight percent of the articles it receives, while the esteemed New England Journal of Medicine publishes less than six percent. Even if the idea passes muster, it usually takes an additional year between submission and publication.

New theory about the first humans to arrive in North America

So in 1999, when archeologist Dennis Stanford and paleolithic tool expert Bruce Bradley were presenting their radical new hypothesis on how the first humans arrived in the Americas, "the backlash was amazing," Bradley says. "We weren't terribly shocked, but surprised by the vehemence of it. Rather than backing off, because that's not the way science works, we kept looking at the evidence because no one should be intimidated or shouted down."

Succinctly, they hypothesize that the first humans to arrive in North America came from western Eurasia (what is now Europe) about 20,000 years ago, crossing the Atlantic Ocean in boats during the last Ice Age. It's known as the Solutrean hypothesis and is the subject of the new Nature of Things documentary Ice Bridge.

Scene from the film: "It's a nice story, but it doesn't hold up to the evidence."

"They thought we were off our rocker," Stanford says. "And they still think so." 

Predictably, when it came to getting published, Bradley says no journal would touch their work. So they kept plugging away, presenting their hypothesis to amateur archeological societies and getting media attention along the way. In 2012 they co-wrote the book "Across Atlantic Ice" to detail their findings.

"There's quite a bit written about the scientific process, about the method," Bradley says. "It should be slow and incremental, almost generational. Where someone picks up an idea, it's studied and becomes the paradigm, and it takes something major to change that.”

Other examples of controversial theories

Bradley cites the example of when Alfred Wegener presented his "nutty theory" on Continental Drift in 1915. Wegener posited that the earth's continents fit together like a jigsaw puzzle and were perhaps all joined together in the past. While his idea was met with skepticism at the time, it led to a breakthrough, and he's now known as one of the "Fathers of Plate Tectonics".

Bradley points to another example from archeology, referred to as the "Pre-Clovis Paradigm." For years, archeologists accepted that the first humans to arrive in North America were big game hunters from Asia that followed their prey across a landmass known as Beringia, which joined northeastern Asia to present-day Alaska. Archeologists coined the phrase “Clovis First” because they were named after the distinct tools excavated near Clovis New Mexico in the 1920s, dating back 11,500 years.

scieintists standing by cliff

Paleolithic tool expert Bruce Bradley with archeologist Dennis Stanford.

But from the 1970s to the 1990s, sites were excavated in North and South America dating several thousand years before Clovis. While most archeologists now agree the first humans entered the continent about 14,000 to 16,000 years ago, there are still some holdouts who won’t consider anything but Clovis First. And Stanford and Bradley’s hypothesis — that humans first arrived by boat from Eurasia 20,000 years ago was unthinkable.

"We were taught this stuff in our textbooks. It's a matter of challenging beliefs," says Bradley. "Scientists are human beings and can have great intellectual and emotional investment in ideas. They have egos too.”

How are concepts ‘proven’?

We're also taught in Grade 8 science that the gold standard of "proof" lies in the replication of results.

But here's a bombshell. According to a survey of 1500 scientists conducted by the journal Nature in 2016, more than 70 percent of researchers have tried — and failed — to reproduce another scientist's experiments. 

Perhaps in archeology, where theories are put forward by excavating sites and dating artifacts, the proof is even muddier because the facts are open to interpretation.

Ice Bridge
From Dire Wolves to Giant Bears: Meet The North American Animals of the Ice Age

Sebastien Lacombe, a lithic tool expert from Binghamton University, doesn't necessarily agree with the Solutrean hypothesis but remains open-minded about Stanford and Bradley's work. 

"I find it silly to reject any piece of evidence that could potentially advance our knowledge about the past. But I do know that, even if the eyes can clearly see, it remains harder to convince the mind."  

Lacombe recounts the cautionary tale of French archeologist Édouard Cartailhac.

Archeologist once considered a fraud

Altamira cave in Spain was known for its beautiful paintings but hadn't received much attention until 1868 when archeologist Marcelino Sanz de Sautuola determined Stone Age people created them.

In 1880 Sautuola published his findings, but the scientific community questioned the authenticity of the paintings because they were too well-preserved, with fellow archeologist Cartailhac, going so far as accusing Sautuola of forgery.

Paleolithic art from Altamira Cave

Paleolithic art from Altamira Cave. Credit: Yvon Fruneau, UNESCO

It wasn't until other Paleolithic paintings were discovered in France in 1902 — making forgery less likely — that Cartailhac published "Mea culpa d'un sceptique," apologizing for being one of Sautuola's harshest critics and holding back his work. Tragically, Sautuola died without ever knowing the value of his discovery.

Lacombe says archeology is riddled with stories like this and wouldn't be surprised if Stanford and Bradley are considered pioneers 20 years from now.   

Proof of the Solutrean hypothesis for Lacombe would be "to find an exact replica of a Solutrean site with all the laurel leafs and artifacts intact. But it may not exist."  A laurel leaf is a signature of the Solutreans because it’s carved in a distinct way.

One thing's for sure. Stanford and Bradley will never stop looking.

Watch Ice Bridge on The Nature of Things.