If you have been following genetic and epigenetic studies conducted within the edifices of modern science over the past couple of decades, you likely have suspected what I am about to tell you: Mr. Darwin has already left the building, his disheveled ‘Theory of Evolution’ in tow.
A massive new genetic study by Mark Stoeckle from The Rockefeller University in New York and David Thaler at the University of Basel in Switzerland puts a few more nails into an already-rotting coffin, opening the door for new theories about our origins and the mechanisms behind the evolution of species on our planet.
Challenges To Convention
In the conventional narrative of how evolution proceeds through survival-of-the-fittest and adaptation to new environments based on random genetic mutations, it is natural to expect that species with large, far-flung populations like ants and humans will become more genetically diverse over time than species who remain in one milieu. But is it true?
“The answer is no,” said Stoeckle, lead author of the study, published in the journal Human Evolution. In fact, the genetic diversity of most species on the planet “is about the same”, no matter their history of migration, relocation or proliferation.
The study’s most startling result, perhaps, is that nine out of 10 species on Earth today, including humans, came into being 100,000 to 200,000 years ago.
“This conclusion is very surprising, and I fought against it as hard as I could,” said David Thaler.
Indeed it is surprising–since it presents a stunning invalidation of the commonplace notion that evolution on the planet has been slow, linear, progressive, and unbroken. Previous challenges to this notion in the form of ‘missing links’ could be perceived as grounded in a lack of physical evidence which one day would be resolved. Now, we are really forced to start looking at things in a completely new way.
The study relies not on an examination of regular ‘nuclear’ DNA, but rather mitochondrial DNA. As this article in AFP explains,
All animals also have DNA in their mitochondria, which are the tiny structures inside each cell that convert energy from food into a form that cells can use. Mitochondria contain 37 genes, and one of them, known as COI, is used to do DNA barcoding.
Unlike the genes in nuclear DNA, which can differ greatly from species to species, all animals have the same set of mitochondrial DNA, providing a common basis for comparison. Around 2002, Canadian molecular biologist Paul Hebert–who coined the term “DNA barcode”–figured out a way to identify species by analysing the COI gene.
“The mitochondrial sequence has proved perfect for this all-animal approach because it has just the right balance of two conflicting properties,” said Thaler. On the one hand, the COI gene sequence is similar across all animals, making it easy to pick out and compare. On the other hand, these mitochondrial snippets are different enough to be able to distinguish between each species.
In analysing the barcodes across 100,000 species, the researchers found a telltale sign showing that almost all the animals emerged about the same time as humans. What they saw was a lack of variation in so-called “neutral” mutations, which are the slight changes in DNA across generations that neither help nor hurt an individual’s chances of survival. In other words, they were irrelevant in terms of the natural and sexual drivers of evolution. How similar or not these “neutral” mutations are to each other is like tree rings–they reveal the approximate age of a species.