Massive Genetic Study Reveals 90 Percent Of Earth’s Animals Appeared At The Same Time

Landmark new research that involves analyzing millions of DNA barcodes has debunked much about what we know today about the evolution of species.

In a massive genetic study, senior research associate at the Program for the Human Environment at Rockefeller University Mark Stoeckle and University of Basel geneticist David Thaler discovered that virtually 90 percent of all animals on Earth appeared at right around the same time.

More specifically, they found out that 9 out of 10 animal species on the planet came to being at the same time as humans did some 100,000 to 200,000 years ago.

"This conclusion is very surprising," says Thaler, "and I fought against it as hard as I could."

What Is DNA Barcoding?

Over the last decade, hundreds of scientists collected around 5 million DNA barcodes from 100,000 animal species in different parts of the globe. Stoeckle and Thaler looked through these 5 million genetic imprints to find one of the most surprising discoveries about evolution to date.

There are two types of DNA. Most people know nuclear DNA. This is the DNA containing the genetic blueprint for each single individual. It is passed down from the parents to the offspring. The genome is made from kinds types of molecules arranged in pairs. There are 3 billion of these pairs, which are then used to form thousands of genes.

The other, less familiar type of DNA is one found in the mitochondria of cells. The mitochondria generate energy for the cell and contains 37 genes. One of these is the COI gene, which is used to create DNA barcodes. All species have a very similar mitochondrial DNA, but their DNA is also different enough so we can distinguish between species.

Paul Hebert, biologist and director of the Biodiversity Institute of Ontario, developed a new way to identify species by studying the COI gene.

Born Around The Same Time

In analyzing the COI of 100,000 species, Stoeckle and Thaler arrived at the conclusion that most animals appeared simultaneously. They found that the neutral mutation across species were not as varied as expected. Neutral mutation refers to the slight DNA changes that occur across generations. They can be compared to tree rings because they can tell how old a certain specie or individual is.

As to how that could have happened, it's unclear. A likely possibility is the occurrence of a sudden event that caused large-scale environmental trauma and wiped out majority of the Earth's species.

"Viruses, ice ages, successful new competitors, loss of prey — all these may cause periods when the population of an animal drops sharply," explains Jesse Ausubel, director of the Program for the Human Environment.

Such times give rise to sweeping genetic changes across the planet, causing new species to appear. However, the last time such an occurrence took place was 65 million years ago, when an asteroid hit the Earth and killed off the dinosaurs and half of all other species on the planet.

The study is published in the journal Human Evolution.

Photo: Lars Plougmann | Flickr

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