ZAP // Fabio Paiva; IvanM77 / Depositphotos
A new study suggests that evolution progresses at different speeds, especially when a large group of organisms first emerges.
The famous analogy, which we remember hearing from the astrophysicist Carl Sagantells us that, if the entire geological history of the Earth were compressed into a single yearmodern humans would only have appeared around the 11:50 pm on New Year’s Eve.
Recorded human history suggests that this may have happened even later than that. Considering our planet’s immense past, it is absolutely remarkable how much our humble species has learned in those last few minutes before midnight.
However, although we have developed a reliable model to explain how life emerged from single-celled organisms to the complex web we see today, in the form of Charles Darwin’s Theory of Evolutionimportant questions remain, note a .
Chief among them is the apparent fossil gap between the time when scientists believe complex life emerged and when we observe very first fossils — in this case, in the form of a worm-like creature of the genus Treptichnusdated to around 538 million years ago.
We are missing a missing link in Evolution, or famous Darwin’s Dilemma.
Using the idea of Molecular Clockwhich, at its most basic level, consists of working retrospectively through the genetic record assuming that genetic changes occur constantlyscientists estimate that there is a gap of approximately 30 million years which is currently not explained by what we see in fossils.
Naturally, fossils are difficult to find at firstand one theory is that these first animals They were just incredibly small.due to low oxygen levels, and therefore difficult to find.
However, one of Graham Buddpaleontologist at Uppsala University, and Richard Mannmathematical ecologist at the University of Leeds, published last year in Systematic Biology, questions the very idea of a Molecular Clockand suggests that the evolution does not “advance” so steadily as we might expect.
In their study, Budd and Mann, both with long experience in analyzing the Molecular Clock and having even developed mathematical models to determine how the main groups of animals arise in evolution, present a different model, which they call Covariant Evolutionary Paceto help explain some of the inconsistencies between the molecular clock and the fossil record.
“The Covariant Evolutionary Rhythm model predicts that diversity is dominated by one small number of extremely large clades in any historical period, including the present”, explain the two researchers.
According to this model, it is expected that these large clades are characterized by explosive initial radiation accompanied by high rates of molecular evolution, and that it is likely that existing organisms evolved from species with unusually fast evolutionary ratesexplain the authors.
In an article in , the evolutionary biologist Max Telfordfrom University College London, explains the model by demonstrating how it variable pace it could drastically reduce the time gap that we expect between the emergence of complex life and the first observable fossils.
Telford explains that humans and chimpanzeesfor example, are separated by six million years of evolution. To put it simply, if there are six genetic changes between these two species and the molecular clock is constant, this suggests one genetic change every million years.
However, the Covariant Evolutionary Rhythm model suggests that when a large group of organisms emerges, evolution effectively accelerates.
This would seem like more time was passingwhen, in reality, the evolution was just going through rapid advancementdifferentiating into several groups that eventually emerged in the fossil record.
“While the accelerated clock idea needs to be tested,” Telford wrote, “could explain other discrepancies between molecular clocks and the fossil record”.
Ready. Everything we knew about chronology of evolution may be at issue. If Darwin were alive, he would definitely have a huge headache.
