Great white sharks older than previously thought, study says
{{#rendered}} {{/rendered}}Sharks have been on Earth for nearly 400 million years, but a variant of the great white that lives in the Mediterranean has been around for 3.2 million years, significantly longer than experts previously thought, according to a new study.
The research, published in the Journal of Biogeography, looked at DNA sequences of Mediterranean white sharks and found they're closer genetically to those in the Pacific Ocean than those that live in the Atlantic Ocean.
"White sharks have a complex evolutionary history, they are unusual," the study's lead author, Agostino Leone, said in a statement. "They evolved into sedentary populations scattered around the globe. Among these, there are the Mare Nostrum white sharks, which are really unique."
{{#rendered}} {{/rendered}}Historical Great White Shark jaws front. Credit: University of Bologna
370M-YEAR-OLD COMPLETE SHARK SKELETON FOUND FOR FIRST TIME EVER
"White sharks in the Mediterranean have a very low genetic variability, which may hint at a very small and endangered group of sharks," Leone added.
Mediterranean great whites have not been as well studied as other great whites, due in large part to population declines. In August 2019, Fox News reported that great whites had not been spotted off South Africa for 18 months, baffling experts.
{{#rendered}} {{/rendered}}In an effort to solve the lack of research, experts have begun to study teeth, jaws and vertebrae from the past 200 years in museums and private collections. Thanks to technological advancements in DNA sequencing, researchers were able to compare the Mediterranean great whites to other great white populations around the globe.
"This new data allowed us to observe the biological diversity of white sharks living in the Mediterranean," Leone said. "By analyzing and comparing different specimens, we were able to estimate that the white shark population in the Mediterranean started to evolve differently from other cognate populations around 3.2 million years ago. This essentially proves that those theories about sharks colonizing the Mediterranean around 450,000 years ago are wrong."
{{#rendered}} {{/rendered}}Leone and the other researchers have found that the Mediterranean sharks originated in the Pacific, traveling through the Central American waterway before the Isthmus of Panama was formed, some 3.5 million years ago.
As a result of the shifting geographical landscapes, several drastic changes occurred in the climate, which may have caused several fish species to go extinct, impacting the great white species in the Atlantic.
Given the sparse population in the Mediterranean, Leone said it's likely that these great white sharks are a "small, endangered community."
{{#rendered}} {{/rendered}}"To save them, it is fundamental to act quickly: Their extinction would be detrimental to the ecological balance of the Mediterranean Sea as well as to the already highly unstable global situation of these majestic sea predators," Leone explained.