The first canines emerged in North America, where climate change transformed them from mongoose-like forest dwellers into pursuit-and-pounce predators, new research finds.
The discovery adds to the growing body of evidence that climate change dramatically affects the evolution of both predators and their prey.
"It's reinforcing the idea that predators may be as directly sensitive to climate and habitat as herbivores," co-author Christine Janis, a professor of ecology and evolutionary biology at Brown University, said in a press release. "Although this seems logical, it hadn't been demonstrated before."
Photos: The Earliest Dogs
The study, published in the journal Nature Communications, also reinforces prior findings that the earliest ancestors of dogs were native to North America.
"Dogs, that is the family Canidae, originated in North America, and did not spread to other parts of the world until around 7 million years ago, when they turn up in Africa and Eurasia, and they got to South America around 2 million years ago," Janis told Discovery News.
She added, "Only the subfamily Caninae ever made it out of North America; the Hesperocyoninae and Borophaginae were exclusively North American."
Janis conducted the new research with lead author Borja Figueirido of the Universidad de Málaga, Jack Tseng of the American Museum of Natural History and their team.
The scientists examined the elbows and teeth of 32 species of dogs spanning the period from around 40 million years ago to 2 million years ago.
Janis explained, "The elbow is a really good proxy for what carnivores are doing with their forelimbs, which tells their entire locomotion repertoire."
Video: Are Some Dog Breeds More Aggressive?
As a result, the researchers were able to identify distinct patterns in the fossils that they believe corresponded to climate change.
The scientists determined that as forests slowly gave way to open grasslands due to cooler yet drier conditions, canines evolved from being wily ambush predators into hunters like modern coyotes or foxes that are known as pursuit-pounce predators.
As time went on, the predators further evolved into what the researchers say were "dogged, follow-a-caribou-for-a-whole-day pursuers like wolves in the high latitudes."
Canine elbows at first could swivel (palms could be inward or down), permitting grabbing and wrestling prey. They gradually evolved to become always downward-facing and specialized for endurance running.
While all of this was happening, the canines' teeth evolved to become more durable, perhaps with, as the researchers noted, "the need to chow down on prey that had been rolled around in the grit of the savannah, rather than a damp, leafy forest floor."
Dogs' Ancestors Likely Domesticated Themselves
The authors further explained that it was not advantageous to operate as a pursuit-and-pounce predator until there was room to run.
"There's no point in doing a dash and a pounce in a forest," Janis quipped. "They'll smack into a tree."
Since canines and other predators appear to have evolved with climate change over the last 40 million years, then they likely will continue to do so in response to the human-created climate change underway now, according to the researchers.
The new findings could therefore help to predict the effects we are setting into motion.