T-Rex May Be More Similar to Humans Than We Thought
We both likely evolved as endurance runners
Not many people when face-to-face with a T-rex skeleton have thought, “Wow, that’s just like me!”
Humanoid is not the first adjective to come to mind for a skull whose bite force is best measured against the weight of cars.
Yet a new study suggests that humans and Tyrannosaurus rex may actually have evolved to fill similar niches. In a sense, that’s not all that surprising: we’re both apex predators, we’re both bipeds, and we have basically the same size arms.
What this new study adds is that we also both may have evolved as endurance hunters/scavengers.
The Persistence Hunting Hypothesis
To make sense of this, let’s first back up to the endurance running hypothesis. This interpretation of human evolution starts with the observation that we’re pretty underwhelming, as far as apex predators go. We’re not terribly strong, we don’t have menacing teeth or claws, and we’re at best middling in a sprint.
However, we humans are remarkably well-adapted for endurance running. We have all the right tendons and ligaments, our toes are the right length, and we have exquisite springs in our Achilles' tendons and the arches of our feet, which help us maximize efficiency. We also have an uncanny ability to sweat, which, despite the disadvantage of washing sunscreen into our eyes, is a far more effective way to cool down than panting, as many other animals do.
To some, this suggests that at some point in our evolutionary past, we may have been persistence hunters and/or scavengers. Our ancestors wouldn’t have been able to catch prey in a sprint, but they could have kept chasing them down at a moderate pace until the animals were too exhausted and overheated to keep running away.
In the related scavenging scenario, distance running would have helped early humans get to a fresh carcass, perhaps signaled by circling birds, before it was gone.
Marathonus Rex?
While Jurassic Park has T. rex chasing down speeding Jeeps, a new study suggests that may not be completely accurate. In the real Jurassic, Tyrannosaurus probably simply stalked Jeeps until they ran out of gas.
Again like humans, T. rex evolved relatively long legs. For most animals, longer legs generally correlate with faster running speed — compare, for example, a whippet to a wiener dog. However, since T. rex was so large, its top speed was probably limited by its bulk, not by its inseam.
That means the long legs of T. rex must have evolved for some reason other than speed. According to the study, that reason may have been endurance. The longer legs carried T. rex further with each step, helping it cover more ground with less energy.
This isn’t to say T. rex was exactly a slowpoke; its downward revised top speed was still around 12 miles per hour, giving it about a 5-minute mile. However, that’s a lot slower than the 40 miles per hour scientists had been bandying about before, and nowhere near today’s speediest predators, like cheetahs.
Of course, as with any interpretation of the distant past, both ancient human and Tyrannosaurus hunting practices remain open to debate. The persistence hunting hypothesis for human evolution, in particular, is not without its detractors. However, the next time your dog gets off-leash and you have to chase it around for 10 minutes before it gets tired and sits there panting while you collar it, just think, you may be channeling your inner T. rex.
