(ORDO NEWS) — Imagine that 66 million years ago an asteroid flew by and the dinosaurs survived. Imagine highly evolved predators planting their flag on the moon.
Dinosaur scientists discovering the theory of relativity or discussing a hypothetical world in which, unbelievably, mammals have taken over the Earth.
This may sound like weird science fiction, but it raises some deep philosophical questions about evolution . Humanity appeared by chance or is the evolution of intelligent tool users inevitable?
Brain, tools, language and large social groups make us the dominant species on the planet. There are 8 billion Homo sapiens on seven continents. There are more people by weight than all wild animals.
We have changed half of the earth’s land mass to feed ourselves. It can be argued that beings like humans must have evolved.
In the 1980s, paleontologist Dale Russell proposed a thought experiment that turned a carnivorous dinosaur into an intelligent tool user. This “dinosaur” had a large brain with opposable thumbs and walked upright.
It’s not impossible, but unlikely. The biology of an animal limits the direction of its evolution. Your starting point limits your end points.
By the end of the Cretaceous period, 80 million years later, tyrannosaurs and platypuses had developed larger brains.
But despite its size, the T.rex brain still weighed only 400 grams. The brain of a Velociraptor weighed 15 grams. The average human brain weighs 1.3 kilograms.
In the 100 million years of dinosaur history , there is little to indicate that they would have done something radically different if an asteroid had not intervened.
We would probably still have these supergiants, long-necked herbivores and huge tyrannosaur-like predators.
They may have developed slightly larger brains, but there is little evidence that they turned into geniuses.
It is also unlikely that mammals would have displaced them. Dinosaurs monopolized their habitat until the very end when an asteroid hit.
Meanwhile, mammals had other limitations. They never evolved into supergiant herbivores and carnivores. But they repeatedly developed large brains.
Massive brains (as big or bigger than ours) have evolved in killer whales, sperm whales, baleen whales, elephants, leopard seals, and monkeys.
Today, several descendants of dinosaurs birds such as crows and parrots have complex brains. They can use tools, speak and count.
But it is mammals like monkeys, elephants and dolphins that have developed the largest brains and most complex behaviors.
So did the destruction of dinosaurs guarantee the development of intelligence in mammals? Well, maybe not.
The evolutionary history of primates suggests that our evolution was anything but inevitable.
In Africa, primates evolved into big-brained apes and produced modern humans over 7 million years. But elsewhere, primate evolution followed very different paths.
When monkeys reached South America 35 million years ago, they simply evolved into other kinds of monkeys.
And primates reached North America at least three times: 55 million years ago, 50 million years ago, and 20 million years ago.
However, they have not evolved into the kind that produces nuclear weapons and smartphones. Instead, for reasons we don’t understand, they became extinct.
In Africa, and only in Africa, primate evolution has taken a unique direction.
Something in African fauna, flora, or geography led to the evolution of great apes: terrestrial, large-bodied, big-brained, tool-using primates.
Even with the extinction of the dinosaurs, our evolution needed the right mix of opportunity and luck.
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