Sixty-six million years in the past, an asteroid hit the Earth with the pressure of 10 billion atomic bombs and altered the course of evolution. The skies darkened and crops stopped photosynthesising. The crops died, then the animals that consumed them. The meals chain collapsed. Over 90% of all species vanished. When the mud settled, all dinosaurs besides a handful of birds had gone extinct.
But this catastrophic occasion made human evolution potential. The surviving mammals flourished, together with little proto-primates that may evolve into us.
Imagine the asteroid had missed, and dinosaurs survived. Picture extremely developed raptors planting their flag on the moon. Dinosaur scientists, discovering relativity, or discussing a hypothetical world by which, extremely, mammals took over the Earth.
This would possibly sound like unhealthy science fiction, however it will get at some deep, philosophical questions on evolution. Is humanity simply right here by likelihood, or is the evolution of clever tool-users inevitable?
Brains, instruments, language and large social teams make us the planet’s dominant species. There are 8 billion Homo sapiens on seven continents. By weight, there are more humans than all wild animals.
In the Eighties, palaeontologist Dale Russell proposed a thought experiment by which a carnivorous dinosaur evolved into an intelligent tool user. This “dinosauroid” was big-brained with opposable thumbs and walked upright.
It’s not unimaginable however it’s unlikely. The biology of an animal constrains the course of its evolution. Your start line limits your endpoints.
If you drop out of faculty, you most likely will not be a mind surgeon, lawyer or Nasa rocket scientist. But you could be an artist, actor or entrepreneur. The paths we soak up life open some doorways and shut others. That’s additionally true in evolution.
Consider the scale of dinosaurs. Beginning within the Jurassic, sauropod dinosaurs, Brontosaurus and kin evolved into 30-50 tonne giants as much as 30 metres lengthy – ten instances the load of an elephant and so long as a blue whale. This occurred in a number of teams, together with Diplodocidae, Brachiosauridae, Turiasauridae, Mamenchisauridae and Titanosauria.
This occurred on totally different continents, at totally different instances and in numerous climates, from deserts to rainforests. But different dinosaurs residing in these environments did not turn into supergiants.
The frequent thread linking these animals was that they had been sauropods. Something about sauropod anatomy – lungs, hole bones with a high strength-to-weight ratio, metabolism or all these things – unlocked their evolutionary potential. It allow them to develop huge in a means that no land animals had ever earlier than, or have since.
Likewise, the carnivorous dinosaurs repeatedly developed large, ten-metre, multi-tonne predators. Over 100 million years, megalosaurids, allosaurids, carcharodontosaurids, neovenatorids and at last tyrannosaurs developed large apex predators.
Dinosaurs did huge our bodies properly. Big brains not so much. Dinosaurs did present a weak pattern in the direction of elevated mind dimension over time. Jurassic dinosaurs like Allosaurus, Stegosaurus and Brachiosaurushad small brains.
By the late Cretaceous, 80 million years later, tyrannosaurs and duckbills had developed bigger brains. But regardless of its dimension, the T. rex mind nonetheless weighed simply 400 grams. A Velociraptor mind weighed 15 grams. The common human mind weighs 1.3 kilograms.
Dinosaurs did enter new niches over time. Small herbivores turned extra frequent and birds diversified. Long-legged varieties developed afterward, suggesting an arms race between fleet-footed predators and their prey.
Dinosaurs appear to have had more and more complicated social lives. They began residing in herds and developed elaborate horns for preventing and show. Yet dinosaurs principally appear to repeat themselves, evolving large herbivores and carnivores with small brains.
There’s little about 100 million years of dinosaur historical past to trace they’d have finished something radically totally different if the asteroid hadn’t intervened. We’d possible nonetheless have these supergiant, long-necked herbivores and big tyrannosaur-like predators.
They might have developed barely larger brains, however there’s little proof they’d have developed into geniuses. Neither is it possible that mammals would have displaced them. Dinosaurs monopolised their environments to very finish, when the asteroid hit.
Mammals, in the meantime, had totally different constraints. They by no means developed supergiant herbivores and carnivores. But they repeatedly developed huge brains. Massive brains (as massive or bigger than ours) developed in orcas, sperm whales, baleen whales, elephants, leopard seals and apes.
Today, a couple of dinosaur descendants – birds like crows and parrots – have complex brains. They can use tools, speak and depend. But it is mammals like apes, elephants and dolphins that developed the most important brains and most complicated behaviours.
So did eliminating the dinosaurs assure mammals would evolve intelligence?
Well, possibly not.
Starting factors might restrict endpoints, however they do not assure them both. Steve Jobs, Bill Gates and Mark Zuckerberg all dropped out of college. But if dropping out robotically made you a multibillionaire, each faculty dropout can be wealthy. Even beginning in the precise place, you want alternatives and luck.
The evolutionary historical past of primates suggests our evolution was something however inevitable. In Africa, primates did evolve into big-brained apes and, over 7 million years, produced modern humans. But elsewhere primate evolution took very totally different paths.
When monkeys reached South America 35 million years in the past they only developed into extra monkey species. And primates reached North America at the least three separate instances, 55 million years ago, 50 million years ago, and 20 million years ago. Yet they did not evolve right into a species who make nuclear weapons and smartphones. Instead, for causes we do not perceive, they went extinct.
In Africa, and Africa alone, primate evolution took a novel course. Something about Africa’s fauna, flora or geography drove the evolution of apes: terrestrial, big-bodied, big-brained, tool-using primates. Even with the dinosaurs gone, our evolution wanted the precise mixture of alternative and luck.
(Except for the headline, this story has been edited by biznewz employees and is printed from a syndicated feed.)
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