Human Evolution if Dinosaurs never died off

Question

Assuming there were no extinction level threats to the dinosaurs, and they never fully died off (and survived the following ice ages), how would this affect the evolution and technology use of humans if at all?

Given that a T-rex is about the same size and speed as an elephant, and velociraptors are slightly faster than wolves and slower than lions, I presume that we would just handle these dangerous creatures much the same as we handle similar and the major difference would be in fauna and flora.

My question is not how would we survive with them as Could humans survive with dinosaurs? answers, but specifically how them surviving would affect our evolution and technology development.

The linked question specifically states "Okay, quite a few people have asked what technological level the humans are at. Well these humans were on a generation ship before so I would assume space age level." Where i am asking if humans could develop and if so how would their tech change if at all to deal with these creatures.

Very specifically, the other question asks if a pre-existing human civilization could survive if introduced in an environment where Dinosaurs still roamed the Earth. This question is asking if humans could still EVOLVE on such a planet, and if so, what major biological and psychological differences might there be on such a planet.

Answer 1

It is highly unlikely that anything just like us would have evolved had the dinosaurs not gone extinct.

Evolution is essentially chaotic (in the technical sense) and is driven by accidental mutation and accidental matings (both driving randomness) and natural selection weakly selecting each of the new genomes created by random mutations and random egg-meets-sperm events. This goes on over millions of generations.

Natural selection will still result in highly adapted organisms and may well produce intelligence, but it would be very unlikely to look much like us and certainly would not be human in the biological sense of being interfertile.

Would intelligence in any form evolve on a dinosaur-dominated planet? Hard to say because we don't really understand how intelligence evolves or how likely it is to evolve. The evidence is that in our sample of one, it has evolved once in the last hundred million years. This allows us to make a (weak) estimate of intelligence taking on average 100,000,000 years to evolve with huge uncertainty. (Not a good estimate, but it's an estimate based on actual evidence rather than speculation.)

On the more speculative side, we think that social animals are more likely to evolve intelligence. (Basically, that we evolved intelligence because we lived in troops which started out looking a lot like modern baboon troops, with intense social interaction. We evolved intelligence because it allowed us to lie better and to gain higher social position in the troop.

So look for whatever ultimately evolves to come from a social animal.

Answer 2

The un-fun route is to theorize that larger, intelligent mammals would never have had the chance to develop b/c the dinosaurs would have filled every ecological niche.

Alternately, the dominant, human-intelligence life would be reptilian, like the Sleestack. This could be an entertaining avenue, having fun with presumed differences between humans and humanoid reptilians.

Alternately, mammals and monkeys do evolve, but must be absolute ninjas to survive among the ferocious dinos. The baseline human in this scenario would have to be a full-on Strider level Ranger: able to move silently, hide impeccably, stay upwind of threats, and be stronger, faster and more agile than we contemporary humans.

These humans might evolve to be small like Homo floresiensis, to escape the notice of the larger dinosaurs, or, they could evolve from the largest apes, like Gigantopithecus or even larger.

You'd likely still need some environmental disaster to open up ecological niches for the alt-human evolution, but the disaster could be smaller scale, perhaps restricted to a single continent like Australia.

You could also look to a model where Yeti evolve first, since high alpine regions would be inhospitable to many dinosaurs, and humans evolve subsequently from Yeti, losing their hair over millions of years.

Answer 3

There were several extinction events that could have set the dinosaurs back without killing them off, allowing mammals to have an easier time flourishing for a while. You could have the dinosaurs make a comeback later without wiping out the primates.

Humans would likely be faster, perhaps able to still run on all fours to run away from giant predatory dinosaurs or even angry plant eaters. This also means they might have less endurance and would maybe have to eat more plant foods since our endurance irl is unique in the animal kingdom bc we're equipped to run animals to exhaustion. BUT this also means we would have GIANT bellies, which would be required to extract the same amount of nutrition from plant foods as we currently do from meat. This would also lead to humans being less intelligent since the calories required back in the day to support a huge brain would not have been available in plant form.

There is one way to get around this - you could also play around with plant evolution, giving humans a calorie dense food source that could replace meat calories, like a tuber perhaps. Only thing is you would have to work out how the humans evolved to out-compete other animals for the same calorie dense food source. Think BEARS. You could also play around with the enzymes humans evolved with, so we could extract calories from things like plant fiber without having to ferment it like a gorilla with a big pot belly. Think termites.

Alternatively, going with the running-on-all-fours idea, humans could have developed a more stealth focused hunting strategy, sneaking up on and then running down prey animals, kinda like big cats. Humans would have to be bigger, or at least more muscular and more compact with larger lungs.

Answer 4

Assuming there were no extinction level threats to the dinosaurs, and they never fully died off (and survived the following ice ages), how would this affect the evolution and technology use of humans if at all?

If dinosaurs never went extinct, and somehow survived the following ice ages up to the current era, chances are dinosaurs would have evolved to be the dominant species on Earth.

Most likely, if their evolution was not halted, they will eventually become Sentient, or develop higher mental functions like language, maths, arts, etc.. They might also develop a proto-society, which may eventually evolve to villages, cities, metropolis, etc..

As they continue evolving their mental faculties they will become some sort of Reptilian Race, now capable of things similar or more advanced to the ones us Humans are able to do now. It's also likely that they will start draining resources from Earth in a faster manner, and as a side effect prevent other species, like mammals and primates, from evolving into Sentient/Intelligent dominant species.

In short, I'd say that the dominant species on earth would have been this Reptilian derivative, and not us, some Primate derivative.

Answer 5

Assuming that the dinosaurs survived, and somehow humans also evolved to what be what they are now, so dinosaurs exist alongside humans, humans would have hunted most of them to extinction, or at least submission.

Humans don't do well at tolerating animals that threaten humans. Most dinosaurs that live in areas that humans want to live would be killed, domesticated, or driven off.

There would still be dinosaurs in places that humans don't really want to live, such as jungles, savanas, wilderness, etc. which are the same places that the big predators live now.
Things like lions, tigers, and bears live in these places mostly by leaving humans alone. Humans still go into those places to hunt the animals though, so they wouldn't be completely safe.