If there'd been no K-T Asteroid Strike - What Would Have Happened?

[Jokodo]

So did Reptiles ever invest extensively in their young? It seems to me that the Reptile strategy is to have as many young as possible, with quick development times. This likely precludes the social pressure necessary for cognitive ability to emerge, that is unless Mammals arise (which they did).

There have been some examples of reptiles that care for the young over the long term, including the Cretaceous, mosasaurs and other marine reptiles who evidently bore live young. Many dinosaurs did as well.

In terms of pro-social behaviors other than parenting, many carnivorous dinosaurs show evidence of pack hunting.

It definitely happened, although humans (and other primates) seem to be somewhat unique in that regard(...).

Fun fact: among great apes, humans are actually the species whose reproductive strategy comes closest to "have as many young as possible and hope some survive". The interbirth interval and age of weaning are higher in chimpanzees, gorillas, and especially orang-utans than in human hunter-gatherers. Even survival rate to adulthood is higher for orang utans than it was for humans until very recently.

 

[Politesse]

It definitely happened, although humans (and other primates) seem to be somewhat unique in that regard, and it may have taken a certain combination of factors to get there. Bipedalism, and opposable thumbs seem important as well.

Probably when living organisms become a social / intellectual species they look a lot like humans.

A possible factor in our case is one of the longest post-gestational parenting phases in the entire animal kingdom; partly because there was selective pressure for large brains but small os coxae, our young are pushed out so immaturely that they are unable to really support themselves at all for 5-6 years.

 

[Politesse]

Fun fact: among great apes, humans are actually the species whose reproductive strategy comes closest to "have as many young as possible and hope some survive". The interbirth interval and age of weaning are higher in chimpanzees, gorillas, and especially orang-utans than in human hunter-gatherers. Even survival rate to adulthood is higher for orang utans than it was for humans until very recently.

This is also likely due to the dangers of human childbirth and our long infancies. A chimpanzee troop can handle a lower rate of childbirth, because they lose far fewer of their young.

 

[steve_bank]

Humans have no mating season, it is 24/7.

Mama grizzly bears nurture young who learn behavior and what to eat by observation. It last for several years. Same with the big cats.

Elephants appear to have lomg lasting mother-children bonds.

From a bio I read of Bach he had something like 12 kids with different wives, only a few of which survived. That was the norm thrugh the 180s. You had to have enough kids to make things go.

As the level of material security grew and the industrial revaluation birth rates in som countries declined. That is why immigration here has been important.

Birth rates went down but we are still genetically driven to procreate all the time. Birth control.

 

[skepticalbip]

I saw Stephen J Gould speak in Seattle at Benaroya Hall to a packed house. He died a few years later.

Note to self:

Reject any speaking invitation from Benaroya Hall in Seattle.

 

[SLD]

I'm curious to speculate whether an intelligent species of Dinosaurs would have arisen, and if so, where, and whether they would have been able to dominate all of the continents eventually.

At the time of the K-T asteroid, T-Rex was the undisputed predator in North America. But he didn't rule everywhere. I think it's been pretty much debunked that Dinosaurs were already on their way out by the time of the K-T strike. So I would presume they would continue evolving. Would T-Rex and it's food sources continued an evolutionary arms race? Both getting bigger and bigger?

But would one of them evolved more intelligence and could that have made a difference? T-Rex's brain to body ratio, from what I read, could put it on the scale of Chimpanzee intelligence. But I'm not sure about their brain structure. Could they have evolved an even greater intelligence? And if so, how would that have changed them? Or is there simply no such evolutionary pressure on them because they're at the top of the food chain regardless? Could other predators evolve intelligence just in order to compete with T-Rex for food sources. Humans evolved with predators around them, but those predators weren't substantially larger than them. They could at least fend off attacks without modern weaponry.

Europe was mainly a series of Islands and the Dinosaurs were significantly smaller. Maybe it might have been easier for an intelligent species to arise their without the competition from a huge predator like T-Rex, or the other predators that were in South America, or other places.

I don't see the K-T asteroid as inevitable. It easily could have missed and plunged into the sun or some other body. From another article I read, there had been some collision in the asteroid belt about 100 million years before the strike.

Do you have a link in re. chimp-like brain/body ratio? Also, what about the size of the cerebrum?

I just finished Steve Brussate’s book on Dinosaurs. A fascinating book on their evolution. He said that their brain size to size ratio was about the equivalent to a chimp’s. He does say we can’t know for sure because it’s structure is very different. But generally intelligence correlates to brain weight to overall weight. Roughly.

 

[Jokodo]

Fun fact: among great apes, humans are actually the species whose reproductive strategy comes closest to "have as many young as possible and hope some survive". The interbirth interval and age of weaning are higher in chimpanzees, gorillas, and especially orang-utans than in human hunter-gatherers. Even survival rate to adulthood is higher for orang utans than it was for humans until very recently.

This is also likely due to the dangers of human childbirth and our long infancies. A chimpanzee troop can handle a lower rate of childbirth, because they lose far fewer of their young.

That seems a bit post-hoc. If it were the other way round, with inter-birth interval longest for humans, one could equally argue that it's because of humans' long infancy, to make sure the young don't compete with each other for the mother's attention while they still need her support.

 

[Angra Mainyu]

I'm curious to speculate whether an intelligent species of Dinosaurs would have arisen, and if so, where, and whether they would have been able to dominate all of the continents eventually.

At the time of the K-T asteroid, T-Rex was the undisputed predator in North America. But he didn't rule everywhere. I think it's been pretty much debunked that Dinosaurs were already on their way out by the time of the K-T strike. So I would presume they would continue evolving. Would T-Rex and it's food sources continued an evolutionary arms race? Both getting bigger and bigger?

But would one of them evolved more intelligence and could that have made a difference? T-Rex's brain to body ratio, from what I read, could put it on the scale of Chimpanzee intelligence. But I'm not sure about their brain structure. Could they have evolved an even greater intelligence? And if so, how would that have changed them? Or is there simply no such evolutionary pressure on them because they're at the top of the food chain regardless? Could other predators evolve intelligence just in order to compete with T-Rex for food sources. Humans evolved with predators around them, but those predators weren't substantially larger than them. They could at least fend off attacks without modern weaponry.

Europe was mainly a series of Islands and the Dinosaurs were significantly smaller. Maybe it might have been easier for an intelligent species to arise their without the competition from a huge predator like T-Rex, or the other predators that were in South America, or other places.

I don't see the K-T asteroid as inevitable. It easily could have missed and plunged into the sun or some other body. From another article I read, there had been some collision in the asteroid belt about 100 million years before the strike.

Do you have a link in re. chimp-like brain/body ratio? Also, what about the size of the cerebrum?

I just finished Steve Brussate’s book on Dinosaurs. A fascinating book on their evolution. He said that their brain size to size ratio was about the equivalent to a chimp’s. He does say we can’t know for sure because it’s structure is very different. But generally intelligence correlates to brain weight to overall weight. Roughly.

I'm pretty sure it's not brain size to size (which should be far smaller in T-Rex), but Encephalization quotient https://en.wikipedia.org/wiki/Encephalization_quotient , and I'm not sure its applicable to non-mammals in a reliable way.

 

[Politesse]

Fun fact: among great apes, humans are actually the species whose reproductive strategy comes closest to "have as many young as possible and hope some survive". The interbirth interval and age of weaning are higher in chimpanzees, gorillas, and especially orang-utans than in human hunter-gatherers. Even survival rate to adulthood is higher for orang utans than it was for humans until very recently.

This is also likely due to the dangers of human childbirth and our long infancies. A chimpanzee troop can handle a lower rate of childbirth, because they lose far fewer of their young.

That seems a bit post-hoc. If it were the other way round, with inter-birth interval longest for humans, one could equally argue that it's because of humans' long infancy, to make sure the young don't compete with each other for the mother's attention while they still need her support.

Not sure I'm quite following. How would that create selective pressure to the degree of impacting our evolutionary trajectory? Mothers can raise multiple childen simultaneously, and also (among all primates) are almost never the sole caretakers of their young anyway.

 

[hyzer]

I am reading Lone Survivors, how we came to be the only humans on earth, by Chris Stringer. Interesting read, lots of information about brain development and what led to humans as the only extant species from many.

 

[lpetrich]

T. rex was among the largest of the theropod dinosaurs ( Theropoda), and of the non-avian ones, there were lots of smaller ones, all the way down to pigeon-sized ones like Archaeopteryx.

The medium-sized ones seem to have been good candidates for the evolution of sentience, but they had a problem: they apparently did not have much dexterity in their front limbs, something crucial for building technology.

 

[Loren Pechtel]

T. rex was among the largest of the theropod dinosaurs ( Theropoda), and of the non-avian ones, there were lots of smaller ones, all the way down to pigeon-sized ones like Archaeopteryx.

The medium-sized ones seem to have been good candidates for the evolution of sentience, but they had a problem: they apparently did not have much dexterity in their front limbs, something crucial for building technology.

And without the ability to do something useful with intelligence it would not have evolved.

 

[skepticalbip]

T. rex was among the largest of the theropod dinosaurs ( Theropoda), and of the non-avian ones, there were lots of smaller ones, all the way down to pigeon-sized ones like Archaeopteryx.

The medium-sized ones seem to have been good candidates for the evolution of sentience, but they had a problem: they apparently did not have much dexterity in their front limbs, something crucial for building technology.

And without the ability to do something useful with intelligence it would not have evolved.

But "useful" covers quite a broad range, not just technology. The dolphin apparently found intelligence useful even though it has no hands, hasn't mastered fire, or produced any technology like clubs.

 

[Loren Pechtel]

T. rex was among the largest of the theropod dinosaurs ( Theropoda), and of the non-avian ones, there were lots of smaller ones, all the way down to pigeon-sized ones like Archaeopteryx.

The medium-sized ones seem to have been good candidates for the evolution of sentience, but they had a problem: they apparently did not have much dexterity in their front limbs, something crucial for building technology.

And without the ability to do something useful with intelligence it would not have evolved.

But "useful" covers quite a broad range, not just technology. The dolphin apparently found intelligence useful even though it has no hands, hasn't mastered fire, or produced any technology like clubs.

But they don't have anything like our intelligence. They have enough intelligence for what they use it for--coordinated hunting tactics.

 

[Jimmy Higgins]

But "useful" covers quite a broad range, not just technology. The dolphin apparently found intelligence useful even though it has no hands, hasn't mastered fire, or produced any technology like clubs.

But they don't have anything like our intelligence.

They have language, excellent hunters, communal set up, and a vibrant art scene.

The oddity for human evolution was possibly a failed negative mutation that had a long-term benefit. And maybe it was the ability to make with tools that allowed the negative mutation to not influence things as much. If an animal has a communal organization, it provides a stability that allows the negatives to be over looked as well and then the good mutations carry greater weight.

 

[bilby]

But "useful" covers quite a broad range, not just technology. The dolphin apparently found intelligence useful even though it has no hands, hasn't mastered fire, or produced any technology like clubs.

But they don't have anything like our intelligence.

They have language, excellent hunters, communal set up, and a vibrant art scene.

The oddity for human evolution was possibly a failed negative mutation that had a long-term benefit. And maybe it was the ability to make with tools that allowed the negative mutation to not influence things as much. If an animal has a communal organization, it provides a stability that allows the negatives to be over looked as well and then the good mutations carry greater weight.

There are no "good" or "negative" mutations, just those that lead to continued existence and those that lead to extinction. And even those outcomes are characteristic not of the mutation alone, but of the interaction of the mutation both with the phenotype of its possessors, and with the wider environment.

Evolution is not purposeful nor targeted. It just is.

The ability to manipulate and create tools is a feature, but it's not 'good' or 'bad' from an evolutionary perspective. It might lead to the continued survival of a species, or to its extinction. As long as it remains the former, then I guess it's not completely wrong to call that ability (and the many mutations that lead to it) "good", but even then it's very important that we don't mistake "good" for "virtuous".

They don't use tools or have the ability to manipulate macroscopic objects, but the smart long-term money is still on the bacteria. The bacteria always win in the end.

 

[skepticalbip]

But "useful" covers quite a broad range, not just technology. The dolphin apparently found intelligence useful even though it has no hands, hasn't mastered fire, or produced any technology like clubs.

But they don't have anything like our intelligence. They have enough intelligence for what they use it for--coordinated hunting tactics.

What humans identify as intelligence to rate other species is likely much different than those other species would identify as intelligence. How well would humans measure up on an intelligence test created by dolphins?

 

[Angra Mainyu]

But "useful" covers quite a broad range, not just technology. The dolphin apparently found intelligence useful even though it has no hands, hasn't mastered fire, or produced any technology like clubs.

But they don't have anything like our intelligence. They have enough intelligence for what they use it for--coordinated hunting tactics.

What humans identify as intelligence to rate other species is likely much different than those other species would identify as intelligence. How well would humans measure up on an intelligence test created by dolphins?

I don't know. Do they have the intelligence to create an intelligence test?

 

[skepticalbip]

What humans identify as intelligence to rate other species is likely much different than those other species would identify as intelligence. How well would humans measure up on an intelligence test created by dolphins?

I don't know. Do they have the intelligence to create an intelligence test?

Dunno. Maybe they are smart enough to not judge other species intelligence by how closely they mimic dolphin thinking.

 

[bleubird]

https://sites.google.com/site/h2g2theguide/Index/d/919377