Also, this debate has implications for the potential success of SETI. If biological determinism is the case, then it's more likely SETI will detect an alien civilization at some point in the future. This is because we would expect any planet that supports complex life to eventually evolve a similar enough species to ourselves.

However, if evolution is more on the contingent side, then the likelihood is greater we're alone in our region of space (however many light years out SETI could reasonably hope to detect a civilization). This is also brought up in the first chapter. But again, it raises the question of whether it's science or philosophy, and what the boundary is between the two for such matters.

As you alluded to, it has, and is been extensively looked at in context of the Fermi Paradox, and SETI.

The reasoning is that given the vast number of galaxies, stars, and as we recently have come to know also planets, there should be a lot of extraterrestial civilizations.

There are a lot of potential reasons why we haven't detected them yet, and the evolution of human-like brains is only one of them.

The larger debate is more philosophical i'd say because it involves a lot of speculation and estimation, while the investigation into the different reasons can be scientific. For instance, investigation into whether abiogenesis is likely can be done with experiments or by looking for evidence on other planets or moons.

And the possibility of developing intelligent brains can be informed by archealogy that could yield more information about the evolution of other species on our planet, or by finding evidence on other planets with life where intelligent life has or has not developed etc...

I think the development of sufficiently intelligent brains (for civilization) is, at this moment, one of the more likely candidates for being one of the main reason why we haven't detected aliens yet. I don't know what arguments Jonathan Losos gives for concluding that the evolution of a species like us is likely, but from what I've read that doesn't seem to be the consensus now. Large brains seem to bring with them a lot of evolutionary disadvantages, certainly in the beginning. An other argument is that other species on earth generally have gone through many more generations of evolution than primates, and yet haven't develloped more intelligent brains.

And on a more general note, historically philosophy has spawned off more and more sciences as methods and technological development became more advanced, and so the subjects could be investigated scientifically. For instance natural philosophy speculating about the nature of things became more scientific (physics and chemistry) with the invention of the microscope etc...

I think that's the moment it stops being philosophy and becomes a science. So generally this is when we can test theories with evidence, measurements.

As you no doubt know, Poppers famous criterium for science was the possibility of falsification. This has been refined over the years because it wasn't allways all that satisfying. You might want to look into the demarcation problem for more info on that.

Conway's argument, which is based on convergence of various features across non-related species such as eyes, is that evolution would have led to something like us even if the dinosaurs had not gone extinct. Gould's argument was that evolution would most likely result in completely different life forms. The canonical examples here are from Australia, such as Koalas, Kangaroos and Platypuses. — Marchesk

It is interesting to contemplate these kinds of ideas. It really is a toss-up between either option simply because we don't have enough information to even begin to lean one way or another. Let me just say that the marsupials would not be able to compete with the placental mammals and would have died out had they not been cut of from the the rest of the world "down under", so they would not be a good canonical example. We still don't know exactly how life started and how likely it is to start on any given planet, etc., so it can still go either way.

There's an even deeper question here. Rewinding the clock to rerun evolution is counterfactual, as Losos points out. It's a thought experiment. As such, is it more in the domain of philosophy than science? Is this topic a philosophical one? — Marchesk

That's the thing: What IS philosophy without science to prove or disprove philosophy's musings? You can sit and ponder all day about the likelihood of humanoid reptiles building a civilization, or how the mind relates to the body, etc., but it doesn't get you anywhere without acquiring more data, forming an educated guess, and then testing that guess.

It seems to me that philosophy is a science. The conclusion of one branch of the investigation of reality must not contradict those of another. All knowledge must be integrated.

At root, science identifies and integrates sensory evidence (which is the nature of reason). Science is essentially based, not on experiment, but on observation and logic; the act of looking under a rock or into a telescope is the quintessentially scientific act. So is the act of observing and thinking about your own mental processes--a scientific act is completely private. (Proof of one's conclusions to others comes later, but that is argumentative, not inquisitive.) Science is willing to accept and integrate information from any observational source, without concern about persuading other people.

It seems to me that philosophy hasn't come to any conclusions. It is science that provides those while philosophy is more like the impetus for seeking those answers, and asking more questions based on the new knowledge science has provided - like the one in your OP. You just have to wait for science to acquire more data and objective means of testing hypotheses derived from the initial data. Philosophers can be so impatient sometimes. :wink:

Let me just say that the marsupials would not be able to compete with the placental mammals and would have died out had they not been cut of from the the rest of the world "down under", so they would not be a good canonical example. — Harry Hindu

Kangaroos seem like they would do just fine. But there are other examples from outside Australia. Elephants were mentioned in the book. There's only been a few species of elephants and no example of convergent evolution of elephant-like organisms. They appear to belong to a unique line. Same can be said for Hominids, although we do have closer living relatives in the great apes. The closest living relatives to Elephants are probably Manatees and Dugongs.

I find it very unlikely something like Humans would have evolved without the extinctions of the dinosaurs. What type of reptilians do they even suggest would have led to humans evolving? Two of the biggest adaptations that led humans to evolving the way they did was the brain and the stamina humans have. (our ability to generate a thin layer of sweat) I don't see how these would develop in a world dominated by massive reptiles.

There's an even deeper question here. Rewinding the clock to rerun evolution is counterfactual, as Losos points out. It's a thought experiment. As such, is it more in the domain of philosophy than science? Is this topic a philosophical one? — Marchesk

It's speculation based upon untestable scientific hypotheses. There also is minimal effort put in this enterprise, largely because it has no practical significance so the "what if the dinosaurs lived" question hasn't gotten much funding. What it really is is science fiction. It'd make for a cool movie. I'd pay to watch it.

My assumption is that evolution would still have promoted intelligence and those that learned to kill the dinosaurs, like those that killed the bears and lions, would have eventually prevailed. Or maybe we'd all look like ET and there'd be flying bicycles.

Two of the biggest adaptations that led humans to evolving the way they did was the brain and the stamina humans have. (our ability to generate a thin layer of sweat) I don't see how these would develop in a world dominated by massive reptiles. — yatagarasu

Also that our ancestors came out of the trees. I don't know that the Velociraptor line would have gone to the trees for long enough to develop the kind of hands we have.

Or maybe we'd all look like ET and there'd be flying bicycles. — Hanover

Or have acid for blood.

Or maybe we'd all look like ET and there'd be flying bicycles. — Hanover

THIS. NOW! :grin:

Also that our ancestors came out of the trees. I don't know that the Velociraptor line would have gone to the trees for long enough to develop the kind of hands we have. — Marchesk

Many things (like that) make the question fun to think about (at least for a bit), but not very useful or that feasible. What pH level though? I want to be able to melt my worst adversaries at least! :halo:

Star Trek 2nd Generation is as valid as any other source here, so let me site the case of a virus or force field or oil slick or something that caused the crew of the Enterprise to regress backward a few million years. Most of the crew became apes, of course, and were depicted by chimps who didn't receive so much as a penny in royalties for their efforts.

The Klingon Worf reverted to his reptilian ancestor.

So, there you have it -- humans could have evolved from dinosaurs (look at those problem solving corvids). We probably would have looked more like Worf.

Now where the Cardassians (not kardashians) came from, or the Rumulans has not been revealed. The Kardashians came from Planet 9 in Outer Space and descended from crotch lice.

The Kardashians came from Planet 9 in Outer Space and descended from crotch lice. — Bitter Crank

Truly a great example of convergent evolution.

This has taken a silly scifi turn, but it is an ongoing debate in biology (not the Kardashian part, I sincerely hope).

The whole group of dinosaurs were around for what... 100 million years? A long time, and they filled many niches. Any body happen to know how big the brain case of velociraptors was? They'df be my choice for "most likely to make it to sentience in another million years" -- not because of their role in Jurassic Park, but because they were relatively small hunters. They didn't have T Rex's size advantages.

On a more specifically biological point, I would like to point out that human beings are descendants of fish -- vertebrates. Fish established the basic facts of life for vertebrates, T Rex, small mammals, and birds--and us. How much fish is in us? Quite a bit, actually. For instance, our inner ears contain repurposes parts of fish jaws -- two relatively mobile bones which over time were incorporated into the mammalian jaw, and eventually into the inner ear.

For a good time, read Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body by Neil Shubin

I find it very unlikely something like Humans would have evolved without the extinctions of the dinosaurs. What type of reptilians do they even suggest would have led to humans evolving? Two of the biggest adaptations that led humans to evolving the way they did was the brain and the stamina humans have. (our ability to generate a thin layer of sweat) I don't see how these would develop in a world dominated by massive reptiles. — yatagarasu

Also that our ancestors came out of the trees. I don't know that the Velociraptor line would have gone to the trees for long enough to develop the kind of hands we have. — Marchesk

Two things. First, your mistake here is that you are considering a tiny counterfactual neighborhood of human evolutionary history. It is unreasonable to suggest that sweat glands or arboreal habitat are a sine qua non for evolving human-like intelligence in any species, just because these factors (allegedly) played an important role the evolution of human intelligence.

Second, dinosaurs are not extinct. Look out the window and you'll likely see some. When you think of dinosaurs, you might have a picture of comic-book giant reptiles in your imagination; if so, you are seriously underestimating the potential for variety in that lineage. Also, what @Bitter Crank said: if you didn't know better, would you expect fish to evolve into something like us?

if you didn't know better, would you expect fish to evolve into something like us? — SophistiCat

Maybe not if the tape was rewound, or another planet.

Second, dinosaurs are not extinct. Look out the window and you'll likely see some. — SophistiCat

I think the meaning of the dinosaurs going extinct where the big ones occupying all the niches that kept mammals to a small size.

Maybe not if the tape was rewound, or another planet. — Marchesk

Yeah, I have no definite opinion on this myself. Was there always a potential niche for a land-dwelling, mid-size generalist with highly developed cognitive faculties, just waiting to be filled? I am no Gould or Conway Morris, but I think that even coming from the best theoreticians, any conjecture on alternative evolutionary history would be very speculative.

One interesting perspective on this question comes from the field of thermodynamics, of all things. Our universe (or at least the part of it that we inhabit), on average, has a rather low entropy. It is a far-from equilibrium thermodynamic system. A system that is at thermodynamic equilibrium is static; nothing interesting happens there. A system that is only slightly disturbed will evolve towards equilibrium in a fairly orderly fashion - this is what we learn in high school and undergraduate physics. But in far-from-equilibrium systems more interesting things can happen, such as spontaneous formation of persistent energy-dissipating structures. (This goes against the common stereotype that equates entropy with disorder!)

It is said that, looking from the global thermodynamic perspective, things like stars and planets and complex chemistry - and life - play the role of energy-dissipating, entropy-producing subsystems that spontaneously form as part of the dynamics of a far-from-equilibrium system that is our universe. As one might expect, some of these subsystems are more efficient at producing entropy than others. According to some approximate calculations, it turns out that the more complex things, such as living organisms, are more thermodynamically wasteful, producing more entropy per unit mass than, for example, star cores. And human brains are right there near the top of the hierarchy as super-efficient entropy generators. So perhaps there is something to the infamous "great chain of being," after all! Or, more seriously, perhaps it is the Second Law of Thermodynamics that pushes the universe at this point of its evolution to form more and more complex structures, up to and perhaps beyond intelligent life (all to hasten its eventual heat death...)

I think the meaning of the dinosaurs going extinct where the big ones occupying all the niches that kept mammals to a small size. — Marchesk

An alternative history could have dinosaurs diminished (to more than just the bird lineage), but not extinct, sharing space with mammals; think, for example, of how marsupials now coexist with placental mammals. Or perhaps dinosaurs could eventually produce a highly intelligent species. If they could produce something as un-dinosaur-like as birds (and some birds are pretty intelligent!), why not?

Two things. First, your mistake here is that you are considering a tiny counterfactual neighborhood of human evolutionary history. It is unreasonable to suggest that sweat glands or arboreal habitat are a sine qua non for evolving human-like intelligence in any species, just because these factors (allegedly) played an important role the evolution of human intelligence. — SophistiCat

Organisms need ways to deal with overheating. Humans have that while also being able to move during peak hunting periods. Humans are also the best long distance runners because of their ability to cool down through their glands. This is critical for our survival vs other organisms, and hence our ability to survive anywhere. That trait allows us to move great distances and change our environments, instead of being beholden to it, not to mention the hunting benefits. Humans then had access to various forms of nutritious flora and fauna. Being able to move about unhindered by temperatures relative to your competition is a massive advantage. This is absolutely necessary for the evolution of human like intelligence. It allows humans to move, protect their very very soft (basically premature offspring), hunt for meat (critical to making sure the caloric intake is high enough), among many other things, at a much higher rate than other species. Tree living isn't necessary though.

Second, dinosaurs are not extinct. Look out the window and you'll likely see some. When you think of dinosaurs, you might have a picture of comic-book giant reptiles in your imagination; if so, you are seriously underestimating the potential for variety in that lineage. Also, what Bitter Crank said: if you didn't know better, would you expect fish to evolve into something like us? — SophistiCat

I assumed we were talking about the group that got killed off by the ice age. Those are extinct. Saying they aren't extinct because birds exist would make the word extinct useless, as practically nothing would technically be extinct then. Yes. I could because they did. But to suggest it could go down the line and avoid a similar path to Homo sapiens sapiens is a completely different story.

This is absolutely necessary for the evolution of human like intelligence. — yatagarasu

Again, you are only considering a narrow neighborhood of Homo sapiens when judging what is necessary to fulfill a broad requirement. This is a myopic view, as demonstrated by the great variety of adaptations and numerous convergencies that can be seen in life on Earth. Besides, as I said, you are underestimating the potential for variety within a lineage; this is why I brought up birds, some of whom, by the way, move about over much wider ranges than humans ever did for most of their existence - without the benefit of sweat glands. Fish didn't have sweat glands either, and yet here we are.

Or, more seriously, perhaps it is the Second Law of Thermodynamics that pushes the universe at this point of its evolution to form more and more complex structures, up to and perhaps beyond intelligent life (all to hasten its eventual heat death...) — SophistiCat

That's a really interesting thought.

Or perhaps dinosaurs could eventually produce a highly intelligent species. If they could produce something as un-dinosaur-like as birds (and some birds are pretty intelligent!), why not? — SophistiCat

Maybe so. There was a Star Trek Voyager episode where they came across advanced aliens who were descendants from Earth's dinosaurs, and left the planet for some reason before the big extinction event. I guess they just didn't leave any evidence behind for humans to find millions of years later, unlike fossilized bones and tracks. But it's just a fictional story.

There was a Star Trek Voyager episode where they came across advanced aliens who were descendants from Earth's dinosaurs, and left the planet for some reason before the big extinction event.

If aliens were here millions of years ago, they may have taken many creatures, in the name of preservation. If not a zoo, at least a DNA bank would preserve all previous life forms.

Perhaps a decision was made, to give Earth to the mammals, and take the upright intelligent reptiles elsewhere to live and evolve? This was the crux of the STV episode.

I am curious about the difference in brains. Humans have two side-by-side brains, two hemispheres . They are running parallel. Birds [evolved reptiles] and reptiles, have two different brains in a line, running in series.

Birds [evolved reptiles] and reptiles, have two different brains in a line, running in series. — 3rdClassCitizen

And octopuses have nine brains - a central one with and one for each arm.

One thing about intelligence and evolution... Life appeared early in earth's history, and evolution was at work for billions of years BEFORE the Cambrian explosion of multi-celled life forms, a half a billion years ago. Intelligence, even counting the intelligence of dinosaurs, is still very recent in earth-life history, and our intelligence is so recent as to be barely visible on a timeline of earth's existence.

For a long time--most of the time--evolution wasn't tending toward intelligence.

Given that the evolutionary remnant of dinosaurs are birds, and some birds (corvids, parrots) are extremely intelligent (about as capable of solving puzzles as the higher mammals), I think it's quite likely that given about the same amount of time, an intelligent species might have evolved from the dinosaurs.

The worry is in the area of the Fermi paradox, the Drake equation, and the possibility of a "Great Filter" at any one of numerous key stages of evolution. As Robert Burns said, "there's many a slip 'twixt cup and lip," and there are many possible barriers and "filters" of various sorts (natural disasters, epidemics, etc., with bad timing in relation to population spreads, fits of genocidal rage) that could potentially nip the progress of an intelligent species in the bud.

It seems like we've been exceptionally lucky in this sense, and keep slipping through by the skin of our teeth; perhaps there's a threshold or tipping point in the development of consciousness and rationality, whereby the more a species passes its "filters" by luck, the more it develops a canny sense of avoiding "filters," while at the same time getting more and more knowledge that enables it to spot "filters" coming and avoid them in a more conscious, rational way.

On the other hand, I'm inclined to suspect that the truth is probably a bit boring and annoying: I suspect the "filters" are quite powerful, such that perhaps only a handful of species ever reach sentience and scientific awareness per galaxy, and given the vast distances and times involved, they're hardly likely to ever come into contact with each other.

The rather obvious "filter" in our future that we may or may not pass, is weapons of mass destruction in the hands of a species most members of which are still fairly stupid and impulsive (and I would include myself in that categorization in terms of the big picture). Technological development seems to be outpacing moral development and the development of wisdom. Not a good mix.

The real problem with this type of Great Filter scenario (WMD holocaust) is that while there would probably be enough survivors to keep the species going at some basic level after such a global disaster, all the fossil fuels that are readily available from a situation of low tech (coal, oil, etc., close to the surface, get-at-able with relatively primitive tools) have already been used up, so there would be no way of rebooting civilization through another industrial revolution.

That would make the situation even gloomier: perhaps there are numerous species permanently stuck at a sort of mediaeval level of technical development (like in Game of Thrones), with maybe only one or two per dozen galaxies (or a proportion of that order) having passed smoothly and consistently through all the "filters," reaching a level of development way beyond our own.

On yet another hand, we may in fact turn out to be the "Elder Race" in our own galaxy, and we may go on to discover and "uplift" many others in our locale and make new friends. I rather like that scenario, so I'm going to make-believe it's correct :)

Is this topic a philosophical one? — Marchesk

Of course, science and philosophy overlap, now more than any time in our history. The question of our existence but from the evolution of another line of genetics is really down to; would any form of trial and error system through an evolutionary process result in intelligence? And will the result of that process all come to the same conclusion that incorporate how fundamental psychological values of sex, death, well-being, ego, community etc. define what we perceive as the realm of human intelligence? Maybe community and our role in a group together with our sense of distance from the group through our ego manifested itself in form of intelligence. Our pattern seeking abilities made us perceive the world through an analytical mind and the only way to survive as a group was to communicate what we analyzed about our surrounding. If the evolutionary process had the initial steps that we went through being the same, maybe the being at the end of this evolutionary process would function in the same way as we do.

However, there are so many parameters that decide on the end result that it's impossible to say if the being would be like us or totally different. Remember that most of our perception of intelligence is based around cultural interpretations of fundamental values. How we perceive death, love, sex, group, ego etc. define how we view what intelligence is. If another line of evolution had communication through pheromones and smell rather than words and language and if they lived 400 years instead of 100, it would radically change how they act as intelligent beings and would form their society around other values and ideas.

Again, you are only considering a narrow neighborhood of Homo sapiens when judging what is necessary to fulfill a broad requirement. This is a myopic view, as demonstrated by the great variety of adaptations and numerous convergencies that can be seen in life on Earth. Besides, as I said, you are underestimating the potential for variety within a lineage; this is why I brought up birds, some of whom, by the way, move about over much wider ranges than humans ever did for most of their existence - without the benefit of sweat glands. Fish didn't have sweat glands either, and yet here we are. — SophistiCat

And of all of that variety we only see one species with extremely high adaptability and cognition like humans. I wasn't denying the ability for variation, I was just disputing how they would become intelligent enough to create a human like civilization. I highly doubt it's possible unless they have specific adaptations. My evidence is the very specific requirements of a human brain. I feel like it is much more specific, otherwise we have a lot more species evolving these traits. (or at least ones that also lead to high levels of cognition) Both birds and fish have many difficulties to developing human level brains, whether those things are dietary or structural (anatomical). It took animals evolving away from those groups to get to the great apes. For the travel distance part of your response I was only talking about terrestrial land animals. I don't believe civilizations and brains like ours could evolve/exist in non-terrestrial land animals. (trees/sky and oceans are a pain to build stuff on/in haha)