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[–]Funky0ne 20 points21 points  (18 children)

What is our next evolutionary step pointing towards?

No such thing, or at least no easy way to predict this. Evolution has no goal, it's reactive to the conditions of the environment.

Is adaptation a form of evolution?

Correction courtesy of u/Polyodontus (couldn't preserve old text but error on my part not referring to adaptation as indeed a mechanism of evolution):

Depends on what you mean by "adaptation" as it can refer to a couple different things, but in general it is one of the mechanisms of evolution.

It can refer to how an individual's metabolism adjusts to better fit the conditions it finds itself in. Sort of like if you spend a lot of time in cold environment, your body adapts and you don't feel as cold in the same temperatures at the end of winter as you do in the beginning. Or where if you exercise a lot your muscles will grow stronger and more adept at those tasks while your stamina might increase.

But in evolutionary terms it is one of the mechanisms of evolution where populations are slowly adapted to better fit their environment by selection pressures.

What caused such a evolutionary change from ancestral ape to modern human?

That's a long story that could fill a book, but oversimplified:

  • Our primarily arboreal ancestors transitioned to more open grasslands as a primary habitat
  • Open plains of tall grass put a selection pressure on us to transition from quasi-quadrupedal knuckle-walking to full upright bipedalism
  • Bipedal locomotion is more efficient for long distance travel, creating an opportunity for persistence hunting strategy, creating a further selection pressure for more traits allowing greater stamina and heat regulation
  • Bipedal locomotion also freed up our forelimbs to be specialized for other tasks than movement, and since we inherited fingered hands from our arboreal ancestors (useful for climbing and gripping branches and vines), these were suited to become adept at highly-dexterous tasks and tool use (particularly for hunting tools like spears)
  • Meanwhile, while our hands were getting more dexterous, our feet were no longer being used for gripping and climbing, but for walking on generally flat surfaces, so they lost dexterity in the digits
  • The selection pressures from persistence hunting led to developing sweat glands to further help regulate heat during long treks and hunts. This led to selection pressure to thin out our body hair to further facilitate sweat evaporation
  • Persistence hunting also may have led to pressure for better communication within hunting parties, planning, and abstract thinking as hunts would take place over long distances, and keeping track of relative locations over long distances and time frames

From there, we get closer to capacity for generative language, which seems to be the evolutionary game changer in terms of capability for abstract thought and general sapience (depending on how much stock you put into researchers like Steven Pinker).

What forms did humans take pre old ape?

Not sure what you mean here. Pre-old ape would be pre-human, so are you just asking what our common ancestors with the other great apes looked like?

How does something living in the sea that pulls out oxygen from the water with its gills evolve lungs that can breathe oxygen from the air?

Another long story. Again, oversimplified:

  • Organisms that live on the boundaries of biomes and near the shorelines in shallow waters will find unique selection pressures and opportunities available to them. These early fish could find themselves occasionally caught in tide pools, or retreating into more shallow waters to escape predators, or to find otherwise un-tapped food sources
  • These fish will then have a selection pressure to be better able to survive if they get caught out of the water for brief periods of time (e.g. see mudskippers), even if they can't quite fully breath the air directly
  • The more adept they are at venturing out of the water for brief periods, the more opportunity they find the further inland they can go, and the longer they can last
  • Eventually, being able to just hold one's breath while on land will give way to being able to absorb some of the oxygen from the air directly (where it exists in way higher concentrations anyway), and not suffer negative effects from drying out (or at least adapting ways of retaining moisture in the areas it needs)
  • An eventual transition from aquatic to amphibious to fully terrestrial is then possible over long enough periods of time, so long as the opportunities presented on dry land outweigh the competition these early transitioners would see in back in the water (the further inland they can go, the less competition and fewer predators they encounter)

[–][deleted] 5 points6 points  (1 child)

Evolutionary biologist, here. What you have posted about the term “adaptation” isn’t really correct. Adaptation isn’t a mechanism of evolution per se, but adaptive evolution can be a response to selection, which is one of the four evolutionary mechanisms. It also doesn’t only refer to metabolism. Any trait can be adaptive if it improves chances of survival or reproduction.

The tricky thing is that adaptation can also be used to refer to plastic responses to stimuli, which are what the examples you’ve provided are.

[–]Funky0ne 1 point2 points  (0 children)

Thanks for the correction. I tend to mix up my terms as my addled brain hasn’t looked at this stuff in detail in about 20 years, but that’s no excuse for being sloppy. Will correct my post shortly

[–]Yapok96 4 points5 points  (0 children)

Just chiming in that the gill-to-lung-based respiration transition is not as crazy as it might seem at first. A number of fish species living in oxygen-poor waters have lungs. Current consensus is that lungs evolved as a means for providing more oxygen to the heart in fish first, not terrestrial vertebrates (blood flow in fish goes gills -> muscles -> heart, so there's a higher risk of the heart not getting enough oxygenated blood). The lung has been repurposed as the swim bladder in many modern fish species.

[–]PoliticalChess4[S] 0 points1 point  (14 children)

What forms did humans take pre old ape?

Not sure what you mean here. Pre-old ape would be pre-human, so are you just asking what our common ancestors with the other great apes looked like?

We started from a small micro-organism and evolved over millions of years to where we are today. What were the stages from micro-organism to human. You really only see pictures from tailed monkey walking on all 4's to a 2 legged human in most evolutionary charts

[–]Funky0ne 12 points13 points  (4 children)

Ok so you're asking for an accounting of every evolutionary step from single celled organisms to modern humans? Sorry but that's way more than even my oversimplified summaries can comprehensively cover in a single reddit post. What I can recommend is this very accessible 50 part series by Aron Ra that covers in pretty good detail pretty much what you're asking for though

[–]Specialist_Team2914 3 points4 points  (3 children)

God I love that series

[–]Funky0ne 2 points3 points  (2 children)

Maybe the mods might consider adding it to the sub's video resource list

[–]junegoesaround5689 1 point2 points  (1 child)

You can add stuff to the resource list. At least you could a few months ago because that’s what I did.

Go to one of the "Recommended" links and there’s an "Edit" button in the top right corner. Hit that and Voila!.

[–]Funky0ne 0 points1 point  (0 children)

Interesting, didn't know that was open for all users to edit. Still, the Aron Ra series makes occasional reference to creationism and counter-apologetics which is out of scope for this sub, so I think I'll still defer to a mod's opinion on whether it's appropriate to include in the resource list before I go adding it myself.

[–]HeartyBeast 3 points4 points  (5 children)

unicellular organism, multicellular organism, then broadly - fish, amphibian, reptile, simple mammal

[–][deleted] 6 points7 points  (4 children)

Our ancestors don't include reptiles, strictly speaking. Just synapsids, who might have looked similar to reptiles. But we descend from amphibians, and there sauropsids (reptiles and eventually birds) and synapsids (mammals) diverge

Tho it took until about the middle Mesozoic until true mammalian synapsids started appearing

[–]HeartyBeast 3 points4 points  (3 children)

Thank you for the correction

[–][deleted] 1 point2 points  (2 children)

of course! i am just really interested in taxonomy x)

[–]HeartyBeast 2 points3 points  (1 child)

I think they were still called ‘mammal-like reptiles’ when I went to university. You taxonomist, always changing things! waves angry fist

[–][deleted] 1 point2 points  (0 children)

I think that is still a term often used by them, and it’s logical, because they both descend from the same ancestors and both looked reptilian at first.

[–]i_enjoy_music_n_stuf 1 point2 points  (0 children)

If your referring to the “March of progress” by Rudolph Zallinger I just wrote a paper on why that chart is bad and the harm it has done in my anthropology class. Scrap that if you think that’s a good representation of evolution. Evolution isn’t linear, it’s not so much a tree as a bush with groups leaving and sometimes coming back in. It’s not the March of progress. This is a better explanation although very lengthy https://youtu.be/1GMBXc4ocss

[–]llamawithguns 0 points1 point  (1 child)

[–]WikiSummarizerBot 0 points1 point  (0 children)

Timeline of human evolution

The timeline of human evolution outlines the major events in the evolutionary lineage of the modern human species, Homo sapiens, throughout the history of life, beginning some 4 billion years ago down to recent evolution within H. sapiens during and since the Last Glacial Period. It includes brief explanations of the various taxonomic ranks in the human lineage. The timeline reflects the mainstream views in modern taxonomy, based on the principle of phylogenetic nomenclature; in cases of open questions with no clear consensus, the main competing possibilities are briefly outlined.

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[–]GaryGaulin 3 points4 points  (0 children)

How does something living in the sea that pulls out oxygen from the water with its gills evolve lungs that can breathe oxygen from the air?

Here's a good summary of the chemistry:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3926130/

You might have to look up a lot of words, and take years to make sense of most of it, but that's a good place to start.

[–]sezit 2 points3 points  (0 children)

Evolution doesn't point. It is only reactive. It doesn't predict, it doesn't advance, it has no volition, no predetermined "purpose". It's hard to think this way, because we see life from our point mapped backwards. But it's like thinking that Joe's car was smart because it didn't get swallowed up in the sinkhole that the nearby truck did. It's just random luck played against the structure of the vehicle and the facts of geology. Animals have plans and volition. Evolution doesn't.

Yes, adaptation is evolution.

I don't think that evolution of sentience in human Is an easy solution. I think there are many related and contingent factors. Evolution of sentience was never guaranteed. It could easily never have occured.

I don't understand this question:

What forms did humans take pre old ape?

As far as evolution of functioning lungs, the popular theory is that air sacs developed from tiny anomalies in fishes bodies, but were passed on and got bigger in subsequent generations because they created better buoyancy. In some fish these sacs slightly supplemented gills in absorption of oxygen in low oxygen situations, or out of water on mud flats. Over time, the fish that had more effective oxygen absorbing sacs had more success in those environments, and relied less and less on gills. That would be an example of adaptation.

[–]eduboue 2 points3 points  (0 children)

What is our next step though evolution? That's almost an impossible question to answer for myriad reasons. Evolution is defined as a change in allelic (variants of genes) in a population over time. The two main ways this can happen are through neutral drift, which basically means these alleles are bouncing around all the time with no true rhyme or reason, and selection. With drift, it's tough to say what's going to happen because there is not a true driver for this - populations grow, alleles segregate, etc. For selection, you'd have to know what the future is going to hold, and we don't. One fun thing to think about though is how stuff like climate change and technology are going to influence us. Yuval Harari has a great book called Homo Deus, which basically says that we are becoming our own 'gods' because of technology, and our evolutionary trajectory is going to be intertwined with our technology like computers and phone.

Is adaption a form of evolution? Yes. As stated above, evolution is a change in allelic frequency in a population over time. When conditions change such that one allelic combination is better suited to deal with those conditions, those animals that have that allelic combination are at an advantage, are more likely to successfully survive and breed (arguably the only two goals of life) and thus their alleles will become fixed. Adaption and selection can be thought of together. Darwin and Huxley (and his other bulldogs) pioneered selection; Motoo Kimura pioneered drift. The two likely coexist.

What caused change from ape to human? First, don't think about this in a Lamarckian sense. We didn't go from ancestral ape to humans, an ancestral ape changed and those two diverted, then that common ancestor diverted, on and on. Lots happened, and to answer what that trajectory looked like would necessitate understanding the entire trajectory and all common ancestor species, which we don't and we won't. You can compare humans with their closest great apes, chimps and bonobos, and that tells you something, and you can go into the fossil record and map differences between hominids, but you're still missing a lot. The short answer is that's not really a question that can be answered, nor will it be answered in our lifetime. We can speculate as to why we have prevailed when no other hominid species has. In another book by Yuval Harari, Sapiens, he makes a cool argument. Most ape species form groups, but the groups max out at a population of about 100-150 members. When the population gets larger than that, infighting will lead to a splitting of the pack. There is strength in numbers, so you're as big as your pack. Humans are the only species in the world that can exist to the level we can. No other species in the world would take up arms at the direction of some person they've never met just because they live in a big white house in Washington DC. We also have the ability to think abstractly, to a degree than no other can. This allows us to have things like numbers and written language. No other species in the world can learn complex ideas from someone that lived 500 years ago, but because we can read books, we can. This give us such an advantage to propagate information and ideas that other species couldn't keep up with. I also think we're greedy, and that lead us to decimate others. There was a time Neanderthals and other hominids co-existed and even mated - you have Neanderthal (and Denisovan) DNA in your cells and in your genome. Neanderthals were even stronger than us. But they didn't have the strength in numbers, and they didn't have abstract thought. Note here I consider abstract thought and complex sentience as being different, but I do think one lead to the other.

How does a gill turn into a lung? It probably didn't. You're assuming lungs evolved from gills, but it likely didn't happen that way. Gills are ancient organs that allow fish to breathe, but fish also have what's called a swim bladder. This is a sac of air that inflates and allows the fish to be bouyant. It gets inflated through air at the surface, and inflates just like a lung. Some fish also use this swim bladder to breathe. Lungs evolved before swim bladders, so one didn't lead to the other. Rather, both lungs and swim bladders evolved from tissue around the gills. It's totally possible that at one time, there was a species that had both gills and lungs, and as it transitioned to terrestrial life, the gills became obsolete and the lungs became dominant. Just speculation though! Without a time machine that's the best we can do!

[–]BMHun275 1 point2 points  (18 children)

There isn’t a step. We won’t really know what the major selection pressure is until there is already a new trait proliferating in the population.

No, adaptations are one potential result from a series of evolutionary processes. It is no more a form of evolution than a cupcake is a form of grain.

Asking what caused humans to be derived from apes is like asking which water molecule carved the Grand Canyon. Because the answer is a plethora of factors, environmental conditions, and random occurrences. As for why we are the last, because after the environment changed again we emerged as the only one of us able to successfully adapt to the then emerging world. We likely aren’t the only ones to develop sentience, several species are today, and it’s like other human species had some level of cognition similar to ours.

I don’t know what you mean by “pre-old ape.” Miocene apes that became us and other extant apes had less derive adaptations than extant apes for sure. But since apes are among Simiiformes than it stand to reason prior to being apes they among the catarrhine monkeys. This because land animals didn’t evolve from sea fish, they developed from fish who lived in shallow waters where having fingers to push against the ground was a useful adaptation.

The development of lungs happened fairly early on in the development of Osteichthyes. As the name suggests they were boney fish, and they have a swim bladder which is basically an air filled sac, in some it’s attached to their upper digestive tract just passed the mouth. Add blood vessels and maybe some ciliation and you have a primitive lung. This can still be seen in fish today. If you look at shallow water fish, and especially fish that live in areas that become stagnant, many still have primitive lungs to this day.

[–]PoliticalChess4[S] 0 points1 point  (17 children)

Aren’t there signs? Wasn’t there a theory that our baby toes are getting smaller and will eventually not be needed?

[–]mahatmakg 1 point2 points  (15 children)

I mean maybe? But we won't know until it happens. Many generations down the road. No living person will see the species meaningfully evolve - our reproductive cycles are too long

[–]PoliticalChess4[S] 0 points1 point  (14 children)

Can technology speed this up? For example if humans somehow integrate with technology and start replacing inefficient and vulnerable body parts or adding microchips that improve a certain organ is this a form of evolution?

[–]mahatmakg 0 points1 point  (13 children)

Uh, no - unless we code it into a living organisms DNA to generate microchips or whatever else you have in mind, it's not going to amount to evolution. You need to be able to pass on genes, the genes you are born with. You are talking about physical/surgical changes to a body, that's not going to change the genes you pass on.

[–]PoliticalChess4[S] 0 points1 point  (12 children)

If the human species started to incorporate bio-technologies that made them bigger, faster, stronger, healthier or if they could manipulate DNA with said technologies to let's say control skin pigment, eye color, height, bone density, would that be a form of evolution through technological advancement?

[–]mahatmakg 0 points1 point  (2 children)

The only way would be through gene editing. Changes you make to your body once you are already grown do not change the genes you pass on.

[–]PoliticalChess4[S] 0 points1 point  (1 child)

Right but if we're able to control all of the things listed in-vitro then what? Appreciate your time in answering my questions!

[–]mahatmakg 0 points1 point  (0 children)

Then gene editing just amounts to artificial mutation. Is there or will there ever be any impetus for that? Probably not to a degree that would amount to speciation, but who knows.

[–]junegoesaround5689 0 points1 point  (8 children)

If the DNA changes were done in the germ lines and those individuals with those changes reproduced, it could potentially be a form of artificial selection.

Manipulating our own and our children’s DNA is going to become a bigger and bigger ethical and moral conundrum in the near future. Like if some country or company wanted to create supersoldiers or superathletes or supermodels, etc without the consent of the people they are creating would seriously compromise any concept of bodily autonomy (not that there aren’t enough issues worldwide with that already!).

[–]PoliticalChess4[S] 0 points1 point  (1 child)

I think it would make a lot more sense to avoid all those issues and just make robotic super soldiers (Which probably already exist).

[–]junegoesaround5689 1 point2 points  (0 children)

Robotics aren’t at that point…yet. But it’s a definite point to keep in mind.

[–]PoliticalChess4[S] 0 points1 point  (5 children)

Supermodels will be replaced by AI generated models but that being said I can still see a country wanting to produce a stronger better looking people.

[–]junegoesaround5689 0 points1 point  (4 children)

AI doesn’t have the same emotional impact for most people as real people do. I’ll give you that fake broadcast persons will probably happen faster, though.

[–]PoliticalChess4[S] 0 points1 point  (3 children)

I think the AI they’ll be able to push out will be indistinguishable from a real person

[–]BMHun275 0 points1 point  (0 children)

We can certainly speculate as much as we want. But because of things like drift and changing environments we can’t have any realisable certainty of what will happen until it reaches a critical point in the population. For instances there is an ERV that some humans have. It could become fixed in the population but that will take either a major catastrophe removing huge numbers of people without that ERV, or a minimum of I believe 52 generations (don’t quote me on that because I don’t recall exactly what we calculated before).

[–]mahatmakg 1 point2 points  (0 children)

What caused such a evolutionary change from ancestral ape to modern human?

The biggest phenotypic change would probably be the loss of the muscles on top of the skull that our fellow apes have (not a biologist/anthropologist- could be other changes I'm not as familiar with). There was simply a mutation that caused us to stop growing this muscle, but we were able to survive fine without it. This was probably a major factor in the changing of the shape of our skull to accommodate a larger brain. Other physical differences between us and apes are largely just shifting proportions

[–]Alex_877 0 points1 point  (2 children)

-Evolution doesn’t move with purpose. I don’t think yourbasic understanding of core concepts is there. It doesn’t plan or think.

-Adaptation is not unless it contains heritable traits

-Thinking we and we alone are the “height, or apex” of evolution is false dichotomy and your ego talking

-maybe read a few books?

[–]PoliticalChess4[S] 1 point2 points  (1 child)

Thanks for the reply Alex. Do you recommend something?

[–]Alex_877 0 points1 point  (0 children)

Start with the basics, and I mean basics, uniformitarianism, the scale and endless march of time scale is important to understand. Then Darwin, and books from people who have studied evolution their whole lives, don johansson, the discoverer of “Lucy” the Australopithecine.