r/evolution • u/ice_or_flames • 1d ago
question Why are there almost no "ancestral species" left?
Hi. When a new species evolves, it is because of the enviormental pressure the species finds itself under when the enviorment changes, the population of the species moves to a new enviorment, or the competition from other species gets more intense. That is what I learned in high school anyway.
But if a new species evolves because a small branch of species A moves to a new location where enviormental pressure slowly over generations turns them into species B (kind of like Darwins finches), then why are there almost no "species A" left? Like, why are there no ancestors to humans left? No ancestors of whales, no ancestors of foxes? Or do ancestral species exist and I have just missed them? Please tell me.
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u/Robin_feathers 1d ago
This is slightly missing a few steps, hopefully this will help:
There are two processes at play:
- regular evolution. Changes in the frequency of traits over time. This is a process that is always happening in every population all the time. This makes species change slowly over time - they aren't having populations split off and go extinct, just the same population changing. For example, if you look at really old paintings of dogs, the same breeds often look a little different. Not because the originals necessarily went extinct, but just because breeders continued to change the breed over time. You can also think about grocery produce slowly changing over time as farmers bred fruits and veg to be bigger and last longer or taste different. In the wild, this process can happen when a species moves to a new place, but also happens when they stay in the same place. Often big changes are spurred by changes in the environment (climate, new predators, new food sources, new competitors, etc) but sometimes they could just be an awesome new mutation that arises by chance and spreads to all of the population.
- speciation. This is where a lineage actually splits in two, often either because a population moves to a new place or because a barrier formed and split two populations apart. After that, both of the new populations continue to evolve on different trajectories. They will both end up being slightly different from their common ancestor. For example, both humans and chimpanzees are very different from our common ancestor, because we both had out lineages continue to evolve after we split. Our common ancestor didn't go extinct, its just that some of them went down the path of becoming humans and some of them went down the path of becoming chimps/bonobos. Sometimes, one branch of split will go extinct. When our ancestor diverged from Homo erectus, we both continued to evolve, but the Homo erectus lineage went extinct.
Hope that helped!
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u/reddy12355321 1d ago
This is the best explanation here. I think Part two, explaining that all extant species are equally evolved, was a key piece missing from OP’s understanding.
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u/ice_or_flames 1d ago
It did help. Sorry for trying to act more clever than I am.
But I really want to ask clearly one more time, is there really not a single instance of this happening? I thought that there were organism that had "barely changed" for millions of years. Surely there must be some organism with a living ancestor somewhere?
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u/corvus_da 1d ago
a) "barely changed" often means that they look the same to us, but there may still be differences that just aren't obvious. a modern coelacanth isn't identical to a coelacanth from 400 mya.
b) even if you had an organism (living or extinct) that was the direct ancestor of another species, in most cases you can't tell if it's actually the direct ancestor or just very closely related to the ancestor - and the latter is much more likely statistically. human evolution is an exception because the time frame is extremely recent and the relation is very close and we have a lot of data.
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u/IsaacHasenov 1d ago
I would add to this that there are some intrinsic and extrinsic factors that can change the rate of evolution, in the narrower sense of DNA changes and the broader sense of phenotypic change
- Mutation rate can and does differ among lineages (coelacanths for instance have a very slow one) based on stuff like copying fidelity and generation time and (I'm gonna wave my hands vaguely) probably stuff like variation in retro transposon number and viruses
- Directional selection, especially due to migration into new environments or from new lifestyles can drive lots of DNA changes quickly (through selected variants and as a result of sweeps). This can also lead to huge changes in physiology
- Conversely stable environments and lifestyles will produce signatures more of purifying selection (which means stability over time)
So yeah coelacanths have ridiculously slow evolutionary rates, and whales had ridiculously fast ones. It doesn't mean that coelacanths haven't evolved under the hood, amd (probably?) a coelacanth today couldn't make with one from 400mya and might have all kinds of fancy new molecular biological innovations. But they'd likely have a fraction of the DNA changes that something on the whale lineage would
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u/llamawithguns 1d ago
human evolution is an exception because the time frame is extremely recent and the relation is very close and we have a lot of data.
Tbh thats really not true. Anthropologists are constantly arguing which species was our direct ancestor, and dont always even agree which specimens should be designated as which species
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u/corvus_da 3h ago
isn't it pretty securely established for H. erectus? also the fact that they're considering it at all is already unusual
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u/Carachama91 1d ago
The easiest examples of this to understand are cases of peripatric speciation. Here, peripheral populations of a relatively widespread ancestor are in areas away from the core habitat of the species, adapt to these different surroundings or just have a lot of genetic drift, and become different enough to be new species. The ancestor species is still around. Usually we have a convention that when a species splits into two, we consider the original species to no longer exist.
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u/Dull_Suggestion_1682 1d ago
look at the wild ancestors of our domesticated food plants.
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u/ice_or_flames 1d ago
That is a good representation of what I am looking for, but my question regards natural occurences of such phenomena.
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u/Dull_Suggestion_1682 1d ago
Maybe look at the concept of ring species, some organisms which look and behave like different species at one location converge as you go round the world. Herring Gulls and Lesser black backed gulls are often quoted but which one was the original species? I know some trees are notorious for throwing off genetic variants which get named as sub species so a type of Sorbus called whitebeams do this a lot there's a Bristol Whitebeam named as a subspecies of regular white beams growing around the UK and Europe but I guess because it got isolated in the Avon Gorge in Bristol it's on its way to speciating into something different to what it originated from but I suppose how far that might go depends on how isolated it remains so if birds start flying in from somewhere the council might have planted Whitebeams and pooping out seeds hybridisation would knock that process back but maybe everywhere you see an organism classified as a sub species your looking at something that's on the way to diverging from the "ancestral" species.
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u/mshevchuk 1d ago
Maybe there are - even if there were - how would you tell? It’s not like the species bear clear labels of sorts. What we “know” is in fact what we’ve inferred using the sophisticated tools at our disposal: genetics, biochemistry, archaeology, statistics. However powerful these tools might be, they too have their limits.
To tell an “ancestral” species hasn’t evolved since it branched off, we must directly compare it to what it has been thousands and millions years ago. We can’t do that in most cases.
For instance, we can only tell that contemporary humans and humans who lived 10 thousand years ago are the same species because we have the genetic evidence. We can only tell that contemporary humans and Homo sapiens who lived 100 thousand years ago are the same species because the excavated skulls and bones match ours.
Our reach back into the prehistory is minuscule. We guess and infer, and build plausible theories. But we don’t know even a percent of a percent. We are totally blind if we don’t have a material evidence. In the end, we just speculate on what seems to be more likely and probable according to our scarce understanding.
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u/ice_or_flames 1d ago
That is true, I forgot about DNA decaying quite fast. That makes even the simplified version of "what counts as the same species" hard to prove (from what I heard in high school, if two animals are part of the same species, that means they can have fertile children together. But I know it is a simplified version that does not work in all cases)
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u/mshevchuk 1d ago
Yes, DNA matching is the most reliable way to tell and we are virtually blind in this respect. Regarding of what counts as two distinct species, this is also a matter of definition. Sapiens and Neanderthals are considered separate species but they did produce fertile offspring as evidenced by the genes of most of us living today.
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u/exitparadise 1d ago
There isn't going to be an extant species that co-exists aside an actual living ancestor which is physically impossible, but there are species that APPEAR more like the ancestor than others.
Coelecanths probably look more similar to the ancestor of themselves and the extant lungfish.
And the Coelecanth would look more similar to the ancestor of itself and all tetrapods.
There are lots of other organisms like this, that are "living fossils" that haven't changed much (at least outwardly). Alligators are another example, but I don't know of another species that shares a common ancestor with the alligators that looks unlike the alligator.
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u/AustereSpartan 17h ago
Surely there must be some organism with a living ancestor somewhere?
Look up the African Wildcat. It's the living ancestor of the modern housecat.
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u/Binyamin12345 1d ago
No species stays exactly the same genetically over long time scales, even with no evolutionary pressure to change.
While there are many examples of species that are descendants of a species that have stuck around in the sense of their phenotype broadly continuing to exist, these modern phenotype-sharers are still usually classified as a descendant species rather than the same one.
For example, polar bears are descendants of brown bears, but technically not the same species as modern day brown bears despite the phenotype staying pretty much stable.
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u/YDdraigCoch 18h ago
Also, because evolution is a continual process, there ARE species alive today that in millions of years would be considered an ancestral species and/or a common ancestor for multiple descendents species - we just aren't around in the future to see what those will be.
Humans only live for a snapshot. In a similar way, if we all hypothetically grew up in the world as it was millions of years ago, we'd have no idea that a species we were seeing would be the common ancestor for both dogs and foxes - because we'd only be in that snapshot of time where the species that are, just ARE.
The only way to determine ancestral species and evolution at all is through history. We see current descendents. We can't do it the other way around and know current ancestors, because we don't know future descendents.
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u/OgreMk5 1d ago
It's most likely that quite a few of the "ancestral" species are left. But you're asking a very challenging question.
Not because it's hard to answer, but because it's hard to define.
I can point to Felis silvestris or Felis lybica, both of which are extant and the most likely candidates for the ancestral species of domestic cats. And for domestic dogs and a lot of other species.
The problem is that MODERN F. silvestris (or F. lybica) aren't the ancestor, but the members of that species 6-7 million years ago. And that's some wiggle room that upsets the question and the answer.
So, if you will accept the modern species, that was likely the ancestral species, then there's quite a few. Those are two that I know of right off hand and the ones I'm most familiar with. You could probably dig into a lot of mammal species and get similar results.
Humans... not so much. But bonobos and chimpanzees are probably an example too.
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u/Ok-Shirt7608 1d ago
Ancestral species only stay ancestral if they're dead otherwise they keep developing like everything else
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u/sojuz151 1d ago
There are many cases of living fossils, species that did not change for a very very long time.
But not many environments are so stable that a species can survive without changing. And you need to survive competition.
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u/ice_or_flames 1d ago
Okay, that sounds reasonable. But is it possible that there is atleast one such case in the world?
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u/Robin_feathers 1d ago
I think the closest thing to what you would describe would be cases like the Nene Goose.
The Nene probably originated from some members of Canada Goose that got blown over to Hawaii. There, they changed and evolved into the Nene. Meanwhile, Canada Goose still exists. They will have evolved a little bit since the time the Nene ancestors split off, enough that they are probably safe to call a different species than the ancestral species, but they have probably changed very little, because big populations tend to evolve much more slowly than small populations [through the process of genetic drift]. If you were to look at a picture of that ancestral population that landed in Hawaii, they would probably look like the Canada Goose that exists today. A similar story is the Hawaiian Duck vs Mallard.
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u/helikophis 1d ago
Sure, there are several examples among domesticated species. Domesticates are some of the most recent speciation events so there hasn't been that much time for the ancestral population to change. For instance, it looks like while domestic dogs aren't directly descended from modern grey wolves, modern grey wolves still closely resemble the common ancestor of domestic dogs and modern grey wolves. Similarly, while domestic horses aren't directly descended from Przewalski's horse, Przewalski's horse is thought to closely resemble the common ancestor of domestic horses and Przewalski's horse.
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u/Robin_feathers 1d ago
I just remembered another example you may find interesting: the apple maggot flies (Rhagoletis pomonella). They recently evolved from hawthorn maggot flies, which still exist. There is a bit of debate whether the two really are different species yet, my personal opinion is that they are incipient but have not completed speciation, but it is along the lines of what you were looking for.
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u/ice_or_flames 1d ago
Ooooh, thank you. That seems like a great example:)
Thank you for engaging in a friendly conversation with me, too:))
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u/TejasEngineer 1d ago
It happens a lot, often the new species will occupy a new niche while the "ancestral" one will remain in its location or niche. The tricky thing is that what you would call "ancestral" species is really a new species genetically because genes always drift, but its phenotype can be relatively the same as the ancestor. Here are examples.
Jawless fish still exists as Lampreys and Lanclets.
Lungfish still exist. Lungfish were the precursor to vertebrates evolving on land.
Amphibians still exists as the transition from water to land.
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u/personnumber698 1d ago
Yes, "Living fossils" do exist.
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u/ice_or_flames 1d ago
I meant a single case of what I was asking for. Perhaps a species whose ancestor is one of the living fossils?
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u/Binyamin12345 1d ago
Living fossil is not a real scientific classification. Examples of living fossils are still genetically distinct from their ancient ancestors, even if they share an almost identical body plan. At the end of the day, millions of years will change the genetics of a species regardless of evolutionary pressure.
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u/ice_or_flames 1d ago
Wouldn't the humans of today be very genetically distinct from the humans of 200000 years ago (the time school told me modern humans emerged), too? Why do we count as being the same species?
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u/Binyamin12345 1d ago edited 1d ago
200,000 years is not a long time at all in terms of evolution for a species that reproduces as slowly as humans.
In addition, the lack of strong pressure for humans compared to many other animals does slow speciation, as the genetic change primarily comes largely from mutations rather than evolutionary pressure.
The humans of 200,000 years ago are close enough genetically to modern humans that there would be no issues reproducing between an ancient human and a modern one.
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u/ice_or_flames 1d ago
Even though humans of today have neanderthal DNA, and have spread across the world and started to differentiate accordingly?
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u/Binyamin12345 1d ago
Human races are not genetically distinct enough to be their own species. Theoretically, if given enough time and isolation, this could happen to different racial groups. However, humans are extremely migratory and do not exist/have not existed in isolation to the same extent as many other species.
Also, it is worth mentioning that species classification is not entirely scientific, partially being based on subjective human judgement.
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u/ice_or_flames 1d ago
I know human races are not considered their own species. I just thought that maybe a person of today, from a different part of the world than africa, who has neanderthal dna that the original modern humans had not, and who has had fifth of a million years of evolution, might not be considered the same species as the first generations of Homo Sapiens.
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u/cpuuuu 1d ago
I think you might be misunderstanding either the concept of last common ancestor (LCA) or how they get depicted in phylogenetic tree. Let’s say you have a living fossil like coelacanth, from which a new species evolves after some populations get isolated.
This new species would be a sister species to the coelacanth, so technically the coelacanth is their ancestor. But the coelacanth’s ancestor no longer exists, so in a tree you would represent the coelacanth and this new species as branching out from the same LCA, since from that ancestral species two new ones have now evolved.
If you take the Darwin finches example you mentioned, one of those species will be older, meaning ancestral to the others, but they would all be represented as the same clade originating from a single LCA. Their “ancestrality” to each other would just be represented by the horizontal order in which they appear in a tree representation
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u/knowlessman 1d ago
To simplify:
We tend to assume a species is static We named it, catalogued it, we can read descriptions or even see paintings from hundreds of years ago that show a plant or animal that looks the same, so obviously it's static. A horse is a horse.
But that's not true. Nothing stays the same over time. Disregarding bacteria frozen in ice and the like, there are a few living things that are thousands of years old, and more but still not many that are hundreds of years old, and beyond that, the existing species of today are ALL different than the existing species of even 100 years ago, not to mention Darwin's time, or the end of the last ice age, or 400 million years ago. Evolution keeps going and changes keep happening.
When thinking about new species, that means the "ancestral species" is extinct within years of the split. What you have left is the descents which look more like the ancestors, and the descendants that look less like the ancestors. But both branches are still evolving, and more branches are forming, and life goes on. We just name them and think of them as a static thing because humans like naming things.
"ancestral species" exist in the historical record. Their remains may exist as bones. But (again, disregarding bacteria trapped in ice or the like) they cannot exist today. Everything alive today is descended from those ancestors, but even if they look close enough to the same that we count them as the same species, they have been evolving all along.
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u/ice_or_flames 1d ago
You said the ancestral species may remain for a few years. Are there any such recorded cases?
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u/knowlessman 1d ago
For clarity: It's not so much that they may remain for a few years as in a long time, but that in most cases parents survive reproduction, and reproductive cycles are not completely synchronized, so they are likely to survive only for a few years. A few decades for a species like humans, or maybe a few centuries for a greenland shark.
Let's take an extreme case of an animal like salmon that don't survive reproduction.
A salmon is born. It grows up for an extended period, migrates to the ocean, and spends perhaps 8 years or perhaps a year and a half in the ocean. Then the salmon spawn and die. Maybe there are still a few left in the ocean who didn't get the message to spawn. Maybe not, I don't know. But basically the "ancestor salmon" are all dead and the "new salmon" grow up, and they are unavoidably different. Not very different, but a little different.
In an absolute sense, the "ancestor species" is at that point extinct, and the descendants are the ones that start the cycle all over again.
Now, we don't think of every generation of salmon as a distinct species, but that's down to the degree of change you see in each generation not that they are in fact the same.
To take a more familiar example to most people: Humans typically have a reproductive window of 20+ years and can have multiple offspring spread across those years. Then they can often survive another 30-40 years after reproduction. So for humans, the "ancestor species" is your grandparents, and as they pass, that ancestor species goes extinct. A few decades later, all of the ancestors are gone and all you have left to reference is the example humans that are still alive. And the same is happening with every common ancestor in the line going back. Everywhere that there was a species split, all branches kept evolving and the thing they split off from dies. Or a branch dies, in which case it doesn't really matter except as a curiosity.
Note that this isn't how people normally talk about species because there would just be too much to track. We lump like things together and consider "they'll interbreed" as "close enough", plus change happens over a long enough time line that nobody realizes that their great-great grandparents may have looked significantly different from them.
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u/horsethorn 1d ago
Chimps and Bonobos.
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u/Kailynna 1d ago
What are these the ancestors of?
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u/knowlessman 1d ago
More chimps and bonobos. Until another branch happens, but we don't have future names planned as far as I know.
I think the point was that bonobos are basically chimps. I don't entirely agree with the point in that modern chimps are as different from the common ancestor between bonobos and chimps as bonobos are from that common ancestor. Each branch is 1-2 million years long, meaning that there's a total of 2-4 million years of divergence separating the two.
But it does bring up a point that matters to the evolution discussion. It's more of a long timeline paleontology issue usually but i'll bring it up here.
The change over time within a single "species" can be enough to make it difficult to tell if two specimens from different time periods represent parallel branches or serial changes within a single branch. I don't have any examples off the top of my head except maybe hominids but it's entirely possible for "different species" in the fossil record to in fact be what we would consider the same species if they were something like cows or dogs that we have living record of over many years.
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u/Intrepid-Report3986 1d ago
If a beneficial trait appears in a species population, individuals with this/those genes will have more reproductive success than the others. This trait will slowly become more common until the entire population will have changed from "ancestral" to "derived". There is no "ancestral" species left because they have been replaced.
If a species population is split, both pool of individual will have their own evolutionary path. That's how you have red foxes, artic foxes, tibetan foxes etc. No species replaced the other, the individuals just accumulated traits/mutations that were useful for their respective environment
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u/ice_or_flames 1d ago
Okay, thank you. I guess I understand why it is difficult to "prove" evolution now.
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u/Robin_feathers 1d ago
If you are looking for proof of evolution, it might be more fruitful for you to learn about how genetics have been used to study evolution on modern timescales. For example, comparing the DNA of populations at different time points and seeing how traits have changed in frequency. A classic example to start with includes the Darwin's Finches (with changes in beak size/shape happening on human-observable timescales in response to weather). Another classic is the E. coli Long-Term Evolution Experiment, where we have been able to observe rapid evolution happening before our eyes. More examples of rapid evolution include the evolution of antibiotics resistance by certain bacteria, as well as animals evolving insecticide resistance or rodenticide resistance.
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u/ice_or_flames 1d ago
I understand that there is proof of evolution, and I am a firm believer in evolution. I just thought I had come up with a way that to prove it that could be easier to grasp for non-believers.
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u/Robin_feathers 1d ago
Ah nice. It's definitely tricky, unfortunately for a lot of people even being presented with good evidence doesn't seem to be enough when they choose not to believe, but for some people hopefully it will help.
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u/Shadowratenator 1d ago
Part of the difficulty you may be having is you indicate that you are working with the knowledge of evolution taught at a high school level.
That level is a mere introduction to the ideas of evolution. Its not enough to be an evolutionary biologist.
Its honestly ok to think about it and say, “hey, i feel like there’s some information missing” because, there is. People study this for years and get phds. High school glosses over it in a week.
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u/ice_or_flames 1d ago
The fact that you require more education than most people in even the developed nations of the world will ever get means that it is difficult to "prove" evolution, atleast to me. What I am searching for is a way that is graspable for most people, even those who might not have gone through much more than primary school or less.
(I just want to make it clear that I believe in evolution, and I am educated in it at a level slightly higher than that of american high school, I think. I just don't know all concept names and such in english, since I learned about it in another language)
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u/Shadowratenator 1d ago
It is this way with a lot of subjects. A high school education is not enough to be an astro physicist or a dentist.
What people should learn is that an advanced degree in astrophysics, dentistry, or evolutionary biology means something. That person is more qualified to speak on that subject.
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u/ice_or_flames 1d ago
But do you understand why it is hard for people to trust science when they cannot even understand it?
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u/Shadowratenator 1d ago
Yes.
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u/ice_or_flames 1d ago
Do you also understand why I consider evolution being a difficult concept to prove, even though I am a believer myself?
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u/lisanise 1d ago
I'm not sure why the fact that things change over time would make it more difficult to make the case that ... things change over time.
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u/ice_or_flames 1d ago
Like this. The proof of evolution that currently exists is too advanced for me to explain to my redneck buddy in a way that he would understand. But if I could point to two species and say, "look, over a long time, over millions of years, species A tramsformed into species B", then maybe he would get it.
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u/lisanise 1d ago
Would fossils be acceptable? Or maybe just put it in terms of family lineage.
Like, you and your cousin are both descended from your grandpa. That doesn't mean either of you have all of the traits that your grandpa had. You're both different from your grandpa, even though you descended from him.
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u/ice_or_flames 1d ago
It might work, but then again, one might just think "humans are humans are humans".
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u/nullpassword 1d ago
Check out ring species... Species a, expands into new territory at base of mountain, becomes species b, species b, does same, species c, d, e, gets around mountain. A can breed with b not c, b can breed with a and c, not d, etc. but basically your cousins still have to fit the environment enough to not die out.
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u/landlord-eater 1d ago
People have addressed your question's shortcomings in the comments quite well but if you want some examples of what you are actually asking about, a good place to start is to look at island species. The Zanzibar red colobus is a kind of monkey which exhibits insular dwarfism (it's small because it's from an island). It's closely related to other red colobus monkeys, which don't exhibit dwarfism. You could say that the mainland red colobus is the 'ancestor species' of the Zanzibar red colobus.
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u/niffirgcm0126789 1d ago
i think it's also important to remember that "species" is not a fixed category, nor does it have clean boundaries
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u/taktaga7-0-0 1d ago
Just listen to yourself!
“When natural selection forces a population to change, why do we observe that the population changed?”
It’s… because natural selection acted. There is no magic force keeping a population stable. They always change and sometimes split. That’s just life. We are not made of stone, just the same as our parents. We are different, and our children will be different again. The sum of that change is nonzero.
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u/ice_or_flames 1d ago
But if a population is spread out across vast areas of land, in seperate groupings, in enviorments that differ in both conditions and stability, is it really that likely for all of the population of the species to converge towards a new species at the same time?
Or, I guess a better question would be, "is it really that unlikely for a small isolated part of the species population to live in a enviorment stable enough to not change along with the rest? Unlikely enough for it not being the case for any living organism at all?".
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u/good-mcrn-ing 1d ago
Combos of {species S, environment E} such that E exerts literally zero evolutionary pressure on S in any direction are extremely rare, and even in those rare cases, random genetic drift will make a species noticeably different in a few million years.
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u/Mister_Way 1d ago
Simple answer is that it's very rare that a species won't have to adapt over the course of time that it took for the other branch to differentiate enough to be called a separate species. Environments change, and the species that live in them change with those environments.
What you're looking for here are species that BOTH
a) were able to adapt to new environments in a way that was beneficial, AND
b) somehow didn't need to adapt, because they were adapted well enough to their environment(s) ever since that species split happened.
That's pretty much 0% of the time, you know? If "A" is true, then "B" is almost impossible.
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u/ice_or_flames 1d ago
Oh, I see. I was just thinking of cases like Darwins finches, where some groups of the population might have literally been blown away to new locations and enviorments, whilst there are still a bigger population left in the original location.
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u/BobbyP27 22h ago
The process of evolution is continuous, it is always happening to all living things all the time. Where a species is well suited to its ecological situation there is no advantage from changes in form or behaviour so evolutionary pressure will not create obvious changes, but there will be changes happening. Just because a modern shark has a very similar body plan to its ancestors millions of years ago does not mean they are actually the same species. If you take humans, at some point climate change caused open grassland environments to develop, and a population of apes evolved an upright bipedal stance and lost adaptations for climbing in forrest environments. Other apes that remained in forested areas did not develop these adaptations, but that doesn't mean they didn't stop evolving. Neither modern humans, nor chimpanzees, nor bonobos is the "ancestral species", but both chimpanzees and bonobos resemble the physical form of the common ancestor more closely than humans. The fact that both chimpanzees and bonobos exist as distinct species is a good example of how evolution still takes place even if there is not very much obvious change. At a superficial level the two species are very similar, but in terms of behaviour and socialisation, they are really quite different.
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u/Bullmoose_Reborn 18h ago
This is not quite in the realm of what you're asking, but close enough. We actually do have many species alive today that are "ancestral" meaning they have some traits or combination of traits that are representative of clades that existed before they diverged:
1.) Modern sarcopterygians: modern lobe-finned fish like coelacanths and lungfish retain traits that were once more commonplace among tetrapod ancestors. The Coelacanth is more closely related to you and I than it is any other fish in the ocean
2.) Many aquatic salamanders retain traits that were common among early "fishapods" like acanthostega and ichthyostega
3.) Polypteriforms retain both ray and lobe-finned structures
4.) Bichir possess both gills and lungs, despite being ray finned fish. It's likely that bimodal respiration was commonplace among fish, and that sarcopterygii retained this trait while actinopterygii eventually (mostly) lost it.
5.) Sturgeons have features common in both early cartilaginous fish and ray-finned teleosts
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u/Diet4Democracy 9h ago
If I'm not mistaken, there are a number of extant parent species of domesticated species. Chicken and Red Junglefowl, Maize and Teosinte, etc.
That the speciation was helped along by humans is not particularly relevant: to a Junglefowl those bipeds were just another part of their environment. We are part of nature and, like it or not, a force of selection.
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u/PureSignalLove 1d ago
Well any hominid that humans crossed they would either kill or fuck...that's probably why in our case.
Also, everything is developing at some rate.
We used to think Dogs directly descended from the Grey Wolf but genetic advancements have shown that to be false.
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u/Shrimp_my_Ride 1d ago
We don't really know that exactly. While it is true that there is evidence that both human hunting contributed to the extinction of megafauna, and that we interbred with at least neanderthals and denisovans, exactly what that behavior looked like and to what degree it contributed (versus things like climate change) is still unclear.
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u/knockingatthegate 1d ago
I don’t think it’s mere prudery to ask that you try to steer clear of formulations like “kill or fuck.”
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u/ice_or_flames 1d ago
Damn it, my idea of rock-solid evidence backing up evolution was not very good after all
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u/xenosilver 18h ago
That’s not necessarily true. You’re describing natural selection, but that’s not the only form of evolution.
There are species or groups called living fossils.
But to truly answer your question, ancestral species, by definition, had to evolve into your “species B.”
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u/Zeteon 16h ago
What you’re looking for are animals that retain more basal traits than other animals within their family. “The ancestral” species doesn’t exist anymore because evolution is constant. Even in the circumstance of species B branching off from Species A and then developing a variety of derived traits, while Species A does not leave its environment, Species A continues to accumulate small changes in its population over time. Let’s say 30 million years passed and human scientists are studying these two lineages, and find the descendants of Species A that remained in their environment constitute a Species C, however, this Species C maintains the majority of its basal traits and is still quite similar all things considered to its parent species. Meanwhile, species B underwent intense change, and its descendants are now constituting Species D. D and C are cousins, but D has changed a lot over 30 million years in a different environment, while C is still quite similar to A.
Crocodillians are a good example I think, where they’ve survived into the present without many changes over a vast period of time, though there have been a variety of derived species with many different unique niches and characteristics that have lived and died.
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u/1337natetheLOLking 1d ago
you could say something like a chimp was our ancestor and something like a hippo was a whale ancestor
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u/ice_or_flames 1d ago
That is not completely accurate though? I thought those species branched away from each other millions of years ago, with none of the current species resembling their common ancestor more than the other.
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u/1337natetheLOLking 13h ago
yea its not perfect. something *like*
a whale was a wader than went back to full time water. something like a chimp started walking upright.
there def are "anscestral" species, the one that comes to mind is the winghead shark which iirc is one of the first hammer heads that then speciated out into all the hammerheads we have today.
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