What is Newsweek's deal these days? I keep reading their Wikipedia article to gain some insight into their acquisition, but keep coming away with nothing.
“Selection” is a very easily misunderstood technical term which overlaps with concepts people often find more familiar. “Natural” is basically whatever anyone wants it to mean. Without intentional study, basic foundations of evolutionary biology are easily misinterpreted. To the extent I can give you the benefit of the doubt that you’re an outlier and understand it better… you’re an outlier. Not the people who you’re judging.
I mean just the basic concept of survival of the fittest, which doesn't require deep understanding of biology. The same concept also applies to lots of things besides biological evolution.[0]
> I mean just the basic concept of survival of the fittest, which doesn't require deep understanding of biology.
Even that can be tricky for some people, since it requires people to think about fitness in a holistic way. But laypeople are culturally primed to think of athleticism. When talking to people skeptical of evolution, this sort of confusion comes up a lot. A lot of "If evolution makes things stronger then why were dinosaurs stronger than me?"
This. And, still biological, “why have some places selected for greater disability like deafness, or seeming disadvantages like below average height?” I don’t want to give too much weight to the “universal” concept, but it’s easy to imagine similar questions about why certain pockets of culture are places where seemingly disadvantaged traits thrive.
“Fit” is probably something better explained literally for an introduction, as in fitting a particular set of circumstances. But that’s really complicated and not something everyone grasps when the language is almost always surrounded by superlatives.
I'm not sure if I'm misunderstanding your comment, but some animals that live all their life in caves and some parasites are blind or have lost their eyes completely.
“Survival” and “fitness” are just as commonly misunderstood for overlapping lay concepts. The concept of “survival of the fittest”, as expressed by Darwin, is a technical term I don’t expect most people to grasp. I question some of the well educated interpretations in the article you linked. In particular “fittest” seems to be the most challenging for people to understand, and the most vulnerable to being misinterpreted or misappropriated.
I'd never guess that those specific words would be an obstacle for understanding the concept. Biological evolution is usually taught by explaining random mutation and reproduction, and that surviving mutations are passed on to the next generations. From there it should be quite intuitive to understand how it works as a basic concept.
Maybe it's a consequence of a bias toward essentialism? We see that bias in racism and hostility towards variant human phenotypes, particularly with respect to sexuality.
The question is phrased in a dumb way, but I think there's a kernel of a fair question in there. Evolution is the how and why, but it doesn't answer what about the crab shape makes crabbiness so effective.
For a given gravity, temperature, salinity and life cycle there are a single best and more efficient solution for moving and survive. Evolution will prune all the bad paths so with enough time will go closer and closer to the more efficient design, Crabs evolved to protect their delicate eggs from mud and debris. You need that if you pass most of your time hiding buried in the mud.
This means also that with enough data about other planets we could even made a raw guess the shape of creatures that could live there.
Yeah, I would say I come from the ancient hacker culture. Don't be too critical of that, as RMS and the GPL are full derivatives of that culture. And the products of the GPL have been sorta useful to the HN community.
Or at least the programming side. The others were there back then, but they weren't interest in hacking, just in counting.
One of the things I love about the way Eons cover topics is how they don't just focus on what we know, but also how we know, who figured things out, and what we got wrong along the way.
Can't endorse their style of science journalism enough.
PBS space time is another good channel. Their series on general theory of relativity is really nice. They try to explain it as close as possible to the real thing but still make it accessible without resorting to innacurate analogies
Saber tooth tigers and humans coexisted for a while, and the tigers were probably very dangerous to us. That and having to adapt to the end of the ice age, I don't think we know what was the bigger factor.
They may wekk evolve again, given the right circumstances. Giganticism in both predator and prey is a response to plentiful food. It happened with both dinosaurs and mammals. By the same token, animals respond by evolving into smaller forms in food sparse environments. On the Indonesian island of Flores, both hominids and elephants became tiny.
There was a recent article on here about how species that looked alike were not necessarily related and is was more common to have physically dissimilar but geographically close species that were evolutionary relatives. One of the points was that convergent evolution was more common than people thought. These stories appear to support the convergent evolution assertion
I wasn't aware of that some time ago, it's a fascinating insight.
I got a lightbulb (going wtf/dark actually!) when watching cartoon or something with triceratops.
They looked so much like rhinos.
But had eggs.
I had trouble reconciling it with evolution.
They were so far ancestor-wise but so close physically-looking wise.
Convergent evolution is very interesting.
It suggests aliens may not be that different from us after all, if exist.
I often wonder if we see time as linear just because we're falling through it in a forced direction. Maybe there is no before or after. Just everything possible existing all at the same time. Like, would a conscious falling star think there is only one direction in space?
This has me thinking of some surrealistic scifi with a Space Crab Parliament that only allows species that have sufficiently carcinized so as to be indistinguishable from the existing members.
My understanding is that eggs and no-eggs are not as different as might be expected. After all, the no-eggs still have eggs but, just, don't lay the eggs or let us make French toast, custards, or omelets! Maybe a key issue would be the amazing placenta. But maybe the egg animals are not so far from having a placenta because they still DO have to be willing to accept the male sperm without killing it, and part of what is amazing about a placenta is that it lets the foreign tissue of the baby exist and thrive in the womb of the mother without destroying it as foreign tissue -- in part, tolerating the sperm, the egg animals already have to do that. These are some details the hookup culture will want to use as sources of conversation? Maybe?
Yes, that's different subject on how egg, roe and womb is really the same kind of thing.
What was striking to me was how far in ancestry chain you have to go back with rhinos to meet common ancestor with egg-lying triceratops - this ancestor will not look like any of them, however they did meet from completely divergent dna to be so look alike, crazy.
Yup, maybe that looking alike is called convergence. Apparently a big instance is eyes, apparently developed several times with surprisingly close to the same design.
Pigs, rhinos, hippos, ..., triceratops all look much the same to me!
Hmm ...? Would the real test of sameness be to see if they make similar BBQ???
If you look at dolphins, ichthyosaurs, and sharks you will see another strong example of convergent evolution from very different ancestries. You have to to go back to the first fishes with jaws to find a common ancestor.
Considering how little time humans (or any kind of primates) have had on this planet, our overall design doesn't seem super stable. I would bet on crab-like aliens.
I'd argue that rats are exceptionally close to humans (both are mammals). Similarly other potential candidates: raccoons, bear, possibly dolphins or other cetaceans.
Insect, plant, or colonial intelligences would be interesting.
"They found that the animals grouped together by molecular trees lived more closely together geographically than the animals grouped using the morphological trees."
Curious if that applies to humans as well. I’m from S Asia and well.. I do have my distinct looks that I share with my family and community, that are different from other communities. Are humans like that as well? I am aware of the migration theories and people crossing ice bridges and all that, but did people evolve in different areas and then spread out after settling their original area?
The closest example of convergent evolution in humans would probably be native populations in South America redeveloping darker skin tones to deal with sun burn the same way we initially had it in Africa. I don’t know the exact genetics, but it seems to be an independent adaptation rather than a holdover from an older population.
There might be some others such as lactose tolerance that are less obvious.
I'd be very interested in hearing about that. My guess would have been that it was more a matter of the previously suppressed genes for dark skin coming back to the fore.
I agree. Humans reached South (and even North) America only relatively recently in the evolutionary terms - 14-16 thousand years before present. It's not enough time for evolutionary processes to start kicking-in.
Another possible explanation (speculation) is that they met and mixed with yet undiscovered hominid species.
Several things have changed as recently as 11,000 years. “Examples for adaptations related to agriculture and animal domestication include East Asian types of ADH1B associated with rice domestication,[71] and lactase persistence.” https://en.wikipedia.org/wiki/Recent_human_evolution
From genetic studies, we can safely say that all humans are closely related and members of the same species. We are not an example of convergent evolution.
Another good example of convergent evolution in humans is adaptation to high altitudes. Andean, Tibetan, and Ethiopian populations all separately evolved distinct mechanisms to thrive in relatively hypoxic environments [0].
Eyes evolved independently in six different phyla. Compound, lensed, eyes are even found in brainless box-jellyfish, which helps them negotiate the mangrove swamps where they live.
This is especially weird for me since I still don't understand what advantage they provide. It doesn't look like you can really use them for biting, can you? So do you just use them like a grappling hook fixed to your face? I've never seen a convincing answer.
Wikipedia has a few convincing hypothesis. One is that sabre teeth are important for biting deep and reaching vital organs on large prey. After the megafauna went extinct, so did saber-toothed animals, and this adaptation was no longer needed.
> We know the process has occurred multiple times and our current grant is aimed at better understanding the drivers and implications
What can they actually discover? 10 legs good? But how about 12? [1]
> The crab with the longest legs is the Japanese spider crab. It’s not related to spiders, despite its name. When extended, its legs can be as long as 12 feet.
If the habitat was the bottleneck, we could learn about a convergence point that tells us about possible non-Earth life.
"Whatever the advantages are, they do not apply in all habitats because some groups have also lost carcinization; one modern example being the frog crab."
Fun fact: life has terraformed the Earth (pun fully intended) into what it is today:
- Photosynthesis created and maintains the current composition of the athmosphere. By removing too much CO2, it likely also contributed to several ice ages.
- Early life sequestered almost all the iron in the primordial Earth's sea into sediments, which turned into iron ores.
- We take the presence of such a basic thing as soil for almost granted, yet soil is created and maintained by life itself. At the same time, soil is only absent in environments where only extremophiles can survive. From this follows that it must have taken a lot of time for life to conquer the land and make it hospitable by creating a soil covering.
From these things, I (perhaps hastily) conclude that planets with life could actually look a lot like Earth. Or they can at least be recognized by the presence of chemically and physically unlikely features such as reactive elements like oxygen in their athmospheres.
Something farmers who are now inherently dependent on synthetics forgot is that plants can form soil on their own. Plants use deep root systems and can send up to half their glucose into the soil to build up organic matter in the soil. Bacteria and fungi digest the glucose and create small pores in clay soil which lets water infiltrate instead of washing nutrients away at the top. Droughts are rarely the result of a lack of water, they are the result of poor water retention.
The point is that plants are capable of terraforming the planet on their own. It isn't even a slow process if humans help the plants do their job.
Maybe there are also path-dependent constraints. We shouldn't assume Earth life has tried every existing possibility so far. Or that we would know about every path taken.
This is my favorite random fact about our biosphere: that for some reason it just keeps making crabs.
The interesting part about it is whether they represent a local minima that optimization gets stuck in - i.e. the returns on building yourself an exoskeleton keep increasing the more exoskeleton you add, so once you chance onto that path every other direction then "more exoskeleton" is a net negative for the next generation.
Well, the frog crabs might indicate that they could both evolve an exoskeleton and then reverse course.
"Whatever the advantages are, they do not apply in all habitats because some groups have also lost carcinization; one modern example being the frog crab."
Ive always wondered this: has a species have an evolutionary history where they originated in land but adapted to living in water and then adapted to living on land again?
Not exactly what you’re asking but whales used to be land mammals.
> It is believed that modern-day whales evolved from land-based animals about 55 million years ago. These land-based mammals are believed to be hoofed mammals, sharing a common ancestry with even-toed ungulates such as the cow and the deer.
> Evolution of Whales
Whales started their journey as all other organisms have, as single-celled bacteria.
An evolutionary picture of the whales can be broken down as follows:
- 3.8 billion years ago: The first single-celled organisms appeared (Bacteria)
- 3 billion years ago: Viruses (also single-celled organisms) became present
- 2 billion years ago: Eukaryotic cells are present. These are cells that contain organelles, or tiny organ-like structures
- 1.5 billion years ago: Eukaryotic cells evolved three ways. These cells evolved into the ancestors of plants, animals, and fungi
- 900 million years ago: The first multicellular structures became present
- 800 million years ago: The animal strain of organisms undergoes its first split and continues into basic marine organisms such as sponges
- 540 million years ago: The first chordates or animals with backbones are present
- 530 million years ago: The first true vertebrate or boned organism is present
- 500 million years ago: Animals first started exploring the land
- 417 million years ago: Lungfish became present. Lungfish are the first organisms to breathe both on land and in the water with both lungs and gills
- 397 million years ago: The first tetrapods or four-legged species are present
- 340 million years ago: Amphibians branch off from the other tetrapods
- 310 million years ago: The remaining tetrapods split into what will be reptiles, birds and dinosaurs, and mammals
- 200 million years ago: A mass extinction occurred and warm-blooded proto-mammals developed
- 140 million years ago: Placental mammals also known as eutherians are present
- 105-85 million years ago: The placental mammals split into four major groups, including laurasiatheres, which will contain the whale species.
- 65 million years ago: The greatest extinction event so far wipes out the dinosaurs providing more potential for mammals to colonize the planet
- 50 million years ago: Artiodactyls pakicitus, a mammal, resembling a wolf and tapir mix with cloven hooves begins evolving into what we know as whales
- 47 million years ago: Early forms of whales live in shallow seas, returning to land to mate and give birth
- 35-45 million years ago: The first fully aquatic whale is present (Basilosaurus)
Modern-day whales are believed to have moved into the oceans around the Tethys Sea, now the Mediterranean Sea and Asia.
It's interesting to look at the primary literature, because then you realize how hard it is to sort these questions out and how many uncertainties there are, because there are a lot of different extinct lineages that might or might not have led to whales or hippos.
Here's the general group people seem to be fairly sure led to hippos; the ones that led to whales might have been an earlier group that gave rise to this group, or perhaps one of these, or perhaps not all whales share a 'root whale':
The actual kind of data they use to make these judgements is mostly bone fragments from fossils, as comparing modern DNA of hippos and whales can only tell you so much. Here's an example study from 2003 on the hippo lineage:
I very much doubt you can pinpoint the date of the appearance of viruses, let alone a full 800 million years after the appearance of bacteria. That site is a click-farm operation.
The evolutionary tree, maybe more accurately the phylogenetic tree, wouldn't loop as it is derived from genetics in modern times. Our ancestors' attempts at making evolutionary trees from morphology (can't fault them for not sequencing DNA) have got a lot of things wrong because seemingly relating creatures were not at all. Convergent evolution being a major reason for stuff they got wrong, making morphology a poor approximation of phylogeny.
Even if 2 distinct species eons apart ended up literally identical and sexually compatible thru some cosmic luck, they wouldn't show up as a loop since we could tell how far apart they are by looking at how mutated some useless and asexually transmitted gene is (mitochondria DNA provides that for eukaryotes, say cytochrome oxidase I gene). The key part is that the gene doesn't receive any evolutionary pressure, so that it only drifts thru random mutations (considering they can't provide a reproductive advantage/increase "fitness"). If you know the mutation rate (which we do), you can date how far back a common ancestor goes between two species' by basically running a diff script on their COI gene sequences.
Considering every known form of life descends from a single ancestor (LUCA [1]), a tree (or root system) analogy is quite apt.
On a large scale, there can not be loops, unless we accept the existence of time travel. But there are indeed some complications that make the concept of a tree of life surprisingly subtle:
- ring species
- species complexes
- hybrid species (turning the tree into a Directed Acyclic Graph)
- horizontal gene transfer via plasmids (between bacteria) or viruses
It’s strongly theorized that turtle ancestors went from land to sea and then back to land. However, it’s tough to completely pin down because turtles have a very bizarre evolutionary history. For example there are proto turtles with shells but without beaks but also proto turtles with beaks but without shells suggesting that either beaks or shells evolved twice and one of those lines died out.
Maybe tortoises. There’s a wide variety of ancestors and related animals that lived in the sea, in freshwater, on land. It’s difficult to trace an exact lineage, but they have a lot of cousins in the water and on land.
The title says "crustaceans" but then the article keep saying "species" as if everything is converging to crabs. I'm no biologist but if you look at the crustaceans, they don't seem far off from crabs
> The paw of the dog, the hoof of the horse, the manus (forefoot) and pes (hindfoot) of the elephant, and the foot of the human all share some common features of structure, organization and function.
Something related I wonder about: consider seals, sea lions, elephant seals, walruses and whales. In those species are we seeing the process of the convergent evolution of a land occupying species toward a purely oceanic going whale form species, where the boundary between land and sea represents a transitional niche which can be occupied only by evolutionarily unstable forms? So that if you could see a sort of extreme time lapse video of this transitional zone, you would repeatedly see a land animal gravitate toward the sea, be caught by the surf, and then “melt” into it and into the form of a whale, then disappear, to be replaced by another land animal, and so on.
As far as I can tell, there is some degree of convergent evolution, with current sea mammal all coming from three separate earth-to-sea ancestors. There’s the seal, sea lion, walrus line. The whale, dolphin line. And finally the humble sea cow / manatee line.
137 comments
[ 2.4 ms ] story [ 216 ms ] threadThat's not how evolution works. Survival of the fittest isn't about aspiration. It's what's left when the fittest are left standing.
[0] https://en.wikipedia.org/wiki/Universal_Darwinism
Even that can be tricky for some people, since it requires people to think about fitness in a holistic way. But laypeople are culturally primed to think of athleticism. When talking to people skeptical of evolution, this sort of confusion comes up a lot. A lot of "If evolution makes things stronger then why were dinosaurs stronger than me?"
“Fit” is probably something better explained literally for an introduction, as in fitting a particular set of circumstances. But that’s really complicated and not something everyone grasps when the language is almost always surrounded by superlatives.
This means also that with enough data about other planets we could even made a raw guess the shape of creatures that could live there.
We've changed the silly title (edit: I meant the article's own linkbaity title) to a more interesting sentence from the article body.
Maybe it’s just your culture?
Or at least the programming side. The others were there back then, but they weren't interest in hacking, just in counting.
Wow, that was a while ago though.
https://news.slashdot.org/story/03/06/08/1534249/esr-recasts...
One of the things I love about the way Eons cover topics is how they don't just focus on what we know, but also how we know, who figured things out, and what we got wrong along the way.
Can't endorse their style of science journalism enough.
I got a lightbulb (going wtf/dark actually!) when watching cartoon or something with triceratops. They looked so much like rhinos. But had eggs. I had trouble reconciling it with evolution. They were so far ancestor-wise but so close physically-looking wise. Convergent evolution is very interesting.
It suggests aliens may not be that different from us after all, if exist.
Alternatively, they are the more evolutionally convergent species and we will evolve towards something inhuman
Characters in the show are frequently forced to confront situations in terms of either coincidence, synchronicity or divine intervention.
The quote underlines a recurring theme in the show and how people adapt to it (though later on gets rather heavy handed).
What was striking to me was how far in ancestry chain you have to go back with rhinos to meet common ancestor with egg-lying triceratops - this ancestor will not look like any of them, however they did meet from completely divergent dna to be so look alike, crazy.
Pigs, rhinos, hippos, ..., triceratops all look much the same to me!
Hmm ...? Would the real test of sameness be to see if they make similar BBQ???
Edit: dropped word
I'd argue that rats are exceptionally close to humans (both are mammals). Similarly other potential candidates: raccoons, bear, possibly dolphins or other cetaceans.
Insect, plant, or colonial intelligences would be interesting.
"They found that the animals grouped together by molecular trees lived more closely together geographically than the animals grouped using the morphological trees."
There might be some others such as lactose tolerance that are less obvious.
Another possible explanation (speculation) is that they met and mixed with yet undiscovered hominid species.
https://en.wikipedia.org/wiki/Settlement_of_the_Americas
Several things have changed as recently as 11,000 years. “Examples for adaptations related to agriculture and animal domestication include East Asian types of ADH1B associated with rice domestication,[71] and lactase persistence.” https://en.wikipedia.org/wiki/Recent_human_evolution
[0] https://royalsocietypublishing.org/doi/10.1098/rstb.2018.023...
What can they actually discover? 10 legs good? But how about 12? [1]
> The crab with the longest legs is the Japanese spider crab. It’s not related to spiders, despite its name. When extended, its legs can be as long as 12 feet.
Now there's a nightmare for you.
[1] https://www.reference.com/pets-animals/many-legs-crab-4c30fb...
"Whatever the advantages are, they do not apply in all habitats because some groups have also lost carcinization; one modern example being the frog crab."
- Photosynthesis created and maintains the current composition of the athmosphere. By removing too much CO2, it likely also contributed to several ice ages.
- Early life sequestered almost all the iron in the primordial Earth's sea into sediments, which turned into iron ores.
- We take the presence of such a basic thing as soil for almost granted, yet soil is created and maintained by life itself. At the same time, soil is only absent in environments where only extremophiles can survive. From this follows that it must have taken a lot of time for life to conquer the land and make it hospitable by creating a soil covering.
From these things, I (perhaps hastily) conclude that planets with life could actually look a lot like Earth. Or they can at least be recognized by the presence of chemically and physically unlikely features such as reactive elements like oxygen in their athmospheres.
The point is that plants are capable of terraforming the planet on their own. It isn't even a slow process if humans help the plants do their job.
The interesting part about it is whether they represent a local minima that optimization gets stuck in - i.e. the returns on building yourself an exoskeleton keep increasing the more exoskeleton you add, so once you chance onto that path every other direction then "more exoskeleton" is a net negative for the next generation.
"Whatever the advantages are, they do not apply in all habitats because some groups have also lost carcinization; one modern example being the frog crab."
> It is believed that modern-day whales evolved from land-based animals about 55 million years ago. These land-based mammals are believed to be hoofed mammals, sharing a common ancestry with even-toed ungulates such as the cow and the deer.
> Evolution of Whales Whales started their journey as all other organisms have, as single-celled bacteria.
An evolutionary picture of the whales can be broken down as follows:
- 3.8 billion years ago: The first single-celled organisms appeared (Bacteria)
- 3 billion years ago: Viruses (also single-celled organisms) became present
- 2 billion years ago: Eukaryotic cells are present. These are cells that contain organelles, or tiny organ-like structures
- 1.5 billion years ago: Eukaryotic cells evolved three ways. These cells evolved into the ancestors of plants, animals, and fungi
- 900 million years ago: The first multicellular structures became present
- 800 million years ago: The animal strain of organisms undergoes its first split and continues into basic marine organisms such as sponges
- 540 million years ago: The first chordates or animals with backbones are present
- 530 million years ago: The first true vertebrate or boned organism is present
- 500 million years ago: Animals first started exploring the land
- 417 million years ago: Lungfish became present. Lungfish are the first organisms to breathe both on land and in the water with both lungs and gills
- 397 million years ago: The first tetrapods or four-legged species are present
- 340 million years ago: Amphibians branch off from the other tetrapods
- 310 million years ago: The remaining tetrapods split into what will be reptiles, birds and dinosaurs, and mammals
- 200 million years ago: A mass extinction occurred and warm-blooded proto-mammals developed
- 140 million years ago: Placental mammals also known as eutherians are present
- 105-85 million years ago: The placental mammals split into four major groups, including laurasiatheres, which will contain the whale species.
- 65 million years ago: The greatest extinction event so far wipes out the dinosaurs providing more potential for mammals to colonize the planet
- 50 million years ago: Artiodactyls pakicitus, a mammal, resembling a wolf and tapir mix with cloven hooves begins evolving into what we know as whales
- 47 million years ago: Early forms of whales live in shallow seas, returning to land to mate and give birth
- 35-45 million years ago: The first fully aquatic whale is present (Basilosaurus)
Modern-day whales are believed to have moved into the oceans around the Tethys Sea, now the Mediterranean Sea and Asia.
https://northamericannature.com/how-did-whales-evolve/
Here's the general group people seem to be fairly sure led to hippos; the ones that led to whales might have been an earlier group that gave rise to this group, or perhaps one of these, or perhaps not all whales share a 'root whale':
https://animals.fandom.com/wiki/Anthracotheriidae
The actual kind of data they use to make these judgements is mostly bone fragments from fossils, as comparing modern DNA of hippos and whales can only tell you so much. Here's an example study from 2003 on the hippo lineage:
https://wp.ufpel.edu.br/cdrehmer/files/2017/06/hipopotamo-ST...
http://www.onezoom.org/life/@Hippopotamidae=510764?img=best_...
https://en.m.wikipedia.org/wiki/Pakicetus
> the closest living non-cetacean relative being the hippopotamus.
You want to know if there are e.g. 3) land animals that evolved from aquatic mammals?
Not that it isn't an interesting question, but what exactly would this tell us?
Even if 2 distinct species eons apart ended up literally identical and sexually compatible thru some cosmic luck, they wouldn't show up as a loop since we could tell how far apart they are by looking at how mutated some useless and asexually transmitted gene is (mitochondria DNA provides that for eukaryotes, say cytochrome oxidase I gene). The key part is that the gene doesn't receive any evolutionary pressure, so that it only drifts thru random mutations (considering they can't provide a reproductive advantage/increase "fitness"). If you know the mutation rate (which we do), you can date how far back a common ancestor goes between two species' by basically running a diff script on their COI gene sequences.
Considering every known form of life descends from a single ancestor (LUCA [1]), a tree (or root system) analogy is quite apt.
1: https://en.wikipedia.org/wiki/Last_universal_common_ancestor
- ring species
- species complexes
- hybrid species (turning the tree into a Directed Acyclic Graph)
- horizontal gene transfer via plasmids (between bacteria) or viruses
(edited for formatting)
https://en.wikipedia.org/wiki/Cape_Barren_goose
E.g.: https://i.imgur.com/t8GXYsB.jpg
"Scientists are puzzled!, Scientists don't know why!, Scientists pull out their moustaches by frustration!"
(What scientists really say):
"Evolution, duh..., nice one, where is my coffee?, sip, sip, show me the pleopods"
https://en.m.wikipedia.org/wiki/Comparative_foot_morphology
> The paw of the dog, the hoof of the horse, the manus (forefoot) and pes (hindfoot) of the elephant, and the foot of the human all share some common features of structure, organization and function.