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Comment by samatman | Hacker News Reader

Even more wild to me is that saber-toothed cat-like predators evolved seven separate times: https://en.wikipedia.org/wiki/Saber-toothed_predator

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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

This one? https://news.ycombinator.com/item?id=29621646

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.

> 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

All of this has happened before before.

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?

It was a Battlestar Galactica reference.

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).

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?

Hookup culture and milt are probably not a match waiting to be made in (seven minute underwater) heaven.

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.

Edit: dropped word

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.

Didn't we have monkey- vs octopus- vs rat- like game where monkey- won the race?

Corvids have entered the chat.

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.

Here's another: https://www.sciencedaily.com/releases/2022/06/220601111749.h...

"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.

https://en.wikipedia.org/wiki/Settlement_of_the_Americas

The current view is skin color is simple evolutionary response which can easily occur on those timescales. https://www.psu.edu/impact/story/the-evolution-of-skin-color...

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

Very neat. I didn't know about the folate angle selecting for dark skin in the first place.

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].

[0] https://royalsocietypublishing.org/doi/10.1098/rstb.2018.023...

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.

The teeth are already there. A few gradually longer ones makes obvious sense to be a better predator, giving them an evolutionary advantage.

Then why aren't they still around? Why don't they evolve again?

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.

The large teeth may have been useful to hit vital organs on large prey that used to be common but now extinct. No large prey - no sabre teeth needed.

Probably climate change and humans.

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.

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.

"Dirk cats" were featured in the sci-fi series starting with Souls in the Great Machine, another convergence to a saber-toothed feline.

Someone keeps submitting the “saber tooth” product and it keeps getting rejected - no market fit?

But the idea is just too cool to die.

The Evolution app store

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