Dolphins and orcas have passed the evolutionary point of no return to ever live on land again
Dolphins and orcas have passed the evolutionary point of no return to ever live on land again
Scientists have discovered that once a mammal has become fully aquatic, it passes a threshold that makes a return to terrestrial landscapes almost impossible.
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Reading the study (the actual paper, not the linked article), it seems expected and sensible.
A conjecture is that aquatic adaptation is not reversible because there are already animals on land that can out-compete animals attempting to adapt back onto land (similar to how there have been very few transitions from aquatic to land in the first place).
Of course, in actuality this does not mean the transition from aquatic to terrestial is not reproducible, just that it would require a removal of the prohibiting factor such as a mass extinction event killing off most or all life on land.
Well, since mass extinctions are around the corner, I guess there could be a chance! Once we've cooked the earth, maybe the next global apex comes from the ocean.
Mass exctincrions aren't "around the corner," they're just a part of life on Earth. They've happened several times before, and they will probably continue to happen. It's not a coming thing--it's the reason mammals rule the Earth right now, and why almost all life uses oxygen.
Holocene extinction: currently ongoing. Extinctions have occurred at over 1000 times the background extinction rate since 1900, and the rate is increasing. The mass extinction is a result of human activity, driven by population growth and overconsumption of the earth's natural resources. The 2019 global biodiversity assessment by IPBES asserts that out of an estimated 8 million species, 1 million plant and animal species are currently threatened with extinction. In late 2021, WWF Germany suggested that over a million species could go extinct within a decade in the "largest mass extinction event since the end of the dinosaurs.
source: https://en.wikipedia.org/wiki/Extinction_event?wprov=sfla1
I think you might have misunderstood me. I'm not arguing that we're not understand one right now. I'm just saying that it happens quite frequently, in geologic time. Definitely not trying to minimize the how harmful of an impact we're having.