New study sheds light on the origin of animals
ox.ac.uk
ox.ac.uk
Of course, by this measure of our own history, we should expect ~3/4 of the Earth-like planets we discover to have nothing more advanced than single-celled life.
Now, the question of how single-celled life could have given rise to multicellular life and the origination of chromosomes, etc. is a whole other question, see slime molds.
More than half your body is not human
Isn't that the evolutionary purpose (if there is a purpose at all) of all life?
And are mobile. not rooted. At least thats what I learned as a kid as the main difference between animals and plants.
Like, many life-forms among the Ediacaran biota are more closely related to modern animals than to plants, apparently. But for example charnia was a rooted life-form that was a filter feeder.
https://en.wikipedia.org/wiki/Ediacaran_biota
https://en.wikipedia.org/wiki/Charnia
And obviously that distinction should be messy when we go all the way back to the point where the two first started ti separate.
No, the distinction has not been messier in the early times. On the contrary, the distinction was sharp in the beginning and it became messier later.
All the so-called eukaryotes, i.e. the living beings with nucleated cells, were animal-like in the beginning (perhaps close to two billion years ago), i.e. they were mobile and they fed by ingesting other living beings.
Much later, hundreds of millions of years later, various groups and subgroups of eukaryotes have become sedentary, in some cases because it was more efficient to wait the food to come to them, brought by water currents, than to pursue actively the food, in many other cases because they incorporated phototrophic living beings, e.g. blue-green algae, so they no longer needed organic food, and lastly, many groups have become sedentary after reverting to the mode of feeding of bacteria, i.e. instead of ingesting other living beings, which requires mobility, they went back to absorbing organic substances from the environment through their external surface, which does not require mobility for adults, but only for whatever kind of spores they use for reproduction. This last way of life is characteristic for fungi and for several other groups of living beings which resemble fungi without being related to them.
The first sedentary eukaryotes were the multicellular red algae and green algae (some green algae evolved much later to become the land plants), for which certain fossils are about one billion years old. Dubious fossils of red algae are a few hundred million years older.
During the early evolution of the multicellular animals, many groups have become sedentary as adults (e.g. the sponges), which in the beginning was somewhat unavoidable for any animals that became large, because a small larva could easily swim using cilia, a small adult could also use cilia, but for a big adult animal cilia are inefficient, so strong muscles are needed to move the body parts, to be able to use those parts for locomotion, and several tens of millions of years have passed until the animals evolved to have such muscles.
The start of the Cambrian is defined by the apparition of worms which were strong enough to burrow in the mud from the sea floor.
Personally I think if you can get a good idea of what the land based environment was like back then, you'll have a better idea of what changes are needed to extend lifespans in order to watch evolution taking place before your eyes. Currently only viruses and some bacteria like Gram negative pseudomonas can evolve quickly to changes in their hosts environment.
What makes their discovery interesting is the use of berthierine, an iron rich, aluminium rich clay.
>The analysis found that fossils with exceptional BST-type preservation were particularly enriched in an antibacterial clay called berthierine.
Pseudomonas loves iron in all states, and its bacteria that destroy skeletons, once animals and insects have picked at the flesh, so there might be some mileage in using aluminium based deodorants for a starter, in order to reduce bacterial levels as a strategy to extend lifespans, besides dietary supplements and fine control over our environment, like air quality.
Aluminum might reduce bacterial levels, but it isn't exactly great for human health either. Especially at high concentrations: https://pubmed.ncbi.nlm.nih.gov/9164811/
??? The timeline as some of us know it is: -4,400,000: Ardipithecus ramidus (half-arboreality); -2,300,000: Homo habilis (tools); -1,700,000: Homo erectus (organization and "world conquest"); -315,000: Homo Sapiens, approximate anatomy; -250,000: Homo Sapiens, current anatomy.
«Tens of thousands» may refer to the "Cro-Magnons"...
Check the page at https://en.wikipedia.org/wiki/List_of_human_evolution_fossil...
The exception is that some Precambrian fossils come without doubt from some kind of sponges.
Unlike multicellular animals, which have appeared much later, multicellular red algae and green algae were already widespread one billion years ago.
> Estimates for animal antiquity exhibit a significant disconnect between those from molecular clocks, which indicate crown animals evolved ∼800 million years ago (Ma), and those from the fossil record, which extends only ∼574 Ma. Taphonomy is often held culpable: early animals were too small/soft/fragile to fossilise, or the circumstances that preserve them were uncommon in the early Neoproterozoic. We assess this idea by comparing Neoproterozoic fossilisation processes with those of the Cambrian and its abundant animal fossils. Cambrian Burgess Shale-type (BST) preservation captures animals in mudstones showing a narrow range of mineralogies; yet, fossiliferous Neoproterozoic mudstones rarely share the same mineralogy. Animal fossils are absent where BST preservation occurs in deposits ≥789 Ma, suggesting a soft maximum constraint on animal antiquity
> contradicted
There is no contradiction in saying that the earliest found occurrence of x is at some point in time and the first high concentration of x is at some other later point in time. It is actually expected.
E.g.: First tablets found in Sumer: -3500 ; bulk of earlier found tablets in Sumer: -3300.