I want to know what man was in the beginning, before the ape. Was it a bacterium or a shrimp, because I sometimes hear stories like that.

Answer
Dear Louise,
If you could go very far back in time, say a few billion years, you would end up in a world that you wouldn’t recognize. This world consisted of bare rocks and seas. The only life then consisted of bacteria. So it’s true that our most distant “ancestors” were bacteria. The oldest bacteria found as fossils are no less than 3.7 billion years old. It was only much later that the first organisms consisting of a single cell with a cell nucleus, such as the current amoeba, emerged from these bacteria. Later still, the first multicellular organisms arose from this, to which you, I, the monkey and also the shrimp belong. However, the shrimp is an arthropod, just like the insects and spiders, and we are not descended from that. Our oldest ancestor did live with arthropods. How do we know? By studying fossils found in the shales of Burgess in Canada. Those shales, a kind of hard sea clay actually, contain numerous crushed fossils of critters that lived on the sea floor 500 million years ago. Paleontologists call that distant ancestor of ours Pikaia. The fossils of this worm-like creature already had a simple backbone beginning, so they are believed to be the ancestors of all vertebrates: mammals, fish, birds, reptiles and amphibians.
Answered by
Prof. dr. Robert Speijer
Geology – Paleontology – Paleoclimatology. You study geology in Leuven!
Old Market 13 3000 Leuven
https://www.kuleuven.be/
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