New study challenges old views about evolution of early life


A research team led by biogeochemists at the University of California, Riverside has tested a popular hypothesis in paleo-ocean chemistry, and proved it false.

The fossil record indicates that eukaryotes—single-celled and with more complex compared to prokaryotes, such as bacteria—show limited morphological and before 800-600 million years ago. Many researchers attribute the delayed diversification and proliferation of eukaryotes, which culminated in the appearance of complex animals about 600 million years ago, to very low levels of the zinc in seawater.

As it is for humans, zinc is essential for a wide range of basic . Zinc-binding proteins, primarily located in the , are involved in the regulation of .

Eukaryotes have increasingly incorporated zinc-binding structures during the last third of their evolutionary history and still employ both early- and late-evolving zinc- structures. Zinc is, therefore, of particular importance to eukaryotic organisms. And so it is not a stretch to blame the 1-2-billion-year delay in the diversification of eukaryotes on low bioavailability of this trace metal.

But after analyzing marine black shale samples from North America, Africa, Australia, Asia and Europe, ranging in age from 2.7 billion years to 580 million years old, the researchers found that the shales reflect high seawater zinc availability and that zinc concentrations during the Proterozoic (2.5 billion to 542 million years ago) were similar to modern concentrations. Zinc, the researchers posit, was never biolimiting.

Written By: PhysOrg
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  1. A dis-confirmed hypothesis is, as we may see here, very valuable to science and ” advances ” human knowledge.

  2. It is amazing what modern science can calculate and conclude, reaching even as far back as 2.5billion years! What’s also wonderful is that if it hits a brick wall, it will try something different and new until it obtains a plausible and satisfactory explanation while religion has only one holy ancient text which must not even be questioned! How much ‘truth’ about the natural world, about life, can it yield compared to the truths obtained by science?

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