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Billion-year-old algae (“leaves, … branches …”) raise some interesting questions


Including questions researchers are now prepared to discuss:

The recently unearthed tiny fossil, smaller than a single grain of rice, appears to be the world’s oldest known specimen of green algae: It rolls back the clock on the confirmed existence of these algae by a staggering 200 million years. “It’s very daunting. A billion years — that’s at least five times older than the oldest dinosaurs,” said Xiao, who is a senior author on the Nature Ecology & Evolution paper that announced the discovery. “It’s before any animals. The world is very, very different from what we know today.” …

Ancient as the fossilized algae are, they seem to have many of the characteristics also seen in much later green seaweeds. It isn’t just that they were clearly photosynthetic and multicellular — traits that help to define seaweeds but have murky evolutionary origins. “They have leaves, they have branches,” Tang said.

Dana Najjar, “Billion-Year-Old Algae and Newer Genes Hint at Land Plants’ Origin” at Quanta

Just so. And how much time was there for such attributes to develop purely via natural selection acting on random mutation?

This article is noteworthy for considering the complexity of real evolution:

In a commentary on Wong and Melkonian’s paper in Current Biology, Philip Donoghue and Jordi Paps of the University of Bristol expand on the argument that many of the plant genes that look like adaptations to life on land seem to have much deeper histories and may have served different functions in algae originally. …

In fact, some of those genetic histories may reach beyond algae: The Cell paper showed that the genes for surviving the stresses of desiccation may have originally come from soil bacteria and been donated to Zygnematophyceae (or their ancestors) through horizontal transfer.

Dana Najjar, “Billion-Year-Old Algae and Newer Genes Hint at Land Plants’ Origin” at Quanta

Like any real history, evolution is not driven by a single force or idea. Horizontal gene transfer from bacteria obviates the quest for an “ancestor” seaweed. Maybe there isn’t one.

These people sound like they are on the right track though: “There’s no reason to think that algae in all these millennia just went in a straight line,” said Wong. “It just doesn’t work that way.”

Original Nature paper. (paywall) Cell paper. Commentary. (paywall)

See also: Stasis: Life goes on but evolution does not happen


Natural selection: Could it be the single greatest idea ever invented?

Leaves and branches on a nearly microscopic plant.... Emerson said it in 1840: The world globes itself in a drop of dew. The microscope cannot find the animalcule which is less perfect for being little. Eyes, ears, taste, smell, motion, resistance, appetite, and organs of reproduction that take hold on eternity -- all find room to consist in the smallest creature. So do we put all our life into every act. The true doctrine of omnipresence is, that God reappears with all his parts in every moss and cobweb. The value of the universe contrives to throw itself into every point. polistra

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