It was another brilliant piece in the puzzle of evolution reported this week out of Lake Victoria. Published Tuesday in a scientific journal is definitive evidence that proconsul – at least some of his kind – lived in the forest.
Proconsul was an early primate of 23-25 million years ago, and it’s long been conjectured that he was the earliest common ancestor of apes and men.
There have been many fossils of proconsul found but whenever their prehistoric habitat could also be established, it was that they lived on a savannah. While that fit the general linear evolution into a hominin, it complicated the presumption that they also gave rise to the apes.
I’ve always been leery of the concept of “earliest common ancestor” among paleontologists as it tends to reenforce the linear notions of evolution, when in fact with each new piece found to the puzzle we discover how richly branched evolution was.
The idea that there was ever a “single” anything before homo sapiens sapiens seems questionable to me, and in fact there are several if not a half dozen species of proconsul already identified. So think of it more as a family of species rather than a single species.
Then it works brilliantly.
Proconsul is so important because it’s the first species in the paleontological record that is definitely not monkey-like or a lemur, which were the first primates.
The first primates were preceded by a group of early mammals, mostly little vole-like creatures, that flourished about ten million years after the dinosaurs disappeared. After earth shook off the apocalyptic event of the asteroid crashing into earth that killed the dinosaurs, it blossomed.
It was warm and humid and more and more oxygen was being created in the atmosphere in large part because of the growing plants in the sea. Earth became mostly a giant, beautiful forest, quite different from what the dinosaurs had left behind.
And so mammals and primates prospered, and they necessarily became more and more arboreal.
Then things really started to happen about 25 million years ago. The earth began cooling, earth’s tectonics got active, and in Africa the great jungles were split by the formation of the Great Rift Valley which gave rise to savannahs.
At the same time proconsul appeared. It differed from the monkeys and lemurs mostly in not having a tail. That’s not good for a creature that swings through the forest so it made sense he lived on the ground.
Apes live on the ground, much of the time, even though their home is in the forest. So that works, too. Problem was that whenever habitat could be determined with the many proconsuls found, it was always a non-forest savannah.
Alas brilliant field work mostly by Baylor University and University of Rhode Island scientists working on Rusinga Island in Lake Victoria found a proconsul and its fossil preserved habitat of a forest!
Rusinga Island, by the way, is where Lewis Leakey found one of the first proconsuls almost a half century ago. (The first was discovered in 1909.) The island is rich in Miocene fossils and has been worked continuously since Leakey’s earliest discoveries. But it’s taken all this time and all this work to confirm the habitat-creature association that has been presumed by scientists for nearly a half century.
Sometimes, perseverance pays!