This episode topic comes requested by Mac, but we couldn’t bear to squeeze it into just one episode! We discuss the fascinating, complicated, and deeply personal story of Human Evolution.
In the News (from Part 1):
Plesiosaurs’ Four-Flippered Swimming
Researchers built a plesiosaur robot to demonstrate how these marine reptiles’ four flippers could most efficiently navigate the water. [Report]
The Life of a Dodo
Cutting through dodo bones allowed researchers to identify the yearly habits of dodos, including their molting and breeding seasons! [Report]
Eating With Weird Whale Teeth
A statistical analysis of the bizarre teeth of ancient whales suggests they were built best for slicing through prey, not filter-feeding as has been proposed. [Report]
Mutations and the Path of Evolution
A study reconstructed the ancestral form of hormone receptor proteins, and discovered that a key mutation was one of several hundred options, each with their own unique consequences. [Report]
Hominin News! (from Part 2):
Neanderthal Tooth Gunk
An analysis of the DNA from Neanderthal tooth plaque reveals not only what they were eating, but hints at the ways they may have been using plants and interacting with our own species. [Report]
Footprints from the Mediterranean may represent the earliest true bipedal hominins, but not only are they in Europe, they’re way older than expected! [Report]
Where Do the “Hobbits” Fit?
A new detailed analysis of the island dwarf Homo floresiensis suggests this species has much more ancient roots than we previously thought. [Report]
A Sugary Secret to Human History
Researchers have discovered that a certain sugar molecule leaves a signature in ancient bone, and might be able to add new details to the history of human evolution. [Report]
The Story of Us
Humans are animals. And mammals. And primates. And apes.
Many of the features we have are inherited along with other primates from the same ancestors, including our forward-facing eyes, three-color vision, grasping hands, big brains, small faces, complex social structures, and more.
More specifically, we fit right in among the Great Apes (orangutans, gorilas, and chimpanzees+bonobos). All of the species closer to Homo sapiens than to any other living species (all descended from a common ancestor we share with chimpanzees around 6-8 million years ago) are commonly referred to as hominins.
An Astounding Fossil Record
The fossil record is always limited, but there are few evolutionary sequences as well-represented as hominin evolution. Thousands of fossils representing well over a dozen species range from the very recent past back to 6 or 7 million years ago. The fossil data for human evolution is so extensive that paleontologists (and more specifically, paleoanthropologists) are able to ask detailed questions – and have detailed debates – that are simply not possible for other ancient life.
Across the spectrum of hominin evolution, the fossil record presents an incredible view of the transition from the more typical ape-like features of our ancestors to the human-like features we have today: gradual changes in the teeth, jaws, braincase, arms, legs, spine, and even behavior.
Across the first few million years of hominin evolution, we witness a series of very ape-like species gradually accruing features that look more and more like modern humans.
Once the genus Homo appears, it diversifies into a wide array of species. Over the past two million years or so, there have been many populations of various species (or subspecies) of human living at the same time, and often in the same place, across Africa, Europe, and Asia. It’s only in the last 40,000 years or so that Homo sapiens has been alone.
Bipedalism (walking on two feet) was present in Australopithecus, and possibly even earlier, and continued to develop as hominin evolution continued. The human skeleton is highly modified compared to other primates, which features of the skull, spinal column, hips, knees, and feet all adapted in concert to allow us to walk in the very peculiar upright stance we use.
There’s a LOT that we’ve learned about human evolution, and a LOT left to go. Have some links!