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Spanning The Globe February 2024

It’s time to go spanning the globe for anatomy news and notes:

 

Clambering

Maybe us humans went bipedal in phases.

 

That’s the news out of an analysis of an ape’s inner ear.

 

Specifically, a six-million-year-old ape known as Lufengpithecus, an extinct genus of ape from the Late Miocene.

 

The scientists from New York University looked at the interior of the fossil skull using 3D CT scans. Specifically, they studied the bony inner ear, which is critical to maintaining a sense of balance.

 

In analyzing the development of those inner-skull structures, scientists are now proposing that early apes moved in a way similar to modern Asian gibbons, then later used a combination of climbing and “clambering” (both in trees and on the ground), and then finally developed bipedalism from this “diverse locomotor repertoire.”


The work suggests that the answer to bipedalism isn’t only in the postcranial skeleton (that is, the skeleton excluding the skull). It was right there between the ears all along. Thanks to this excellent write-up in Study Finds.

 

By the way, the inner ear is located within the “bony labyrinth” of the temporal bone and contains the cochlea, semicircular canals, utricle, and saccule.

 

And what’s the difference between a labyrinth and a maze? Labyrinths have a single continuous path that leads to the center. In other words, you’ll get there eventually. Mazes have multiple paths and some are dead-ends.

 


Ancient Interactions

Maybe Neanderthals and Homo sapiens lived side-by-side in Northern Europe.

 

We’re talking 45,000 years ago.

 

It’s possible they overlapped for several thousand years before Neanderthals went extinct.

 

Findings from a cave under a castle in Germany (near a town called Ranis) is yielding proof that the two species cohabitated in the same area and occasionally interbred.

 

It also feeds the suspicion that the invasion of Europe and Asia by modern humans some 50,000 years ago helped drive Neanderthals, which had occupied the area for more than 500,000 years, to extinction,” stated this article in EurekAlert!

 

The work was all based on analysis of stone blades and determined to be the handiwork of Homo sapiens. Genetic analysis, isotopic analysis, and radiocarbon dating were all involved in analyzing the Ranis site. 

 

The debate continues over what caused the extinction of Neanderthals. There are plenty of theories to choose from—violence, parasites and pathogens, competitive replacement (from Homo sapiens), competitive advantage of modern humans, anatomical differences and running ability, the domestication of the dog to help with hunting, climate change, and maybe even a volcanic eruption near Naples, Italy.

 

“Bags, Bags and More Bags”

We came across this engaging article by Bethany Brookshire in Scientific American: “The Human Body is Bags, Bags, and More Bags.” Brookshire is the author of Pests: How Humans Create Animal Villains. She also posts musings and discoveries on Tik Tok (and Instagram) in a series called Insomniac Anatomy Academy. (Brookshire says she has trouble sleeping and studies anatomy late at night, turning little tidbits into short videos that are produced with a quirky, upbeat sensibility.)

 

In the Scientific American article, Brookshire makes a great case for the bags theme. Skin, she argues, is a “many-layered sack” that holds our insides together. The stomach is a bag. Bladder, too. The heart has two bags, a fibrous pericardium and a serous pericardium. “The brain and spinal cord are triple-wrapped, with three layers of the meninges,” she writes. “These sacks physically protect our most delicate and essential bits. Inside, there’s another, different sack—a blood-brain barrier of linked cells that prevents most infections from touching the brain. Even the uterus is a bag—one that can be filled with a fetus. That fetus builds its own inner bag in conjunction with the parent, creating the placenta, layers of parental and fetal cells that protect and provide.”

 

Brookshire’s Tik Tok is engaging and full of fascinating takes on human anatomy. For instance, the funny bone is not a bone, the clavicle is “the best bone,” and more about her compelling case for bags. More than anything, we love her enthusiasm! Check her out!

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