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Spanning the Globe IX

It’s time once again to go spanning the globe for anatomy news and notes!


We have said it before and we’ll say it again—eventually we will have a complete and detailed picture of evolution. For now, the pieces continue to fall into place and one of the latest news flashes comes from Australia where scientists have discovered preserved fossilized hearts and other internal organs of the ancient armored fish known as placoderms.


Ancient? We are talking 380 million years ago during the Devonian Period. It was late in the Devonian Period that the first four-legged amphibians emerged, beginning the colonization of land by vertebrates. Back then, a single Northern Hemisphere landmass included what would later become North America, Greenland, and Europe. The Devonian Period was also known as “the Age of Fishes.”


As you no doubt know, soft tissue rarely fossilizes. But scientists found the fish in what’s called the Gogo Formation in Western Australia and the finding gives a “fuller view of the internal anatomy at a pivotal time in the history of vertebrates,” according to this article from Reuters.


Dunkleosteus was among the earliest apex predators. Photo from Wikipedia.


Placoderms are our earliest jawed ancestors. They were about 29 feet long and had asymmetrical tail fins (like a shark). They had shark-like teeth too, and blunt-nose heads. They also shared the shark’s S-shaped, two-chamber heart. The placoderms’ heart was located at the front of the shoulder girdle and, unlike jawless fish, had a clear heart-liver separation like all modern jawed vertebrates.


The development of jaws, of course, was one of the biggest steps in evolution and required a different body plan. With the discovery in Australia, scientists have a record of an animal that demonstrated this shift away from their jawless counterparts. Pretty cool!



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When did the first human being offer medical treatment to a fellow human being? Who knows? But it might have been a long time ago. Say, 31,000 years. According to this fascinating article in Nature, skeletal remains of a young individual from Borneo had the distal third of the lower leg surgically amputated.


The individual who was treated, probably a child, “survived the procedure and lived for another 6–9 years.”


What’s truly fascinating about this discovery is that it shifts some long-held thinking that medical procedures were not needed before human beings stopped foraging, what’s been called “the Neolithic farming transition. “This unexpectedly early evidence of a successful limb amputation suggests that at least some modern human foraging groups in tropical Asia had developed sophisticated medical knowledge and skills long before,” notes the article.


A brief video clip on YouTube also provides a good overview of this story.



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We loved this story about 95-year-old Richard Soller, who is quite the athlete and is proving it’s possible to stay very active even in late life. The story dives into an area of science called cellular senescence. The science is based on the idea that cells eventually stop dividing. They enter a “senescent” state in response to various forms of damage. “The body removes most of them,” says the article. “But others linger like zombies. They aren't dead.”


In fact, they can accumulate in older bodies, which mounting evidence links to an array of age-related conditions such as dementia, cardiovascular disease and osteoporosis.


Leonard Hayflick was the scientist who discovered cellular senescence in 1960. Today, he’s 94 and a professor of anatomy at the University of California, San Francisco, and continues to write, present, and speak on the topic. Hayflick was the first to realize that normal human cells did not replicate forever. In fact, Hayflick was ridiculed at first for this notion. But science (as science does) ultimately proved him to be correct.


As you might expect, drug manufacturers are developing pharmaceuticals. But—no surprise here—exercise and activity also appear to be key.


Exercise “counters the buildup” of senescent cells and helps the immune system clear them out.


That’s it for now; we gotta run!

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