Long ago primitive sharks had ridges running down their sides from gill to tail. Later, muscles grew into the folds, and eventually the central portion of each ridge receded while the ends enlarged to form fins both fore and aft. All was well.
Then one day several hundred million years ago, a fish was swimming blissfully in a shallow pool. The tide went out and much to the fish’s surprise, she could use her five-rayed fins to move around a bit on the rocky bottom. The tide came in and she swam away, never to give this event another thought. The world, however, was forever changed. Read more
After completing military service in World War II and then his orthopedic surgery residency in Boston, Marshall Urist returned to his native Illinois and joined the faculty at the University of Chicago. There he partnered with a physiologist, and they focused their laboratory research on bone growth and bone grafting. Urist noted on patients’ X-rays that new bone would not only form immediately around a graft but also at times some distance away, in muscle tissue for instance. He surmised that some chemical messenger must be stimulating local cells to begin producing bone. Thereafter he directed his research to isolate and identify the messenger. In the mid 1950s, Urist moved to Los Angeles and spent the remainder of his career at UCLA. Read more
Bone tired and soaked to the bone in sweat, Jason crawled into his truck. The long scorching summer working for his paleontology professor in the bone-dry Wyoming bone beds was at its end. Although the work-study program had good bones on paper, in reality, it failed to deliver anything more than bone-numbing tedium. Read more
Horses and cattle, along with deer, goats, and sheep, walk on their tiptoes. This makes their limbs are as long as possible, allowing them to run fast and escape canine and feline predators, which run on their digits planted flat.
Another limb-lengthening and speed-enhancing adaptation of these toe trotters is their cannon bone, named for its tube-like structure. It is an extra long bone in each forelimb in addition to the upper arm and forearm bones and in each hind limb in addition to the thigh and leg bones. To understand a cannon bone’s location, we can sing about the toe trotters’ forelimb anatomy: The arm bone is connected to the forearm bone, … is connected to the wrist bones, … are connected to the cannon bone, … is connected to the finger bones. Similarly for the hind limbs: The thigh bone, … leg bone, … ankle bones, … cannon bone, … toe bones. Read more
You may have considered the description of collagen in the previous blog post a digression, since collagen is tough and does not stretch, and we intuitively know that bone is not stretchy. Rather bone is rigid and resists getting mashed flat. Bone stands up to compression (scientific parlance for mashing) because it consists of calcium crystals deposited on a meshwork of, you guessed it, collagen—like plaster on lath. Read more
Because of its pale color, the prominent Greek physician and philosopher Galen wrote that bone was made of sperm. One thousand years later, Avicenna, a Persian astronomer, physician, and prolific writer, thought that bone was made of earth because it was cold and dry. Now another millennium later, different notions prevail about the nature of bone. We have to start with a little organic chemistry. Don’t glaze over. This is more interesting that it might seem at first. Read more
The previous post recounted the unlikely but accepted fossil find of Charles Dawson near his home in Piltdown, England. British paleoanthropologists wanted to believe that the “Piltdown man” was the missing link in human evolution. Mr. P was also widely celebrated in popular culture. He was a rock star. Dawson wanted to be one too.
Skepticism about the fossils’ authenticity, however, came early and in several forms. The fragmented and limited skeletal pieces were missing their most diagnostic portions. (Some said, “How convenient.”) Also, was the gravel bed where Dawson found the fossils as ancient as he indicated, or were the fossils from a more recent era? Were the jaw and cranial fragments from the same species? From the same individual? Read more
Nobody would likely appreciate having the words hoax and fraud permanently associated with the name of their hometown. Yet in 1908, the discovery of some bone fragments and teeth left local residents of the English village of Piltdown helpless as nationalism, tunnel vision, and wishful thinking hoodwinked the specialists who pondered the findings’ significance. These bones certainly have much to teach, but not, as it turns out, about the discovery of a missing link in the evolution of man.
Since bone decays far more slowly than other human tissues, obtaining burial space in densely populated areas eventually becomes problematic. Historically in European cultures, individuals of high standing were buried within the church, others nearby outside. Those plots, however, were only rented, sometimes for a little as 20 years. After that, making space in the boneyard for the newly deceased necessitated removal of old skeletons. So the old bones were exhumed, sorted, stacked, and stored compactly in underground crypts or catacombs. Read more
Every natural history and anthropological museum in the world seems to have a skeletal replica of Lucy, our 3.2 million year-old human predecessor. The discovery of her bones and close study of their shapes have provided a crucial observation regarding human development. Lucy proves that our ancient ancestors first stood up and walked, and only later did they develop large brains. This was a monumental observation, widely discussed.
My monumental observation, kept to myself until now, did not require any close study but did lead to unsettling questions. Five ribs, not twelve? Only one finger and one toe? Half a pelvis? Lucy, how could you walk with less then one leg? Read more