Wednesday, December 28, 2022

Holiday Readings: Ancient Amputations, First Americans, Fossil Molluscs

Wishing my readers a very Happy New Year! I hope these readings will be to your liking.

1) Can ancient amputations tell us about the care systems of our ancestors? Paleoanthropologist John Hawks surveys the fossil record of ancient humans for signs of severed limbs due to trauma or disease. He also presents cases of limb loss in other primates and offers a perspective on what all this can tell us about past social systems. 

"Both humans and nonhuman primates show us that survival and life after extreme injuries happen under varied circumstances. Bioarchaeologists tend to highlight severe injuries, which stand out from the more subtle patterns of osteological signs of disease that can be understood only across large samples of skeletons. But such individual stories rarely yield unambiguous interpretations".

2) Finding the First Americans. Anthropologist Jennifer Raff brings together often conflicting genetic and archaeological data on this ever vexing and complicated question of how the Americas were populated. 

3) Finding Molluscs. This podcast (with transcript) is part of an excellent continuing series of earth science and paleontology podcasts by Mongabay India. In this episode, host Sahana Ghosh talks with paleoecologist Devapriya Chattopadhyay on her research on fossil molluscs. Dr. Chattopadhyay uses these creatures to track ancient environmental conditions and ecology. She also speaks on the urgent need for India to create a national fossil repository and museum which will help preserve our deep history for future generations.

Tuesday, December 13, 2022

Links: Fire Use, Deep Water, Europa Geology

Sharing some interesting readings:

1) The Discovery of Fire by Humans. Jungle Book's primate king Louie was certainly aware of the transformative power of fire. As J.A.J Gowlett writes in a very informative review, many animals engage in fire foraging, opportunistically increasing their access to resources made available by natural fires. Early hominins too would have interacted with natural fires. The archeological record informs us that human engagement with and ultimately our control over fire was a long and convoluted process with evidence for early fire use going back to 1.5 million years ago. And would you believe it if I told you that the earliest preserved human fingerprint may be 80,000 years old and documents fire use? It was imprinted on a lump of pitch which is made by prolonged heating of tree bark. Pitch was used as a fixative in hafting. Fasinating stuff.  

2) The Deep Cycle of Water: Every schoolkid is taught about the hydrologic cycle wherein water moves between the atmosphere and shallow surface reservoirs. But water is present much deeper inside the earth, in fact it is present thousands of kilometers deep. It occurs not as free flowing H2O, but is incorporated inside the atomic structure of minerals as OH anions. It can escape this prison when minerals dehydrate during metamorphic reactions. The released water then rises and is expelled at the surface via volcanoes. In an alternate pathway, carried by sinking pieces of tectonic plates, water can reach even deeper in the earth, affecting the properties of the lower mantle and even the core. A short summary in Nature Geoscience on the state of our knowledge about this topic. 

3)  Plate Tectonics on Europa. The earth's outer silicate shell is broken up into tectonic plates which move around and jostle driving geologic activity and transforming the surface through geologic time. Scientists are looking to Jupiter's moon Europa and finding that its icy shell shows features indicative of intermittent plate motions, although the driving mechanisms will be different.  In Phys.Org, by Morgan Rehnburg.