Posting some interesting readings:
1) A beautiful theory has been undone by ugly facts. How do coral atolls, those shimmering ring shaped islands set against the blue ocean, form? Charles Darwin had famously reasoned that coral colonies begin growing on the slopes of volcanoes. Eventually the volcanoes sink into the ocean, while the coral keep growing upwards. The central area where the volcano existed becomes a deep lagoon, surrounding by a ring of coral reefs. But he just assumed that the present day corals atolls are growing on a volcanic foundation. Actually, most are not. Tropical region reefs and atolls rest on an earlier generation of coral and limestone. These in turn have grown on an even earlier layer of coral growth and so on through the past few million years.
Darwin at that time didn't know that the climate over the past 2-3 million years had shifted periodically between glacial and inter-glacial phases resulting in sea level changes, and how these repeated sea-level fluctuations can create environments where corals grow during a sea level rise or later dissolve during a sea level fall to form a karst landscape. This jagged uneven surface in turn becomes the foundation for a new generation of corals. A new detailed study of the Pacific Ocean and Indian Ocean reefs demonstrates this elegantly.
Paper- The Origin of Modern Atolls: Challenging Darwin's Deeply Ingrained Theory.
Write up - Darwin's theory about coral reef atolls is fatally flawed.
2) Did Homo sapiens enter India prior to the devastating Toba eruption that took place about seventy four thousand years ago or after? This question is of interest in elucidating the timelines and dispersal routes of our species from Africa. Homo sapiens had reached Australia by around 60,000 years ago with India being one obvious migration path. There are no skeletal human fossils from this time period in India and stone tools have been variously interpreted as belonging either to Homo sapiens or an earlier archaic human. There were few accurately dated sites from the time period of 80,000 years ago to 50,000 years ago. Now, some new work from the Son Valley, Madhya Pradesh, shows long term human occupation in north India from pre Toba eruption times. The layers containing stone tools span from about 79,000 years ago to 65,000 thousand years ago. The tools resemble those from the Middle Stone Age of Africa, Arabia and Australia and are interpreted to have been the handiwork of Homo sapiens.
Paper- Human occupation of northern India spans the Toba super-eruption ~74,000 years ago.
3) The ecologic context of the evolution of our genus Homo is of great interest. A recent study focuses on using carbon isotopes to tease out dietary shifts in herbivore fauna living in East Africa in the late Pliocene to Early Pleistocene. Analysis of herbivore teeth from 3.6 million years ago to 1.05 million years ago reveals a shift from C3 derived food (woody vegetation) to C4 derived food (grasses), first around 2.7 million years ago and again later around 2.1 million years ago. Woodlands were giving way to more open savanna, a change that coincides with the evolution of Paranthropus and Homo.
Paper- Dietary trends in herbivores from the Shungura Formation, southwestern Ethiopia.
Write up - Researchers use fossilized teeth to reveal dietary shifts in ancient herbivores and hominins.
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