cave
dr. dolittle | September 22, 2017 Image of cave dwelling Mexican tetra By Citron via Wikimedia Commons
Mexican tetra (Astyanax mexicanus) are a fascinating example of divergent evolution. Over time, some of these freshwater river fish washed into caves where they continue to live. With perpetual darkness, these cavefish have lost their ability to see along with their skin pigmentation. Oxygen and food are also hard to come by in the caves. In fact, the cave dwelling fish may go for months without eating as they wait for seasonal floods to deliver foods. Dr. Cliff Tabin (Harvard Medical School) recently presented his…
dr. dolittle | September 25, 2014 Image of eyeless Mexican tetra fish from www.seriouslyfish.com by H-J Chen.
The metabolism of most animals follows a circadian rhythm that differs between the day and night. Mexican cavefish living in constant darkness, lost this circadian rhythm some time ago. In a newly published study in PLOS ONE, researchers compared the metabolic rate of both cave- and surface-dwelling Mexican tetra fish (Astyanax mexicanus). They hypothesized that since the fish living in each location naturally experience differences in food, predation as well as exposure to daily light fluctuations, they might also…
dr. dolittle | April 5, 2014 Image from LiveScience. Credit: Richard Borowsky
Heat shock protein 90 (HSP90) helps keep proteins in the body folded properly and is thought to compensate for variations that occur in proteins over time. In a study published in Science magazine, Dr. Nicolas Rohner and colleagues showed that stress can affect the ability for HSP90 to do its job thereby unmasking these alternative versions of proteins which may lead to adaptation in some cases.
The theory was tested in fish called Mexican tetra (above), some of which adapted to life in caves leading to eventual loss of, or diminished,…
laelaps | May 3, 2010
Breaking down a hyena kill. Given competition with other carnivores, prehistoric hyenas (like their living counterparts) would probably have disarticulated and transported parts of horses they killed. From Diedrich 2010.
In Hollywood films, there is nothing like an assemblage of bones strewn about a cave floor to testify to the power and voraciousness of a predator. Every skeleton is a testament to the hunting prowess of the carnivore, which causes even more alarm when the person who has stumbled into the cave realizes that they have just walked into a literal dead-end.
Although amplified…
laelaps | April 8, 2010
A diagram of how the skeletons of Australopithecus sediba came to be preserved in the Malapa cave deposit. From Dirks et al, 2010.
A little less than two million years ago, in what is now South Africa, a torrential downpour washed the bodies of two humans into the deep recesses of a cave. Just how their remains came to be in the cave in the first place is a mystery. Perhaps they fell in through the gaping hole in the cave roof just as hyenas, saber-toothed cats, horses, and other animals had, but, however the humans entered the cave, their bones ultimately came to rest in a natural bowl…
edyong | March 1, 2010Souvenir shops in South Africa are full of lamps made out of ostrich eggs. The eggs are so big and strong that you can carve and cut intricate designs into their shells. The egg's contents are emptied through a hole and a bulb can be inserted instead, casting pretty shadows on walls and ceilings. The results are a big draw for modern tourists, but ostrich eggs have a long history of being used as art in South Africa. The latest finds show that people were carvings symbolic patterns into these eggs as early as 60,000 years ago.
Pierre-Jean Texier from the University of Bordeaux discovered a…
laelaps | February 17, 2010
Detail of a Charles R. Knight mural depicting a family a mastodons.
Fossils often turn up in unexpected places. As people have dug swimming pools, tilled farms, blasted through mountains, and quarried the land for minerals traces of ancient life sometimes come to the surface, from isolated shark teeth to skeletons of our extinct hominin relatives. Even fossil graveyards are found this way every now and then, like the one found in a southern Pennsylvania quarry a little more than a century ago.
In late April 1907 William Jacob Holland, a paleontologist and director of Pittsburgh's Carnegie…
edyong | June 24, 2009
Thirty-five thousands years before the likes of Kraftwerk, Nena and Rammstein, the lands of Germany were resounding to a very different sort of musical sound - tunes emanating from flutes made of bird bones and ivory. These thin tubes have recently been uncovered by Nicholas Conard from the University of Tubingen and they're some of the oldest musical instruments ever discovered.
The ancient flutes hail from the Hohle Fels Cave in Germany's Ach Valley, a veritable treasure trove of prehistoric finds that have also yielded the oldest known figurative art. The flutes were found less than a…