There is a discussion on the internet about Junk DNA, that includes a discussion at Sandwalk (Larry Moran’s blog) … I made a comment there about genome size that was responded to by T.R. Gregory. I started to write my response in Larry’s Little Box, but realized that it would not fit. So it is here: Continue reading Genome Size, Adaptations, Constraints, Exaptations, Aptations, and so on…
New research published in Science on the origins of multicellular life reveals an interesting pattern. The Cambrian Explosion may have been samosamo. Continue reading Avalon and the origin of multicellular life
Plant and animal fossils recently discovered from an island in the Bahamas tell a story of habitat change and human involvement in local extinction. Continue reading The Bahamas Yield Amazing Fossil Finds
Homo floresiensis more widely known as the “Hobbit,” may have had arms that were very different from those of modern humans.
A paper in the current issue of the Journal of Human Evolution explores the anatomy of H. floresiensis. To explore this we first have to understand the concept of “Humeral torsion.” Humeral torsion is the orientation of the humeral head relative to the mediolateral axis of the distal articular surface. Don’t bother reading that sentence again, I’ll explain it.
OK, so you are vacuuming the house, and along the way, you suck up a couple of spiders, some spier eggs, a beetle or two, and as the cat or dog walks by, you figure you’re probably sucking up some fleas and flea eggs, and so on and so forth.SO you know all these cooties are now in the vacuum cleaner bag. When you are done vacuuming, you put the vacuum cleaner away. The thought is in your brain… all these creepy crawlers are now going to slowly work their way out of the vacuum cleaner and go back to their crawly creepy business. But you stop yourself from thinking further about it and live your life in denial of what might be a horrific reality. Continue reading Where The Cooties Go To Die
The Central African Rainforest (as distinct from the West African Rain Forest) spans an area from the Atlantic coast to nearly Lake Victoria in Uganda and Tanzania. In fairly recent times (the mid Holocene) this forest was probably continuous all the way to Victoria, and probably extended farther north and south than one might imagine from looking at its current distribution.Within the forest are major rivers, including the Congo. The Congo River is the only major river in the world that crosses the Equator twice. This trans-equatorial configuration guarantees that the rivers picks up rain from both of the equatorial rainy seasons, making it a huge and virtually uncrossable barrier for terrestrial mammals. During glaical periods, the forest is believed to have shrunk to either small refugia, or to have virtually disappeared entirely with only riverine forest remaining. Between the shrinkage of the forest and the major riverine barriers, terrestrial (non-flying, non-swimming) forest-dwelling animals that might have had a more continuous distribution would have been broken into many smaller units. Likely, many of these small populations would have gone extinct, but others may have changed over time such that when the forest was re-established, they may have constituted different subspecies or species. This breaking up and rejoining of the rain forest, over and over again, during the Pleistocene is thought to have caused much of the modern day variation we see among closely related forest species of primates, small carnivores, and forest ungulates such as duikers. Continue reading Scientists Investigate Gorilla Biogeography
There seems to be some interesting things going on with the recently reported study of rates of evolution in humans. We are getting reports of a wide range of rather startling conclusions being touted by the researchers who wrote this paper. These conclusions typically come from press releases, and then are regurgitated by press outlets, then read and reported by bloggers, and so on. Here is, in toto, the press release from the University of Wisconsin, where John Hawks, one of the authors of the study, works. I reproduce the press release here without further comment. Continue reading Human Evolutionary Rate Study
All I have is the press release, but it’s fun:
Cosmopolitan microbes — hitchhikers on Darwin’s dustScientists have analysed aerial dust samples collected by Charles Darwin and confirmed that microbes can travel across continents without the need for planes or trains – rather bacteria and fungi hitch-hike by attaching to dust particles.In a paper published in Environmental Microbiology, Dr. Anna Gorbushina (Carl-von-Ossietzky University, Oldenburg, Germany), Professor William Broughton (University of Geneva, Switzerland) and their colleagues analysed dust samples collected by Charles Darwin and others almost 200 years ago. Geo-chemical analyses showed that these samples contained wind-fractionated dust from West Africa and some travelled as far as the Caribbean. Their results clearly show that diverse microbes, including ascomycetes, and eubacteria can live for centuries and survive intercontinental travel.Desert storms stir up and deposit 50million tonnes of dust particles from the Sahara to the Amazon every year. The largest, single source of dust on the planet is the BodÃ©lÃ© Depression in Northern Chad. As surface sand is whipped up into the air, larger particles are continually lost, and only the finest (< 10microns) reach the troposphere where they are blown on Trade Winds across the Atlantic. Similar fractionation of microbes also occurs, and only some survive travel across oceans."These findings push forward our understanding of planetary microbial ecology." said Professor Broughton.But could inter-continental spread of microbial hitch-hikers lead to the spread of contaminants or disease? "Obviously, intercontinental spread of micro-organisms has been with us for a very long time, so unless land-use patterns in the Western Sahara have changed recently, disasters like the demise of coral in the Caribbean, cannot be ascribed to the intercontinental travel of desert bugs" said Professor Broughton.
Or, to be less crude, did modern humans, having already evolved in Africa, interbreed with the local Europeans who were Neanderthals, and if so, did they produce fertile offspring … and, did this happen in sufficient degree to have mattered at all to the genetics of later (but not necessarily living) people? Continue reading Modern Humans and Neanderthals: Did they”do it?”
Or, to be less crude, did modern humans, having already evolved in Africa, interbreed with the local Europeans who were Neanderthals, and if so, did they produce fertile offspring … and, did this happen in sufficient degree to have mattered at all to the genetics of later (but not necessarily living) people?
Repost from gregladen.comOne day, about six thousand years ago (or more like 15 thousand … the timing of this is disputed) a volcano in the vicinity of Mwea, Uganda blasted a huge volume of stuff into the air, covering the surrounding landscape and choking off most of the life forms living in a nearby lake. (A very nearby lake … the current configuration of the lake suggests that the volcano may have actually been beneath the lake at the time of the eruption). Continue reading Crocs Afar