There is a new paper out suggesting that the Flores hominids, known as Hobbits, were “human endemic cretins.”From the abstract of this paper:
… We hypothesize that these individuals are myxoedematous endemic (ME) cretins, part of an inland population of (mostly unaffected) Homo sapiens. ME cretins are born without a functioning thyroid; their congenital hypothyroidism leads to severe dwarfism and reduced brain size, but less severe mental retardation and motor disability than neurological endemic cretins. We show that the fossils display many signs of congenital hypothyroidism, including enlarged pituitary fossa, and that distinctive primitive features of LB1 such as the double rooted lower premolar and the primitive wrist morphology are consistent with the hypothesis. We find that the null hypothesis (that LB1 is not a cretin) is rejected by the pituitary fossa size of LB1, and by multivariate analyses of cranial measures. We show that critical environmental factors were potentially present on Flores, how remains of cretins but not of unaffected individuals could be preserved in caves, and that extant oral traditions may provide a record of cretinism.
Across Africa, and to some extent Asia, existing large parks and preserves are being combined into very large parks in order to serve several important functions. One is to make the parks so large that there will be interior areas that are impractical for most poaching or other encroachment. Another is to allow movement of migratory animals into new areas when their populations grow (presumably with some degree of natural culling cycling the process down now and then). Another is to allow a park to always contain a minimal range of a certain habitat even when secular or long term climate variation reduces that habitat. Yet another may be to make the park more attractive to tourism.With animals like tigers, who have relatively low population densities, it is essential to have large contiguous areas in order to have a viable population size both for genetic diversity and to get past periods of decimation by periodic disease or starvation episodes. Continue reading →
In 1833, Darwin spent a fair amount of time on the East Coast of South America, including in the Pampas, where he had access to abundant fossil material. Here I’d like to examine his writings about some of the megafauna, including Toxodon, Mastodon, and horses, and his further considerations of biogeography and evolution. Continue reading →
Everyone knows about Darwin’s Finches, of the Galapagos Islands. But of course, Darwin made observations of birds throughout his travels on The Beagle. Here, I present a number of passages from The Voyage that include some of these observations. Continue reading →
Fallback foods are the foods that an organism eats when it can’t find the good stuff. It has been suggested that adaptive changes in fallback food strategies can leave a more distinct mark on the morphology of an organism, including in the fossil record, than changes in preferred food strategies. This assertion is based on work done by the Grants and others with Galapagos Island finches, by Richard Wrangham and me with hominids, and by Betsy Burr and me with rodents. Continue reading →
Charles Darwin wrote a book called Geological Observations on South America. Since Fitzroy needed to carry out intensive and extensive coastal mapping in South America, and Darwin was, at heart, a geologist more than anything else (at least during the Beagle’s voyage), this meant that Darwin would become the world’s expert on South American geology. Much of The Voyage is about his expeditions and observations. Part of this, of course, was figuring out the paleontology of the region. Continue reading →
When reading the Voyage, it is impossible to miss the observation that much of the time Darwin was engaged in adolescent boy behavior: Pulling the heads off insects, noting how long they would wiggle after cut in half, closely examining the ooze and guts, occupied much of his time. Obviously, careful observation and a strong stomach were not all that was required to think up Natural Selection and his other theories, or the Origin of Species would have been written dozens of times by dozens of grown up kids. Continue reading →
Proposals to give the latter part of the present geological period (the Holocene) a new name … the Anthropocene … are misguided, scientifically invalid, and obnoxious. However, there is a use for a term that is closely related to “Anthropocene” and I propose that we adopt that term instead. Continue reading →
The loss of sight in cave dwelling species is widely known. We presume that since sight in utter darkness has no fitness value, the mutation of a gene critical to the development of the sense of sight is not selected against. Over time, any population living in darkness will eventually experience experience such mutations, and these mutations can reach fixation. Continue reading →
ï»¿Did humans wipe out the Pleistocene megafauna? This is a question that can be asked separately for each area of the world colonized by Homo sapiens. It is also a question that engenders sometimes heated debate. A new paper coming out in the Journal of Human Evolution concludes that many Pleistocene megafauna managed to go extinct by themselves, but that humans were not entirely uninvolved.
The end-Permian mass extinction event was the big daddy of all the known mass extinction events. Life on the planet Earth was almost entirely wiped out. A new paper explores the post-extinction recovery of ecological systems. Continue reading →
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 →
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 →
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 →
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 →
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 →
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 →