Origins of Darwin’s Evolution: Solving the Species Puzzle Through Time and Place by J. David Archibald does something that not enough studies of Darwin’s work do: Get off the island. Continue reading Origins of Darwin’s Evolution: Solving the Species Puzzle Through Time and Place
The Triassic is old. This book is new. That is a hard to beat combination.
Continue reading Triassic Life on Land: I love this book
Does your back yard slope up, away from your house, or does it slope down?
The likelihood that your yard slopes one way or the other … statistically … depends in large part on what region you live in. (Here I’ll be speaking mainly of the US, but the principle applies broadly.) If you live in New England, your yard is more likely to slope up. If you live in the Midwest/Plains, your yard is more likely to slope down
Continue reading How geology affects your dog’s demeanor and the view from your back yard
It turns out that a recently discovered population of land iguanas on the Galapagos is probably a new species that represents the basal (original) form of Galapagos land iguana. Moreover, this iguana is found in an unexpected place, according to a paper just coming out in the Proceedings of the National Academy of Sciences (PNAS).
And it’s pink.
Continue reading Pink Iguanas and Disappearing Islands
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 Very Large Parks are the Wave of the Future
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 Darwin and the Voyage: 11 ~ Elephants and Horses
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 Darwin and the Voyage: 10 ~ Rheas and the Birth of Evolutionary Theory
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 The Potato and Human Evolution
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 Darwin and the Voyage: 09 ~ Fossil Quadrupeds
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 Darwin and the Voyage: 06 ~ Bugs
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 Are We In The Anthropocene? No.
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 Hybrids of Blind Fish Can See
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 After the End Permian Mass Extinction