Today is Darwin Day, or to put it another way, the 203rd anniversary of Darwin’s birth. You can find various posts around the web, as well as various activities to participate in, by searching on “Darwin Day.” My own contribution is below. Continue reading
Falcon-Lang’s find was a collection of 314 slides of specimens collected by Darwin and other members of his inner circle, including John Hooker — a botanist and dear friend of Darwin — and the Rev. John Henslow, Darwin’s mentor at Cambridge, whose daughter later married Hooker.
The first slide pulled out of the dusty corner at the British Geological Survey turned out to be one of the specimens collected by Darwin during his famous expedition on the HMS Beagle, which changed the young Cambridge graduate’s career and laid the foundation for his subsequent work on evolution.
More info can be found here. Apparently, there is also a more formal writeup in Geology Today, but I haven’t been able to track that down yet.
Ruminant diets and the Miocene extinction of European great apes in Proceedings of the Royal Society B. From the abstract:
The successful evolutionary radiations of European hominoids and pliopithecoids came to an end during the Late Miocene. Using ruminant diets as environmental proxies, it becomes possible to detect variations in vegetation over time with the potential to explain fluctuations in primate diversity along a NW-SE European transect. Analysis shows that ruminants had diverse diets when primate diversity reached its peak, with more grazers in eastern Europe and more browsers farther west. After the drop in primate diversity, grazers accounted for a greater part of western and central European communities. Eastwards, the converse trend was evident with more browsing ruminants. These opposite trends indicate habitat loss and an increase in environmental uniformity that may have severely favoured the decline of primate diversity.
The article is open access.
Darwin was quite experienced with the microscope. In this experiment we see another aspect of the “experimental Darwin”. Here Darwin is examining the effect of ammonia on plants (this is part of his research in insectivorous plants) Continue reading
I was somewhat surprised to receive a copy of Darwin in Galapagos: Footsteps to a New World. Since I moved here from ScienceBlogs I haven’t really requested any review copies of books. Mainly because my audience has shrunk dramatically. Darwin in Galapagos: Footsteps to a New World is an interesting book, published this year, that focuses on Darwin’s time in the Galapagos. Written by K. Thalia Grant (daughter of Rosemary and Peter Grant) and Gregory B. Estes, the book attempts to trace Darwin’s path through the Galapagos. Continue reading
The journal Origins of Life and Evolution of Biospheres has an interesting paper on Darwin’s views on the origin of life. The paper can be found here. The short version is that Darwin felt that the origin of life could be explained by natural mechanisms and that such an explanation was beyond the scope of scientific methodology of the time. For the long version read the paper.
On my view of descent with modification, the origin of rudimentary organs is simple. We have plenty of cases of rudimentary organs in our domestic productions,—as the stump of a tail in tailless breeds,—the vestige of an ear in earless breeds,—the reappearance of minute dangling horns in hornless breeds of cattle, more especially, according to Youatt, in young animals,—and the state of the whole flower in the cauliflower. We often see rudiments of various parts in monsters. But I doubt whether any of these cases throw light on the origin of rudimentary organs in a state of nature, further than by showing that rudiments can be produced; for I doubt whether species under nature ever undergo abrupt changes. I believe that disuse has been the main agency; that it has led in successive generations to the gradual reduction of various organs, until they have become rudimentary,—as in the case of the eyes of animals inhabiting dark caverns, and of the wings of birds inhabiting oceanic islands, which have seldom been forced to take flight, and have ultimately lost the power of flying. Again, an organ useful under certain conditions, might become injurious under others, as with the wings of beetles living on small and exposed islands; and in this case natural selection would continue slowly to reduce the organ, until it was rendered harmless and rudimentary.
Any change in function, which can be effected by insensibly small steps, is within the power of natural selection; so that an organ rendered, during changed habits of life, useless or injurious for one purpose, might easily be modified and used for another purpose. Or an organ might be retained for one alone of its former functions. An organ, when rendered useless, may well be variable, for its variations cannot be checked by natural selection. – Charles Darwin, On the Origin of Species