Evolutionary Biology
gregladen | January 10, 2008 Why is there no Birth Control Pill for men?
This latest "Ask a ScienceBlogger" question will certainly engender a wide range of responses from the Scienceblogs.com team. Answers may address physiology, endocrinology, pharmacology, economics, and other areas of scientific thinking and practice. The answer I'd like to propose can be summed up in two closely linked words pilfered from the question itself:
Men. Control.
Myriad aspects of life can be understood by recognizing a single critical fact, and the layered, sometimes complex, deeply biological effects of that fact. Males, by…
gregladen | January 6, 2008As E.O. Wilson accepts his 2007 TED Prize, he makes a plea on behalf of his constituents, the insects and small creatures, to learn more about our biosphere. We know so little about nature, he says, that we're still discovering tiny organisms indispensable to life; yet we're still steadily destroying nature. Wilson identifies five grave threats to biodiversity (a term he coined), using the acronym HIPPO, and makes his TED wish: that we will work together on the Encyclopedia of Life, a web-based compendium of data from scientists and amateurs on every aspect of the biosphere.
gregladen | January 3, 2008
New research published in Science on the origins of multicellular life reveals an interesting pattern. The Cambrian Explosion may have been samosamo.
What is evolution about? Why are there different species, rather than just one (or a few) highly variable species? Is there a close correspondence between the ecological "spaces" that organisms can fit and the adaptations ... represented by morphology, for instance ... of the species that do exist? Can you imagine a different world where instead of having 10,000 species of birds there is only one bird that is highly adaptable in its…
gregladen | December 17, 2007Planarian worms can regenerate new body parts (well, I know they don't look like "parts" but you get what I mean). How do they do this? No one was quite sure until now.
An MIT research team led by Peter Reddien has discovered a gene that apparently produces a product that facilitates this sort of regeneration.
"Evolution has selected for mechanisms that allow organisms to accomplish incredible feats of regeneration," and planaria offer a dramatic example, Reddien said. "By developing this model system to explore the molecular underpinnings of regeneration, we now have a better…
gregladen | December 15, 2007
Fins into Limbs: Evolution, Development, and Transformation by Brian K. Hall, Ed., University of Chicago Press, Chicago, 2007. 459 pp.
Reptile and mammal limbs and bird wings are all modifications of the original tetrapod limb that, in turn, arose from the fins of earlier fish. That original transition was complex with some parts of the original fin being incorporated in the new limb, others not. Subsequent modification of the tetrapod limb has also, obviously, been diverse, including the functional reversal that involved the forelimbs of the forms ancestral to whales, seals, etc. turning…
gregladen | December 13, 2007The 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…
gregladen | December 12, 2007A new hypothesis for how life got started has been proposed, by Helen Hansma, of UC Santa Barbara.
Mica.
Here's the essential problem. Cells work because they have membranes surrounding them. These membranes protect the cells from nasty outside things, keep the stuff that is supposed to be working together in the cell in one place, and also, provide a communication and transport boundary for what goes in and out of the cell (various molecules as well as information).
However, a lot of the mechanisms involved in cells involve making, maintaining, and using this membrane. It is all very…
gregladen | December 12, 2007Some of the base pairs in a given genome are strung together into templates that code for proteins or RNA molecules. These are the classic "genes." Other base pairs probably have little or no function. Among the DNA that is not in classic gene-templates, however, there is a lot of important information, including "control regions."
How much of each "type" of DNA exists in a particular genome varies. A recent study suggests that the currently used methods for scanning DNA for regulatory sequences may systematically m miss more than half of that information.
Looking specifically at the DNA…
gregladen | December 12, 2007This could be the proof of god:
The assertion made by the "Does God Exist" people is that a pattern must be designed, and that patterns don't occur in nature. But it is possible that there is another way to look at this.
Like, the Fibonacci sequence is the natural outcome of common aspects of additive growth, or of packing.
Plants do not know about this sequence - they just grow in the most efficient ways. Many plants show the Fibonacci numbers in the arrangement of the leaves around the stem. Some pine cones and fir cones also show the numbers, as do daisies and sunflowers. Sunflowers…
neurophilosophy | December 10, 2007Yesterday's Sunday Feature on BBC Radio 3 was program about the evolution of music, by Ivan Hewitt. It isn't available online yet, but should be uploaded onto the Sunday Feature page soon, and will remain there for a week.
The progam features linguist Steven Pinker of Harvard University, who argues that music is a kind of evolutionary by-product, and anthropologist and cognitive archaeologist Steven Mithen from the University of Reading in the UK, who believes it was fundamental to human evolution.
And on NPR, there's an interview with husband-and-wife primatologists Dorothy Cheney and…
gregladen | December 10, 2007There is a new paper, just coming out in Proceedings of the National Academy of Sciences, that explores the idea that humans have undergone an increased rate of evolution over the last several tens of thousands of years.
By an increased rate of evolution, the authors mean an increased rate of adaptive change in the genome. By recent times, the authors mean various things, depending on which part of the analysis you examine, and depending on what is meant by "increased." ... In other words, the timing of an event that is not really an event (but rather a change in rate of something) is hard…
gregladen | December 5, 2007The flagellum is said to possess "irreducible complexity," meaning it could not have been produced by evolution. This argues for an outside intelligent designer operating beyond the laws of nature.
From Conservapedia.
gregladen | December 5, 2007An intelligent new way to support the teaching of evolution
New journal Evolution: Education and Outreach debuts on 28 November
The world-renowned evolutionary scientist Niles Eldredge and his son Greg Eldredge, a high school science teacher, believe it's time to help science educators fight back against the strong pressure creationists exert on public education. So they joined forces with the scientific publisher Springer and, on Darwin's birthday in February this year, announced plans to publish a new journal, Evolution: Education and Outreach. ...
Details here, at WebWire
gregladen | December 4, 2007Go to any bar and you'll see a lot of males standing and sitting around not mating. I'll bet you would have guessed that the reason they are not mating is that no females will mate with them for one reason or another. But there is the distinct possibility that they are very inconspicuously resisting mating opportunities. It turns out that males can do this .... avoid mating without conspicuous resistance ... more easily than females. For obvious reasons.
This could be why what has become (inappropriately) known as "reversed sexual aggression" often goes unnoticed, and a recent study of the…
gregladen | December 4, 2007Researchers have discovered a form of DNA modification not previously known to occur in nature. Lab scientists often use the addition of sulfer to the DNA sugar-phosphate backbone to make the DNA resistant to nucleases (DNA-cutting enzymes) in order to use the DNA for other (i.e. theraputic) purposes. This was assumed to be something invented by scientists. IT turns out that bacteria do something like this in nature.
From an MIT press release:
... [researchers] were surprised to discover that a group of bacterial genes, known as the dnd gene cluster, gives bacteria the ability to employ…