Evolutionary Biology
gregladen | July 27, 2009Is the Natural World a valid source of guidance for our behavior, morals, ethics, and other more mundane areas of thought such as how to build an airplane and what to eat for breakfast?1 When it comes to airplanes, you'd better be a servant to the rules of nature (such as gravity) or the airplane will go splat. When it comes to breakfast, it has been shown that knowing about our evolutionary history can be a more efficacious guide to good nutrition than the research employed by the FDA, but you can live without this approach and following FDA guidelines will not do you in. A naturalistic…
neurophilosophy | July 3, 2009THE human brain is a true marvel of nature. This jelly-like 1.5kg mass inside our skulls, containing hundreds of billions of cells which between them form something like a quadrillion connections, is responsible for our every action, emotion and thought.
How did this remarkable and extraordinarily complex structure evolve? This question poses a huge challenge to researchers; brain evolution surely involved thousands of discrete, incremental steps, which occurred in the mists of deep time across hundreds of millions of years, and which we are unlikely to ever fully understand.
Nevertheless,…
gregladen | June 30, 2009 Although the paper addresses Tanzanian lions, this is a photograph of a Namibian lion Starting some years ago, we began to hear about revisions of the standard models of lion behavioral biology coming out of Craig Packer's research in the Serengeti. One of the most startling findings, first shown (if memory serves) as part of a dynamic optimization model and subsequently backed up with a lot of additional information, is the idea that lions do not benefit by living in a group with respect to hunting. They live in groups despite the fact that this sociality decreases hunting effectiveness…
gregladen | June 24, 2009In an BBC article describing a Royal Society paper on the rate of mutation in warm vs. cooler climates, the BBC made this statement:
DNA can mutate and change imperceptibly every time a cell divides and makes a copy of itself.
But when one of these mutations causes a change that is advantageous for the animal - for example, rendering it resistant to a particular disease - it is often "selected for", or passed down to the next few generations of that same species.
Such changes, which create differences within a population but do not give rise to new species, are known as "microevolution".
I…
gregladen | May 14, 2009Why does a soldier throw himself on a hand grenade to save the lives of a half-dozen unrelated fellow soldiers? Why does someone run into a burning building they happen to be passing to save a child they don't know? From a Darwinian perspective these seem to be enigmatic behaviors that would "select against" such individuals (or more properly, select against the heritable component of this behavior).
There are several possible explanations for this....
...The most important one might be that this sort of behavior doesn't really happen very often. It is so rare that it can be ignored and…
gregladen | May 12, 2009According to a study just coming out in the Journal of Sexual Medicine, "variations in emotional intelligence--the ability to identify and manage emotions of one's self and others--are associated with orgasmic frequency during intercourse and masturbation."
In short, the study found:
Emotional intelligence was not associated with ... age and years of education, nor did we find a significant association between emotional intelligence and potential risk factors for [female orgasmic disorder] FOD such as age, body mass index, physical or sexual abuse, or menopause. We found emotional…
gregladen | April 28, 2009Gallup has taken on the task of explaining, in ultimate terms, the evolutionarily designed features of the human penis. He works this as an engineering problem from the perspective of evolutionary psychology, which is always a little bit dangerious, but gallup isn't quite the arm waiver that a lot of other EP's are, so he may be doing it right.
Gallup's work is written up an an all-too-sophomoric Scientific American article by Jesse Bering which just barely falls short of explaining this important biological phenomenon in terms of a pair of headlights, a flashlight, and a little red waagon.…
gregladen | April 18, 2009Or, more exactly, where are they all going to go during the next two or three months?
I'm sitting here between a large frozen lake and a small "pond" (connected to the lake with a channel) that has patches of open water on it. (The melting on the pond is probably because the bioactivity at the bottom of the pond increases water temperature.) There is a pair of mallards on the pond, and I expect that in a few weeks there will be two or three mallards and three or for mergansers, all females, and each with between six and 12 or so ducklings. These 60 ducklings will initially hang out only…
gregladen | March 25, 2009As you know if you read my blog, Trivers Willard is an important theoretical construct which has been tested numerous times. TW works in some species, not in others, and overall, that should be predictable (accroding to TW).
It turns out that finches control the sex of their offspring, and do so in a way that TW would predict, apparently. There is a paper in Science that I'll probably eventually get to writing up for you, and in the mean time, here's a quick news report from Scientific American.
See if you can figure out how Trivers Willard is working here, and why the important…
grrlscientist | March 22, 2009tags: evolutionary biology, mate choice, sex determination, genetic compatibility, behavioral ecology, Gouldian Finch, Erythrura gouldiae, peer-reviewed paper
The three color morphs of Gouldian finches, Erythrura gouldiae.
Image: Sarah Pryke, Macquarie University.
Gouldian finches, Erythrura gouldiae, are small cavity-nesting passerines that are endemic to open savannahs adjacent to mangrove swamps in northern Australia. These finches eat a variety of native grass seeds, but to meet the increased energetic and nutritional demands of rearing chicks, they primarily eat insects when breeding…
gregladen | March 9, 2009Why is there "junk DNA"? What is Junk DNA? What is a Pseudogene? What is Gene Duplication?
Goodness, you certainly do have a lot of questions. And some of them can be answered, or at least addressed, on examination of a very interesting new paper recently published about a gene that became a useless "pseudogene" a very long time ago and has recently been revived by evolution to serve once again as an active member of the community we know of as the genome. In humans.
"Junk DNA" is mainly DNA that is not used in the day to day course of coding for various products such as proteins…
gregladen | March 5, 2009Dawkins gave a talk that could be criticized as not particularly new, in that his main idea is that human brains are too powerful and adaptable to continue to function primarily within an adaptive program serving as a proper adaptive organ. Instead, human brains think up all sorts of other, rather non-Darwinian things to do. This idea has been explored and talked about in many ways by many people. Kurt Vonegut Jr.'s character in Galapagos repeatedly, in a state of lament, quips "Thanks, Big Brain..." as evidence accumulates that our inevitable march towards extinction is primarily a…
gregladen | February 27, 2009Perhaps we are all subject to falling into the trap of what I call the Hydraulic Theory of Everything. If you eat more you will be bigger, if you eat less you will be smaller. Emotional states are the continuously varying outcome of different levels of a set of hormones, forming "happy" or "stressy" or "angry" cocktails. Your brain is a vessel into which life pours various elixirs. Too much of one thing, and there will not be enough room for something else. Even political arguments are hydraulic. The 'balanced' middle view between two arguments is like the mixture of contrasting primary…
gregladen | February 25, 2009Go 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 | February 25, 2009 Why is there no Birth Control Pill for men?
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 definition, can't have babies.
All mammalian males contribute to the reproductive endeavor, but often this contribution consists of a single cell, one per offspring. True, that cell contains a haploid copy of the male's DNA, the quality of which is…
gregladen | February 24, 2009
Why did the evolution of a large brain happen only once (among mammals, and in particular, primates?)
Larger brains have evolved a number of times. It seems that there has been a trend over several tens of millions of years of evolution of larger brains in various clades, such as carnivores and primates. There is probably a kind of arms race going on among various species in which a larger brain is an asset.
However, as you imply, a really large brain (like the extraordinarily large human brain) seems to be very rare. One of the reasons for this is that there are at least two major kinds…
gregladen | February 19, 2009From the people who brought you the Tree of LIfe:
You can click on a node and get the info on the date of that node. Here.
gregladen | February 19, 2009Diatoms are algae with hard parts. They make up a major part of the plankton found in fresh and salt water environments. Usually, diatoms exist as single celled free floating organisms, but they can also be colonies of several single cells. Their tiny little 'shells' are made up of silica (these shells are called "fustules").
The fustules have a characteristic shape that goes with each species, and since these are hard (essentially, made of glass) they are often well preserved in sediments. Thus, diatoms actually provide an excellent, even if very tiny, fossil record. In addition, since…
gregladen | February 14, 2009It's been a great pleasure to read the Origin of Specie ... I had forgotten how clever Darwin was and how he carefully weighs his arguments for evolution.
I had also fallen prey to several myths about the book. For example, I didn't realize that Origin of Species is all about speciation and the difference between species and varieties.
Go read all about it. Very much worth a look.