Human Evolution
gregladen | January 17, 2008Every time I put this video up, You Tube eliminates it. So look quick before it goes away again.
gregladen | January 17, 2008Things are just not like what they used to be. You know this. You know that the Age of Dinosaurs, for instance, was full of dinosaurs and stuff, and before transitional fossil forms crawled out of the sea to colonize the land, all animals were aquatic, etc. But did you know that from a purely modern perspective, the Miocene was the most important geological period?
First, lets get one thing straight. We are not in the so-called "Holocene." The so-called "Holocene" is a totally bogus geological period. Saying "Hey, we're in the Holocene, not the Pleistocene ... the Pleistocene is over…
gregladen | January 8, 2008
From a University of Bristol Press Release: "Rather than being gentle giants, new research reveals that Pleistocene cave bears, a species which became extinct 20,000 years ago, ate both plants and animals and competed for food with the other contemporary large carnivores of the time such as hyaenas, lions, wolves, and our own human ancestors."
Joao Zilhao, Professor in Palaeolithic Archaeology at the University of Bristol, Professor Erik Trinkaus of Washington University and colleagues in Europe made the discovery while dating the remains from Europe's earliest modern humans. Cave bears (…
gregladen | January 8, 2008Pumice is rock that is ejected from a volcano, and has so much gas trapped in it that it can float. So when a pumice-ejecting volcano (not all volcanoes produce pumice) goes off near a body of water, you can get a raft of rock floating around for quite some time. By and by, water replaces the gas within the rock and it sinks. Like a rock. So, you can get layers of pumice on the bed of lakes, seas and oceans. A forthcoming paper in Deep Sea Research I describes two such pumice deposits of "Drift Pumice" in the Indian Ocean.
The fact that the two deposits are more or less on the surface of…
gregladen | December 24, 2007From Oxford University Press Blog, regarding Aaron Filler's recent, very controversial, and very interesting publications.
It's easy enough for anyone to tell the difference between a human and an ape today, but how easy would it have been six million years ago, around the time of the split between the lineage of modern humans and the lineage of the chimpanzees. If you were to see the common ancestor would you think "human" or would you think "ape?"
Over the past 50 years there has been an understanding in the scientific community that the common ancestor would look somewhat like a knuckle-…
gregladen | December 19, 2007Homo 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.
The humerus is the upper arm bone, that runs between your shoulder and your elbow. The humeral head is…
gregladen | December 18, 2007From Scientific American, a piece on the "Cooking Hypothesis" (which yours truly helped develop some years back).
Our hominid ancestors could never have eaten enough raw food to support our large, calorie-hungry brains, Richard Wrangham claims. The secret to our evolution, he says, is cooking
Cooking does indeed turn a lot of stuff that is not edible to humans (or any primate) into usable energy. We think the increase in body size that comes along with the genus Homo (with Homo erectus and kin) is itself a biological signal of cooking.
The problem with his idea: proof is slim that any…
gregladen | December 17, 2007
Every few years a paper comes out "explaining" short stature in one or more Pygmy groups. Most of the time the new work ads new information and new ideas but fails to be convincing. This is the case with the recent PNAS paper by Migliano et al.
From the abstract:
Explanations for the evolution of human pygmies continue to be a matter of controversy, recently fueled by the disagreements surrounding the interpretation of the fossil hominin Homo floresiensis. Traditional hypotheses assume that the small body size of human pygmies is an adaptation to special challenges, such as…
gregladen | December 17, 2007The new Anthronotes is available, here
This is a Smithsonian publication. This issue has, among other things, a very nice article on the Flores Hobbits and a piece on teaching Human Evolution. Teachers should take special note of this, the material in this publication is usually perfect for 10th through 12th grade Life Sciences.
[Hat Tip: Ed Hessler].
gregladen | December 16, 2007
Every few years a paper comes out "explaining" short stature in one or more Pygmy groups. Most of the time the new work ads new information and new ideas but fails to be convincing. This is the case with the recent PNAS paper by Migliano et al.
From the abstract:
Every few years a paper comes out "explaining" short stature in one or more Pygmy groups. Most of the time the new work ads new information and new ideas but fails to be convincing. This is the case with the recent PNAS paper by Migliano et al.
From the abstract:
Explanations for the evolution of human pygmies continue to be a…
gregladen | December 11, 2007There 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.
Genome study…
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 7, 2007There was a time, not so long ago, when you could "Google" the terms "Greg Laden" and "Idiot" and get, well, besides the several thousand hits about me being an idiot and stuff, an Amazon.com page for "The Idiot's Guide to Human Prehistory by Greg Laden"
This is a book I never wrote. But the publishers wanted me to. However, there were complications. The first complication was that I found out (from an excellent source) that the owner of the company had "a problem" with evolution, and I came to believe it was likely that certain things would be changed prior to publication. In…
gregladen | December 1, 2007It has always been suggested, by a wide range of evidence, that australopiths in general, and robust australopiths in particular, have a higer degree of sexual dimorphism than chimps, and possibly, dimorphism in body size as high as one sees in any ape. Resent research on growth patterns, just published in Science, examines this.
In dimorphic primates, the larger size of the male is usually obtained by an extended period of growth of the males, so they essentially "grow past" the females. In addition, there are usually additional traits that the larger, adult males have that re not seen…
gregladen | November 25, 2007According to a story in the last issue of Psychological Science:
... for most women, high sex drive is associated with increased sexual attraction to both men and women. For men, however, high sex drive is associated with increased sexual attraction to only one sex or the other, depending on the individual's sexual orientation. These results suggest that the correlates of sex drive and the organization of sexual orientation are different for women and men.
[This is a repost from Gregladen.com]
This is one of those studies where a perfectly good (i.e., falsifiable) hypothesis was being tested…
gregladen | November 18, 2007Or, 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?
In my opinion, the answer is, of course they interbred. There are many reasons to believe this if almost no way to prove it. Indeed, the evidence of this interbreeding is virtually nil. With every additional test of the interbreeding hypothesis using DNA, the null hypothesis of no…
gregladen | November 12, 2007Many years ago a couple of researchers (Hatley and Kappleman) suggested omnivory, including eating of roots, to be a common theme in the adaptations we see in bears, humans, and pigs. Some years later, Richard Wrangham and I independently and for different reasons came to the idea that roots are potentially important in human evolution, so we collaborated on a paper suggesting this. Subsequently, bits and pieces of data have been accumulating to support this hypothesis (the "root hypothesis"). And here, Jim Moore of San Diego, is reporting on living chimps eating roots in a relatively…
gregladen | November 12, 2007I find it absolutely fascinating that scientists often bother to estimate the effects of diet by feeding controlled quantities of food, especially plant food, to rats to see what happens.
For example, there is a common substance in cooked food that, if fed in even modest quantity to rats, causes the rats to get cancer and die in no time. This raises concerns for humans because, well, the rats died. So the substance must be "bad for you."
But this approach to nutritional science, and the reasoning that goes with it, is deeply flawed.
Now, you may wish to jump in and say, "No, wait,…
gregladen | November 12, 2007You can now read the Krause et al (2007) paper from Current Biology regarding the FOXP2 variant found in Neanderthals in an open-access on-line form at Current Biology Online.
Here is the summary of the article:
Although many animals communicate vocally, no extant creature rivals modern humans in language ability. Therefore, knowing when and under what evolutionary pressures our capacity for language evolved is of great interest. Here, we find that our closest extinct relatives, the Neandertals, share with modern humans two evolutionary changes in FOXP2, a gene that has been implicated in…
gregladen | November 7, 2007[A repost from gregladen.com, unmodified]
There is a ceremonial burial in Britain .. ceremonial because it has some red stuff smeared on bone ... that has now bee dated to a few thousand years earlier than previously thought (to ca 25,000 years old).
Age of earliest human burial in Britain pinpointed from PhysOrg.com
The oldest known buried remains in Britain are 29,000 years old, archaeologists have found - 4,000 years older than previously thought. The findings show that ceremonial burials were taking place in western Europe much earlier than researchers had believed.
[...]
Some have…