The question is basic: Is evolutionary change largely random or is it more often shaped by selective forces? The former is linked to what is called Neutral Theory, and it has a lot of support, to the extent that it most likely true. The latter is part of what is sometimes known as the Adaptationist Program, and it is certainly correct. New research on the Development of the Nematode Vulva is sure to cloud the issue even further.. Continue reading The Nematode Vulva and the Nature of Evolution
Tag Archives: Evolutionary Biology
Early, somewhat controversial hominid walked like an Australopith
The ape human split is a bit of a moving target. In the 1970s and early 1980s, there were geneticists who placed it at very recent (close to 4 million years ago) and palaeoanthropologists, using fossils, who placed it at much earlier. During the 1980s, the ape-human split moved back in time because of the importance of sivapithecus, then later in time when Sivapithecus slipped and fell out of the hominid/hominin (human ancestor) family tree. Meanwhile the geneticists were moving towards a more and more recent split. At one point not too long ago, all the evidence converged with the split being around five million years ago. The fossils and the genes agreed, and there were rumors (but nothing published) saying that palaeoanthropologists working in Ethiopia were prepared (soon) to announce that one of the fossils dating to this time had “less then fully developed” bipedalism.But science marches on, and the kinds of questions we are asking of the human fossil record are more detailed than the fossil record usually gives up in a mere few decades of research. So new finds came along and everything changed again. Now, there is a new paper by Richmond and Jungers suggesting that one of the earliest hominid, Orrorin tugenensis, was just as bipedal as any australopith, yet is much farther back in time than, and in many ways, different from our genus (Homo). Continue reading Early, somewhat controversial hominid walked like an Australopith
Berry Go Round #3
Welcome to Berry Go Round #3, the blog carnival deicated to all things botanical.The previous installment, Berry Go Round #2, is located here, at Further Thoughts. If you would like to submit an item to the next Berry Go Round, you may use this handy submission form. The Berry Go Round Home Page is here. Continue reading Berry Go Round #3
The Shape of Life 6
The Shape of Life 5
The Shape of Life 4
Genetics of Behavior: Fire Ants
A common presumption is that behavior is part of phenotype, and since phenotype arises from genotype (plus/minus Reaction Norm), that there can be a study of “behavioral genetics.” This is certainly an overstatement (or oversimplification) for organisms with extensive and/or complex neural systems, such as humans and mice. Neural systems probably evolved (not initially, but eventually) to disassociate behavior with the kind of pre-determined micro-management of behavior that a simple gene-behavior link requires. However, in organisms with neural systems the size of the period at the end of this sentence, we often do see cases of allelic variations causing behavioral variation in the whole organism. The study discussed here is an example of this. Continue reading Genetics of Behavior: Fire Ants
The Shape of Life 3
The Shape of Life 2
The Shape of Life 1
Stay tuned, more coming.This episode 8 of the PBS series in six bite sized parts
Craig Venter: On the verge of creating synthetic life
“Can we create new life out of our digital universe?” asks Craig Venter. And his answer is, yes, and pretty soon. He walks the TED2008 audience through his latest research into “fourth-generation fuels” — biologically created fuels with CO2 as their feedstock. His talk covers the details of creating brand-new chromosomes using digital technology, the reasons why we would want to do this, and the bioethics of synthetic life. A fascinating Q&A with TED’s Chris Anderson follows (two words: suicide genes).
Continue reading Craig Venter: On the verge of creating synthetic life
Why the Hobbits of Flores Were Probably Not Broken People
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.
Continue reading Why the Hobbits of Flores Were Probably Not Broken People
Myers, Musgrave, Attacked by Wells
Jonathan Wells has launched a nasty attack on PZ Myers and Ian Musgrave on the discredited Discovery Institute web site. Continue reading Myers, Musgrave, Attacked by Wells
Teachers Under Fire
It is very common, across the U.S., for science teachers to dread the “evolution” unit that they teach during life science class. As they approach the day, and start to prepare the students for what is coming, they begin to hear the sarcastic remarks from the creationist students. When the day to engage the evolution unit arrives, students may show up in the classroom with handouts from anti-science sites like Answers in Genesis, to give to their friends. They may carry a bible to the lab station and read it instead of doing the work. If there is a parent conference night around that time, the teacher may be verbally abused by some of the parents for not including “alternative theories” in the classroom. Continue reading Teachers Under Fire
The Origin of the Human Smile
A colleague and grad student of mine, Rob, just sent me the following question, slightly edited here:
A student in my intro class asked me a good question the other day to which I had no answer. When did smiling cease to be a threat gesture? I have a couple of ideas. One is that with reduced canines, smiling became a way to say “look, I have small canines, I am not a threat to you.” The other is that smiling is based more on a “fear-grin” than a threat. Under this idea, smiling might have been a way of showing deference to others. If everyone shows deference, it would be egalitarian, until the one guy comes along who never smiles. Maybe that’s why bosses often don’t smile. … let me know when you have some free time to have lunch. Tuesdays andWed’s probably work best for me.
Good question, and good ideas as to a possible answer. I have a couple of other ideas to contribute…. Continue reading The Origin of the Human Smile