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
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
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.
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
Fallback foods are the foods that an organism eats when it can’t find the good stuff. It has been suggested that adaptive changes in fallback food strategies can leave a more distinct mark on the morphology of an organism, including in the fossil record, than changes in preferred food strategies. This assertion is based on work done by the Grants and others with Galapagos Island finches, by Richard Wrangham and me with hominids, and by Betsy Burr and me with rodents. Continue reading The Potato and Human Evolution
Comparing living chimpanzees to living humans, in reference to the species that gave rise to these two closely related species, is one way to frame questions about the evolution of each species. Continue reading What did the immediate ancestor of chimps and humans look like?
According to one of the leading experts on the human circulatory system, blood flowing through veins is blue. Continue reading Is Blood Ever Blue? Science Teachers Want to Know!
… but it might be a sexual organ…
The Federal Communications Commission has proposed a $1.4 million fine against 52 ABC Television Network stations over a 2003 broadcast of cop drama NYPD Blue….The fine is for a scene where a boy surprises a woman as she prepares to take a shower. The scene depicted “multiple, close-up views” of the woman’s “nude buttocks” according to an agency order issued late Friday….The agency said the show was indecent because “it depicts sexual organs and excretory organs , specifically an adult woman’s buttocks.”The agency rejected the network’s argument that “the buttocks are not a sexual organ.”[source]
UC Berkeley biologist Robert Full shares his fascination with spiny cockroach legs that allow them to scuttle at full speed across loose mesh and gecko feet that have billions of nano-bristles to run straight up walls. His talk, complete with wonderful slow-mo video of cockroach, crab and gecko gaits, explains his goal of creating the perfect robotic “distributed foot.”
Pilobolus dance company members Otis Cook and Jennifer Macavinta perform the sensuous duet “Symbiosis.” Does it trace the birth of a human relationship, or the co-evolution of a pair of symbiotic species? That’s left for you to decide. Gorgeous, organic choreography blurs the boundaries between the two performers, who use the body’s own geometry to lift, move and combine. The music, recorded by the Kronos Quartet on Nonesuch Records, is a compilation of works: “God Music” from Black Angels by George Crumb, “Fratres” by Arvo PÃ¤rt, and “Morango … Almost a Tango” by Thomas Oboe Lee.