So how many species of giraffe are there? 1? 6? 11? You’ve got to love how messy and complicated biology is.
Pharyngula
Evolution, development, and random biological ejaculations from a godless liberal
So how many species of giraffe are there? 1? 6? 11? You’ve got to love how messy and complicated biology is.
A while back, I summarized a review of the evolution of eyes across the whole of the metazoa — it doesn’t matter whether we’re looking at flies or jellyfish or salmon or shrimp, when you get right down to the biochemistry and cell biology of photoreception, the common ancestry of the visual system is apparent. Vision evolved in the pre-Cambrian, and we have all inherited the same basic machinery — since then, we’ve mainly been elaborating, refining, and randomly varying the structures that add functionality to the eye.
Now there’s a new and wonderfully comprehensive review of the evolution of eyes in one specific lineage, the vertebrates. The message is that, once again, all the heavy lifting, the evolution of a muscled eyeball with a lens and retinal circuitry, was accomplished early, between 550 and 500 million years ago. Most of what biology has been doing since is tweaking — significant tweaking, I’m sure, but the differences between a lamprey eye and our eyes are in the details, not the overall structure.
We’ve got a splendid new analysis of a southeast Asian artiodactyl from the Thewissen lab that reveals that these little deer-like animals are a sister taxon to whales — so this pushes our understanding of the ancestry of whales yet further back. Carl Zimmer has already described the essentials — I’ll just show a few pictures of the fossils.
Larry Moran has had a couple of articles up lately on Dr Sharon Moalem, a fellow who has a book out called Survival of the Sickest, and who also has a blog. Larry noticed a couple of things: he’s writing utter tripe about junk DNA, he’s editing and deleting comments about his science from his blog, and he’s been misleading about his credentials — although, to be fair, Moalem does plainly and accurately list his background on the endflaps of the book (some of this has come from a student blog that has been dissecting his dubious claims).
If you’ve got an hour free, this interview with Kevin Padian is a pleasant listen. The interviewer is a bit of a bore, but Padian is always an intelligent conversationalist — I’d like to have seen a more aggressive counter to some of the silly stuff brought up by the interviewer, but this was not an antagonistic situation so I can also see why the discussion goes in the direction it does. There were a lot of places where I would have said, “Padian is exactly right, but…” — but then I think I’m just intrinsically crankier.
Well, there is a part about halfway through where he says the role of chance is negligible that I would take strong exception to…
Those of you who have been pregnant, or have been a partner to someone who has been pregnant, are familiar with one among many common consequences: lower back pain. It’s not surprising—pregnant women are carrying this low-slung 7kg (15lb) weight, and the closest we males can come to the experience would be pressing a bowling ball to our bellybutton and hauling it around with us everywhere we go. This is the kind of load that can put someone seriously out of balance, and one way we compensate for a forward-projecting load is to increase the curvature of our spines (especially the lumbar spine, or lower back), and throw our shoulders back to move our center of mass (COM) back.
Here’s the interesting part: women have changed the shape of individual vertebrae to better enable maintenance of this increased curvature, called lordosis, and fossil australopithecines show a similar variation.
Here’s a useful excercise: can you summarize a key concept in your field in less than a minute? Chris Mims takes a stab at explaining evo-devo — he’s not trying to explain the whole field, actually, but the central concept of a master gene. He uses the analogy of a power strip for a transcription factor, which I like quite a bit, and I’m probably going to have to steal it someday.
Today is the 148th anniversary of the publication of Charles Darwin’s On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. Enjoy those Thanksgiving leftovers!
Scooped! I’ve long adored vulvas, having written a few things on how to develop a vulva and how to evolve a vulva, so I’m a little peeved that this upstart at scienceblogs, Greg Laden, has written up a recent story on nematode vulva evolution before me. Aaargh, all vulvas must be mine! I’ve just got too much other work stacked in front of me.
I may have to revisit this story later, though. I made a quick skim of the paper and don’t see quite how they arrived at their conclusion, that vulva evolution is dominated by selective events rather than chance. I can’t say they’re wrong, but I’m going to have to read it more carefully before I can agree with it.
Wilkins is about to review a new paper on sociobiology by Wilson and Wilson, but he hasn’t quite done it yet. I’ll be looking forward to it, though.
