I’m aware that I’ve already broken my promise not to talk about coronavirus, so I guess it won’t hurt if I break it again, right? Anyway, you may be concerned about all this talk of variants in the news, particularly the India variant that is wreaking such havoc in Asia. There is justifiable concern that the vaccines we’ve developed may not be as effective against variants that will evolve. This, of course, is one good reason why we should aim to get as close to “zero covid” as possible: keeping the number of cases down limits the possibility of advantageous (to the virus) mutations to arise, potentially ones that we would have to develop new vaccines against, in a potentially endless cycle.
But what if we could make a global coronavirus vaccine that would not only be effective against all the different variants of covid-19, but also potentially against other deadly coronaviruses like MERS and SARS-CoV-1? This could preventially prevent the next pandemic. Researchers are already looking into this, as this interesting and thoughtful (and hopeful!) piece in Science explores. Many of these are targeting the common “spike” protein that these viruses use to infect cells, but focusing on generating antibodies against multiple different regions, particularly those that are common across different virus species and that do not vary as much. Others take the approach of trying to active T-cell responses, rather than B-cell producing antibodies, or even the old-school tried and tested means of using a combination of inactivated whole viruse to generate an immune response. It’s encouraging that scientists are already thinking ahead and trying to tackle this problem.
Why are humans so sweaty? Sorry: but yes, we are. Really sweaty. Compared to most other primates, we have 10x the density of sweat glands in our skin. This is our key way of regulating our body temperature and helping us to cool down. Unlike most other apes, we evolved on the hot, dry African savannah, and not the jungle. Not only that, but we relied heavily on the ability to run to hunt prey, particularly over long distances. All that makes for a hot hot human who needs to cool down: sweating works by evaporative cooling, in which the heat energy dissipates as the moisture on our skin vaporises.
But how did we evolve this ability? A lot of the traits that we think of as human are complex, evolving changes in multiple genes. Increasing the density of sweat glands, however, appears to have been relatively simple. This is controlled by the activity of the gene Engrailed (first discovered in fruit flies – another example of how important this model organism has been). By altering the activity of control “enhancer” elements of Engrailed in mice, researchers have demonstrated that multiple changes in the control regions of this gene have resulted in higher levels of Engrailed, and so more sweat glands. It’s a really neat piece of work that also demonstrates a key theme of evolutionary developmental biology: changes in regulatory DNA often have more profound effects than changes in the bits that actually code for proteins. There’s an accessible Science Daily article here:
Today’s amazing animal is, alas, extinct. It’s an extremely bizarre (and cute) dinosaur called the shuvuuia that had extremely good hearing and night vision, judging by analysis of fossils of its skull. Of course, birds are descended from dinosaurs (theropod dinosaurs, to be precise, which are the ones that tended to walk on two legs, like T. rex) but it’s interesting to see that some had specialised adaptations that we see in much later bird species, like barn owls. Shuvuuia is part of a group of dinosaurs called alvarezsaurids, which share a unique characteristic in common with modern birds: they can lift the upper part of their jaws in relation to their skulls. Indeed, the alvarezsaurids may be more “bird” than “dinosaur”. It may also help explain the shuvuuia’s bizarre appearance: this funny little creature not only had feathers, but long legs and tough little forearms with a single claw. Likely it hunted insects at night and used the claws to excavate prey from burrows. Original paper published in Science here, with a brief news piece here (both paywalled, alas).
Shuvuuia deserti: artist’s impression by Victor Radermaker