New Scientist Highlights of 2020 – Part Two

Photo by Gerry Matthews (Alamy) from https://www.newscientist.com/article/2255352-coronavirus-lockdown-changed-how-birds-sing-in-san-francisco/

White-crowned sparrow (Zonotrichia leucophrys) (Photo One)

Dear Readers, before we finally say goodbye to 2020, here are a few final stories from New Scientist that caught my eye.

The first is pandemic-related, as nearly everything seems to be at the moment. White-crowned sparrows (Zonotrichia leucphrys) were found to be singing differently during the Covid lockdown in San Francisco, and scientist Elizabeth Derryberry, from the University of Tennessee, wondered how, and why.

The birds were found to be singing more quietly and at a deeper pitch – it’s known that birds react to the low-frequency background drone of traffic and air conditioners by singing not only louder, but at a higher frequency so that they can be heard over the racket. The noise level in San Francisco had dropped by a full 7 decibels, and so the birds seem to have reverted to their older, sexier songs – birds actually seem to prefer deeper sounds (think Barry White as opposed to Tiny Tim). If you go to the full article here, you can hear both birdsongs. The scientist says that ‘they sing like they used to thirty years ago’. I suppose this is both sad, but also hopeful – birds and other urban animals seem to be so much more adaptable than we thought.

Photo Two by By Ra'ike (see also: de:Benutzer:Ra'ike) - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4540111

Skeleton of cave bear showing enormous sinuses! (Photo Two)

But not all animals are able to adapt. The prehistoric cave bears (Ursus spelaeus) that used to weigh over 1000 kilograms, and existed alongside our present-day brown bears (Ursus arctos), probably became extinct because they had over-large sinuses. Who knew? These huge animals, who disappeared about 24,000 years ago, lived on a largely plant-based diet. When the ice-ages made vegetation difficult to come by, the cave bears couldn’t switch to a meat-based diet, because their sinuses meant that they could only chew food with their back teeth, while carnivores typically cut up their food with their incisors and canines at the front. The brown bears had smaller sinuses, and hence could switch from a herbivorous to a carnivorous diet.

But why have such big sinuses in the first place? They are thought to play an important role in gas-exchange during hibernation, allowing the bears to hibernate for longer. However, as the poor cave bears wouldn’t have been able to fatten up due to the lack of plant food, they probably starved while they were sleeping. It was one of those evolutionary trade-offs that failed.

You can read the whole article here.

Photo Three from https://www.newscientist.com/article/2229070-hagfish-tie-their-bodies-into-complicated-knots-to-escape-tight-spots/

Pacific hagfish (Photo Three)

Hagfish are extraordinary animals. Early ancestors of the eel, they have four times as much blood compared to their volume as any other fish, four hearts and only half a jaw. When trapped by a predator or accidentally stuck in a tight spot, they throw complex knots and shapes in an attempt to escape. Because this is a very slippery fast-moving process, it’s taken modern technology and a slow-motion camera to decipher what’s going on. Now, scientist Theodore Uyeno has discovered that the animals prefer more complex knots – the hypothesis is that the simpler ones may be more uncomfortable because the loops are so tight.

So, 45 percent of the time the hagfish do a trefoil knot:

Photo Four from By Jim.belkAnimation: MichaelFrey (talk) - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=75360346

Trefoil knot (Photo Four)

33% of the time they do a figure-of-eight knot…

Photo Five by By Lucasbosch - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=17249329

Figure-of-eight knot (Photo Five)

and 4% of the time they manage a three-twist knot, the only animal able to do so (Moray eels can knock up a knot, but nothing this complicated). Kompologists rejoice!

Photo Six by Original: Jim.belk Animation: MichaelFrey, CC0, via Wikimedia Commons

Three-twist knot (Photo Six)

And finally, how about this little creature with its ‘hats’?

Photo Seven by Alan Henderson at Cover Images. Photo from https://www.newscientist.com/article/mg24632881-200-weird-caterpillar-uses-its-old-heads-to-make-an-elaborate-hat/

Uraba lugens caterpillar – the moth is also known as the ‘gumleaf skeletoniser’ (Photo Seven)

Each ‘hat’ is the moulted skin of the caterpillar’s head – they moult up to thirteen times before they metamorphose into moths, and from the fourth moult on, each ‘hat’ stays stuck. You can see how the size of the head gets bigger from the top down, as the larva munches on eucalyptus leaves: an alternative name is the ‘gumleaf skeletoniser’ because the foliage is eaten right back to the veins.

The ‘hats’ seem to fulfil a useful purpose: biologists have watched the caterpillar using them to swat away predators, and they may also serve to distract a curious bird who will hopefully peck at the wrong ‘head’. You can read the whole article here.

And so, dear readers, onwards and into 2021. Who knows what those scientists will discover next?

Photo Credits

Photo One by Gerry Matthews (Alamy) from https://www.newscientist.com/article/2255352-coronavirus-lockdown-changed-how-birds-sing-in-san-francisco/

Photo Two By Ra’ike (see also: de:Benutzer:Ra’ike) – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4540111

Photo Three from https://www.newscientist.com/article/2229070-hagfish-tie-their-bodies-into-complicated-knots-to-escape-tight-spots/

Photo Four By Jim.belkAnimation: MichaelFrey (talk) – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=75360346

Photo Five  By Lucasbosch – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=17249329

Photo Six by Original: Jim.belk Animation: MichaelFrey, CC0, via Wikimedia Commons

Photo Seven by Alan Henderson at Cover Images. Photo from https://www.newscientist.com/article/mg24632881-200-weird-caterpillar-uses-its-old-heads-to-make-an-elaborate-hat/

6 thoughts on “New Scientist Highlights of 2020 – Part Two

  1. Anne

    The last photograph reminded me of the children’s story “Caps for sale” in which the vendor has caps piled high on his head, only to have them stolen by monkeys. This post has been a joy to read, thank you!

    Reply
  2. Rosalind Atkins

    Absolutely fascinating! However, I have one question for the scientific community. As a woman with huge sinuses, if not cave bear standard, why oh why do I find it so hard to keep the weight off? ;0

    Reply
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