12TH FEBRUARY 2024
Dear Friend of Darwin,
Today marks the 215th anniversary of Charles Darwin’s birth. Happy Darwin Day! And happy 15th anniversary to the Darwin Bicentennial Oak!
In April 1871, the entomologist Roland Trimen wrote to Darwin to ask if he could explain ‘that most ruinous propensity of nocturnal winged animals (chiefly insects) to rush impetuously into bright flames’. It’s a question all of us must have wondered about, as had Darwin. In his reply, he admitted to being somewhat flummoxed:
You ask me whether I have any notion about the meaning of moths &c flying into candles, & birds against light-houses.— I have not.— I have looked at the case as one of curiosity, which is very strong with the higher animals, & I presume even with insects. A light is a very new object, & its distance cannot be judged, but how it comes that an insect is so stupid as to go on flying into the same candle I cannot conceive. It looks as if they were drawn towards it.— Sir C. Lyell, I remember, made years ago the difficulty greater by asking me, what stops all the moths in the world flying every moon-light night up to the moon, or as near as they could get.—Perhaps they have instinctively learnt that this cannot be done.—
Over the years, various potential explanations have been put forward for insects in general—and moths in particular—being attracted to artificial lights. Perhaps they evolved to use the moon for navigation, but were being confused by this new, much closer, night-time light-source. Or perhaps they were attracted to the heat emitted by the light.
Last month, a new study (see Missing Links section below) proposed a compelling new explanation: at night, the sky above a moth tends to be lighter than the ground below, so moths instinctively turn their backs to the light to ensure they stay the right way up. When moths apply the same behaviour to a much nearer artificial light, they end up flying in circles around it!
Darwin would surely have been delighted by this explanation.
A book you might enjoy:
Darwin’s Fossils by Adrian Lister
A beautifully illustrated account of the many fossils collected by Charles Darwin.
Some Darwin-related articles you might find of interest:
- The Complete Library of Charles Darwin - Introduction
Published to mark Charles Darwin’s 215th birthday, the latest stupendous offering from Darwin Online… Following 18 years of research, a digital recreation of the more than 7,350 titles across 13,000 volumes/items that were once to be found in Darwin’s personal library. Discover the works Darwin owned, used and read!
The Complete Library can be accessed here.
- Why are moths attracted to lights? Science may finally have an answer
Insect flight paths were filmed at night using hi-res and infrared technology with surprising results.
Original paper:Why flying insects gather at artificial light
- Blue tit populations closely linked to numbers of moth caterpillars
The critical importance of moth caterpillars numbers to the population size of a common insect-eating garden bird, the blue tit, were highlighted in a new study.
Original paper: Population links between an insectivorous bird and moths disentangled through national‐scale monitoring data
- We’ve found out how earless moths use sound to defend themselves against bats—and it could give engineers new ideas
Ermine moths’ wings make ultrasonic clicking noises during flight, presumably to confuse bats.
Original paper: Buckling-induced sound production in the aeroelastic tymbals of Yponomeuta
- Complex green organisms emerged a billion years ago, says new research
Using modern gene sequencing data, researchers have dated the emergence of multicellularity to almost a billion years ago.
Original paper: Phylogenomic insights into the first multicellular streptophyte
- A newly identified ‘Hell chicken’ species suggests dinosaurs weren’t sliding toward extinction before the fateful asteroid hit
Rather than a juvenile of a known species, several fossilised bones represent a new species—and shed light on the question of whether dinosaurs were already in decline before disaster struck.
Original paper: A new oviraptorosaur (Dinosauria: Theropoda) from the end-Maastrichtian Hell Creek Formation of North America
- The violent birth of the moon
Did a colossal collision with a doomed planet give us our satellite? I found this article of particular interest as it describes the important contribution made by astronomer George Darwin (son of Charles) to our understanding of the moon’s formation.
- Secrets within the teeth of the first Homo fossils
New studies of fossil teeth are helping untangle the human family tree.
Original paper: Dental morphology in Homo habilis and its implications for the evolution of early Homo
- Navel gazing with Philip Gosse
On Darwin’s contemporary, a serious scientist who thought the earth was only 6,000 years old, but had been created to look as if it were much older.
Journal of researches
One of the occupational hazards of running a Darwin-related newsletter while writing a book about Darwin is that I keep discovering new stories about stuff I’ve already covered in the book. This newsletter edition’s (entirely coincidental) preponderance of moth-related stories is a good example: I’ve already written a chapter about the ongoing evolutionary arms-races between moths and bats, but now I have even more stuff to consider for the next draft.
As it happens, a few years back, I contributed a short audio piece about bats to Melissa Harrison’s wonderful podcast The Stubborn Light of Things . The fiasco I went through recording my piece was enough to put me off podcasting for life!
Expression of Emotions
Thanks as always for reading the newsletter. Please feel free to provide comments—and to recommend it to your most discerning friends.
See you next time!
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