The winners of the Readers’ Choice Awards in the categories Original Paper and Review Article were determined by the number of online accesses (HTLM or PDF versions) of pieces that appeared in Volume 207 (2021). These accesses are used as a proxy of ‘popularity’ of a paper. The year 2021, instead of 2022, was chosen to ensure that each article published had been available online for at least 12 months before a decision was made on December 5, 2022.

The winner in the Original Paper category is ‘Coping with the cold and fighting the heat: thermal homeostasis of a superorganism, the honeybee colony’ by Anton Stabentheiner, Helmut Kovac, Monika Mandl, and Helmut Käfer (2021) with 4673 accesses, followed by the article of Madeline Williamson, Alexandra Mitchell, and Barry Condron (2021) with 2453 accesses.

In their study, Stabentheiner et al. (2021) present a comprehensive analysis of thermoregulatory mechanisms in honeybee (Apis mellifera) colonies. Honeybees maintain ‘tropical conditions’ in their brood nest during periods of cold and heat. Precise thermal homeostasis is most important for brood development, and adult bees suffer from behavioral and neuronal deficits when their brood develops outside an optimal temperature range of 34–36 °C (Groh et al. 2004; Jones et al. 2005). Thermoregulatory control in breeding honeybee colonies needs to be examined at the level of a superorganism with thousands of cooperating individuals (Moritz and Southwick 1992; Heinrich 1993).

Stabentheiner et al. (2021) used state-of-the-art technology, such as large arrays of thermocouple probes and temperature/humidity sensors combined with high-resolution thermal imaging camera recordings, to analyze individual body- and brood-comb temperatures under different environmental conditions. The bees’ regulatory behaviors include individual endothermic (wing muscle) heat production, water droplet deposition, and wing fanning, as well as group-level changes in bee densities. The most important outcome of their study is that the starting or set points for the various thermoregulatory mechanisms underlying colony heating and cooling overlap across relatively broad temperature ranges. Together with passive effects, this results in a remarkable thermal constancy of 34.8–35.9 °C in the central brood nest. This enormous precision is comparable to the constancy of core body temperatures in mammals. Whereas in mammals this is controlled by a set point at the level of the central nervous system, the obviously large variation in behavioral set points across thousands of individual bees is required to guarantee smooth stabilization of the brood nest temperature in a decentralized colony-level system. The study by Stabentheiner et al. (2021) is a big step forward towards understanding the many facets underlying thermoregulatory precision in breeding honeybee colonies.

The winner of the Readers’ Choice Award in the Review/Review-History Article category is ‘Einstein, von Frisch and the honeybee: a historical letter comes to light’ by Adrian G. Dyer, Andrew D. Greentree, Jair E. Garcia, Elinya L. Dyer, Scarlett R. Howard, and Friedrich G. Barth (2021). It was downloaded an amazing 322,878 times. This is nearly 253 times the average number of accesses of any of the other review or review-history articles published in 2021—an all-time record!

What is it that has triggered this enormous interest far beyond the regular readership of the Journal of Comparative Physiology A? The soundest explanation appears to be that it was the name of Albert Einstein. Even 68 years after his death, interest in Einstein’s life and work remains unwaning. Approximately one million searches per month are carried out on Google using the term ‘Albert Einstein’, whereas over the same time typically about 2000 searches are conducted related to ‘Karl von Frisch’ (data based on an analysis performed by using Google Trends Supercharged—Glimpse on December 6, 2022). Springer Nature had informed the media about the Dyer et al. (2021) paper shortly before its publication in the Journal of Comparative Physiology A. This press release resulted in global reporting by dozens of news outlets, and the mentions in hundreds of tweets and blogs, of the discovery of a previously unknown letter written by Albert Einstein—a story that prompted, in turn, widespread access of the article published in the Journal of Comparative Physiology A.

The letter was written by Einstein on October 18, 1949, from Princeton (United States) to Glyn Davys in Bournemouth (England). At that time, Davys studied acting, but previously he had served in the British Royal Navy as an engineer working on radar. It seems that his work with the then rather new and exciting technology, and the reporting earlier that year by English newspapers of Karl von Frisch’s discovery of how polarization patterns in the sky may affect the dances and orientations toward food sources of honeybees (von Frisch 1949), motivated him to write a letter to Einstein. Although this letter has not yet been found, it can be inferred from Einstein’s response that Davys had mentioned von Frisch’s studies and asked him how the results of these investigations could be utilized in physics.

Albert Einstein confirmed in his letter that he was well familiar with the work of Karl von Frisch (the two met during von Frisch’s visit to Princeton in the spring of 1949; von Frisch 1957), but that he could not “see a possibility to utilize these results in the investigation concerning the basis of physics.” However, he continued: “Such could only be the case if a new kind of sensory perception, resp. of their stimuli, would be revealed through the behavior of the bees. It is thinkable that the investigation of the behavior of migratory birds and carrier pigeons may some day lead to the understanding of some physical process which is not yet known.” Although the letter was rather brief, it has demonstrated Einstein’s openness to the possibility of discovery of sensory modalities in animals alien to humans, and his (correct) prediction that such new insights might result in a close interaction between biology and physics.

Congratulations to the recipients of the 2023 Editors’ and Readers’ Choice Awards!