The Agents of Climate Justice in Healthcare.

The eusocial insects represent one of the pinnacles of social life [; (–)]. A typical colony of leaf-cutter ants consists of a single reproducing queen and up to 10 million workers. These workers are the ultimate altruists—they are completely sterile and devote their entire adult lives to rearing offspring laid by the queen. The eusocial insects are dominated by the Hymenoptera, the wasps, ants, and bees. Although this order comprises only 6 to 8% of insect diversity, it is thought to have produced more independent origins of eusociality than all other insects combined. Eusociality has independently evolved in multiple arthropod lineages: () ants; () bees; () wasps; () thrips; () beetles () aphids; and () termites. The row (–) represents taxa with haplodiploid sex determination systems; the row (–) comprises taxa with diploid systems. Image credits: Ants: , via Unsplash, Bees: , via Unsplash. Wasps (): , CC BY-SA 3.0, via Wikimedia Commons. Thrips (): , 1907, public domain, via Biodiversity Heritage Library. Ambrosia beetles: , used with permission. Aphids (): , CC BY-SA 3.0, via Wikimedia Commons. Termites ( sp.): , CC0 1.0, via Wikimedia Commons. Hamilton suggested that eusociality has arisen so frequently in the Hymenoptera because they have haplodiploid sex determination, where males develop from unfertilized (haploid) eggs and females from fertilized (diploid) eggs (, ). Haplodiploid sex determination leads to females being more highly related to their sisters (R = 0.75; assuming monandry) than they are to their daughters (R = 0.5), which may make it easier for altruism to evolve. This “haplodiploidy hypothesis” has received support, or mixed support, from three empirical studies, which have reported that the transition rate to eusociality is higher in haplodiploid lineages than in non-haplodiploid (–).