Just a little thing:
The competition to elect New Zealand’s bird of the year has intensified with a vote-rigging scandal and an adult toy store endorsing a small, polyamorous bird with unusually large genitals.
Fair enough. And the large testicle size does seem to be linked to the polyamory bit. Whether of the polygyny type – produce enough to get the job done – or the polyandry – there’s a competition going on there.
The relative size of testes is often influenced by mating systems. Testicular size as a proportion of body weight varies widely. In the mammalian kingdom, there is a tendency for testicular size to correspond with multiple mates (e.g., harems, polygamy). Production of testicular output sperm and spermatic fluid is also larger in polygamous animals, possibly a spermatogenic competition for survival. The testes of the right whale are likely to be the largest of any animal, each weighing around 500 kg (1,100 lb).
Among the Hominidae, gorillas have little female promiscuity and sperm competition and the testes are small compared to body weight (0.03%). Chimpanzees have high promiscuity and large testes compared to body weight (0.3%). Human testicular size falls between these extremes (0.08%).
Humans appear to be slightly polyamorous but not very much.