Unexpectedly, butterflies’ vibrant wing colours play no part in mating but scent is crucial. The green-veined white’s scent, citral, consists of two isomers, geranial and neral; both are needed for the males to successfully woo a partner. They waft this aphrodisiac pheromone around throughout their life to attract females and repel rival males. Females release their own scent to inform the male she is ready to mate too.

— Read more in Old cigar box or zesty lemon: the sweet scent of butterfly romance at The Guardian.

Cheetahs Jake, Oscar and Brooke were caught on camera at the park frolicking in their favourite perfume of the moment - PS Love Noir by Primark. Mr Walker said the bears, meerkats and lynxes love perfume scents too.

— Will Walker, a manager at the Wild Place Project in Bristol, is asking for donations of perfume. Read more in Wild Place Project appeals for aftershave for animals at BBC.

Test rats increased their own helping behavior when they were presented with the smell of a helpful rat. Remarkably, this holds true even though they did not experience this helpful behavior themselves. Furthermore, such a 'smell of cooperation' depends on the actual activity of helping and is not connected to an individual rat.

— Dr. Nina Gerber of the University of Göttingen on the results of her research on rat behavior; read more in Research team finds effect of odor on helpfulness in rats at Phys.org.