If you are hung up on the firetruck, here is another one on newborn macaques preferring faces: https://www.nature.com/articles/srep19669 https://www.nature.com

If you are hung up on the firetruck, here is another one on newborn macaques preferring faces: https://www.nature.com/articles/srep19669 https://www.nature.com/articles/srep19669 Or this one, where adding testosterone to rhesus monkeys causes their female offspring to be "masculinized': https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3146061/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3146061/