What we might fail to realize is that Ursula was merely acting according to the laws of nature and evolution . Her heart's desire is to be the Queen of the Sea, and she wants this not only for power, but also to get even with Triton, who banished her from his kingdom. She was very attracted to him and now feels rejected so she plots her revenge against Triton. But, when she meets Eric, she falls in love with him and she has to compete with Ariel, who is younger and more physically fit than her, for his love. Ursula is not a viable female for reproductions because of her age and her obesity, so she is not appealing to Triton or Eric. She manipulates and deceives Ariel in order to get the Trident from Triton and Eric's love.
According to Charles Darwin's theory of natural selection, Ursula is not fit and natural selection does not benefit her. She is about fifty years old and reaching menopausal onset. When she was younger she pursued Triton as a mate so he could father her offspring but he rejected her and banished her from his domains. Ursula was probably overlooked by Triton as a fit woman because of her obesity. When it comes to sexual selection, which refers to the fitness advantage that some individuals have over others of the same sex in respect with reproduction (Encyclopedia.com), Ursula does not posses the adequate qualities. Her Body Mass Index (BMI) is about 54.2 kg/m2 which indicats that she is extremely overweight .
