Frida was now pregnant and suffered from morning sickness most of the time and was unable to work on the illustrations for Louis's second book, "Adam's Ancestors." At a dinner party given in his honor after a lecture of his at the Royal Anthropological Institute, Gertrude Caton-Thompson introduced her own illustrator, the twenty-year-old Mary Nicol. Louis convinced Mary to take on the illustration of his book, and a few months later companionship turned to an affair. Frida gave birth to Colin in December 1933, and the next month Louis left her and his new born son. She would not sue for divorce until 1936.