Season Five Edit
Professor Holloway was the author of the 1984 book about The Wakened Land. He wrote that war was useless because it took the young and healthy, and instead the old and weak should be made to war. Only by that kind of selective pressure could humans remove themselves from their current "evolutionary cul-de-sac." He posited that our hunter-gather ancestors were actually smarter and more agile than modern humans. The reason for human evolution stalling out was that it had been too long since a mass extinction event, as only microbes could get through modern human defenses.
Sigrid and Van Ark overcame their hatred for each other by realizing they were both followers of Professor Holloway. Sigrid spoke to Holloway many times and knew his daughter. They were both invited to a dinner with Holloway after a lecture.