Ian and Margaret are reclining on the couch, facing each other from opposite ends, when he tosses her a ring and asks her to marry him. She puts the ring on her left hand, then we see, from Margaret's POV, she reaches out her left had to take Ian's right hand. It then switches to Ian's POV and we now see Margaret's left hand resting on her chest, her right hand now outstretched to Ian.
The very free sexual life of bonobos is mentioned. This was not known about in the 1950s. They were not clearly distinguished from chimps, which have very different habits.