One aspect I found interesting about the first book was the all female expedition. Some of my favorite horror has a focus on a single gender such as John Carpenter's The Thing and The Descent. What made you decide to go with a predominantly female cast and was that a challenge?
They were just names on a page--biologist, etc.--when I wrote the rough draft of the first five pages. Before continuing I had to know whether they had names and whether they were men or women. It was soon clear they wouldn't have names and would be all women. Part of this had to do with the Southern Reach's protocols. But I can't say either that making them all women wasn't in a tertiary way a statement about how these kinds of stories tend to be male-dominated. Yet at the same time, that truly is tertiary as in a matter of days I had clear in my head exactly who each of them was, including their histories and backstories, even though this information isn't always there on the page. So, very early on, they were locked in. Was it difficult? I think if you always try to think of each character as a unique person, it helps.