Dr Jaisson reckons that the enormous size of the eggs is the main reason why each individual can only lay twoeggs at a time she probably does not have the capacity to lay more.
To confirm that this is so, Ms Welch stripped the eggs out of several females (not as horrible a process as it sounds), divided each batch of eggs into two, and inseminated half with sperm from a long-calling male and half with sperm from a short-calling male.
In a strange twist on the proverb about not putting all your eggs in one basket, she divides the resources needed to produce a single healthy offspring into two.