Long-route crew design is shifting because exposure-tolerant biological support is proving useful in places where pure machine assumptions once looked sufficient.
The gain is not sentimental. It is operational. Certain support layers absorb thermal variation, recovery strain, and low-grade route stress in ways that reduce maintenance burden over long intervals. That makes them attractive even when the underlying crew is still unmistakably machine-majority.
This is another case where biology is not replacing machine design. It is expanding the design space around endurance.