Ancient nomads, wishing to ward off the evening chill and enjoy a meal around a campfire, had to collect wood and then spend time and effort coaxing the heat of friction out from between sticks to kindle a flame. With more settled people, animals were harnessed to capstans or caged in treadmills to turn grist into meal.

Furthermore, by integrating individually addressable arrays of metadevices, we demonstrated a new class of spatially varying digital metasurfaces where the local dielectric constant can be reconfigured with a bias voltage.

We advise not to culture-jack a natural disaster or some national tragedy.

The law-making or legislative component was the most recessive component of the legal system of hunter-gatherers, although decisions or advice given by mediators were remembered and used again to settle similar violations of rules or disputes among parties.