They walked beside a lake.

The lake was real — its chemistry and extent and history are documented in the geological record of the basin.

Its shores were lined with aquatic vegetation that would have moved in the wind that came off the water.

The water itself would have reflected the sky, which 23,000 years ago was the same sky that covers the Tularosa Basin today, with the same sun and the same stars and the same seasonal rhythm of long winter nights and brilliant summer days.

The giant ground sloths were there.

The mammoths were there.