Axial tilt refers to the angle at which a planet's axis is tilted relative to its orbit around the Sun. It is responsible for the change in seasons on Earth. Full definition
When the cranial base and the caudal part of the skull are shortened the circular model brain becomes increasing ellipsoid and there is greater axial tilt with an increase in height rostrally (white arrow). (journals.plos.org)
I don't have the information right at hand but isn't it understood that in the early holocene the earth was on a slightly different axial tilt with the north pole pointed slightly more toward the sun? (theinconvenientskeptic.com)
Seasons are actually caused by Earth's 23.4 - degree axial tilt. (geekwrapped.com)