With one breast only intact, sister sun (= mother) would shine only during half a year, summer time. In the arctic area they cannot enjoy the nourishing light and warmth of her for more than half of the year. The two breasts of mother means the two main seasons of the year.

If sun is female, then Mother Earth is just a reflection of her. Perhaps once this was the general thought pattern, a pattern later changed by men in order to become more powerful and get more status? The Chinese sign for mother lost its head at some early point in history, a detronisation?

The spine located between her two breasts must be a line between two cardinal points, maybe the line between the equinoxes. The strangely pointing arm, forward and up, should point to summer solstice, that's the time when sun is highest in the sky. The other hand should point to winter solstice, with sun very low. At solstice the direction to the sun at sunrise is not due east but northeast or southeast.

There might be a connection with GD53, where the assymmetry between right and left determining whether it is 'winter' or 'summer' seems to reflect the same thought pattern: In 'summer' the 'breasts' are put forward and in 'winter' they are hidden behind (left). That there are six 'breasts' should not make us hesitate, originally there could have been only one (showing/summer) and one (hidden/winter) and later this pattern could have been extended to include the smaller 'breasts' for (solar) double-months.