Various theories have been suggested that attempt to suggest evolutionary benefits to the human species stemming from the cessation of womens reproductive capability before the end of their natural lifespan. Explanations can be categorized as adaptive and non-adaptive:

Non-adaptive hypotheses
The high cost of female investment in offspring may lead to physiological deteriorations that amplify susceptibility to becoming infertile. This hypothesis suggests the reproductive lifespan in humans has been optimized, but it has proven more difficult in females and thus their reproductive span is shorter. If this hypothesis were true, however, age at menopause should be negatively correlated with the amount of energy expended to maintain the reproductive organs, and the available data does not support this.A recent increase in female longevity due to improvements in the standard of living and social care has also been suggested. It is difficult for selection, however, to favor aid to offspring from parents and grandparents. Irrespective of living standards, adaptive responses are limited by physiological mechanisms. In other words, senescence is programmed and regulated by specific genes. Early human selection shadow
While it is fairly common for extant hunter-gatherers to live past age 50 provided that they survive childhood, fossil evidence shows that mortality in adults has decreased over the last 30,000 to 50,000 years and that it was extremely unusual for early Homo sapiens to live to age 50.
Skew deviation is an unusual ocular deviation (strabismus), wherein the eyes move upward (hypertropia) in opposite directions. Skew deviation is caused by abnormal prenuclear vestibular input to the ocular motor nuclei, most commonly due to brainstem or cerebellar stroke. Other causes include multiple sclerosis and head trauma. Skew deviation is usually characterized by torticollis (head tilting) and binocular torsion. The exact pathophysiology of skew deviation remains incompletely understood. Skew deviation appears to be a perturbation of the ocular tilt reaction, which is itself is most likely a vestigial righting response used to keep fish and other lateral-eyed animals properly oriented.There are three types of skew deviations:Type 1: Upward deviation of both eyes; sound-induced vestibular symptoms; both eyes show counterclockwise rotary upward rotation
Type 2: Hypertropia in one eye; dorsolateral medullary infarctions; excyclotropia in the ipsilateral eye; hypertropia in the contralateral eye
Type 3: Simultaneous hypertropia one eye and hypotropia in the other eye; upper brainstem lesion

References
Further reading
Adams, Raymond D.; Victor, Maurice; Ropper, Allan H. (1997). Principles of Neurology (6 ed.). New York: McGraw Hill, Health Professions Division. ISBN 978-0-07-067439-4.