Lions were Larger in the Past

In an environment where gravity increases over time, large animals must either become smaller or face extinction.

In light of this self evident truth, it's interesting to note that lions have grown smaller over time. They appear to have staved off extinction by becoming smaller.

Furthermore, the strange fact that it is the female lions that do most of the hunting can similarly be explained by an increase in gravity. The smaller females have remained competitive and able to pounce on their prey while the larger males have become too heavy for pouncing, despite growing smaller.

The relatively stronger males still have an important function. They protect the cubs and help in other tasks where strength rather than speed is the most important factor. The division of labor makes sense. However, this division may not have been originally as it is today. In the past, the tasks may have been the other way around.

By Kevin Pluck - Flickr: The King., CC BY 2.0, Link