'What differentiates humanity from the lower animals is that, however self-reliant animals such as lions may seem, they ultimately just take external nature around them for granted, whereas, mankind progressively masters nature.'
How could anyone prove that?
That's not what Darwin's theory claims.
How is human 'labour' different from that of animals?
How has this to do with feminism?
As to why we (as a society) would be bigoted about race - well, because 'race' is a construct developed in order to justify exploitation of one group of people (typically, people who look 'different' and originate from a differnt part of the world, from the people deciding what a 'race' is).
How does sexism stem from racism? How could it?
Btw, 'sexism' and 'patriarchy theory' are not equivalent.
The patriarchy is, IMO, institutionally racist. This is because the patriarchy operates by constructing a binary opposition between the favoured group (men, specifically straight, white, upper class, Western men), and 'Everyone else', when it possibly can.