Natural rights and natural law theories flourished during the 17th and 18th centuries. In this regard you might want to focus your attention on some particular natural rights theorist, e.g. among whom Thomas Hobbes, Grotius, Spinoza, Pufendorf, John Locke, and Jean Jacques Rousseau are only some of the most eminent.
Once again things can get very complicated and you will want to carefully narrow the scope of your paper. Here are some possibilities:
(a) What does Hobbes mean by his term 'a state of nature'? Does this 'state of natue' imply a certain theory of human nature? Does Hobbes (or Locke) have a plausible theory of human nature? See The Politics of Motion by T. Spraggens for Hobbes. Hans Aarsleff's "The State of Nature and the Nature of Man" in ed. John Yolton, John Locke: problems and perspectives; a collection of new essays; Cambridge U.P., London, 1969 is one of the more insightful expositions of Locke's view. A new book which takes a different view is Barbara Arneil's John Locke and America: the defence of English colonialism, Clarendon Press; Oxford Unioversity Press, Oxford, England, 1996.
(b) What is Locke's theory of property in a state of
nature? How does this get modified in civil society? Does this
limit the rights of kings or the state to seize property? See
James Tully,A Discourse on Property, John Locke and his
Adversaries, the C.B. MacPherson The Political Theory of
Possessive Individualism and Ruth W. Grant John Locke's
(c) There is a current debate about Locke's attitude
towards Negro slavery and whether the theory of the Second
Treatise justifies or completely fails to legitimize Negro
slavery. You could start with the Popkin article in your packet
"The Philosophical basis of modern racism" and also M Seliger
"Locke, liberalism and nationalism" in ed. John Yolton, John
Locke: Problems and Perspectives, Cambridge, as well as H.M.
Bracken, "Esence Accident and Race" (see me for a copy).
(d) Along these same lines one might compare the critique of negro slavery in works such as Equiano's Travels and A Narrative of the Life of Fredrick Douglas with Mary Wollstonecraft's arguments against Rousseau on the subjugation of women in A Vindication of the Rights of Women. Note that for this topic you must tease out arguments from these texts. You may well also have to read the relevant portions of Rousseau's Emile.