Sure. You could define a liberal in a number of ways. One possible definition is someone who is "center-left", generally votes for democrats, supports public provisioning of education, healthcare, welfare, and so forth.

Pinker posted regularly on Twitter during the elections, generally supporting Hillary Clinton and opposing Trump.

https://twitter.com/sapinker/status/793455008939401216

In a larger context of liberalism, as opposed to fascism or socialism, again he comes out as a liberal with fairly consistent support for individual rights, in both economic and political realms, although regularly modified by a utilitarian cost-benefit analysis... as is typical of liberals going back to Bentham and JS Mill.

None of what you said about human nature is at odds with his political, economic, and social identification as a liberal. It would've been unusual to find anyone of any era, including the present era, who fully denies the concept of a human nature.

Are there any traits that distinguish humans from anything else? If so, there is a human nature.

>I find it amusing that you believe me a liberal ...

I assumed that you were a member of the radical left, and not a liberal. Anthropology, as a discipline, currently has an overwhelming bias towards this leaning, moreso than nearly any other discipline.