[nommm-nommm]

Race is a social construct because there is no scientific definition of race and is not consistent between cultures or even in the same culture over time.

Species however has a scientific definition - "A species is often defined as the largest group of organisms where two individuals are capable of reproducing fertile offspring." Thus not a social construct, this is a well defined classification. We may reclassify species based on new information or because they evolved, but that doesn't mean its a social construct.

Ranking them by importance is social, however.

[oilywater]

As I've stated in my comment there are more than enough examples where that definition of species is lacking - it's not a line/plane/SVM-hyperplane.

Evolution is gradual, there are no big species jumps.

What was there between sapiens and erectus, X? What was between sapiens and X, and X and erectus, Y and Z?

What was then between sapiens and Y, Y and X, X and Z, Z and erectus?

This can go on forever, evolution is by nature gradual, lets say it in your terms, a regression is more suitable than classification.

What point in this finely continous line do we pick for discrimination? Speciesism discovered!