" one should teach people that “race” is not an actual well-defined biological thing : it is a social construct, and an extremely pernicious one at that. The sooner we get rid of it the better –"
Very true! What we today call Race is nothing more than an effort to determine what differences exist in people from Europe, Asia, and Africa and were established by appearances. But Black skin was caused when people lived in South Africa where the sun was strong, and the black protected from skin cancer. White skin was from North Europe where the sun was much less powerful and greater ability to convert sunlight to Vitamin D was needed.
But somehow between about 200,000 years ago and 80,000 years ago African Homo Sapiens developed a unique language based on syntactic grammar. The Darwinian theory or evolution says this is impossible since it was a sudden massive change, not slowly evolved. It did not evolve in any way that left evidence, but about 80,000 years ago an event called by anthropologists “Out of Africa” led Homo Sapiens to cross the Med to Europe and move east to Asia. The physical traits mistaken for Race developed after that. Today, every healthy child born anywhere in the world starts babbling at about 6 months, moves to making every sound in every known human language, and by age five is attaching meaning and making sentences to whatever language they were born into.
A book called “Why Only Us: Language and Evolution” by Robert C. Berwick and Noam Chomsky advises how language probably developed and how it works. It is unique to homo sapiens and is the reason we can think, imagine, and control our environment. It is a difficult book if you do not understand the science of evolution and how it has applied to primates and human beings. [Why so many languages exist, all learned through the same process by children first exposed to the local language starting about age six months?]
Language has not evolved in the 80,000 years since the Out of Africa event. But any normal child born anywhere in the world WILL learn the language he or she is born into and lives in during the first years of life. That is common to Human Beings worldwide and race cannot be distinguished as a factor.
Genetic evolution of groups living in different parts of the world explain skin color, etc., but not language. All humans speak complex sentences and adopt the local language(s) they are born into, not matter what tribe they come from or what part of the world their family comes from. What people call “Race” is no more than the measure of where their family came from, and as of 80,000 years ago, we all came “OUT OF AFRICA”
The rest of the story is up to each of you to tease out, but you are looking for evidence that does not leave bones to explain brain changes. Behavior will never be definitive - see Berwick and Chomsky.