Race does exist on a biological level because physical anthropologists can tell them apart. Psychologists can note certain differences between different racial groups that hold true even cross-culturally (regardless of upbringing). Medicines work differently on different races and we develop in the womb and age at different rates.
The idea that race doesn't exist was perpetuated by a self-hating Jewish professor named Boas, who was a leftist liberal and laid the foundation for much of this malarkey being taught today that there is no such thing as race.
I believe that each race should separate themselves from others in important ways like only marrying or having children with those of their own race. This preserves each unique subspecies.
I think that you are confusing race with enviromental impact. People in different enviroments will have slightly different features as a result of evolutionary change. However these changes are all controled by the same sets of genes. Interestlngly, although most people think that we and other species adapt to our enviorment, this is not true. Mutation is a totaly random process caused by DNA copy error. Most of the time these changes are lethal, or leave that organisum unable to reproduce, or are netural. (look up the "wobble effect" in amino acid sequences - Its very interesting). Every once in a long time, this random change is of use as it allows for better reproductive sucsess, and therefore conserved in future generations.
This is why meds will work a bit diffferently in certain groups of people. Keep in mind...the genes are the same, It is only the expression of these genes that is altered slightly, so really it is just a variation on the same basic theme, not a "different race" per say.
It is not true that there is a different development in the womb. Any college level genetics text will give a good synopsis of this subject. There are also some very good shows on "the Science channel" etc that are good to watch. I would recommend "In the Wonb", as it is repeated fairly often. To a certain point development of the Human embryo is the same as other mamals and it is very hard to distingush a human from other embryo.
People from all over the world have been puting this work together since Darwin wrote "On the Origon of Specis" in 1850. It is not just a single person who has said this.
I know that there is a dispute among Rabbi's over Evolution, I think someone asked Chiam about this on "Ask JTF" not so long ago. I happen to be a proponent of Evolution, so this is why I gave the response that I have.
Please let me know what you think...I very much enjoy this type of disscussion.