The first Aad (or Ad, sometimes 'ad, depending on the transcription from عاد) you can ever hear of seems to be close to Noah! It's his great-great-grandson.
According to some mythology, this guy have married 1000 wives, got 4000 sons, and lived 1200 years!
"He married a thousand wives, had four thousand sons, and
lived twelve hundred years. His descendants multiplied considerably.
After his death his sons Shadid and Shedad reigned in succession over
the Adites. In the time of the latter the people of Ad were a thousand
tribes, each composed of several thousands of men. Great conquests are
attributed to Shedad; he subdued, it is said, all Arabia and Irak. The
migration of the Canaanites, their establishment in Syria, and the
Shepherd invasion of Egypt are, by many Arab writers, attributed to an
expedition of Shedad."
Those people were said to be big and strong (to the point of having this hoax), they lived in (modern age) Oman and Yemen.
They built Iram with big big buildings. According to the Quran, those people didn't abide to God's prophet Hud and got severely punished:
"Have you not considered how your Lord dealt with Ad
(The people of) Iram, possessors of lofty buildings
The like of which were not created in the (other) cities"
Sura 89: verses 6-9
I don't know what happened exactly, but things changed drastically nowadays: Geographically displaced, we have sizes around 1.7m tall, lifetimes around 60-70 years, and a very moderate number of wives, 1 at a time. I tried to trace back our family tree to check what happened, I just could reach 1845. The problem here is to get older references. Another challenge is keeping track of the evolution, especially that it is spread all around the world. The biggest branches now are mainly in Lebanon and Brazil. I'll try to keep all this information accurate and updated, as much as possible.