The Prologue to the LOTR contains this general description of Hobbits:
Their height is variable, ranging between two and four feet... Their faces were as a rule good-natured rather than beautiful, broad, bright-eyed, red-cheeked.
Tolkien divides the Hobbits into 3 'breeds': Harfoots, Stoors and Fallowhides. He describes them as follows:
The Harfoots were browner of skin, smaller, and shorter, and they were beardless... The Stoors were broader, heavier in build... The Fallohides were fairer of skin and also of hair, and they were taller and slimmer than the others...
Among the Hobbits, as among the Elves, the blondest race is the rarest - the Fallohides are described as "the least numerous" of Hobbits, and the Vanyar are "the smallest host" of the Elves.1 The similarities do not end here. The blond Vanyar are the pre-eminent race among the Elves (the King of the Vanyar is the overall lord of the whole Elvish race), and the Fallohides are natural leaders for the rest of Hobbit kind - "they were often found as leaders and chieftains among the clans of Harfoots or Stoors. Even in Bilbo's time the strong Fallohidish strain could still be noted among the greater families, such as the Tooks and the Masters of Buckland."2
Some readers of British descent have commented that Tolkien seems to be stuck on the old English ideas of hereditary nobility. But LOTR's recurring themes of blood-inherent leadership traits, whether positive or negative, suggest "biology=destiny", which is the underpining of modern racism, not traditional classism. Traditional European ideas of 'blue-blooded' nobility are not based on biology - after all, commoners could gain noble titles through distinguished service to the ruling class, and even 'racial' outsiders such as Jews could become nobles if they abandoned their heritage and adopted the mainstream lifestyle, i.e. convert to Christianity. So there is more at work in LOTR than traditional English classism. It is quite possible that biological racism, which rose to prominence in the modern age, might have a role in shaping Middle Earth.
1. LOTR, p3 and The Silmarillion, p53
2. LOTR, p3 and The Silmarillion, p53