PROTO-INDO-EUROPEAN PHYSIQUE

Ok, since my Austric example was obviously OT, I'll switch my
question into a more Indo-European question. I was wondering, were
the earliest IEs as fair-coloured, tall and long-headed as they say
so. From what I've known, by 4000 BCE they were already similar to
modern-day NW Europeans suggesting a physical evolution in cold
places. Fair-colouring is supposed to have originated as an
adaptation to cold climates right? -- little melanin = little brown
pigment = fair colouring. Yet, tall and slender physique is supposed
to be more adapted to hot climates. But they've lived in the
Eurasian steppes from c.7000-2000 BCE. Can the "fact" that they've
lived previously in the Middle East as a part of the hypothetical
Nostratic macrofamily support this. I need a scientific expalantion
to this. Can anyone help me?

P.S. again, ... forgive me for my "naive guesses" (if that's what
you want to call it). I'm just a 17 year old student, and I'm not
100% sure of the data I've been getting. I told you, I'm not an
expert, just a student who is really interested in this stuff.

Stay Cool dudes!!! :-)
Phil