I lost a great deal of hair long before I started paleo. I'll let you know if any of it comes back. :)

perhaps if you can find a way to inhibit the Prostaglandin D2 (PGD2) GPR44 receptor in the scalp through diet, you'll be on to something?

http://southernresearchco.com/pgd2-inhibitors/

"We show that prostaglandin D(2) synthase (PTGDS) is elevated at the mRNA and protein levels in bald scalp compared to haired scalp of men with AGA.
The product of PTGDS enzyme activity, prostaglandin D(2) (PGD(2)), is similarly elevated in bald scalp.
During normal follicle cycling in mice, Ptgds and PGD(2) levels increase immediately preceding the regression phase, suggesting an inhibitory effect on hair growth.
We show that PGD(2) inhibits hair growth in explanted human hair follicles and when applied topically to mice.
Hair growth inhibition requires the PGD(2) receptor G protein (heterotrimeric guanine nucleotide)-coupled receptor 44 (GPR44), but not the PGD(2) receptor 1 (PTGDR).
(Garza et al, 2012)"

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3319975/ "Prostaglandin D2 Inhibits Hair Growth and Is Elevated in Bald Scalp of Men with Androgenetic Alopecia" March 2012

If you click on the link below, you'll be able to download a free article by Loren Cordain and the Drs Eades on the connections between the SAD and many disparate conditions -- including male pattern baldness. The section on baldness is pretty darn short compared to the whole rest of the article, but if you're truly interested in the issue, the whole thing is definitely worth a read. Great info. (Covers PCOS, cancer, acne, myopia, male baldness, and others.)

Hyperinsulinemic diseases of civilization: more than just Syndrome X

One of the big things leading to hair loss is stress. Part of the Paleo lifestyle is reducing stress, whether through exercise, proper sleep or diet. The diet part is eliminating foods that cause inflammation, thereby reducing physical stress. Another part of it is restoring proper hormone levels, which is another reason we lose hair. In my case genetics plays a very large role, so I am doomed. My hair loss did slow, but has not stopped.

A lot of this is related to DHT vs testosterone - if you don't have enough testosterone receptors in your muscles, the free testosterone gets turned into DHT, which certain hair follicles are susceptible to.

Using polysorbate-80 as a shampoo can help remove the excess DHT and prevent further hair loss... (You'd wet your hair, then rub a small bit of polysorbate-80 in your scalp for about 3-4 minutes, then rinse it out.)

Or you could pack on more muscle.

Adding some zinc can help prevent the conversion too.